Method for completing drawing of certain theme and saving works by two persons

Abstract

The invention discloses a method for completing drawing of a certain theme and saving works by two persons. The method comprises the following steps of: setting a boundary and a size according to a theme, and initializing a first user exclusive drawing area and a second user exclusive drawing area; a first user draws in the exclusive area through a graph drawing assembly, real-time coordinate data is stored as a structured object according to a time sequence, and after completion, a first picture is generated through screen capture and uploaded to a far-end server to be encrypted and stored. And after confirming that the storage is successful, the server synchronizes the drawing completion state of the first user to the second user through a network communication protocol containing an error detection and retransmission mechanism. And after the second user receives the state, obtaining the first picture from the server, performing zooming, translation, rotation and resolution adaptation processing, performing supplementary drawing on the adapted picture, and after completion, performing screen capture to generate a second picture and uploading the second picture to the server. And after both the two pictures finish drawing, carrying out layer fusion and overall adaptation processing on the two pictures, and finally generating a collaborative work.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a method for two people to complete a drawing on a specific theme and save the artwork. Background Technology

[0002] Cocos Creator's Graphics component is a wrapper around the Canvas 2D real-time drawing API, providing a set of path-based drawing instructions. Developers can dynamically call its stroke and fill methods at runtime via scripts, submitting instructions frame-by-frame on the canvas in a CPU-driven manner to generate vector graphics such as points, lines, surfaces, and curves in real time. This mechanism is inherently procedural and dynamic, providing core technical support for implementing functions requiring real-time interaction, such as free drawing and signatures.

[0003] Camera screenshot technology relies on the engine's rendering texture functionality. Rendering textures, as off-screen frame buffers, capture complete image data output by the GPU rendering pipeline by directing the camera's rendering target onto them. When a screenshot is needed, pixel data is asynchronously read from this texture via scripts and converted into Image objects for saving as standard image files (such as PNG / JPG) or dynamically created Sprite nodes for display. This technology can capture high-fidelity scene snapshots containing all visual elements and is primarily used for high-quality static image archiving.

[0004] For example, the invention patent with publication number CN120953400A discloses an image drawing method, apparatus, device, and storage medium, including: acquiring multiple original images uploaded by a user; converting the original images into images to be displayed on a canvas, the size of the images to be displayed being equal to the size of the original images to be displayed in the viewport, the viewport including the area of ​​the canvas to be displayed on the screen; creating a texture atlas, the texture atlas being used to store the texture of each image to be displayed in the viewport, the size of the texture atlas being determined according to the size of each image to be displayed in the viewport and the position coordinates of the images to be displayed; drawing the images to be displayed onto the texture atlas; and drawing the texture atlas onto the canvas area in the viewport.

[0005] For example, the invention patent announcement CN113658293B discloses an image drawing method, apparatus, electronic device, and storage medium, which includes: obtaining a canvas generation request, the canvas generation request including a canvas size; generating a canvas of the specified size according to the canvas generation request; establishing a coordinate system with the upper left corner of the canvas as the origin, obtaining the object to be drawn and its drawing configuration information, the drawing configuration information including the coordinates of the object to be drawn, the coordinate values ​​of which include at least one of a first distance value for the object to be drawn moving downwards from the origin as the center of the reference system, a second distance value for moving to the right, a third distance value for moving to the left with the maximum value of the x-axis as the center of the reference system, and a fourth distance value for moving upwards with the maximum value of the y-axis as the center of the reference system; determining the drawing starting point of the object to be drawn according to the coordinate values ​​in the coordinate information; and drawing the object to be drawn at the drawing starting point in the canvas based on the drawing configuration information to obtain a drawn image.

[0006] However, in the process of implementing the inventive technical solution in the embodiments of this application, it was found that the above-mentioned technology has at least the following technical problems: In existing technologies, the lack of a dedicated state synchronization mechanism, full-stage content saving scheme, and game scene application adaptation processing for collaborative drawing leads to several problems. First, when two people are drawing around the same theme, the state of one person's completed drawing cannot be synchronized to the other person in a timely and reliable manner, making it impossible for the other person to accurately follow up and supplement the drawing, resulting in a collaboration gap. Second, the drawing content of each stage of the two people lacks a systematic saving logic, which easily leads to data loss and irrecoverability. Even if the drawing content is saved, there is no processing flow to adapt it to images that can be displayed in game scenes. As a result, the results of collaborative drawing cannot be applied in games, resulting in poor synchronization and continuity of two-person drawing, lack of secure content retention, and difficulty in applying the technology to game scenes. Summary of the Invention

[0007] This application provides a method for two people to complete a drawing on a specific theme and save the work. This solves the problems in the prior art where the results of two-person collaborative drawing cannot be applied in games, and there are issues such as poor synchronization and continuity of two-person drawing, lack of secure content retention, and difficulty in applying the work to game scenarios. It achieves a breakthrough from collaborative gaps to seamless connection, from easy data loss to reliable retention across the entire chain, and from difficulty in application implementation to precise adaptation to game scenarios, establishing a complete closed-loop two-person collaborative drawing technology system.

[0008] This application provides a method for two people to complete a drawing on a specific theme and save the artwork, including the following steps: One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: 1. By initializing a dedicated drawing area to support cross-device adaptation, real-time coordinate data storage and local persistence, screenshot processing and image adaptation, network communication protocols and error retransmission mechanisms, data encryption and access control, and version rollback functions, the continuity, collaboration, data reliability and security of the drawing process are ensured, thereby achieving efficient, safe and reliable two-person collaborative drawing and the generation and saving of high-quality works.

[0009] 2. By accurately acquiring the pixel reference parameters of the drawing area, configuring the camera viewport one by one, calibrating the projection parameters, and adjusting the world coordinates to the geometric center, the pixel-level alignment between the camera viewport and the drawing area is ensured, effectively avoiding edge clipping problems. This enables high-fidelity capture of the image where the drawing content and background resources are fully integrated, providing a precise and reliable image foundation for subsequent collaborative drawing and artwork generation.

[0010] 3. By establishing a reliable connection using the TCP protocol, the sequentiality and integrity of data transmission are ensured. The sliding window size is dynamically adjusted based on real-time network conditions to optimize bandwidth utilization. Combined with a dynamically calculated timeout retransmission mechanism and a retransmission process that includes priority marking, backoff strategies, and multiple safeguards, efficient and reliable state synchronization and data transmission can be achieved in various network environments. This ensures the real-time state synchronization and smooth collaboration process during the dual-person drawing process.

[0011] 4. By providing real-time progress synchronization and temporary marking functions to achieve seamless collaboration, combining local and end-to-end encryption to ensure data privacy, setting flexible drawing permission controls to clarify creative boundaries, and equipping a complete version backtracking system to record the creative process, a safe, controllable, and traceable collaborative environment is built. This significantly improves the efficiency and experience of two-person collaborative drawing while ensuring users' creative autonomy and data security. Attached Figure Description

[0012] Figure 1 A flowchart illustrating a method for two people to complete a drawing on a specific theme and save the artwork, as provided in an embodiment of this application. Detailed Implementation

[0013] This application provides a method for two people to complete a drawing on a specific theme and save the artwork. This solves the problems in the prior art where the results of collaborative drawing by two people cannot be applied in games, and there are issues such as poor synchronization and continuity in the drawing process, lack of secure content retention, and difficulty in applying the work to game scenarios. The overall approach is as follows: This invention constructs a collaborative creation system that integrates real-time collaborative drawing, precise image processing, reliable data synchronization, and secure access management. Through phased drawing and image fusion technology, it ensures the independence of the creative process and the integrity of the work. Relying on encrypted transmission, dynamic network optimization, and version backtracking mechanisms, it ensures data security, reliable transmission, and reversible operation, ultimately realizing cross-device, high-fidelity, and traceable two-person collaborative drawing and work generation.

[0014] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0015] like Figure 1 The diagram shown is a flowchart of a method for two people to complete a drawing on a specific theme and save the artwork, provided in an embodiment of this application. The method includes the following steps: Based on the theme content, drawing boundaries and sizes are set, and dedicated drawing areas for the first and second users are initialized. These drawing areas support cross-device adaptation. The first user performs drawing operations within their dedicated drawing area using a graphics drawing component. Real-time coordinate data generated during the drawing process is stored in a local array according to the drawing sequence, forming a structured drawing data object. After completing the drawing, the first user takes a screenshot of the first image and uploads it to a remote server for encrypted storage. Once the remote server confirms successful storage of the screenshot, it synchronizes the first user's drawing completion status with the second user via a network communication protocol. The synchronization process includes error detection and retransmission mechanisms. The second user receives the drawing completion status. The system first retrieves a screenshot from a remote server, processes it, and then performs image adaptation processing to ensure that the coordinate system and size parameters of the first image are perfectly matched with those of the area drawn by the second user. This image adaptation processing includes scaling, translation, rotation, and resolution adjustment of the first image. The second user then completes the drawing on the adapted first image, takes a screenshot, generates a second image, and uploads it to the remote server. Once both the first and second users have finished drawing, layer fusion and overall adaptation processing are performed on the first and second images to generate the final artwork. The final artwork is then synchronized to the designated display area of ​​the game application, and an option to save the artwork to a local album is provided, allowing users to choose a long-term display mode.

[0016] In this embodiment, the Graphics component based on Cocos Creator and camera screenshot technology bring significant advantages to collaborative theme creation for two people: the Graphics component ensures the real-time nature and strong interactivity of the creation process, allowing both parties to see each other's brushstrokes on the shared canvas in real time, perfectly synchronizing creative ideas and achieving true joint writing; while the camera screenshot technology ensures the integrity and high fidelity of the final work, capturing and saving the final image, including all dynamic effects and complex scenes, with one click, thus perfectly balancing the two core requirements of flexible interaction during collaborative drawing and accurate archiving after completion. The graphics drawing component is the graphic component of the Cocos Creator engine, and the drawing operations include line drawing, color filling, and erasing functions. The erasing function is implemented through two switchable modes: reverse drawing overlay or pixel transparency adjustment, and supports dynamic adjustment of the erasing range according to the brush thickness. This invention forms a synergistic overall technical effect through multi-dimensional technological innovation, significantly breaking through the limitations of existing single-person drawing technology: on the one hand, based on Cocos... The Creator engine's graphic component-based cross-device adapted drawing system, combined with structured coordinate data time-series storage and local persistence mechanisms, not only fulfills the core requirement of collaborative drawing between two people but also avoids loss of drawing progress through a data restoration function for mid-process exits, greatly improving collaboration flexibility and user experience. On the other hand, the precise camera parameter calibration and pixel-level alignment of the drawing area screenshot solution, along with image processing logic for scaling, panning, rotation, and resolution adaptation, effectively solves the problem of uneven drawing boundaries caused by angles and line widths, ensuring visual consistency of artwork display across different devices. Simultaneously, a dynamic timeout retransmission mechanism combining the TCP / IP protocol suite and sliding window protocol, coupled with HTTPS transmission and... The security system, featuring AES encryption and server-side asymmetric encryption storage, ensures high reliability for drawing state synchronization and data transmission while comprehensively protecting the privacy and security of user-created content. Furthermore, extended features such as drawing permission control, real-time collaborative annotation, work version tracking, local album saving, and designated area display on the game farm beach not only enrich collaborative interaction methods but also strengthen the connection between the game and the user. The final work generated through layer fusion can be flexibly applied in multiple scenarios, enhancing the game's fun and interactivity. Moreover, thanks to its lightweight state data transmission design, multi-device adaptability, and robust error handling mechanism, it broadens the technology's applicability, achieving a comprehensive improvement in collaboration smoothness, work quality, data security, and functional scalability.

[0017] Furthermore, if the first user exits the drawing process midway, the drawing data object is saved through local persistent storage. When the first user re-enters the drawing interface, the historical drawing trajectory and status are restored based on the locally stored data.

[0018] In this embodiment, the local persistent storage and historical drawing trajectory reverse restoration mechanism for the first user exiting the drawing scenario midway has multi-dimensional and significant technical effects, specifically reflected in four core aspects: user experience assurance, collaborative continuity maintenance, artwork integrity protection, and system robustness improvement. From the user experience perspective, it completely solves the pain point of losing all drawing progress when exiting midway in existing single-person drawing technology. Whether the user actively closes the drawing interface, there is an unexpected device failure (such as power outage or crash), or a temporary network interruption, the drawing data objects are firmly retained through local persistent storage (such as structured storage based on the device's local database or file system), avoiding the need for the user to start drawing from scratch when re-entering, greatly reducing user operation costs and time loss, and significantly increasing users' willingness to participate in two-person collaborative drawing. From the perspective of collaborative continuity maintenance, it provides key progress anchors for two-person collaborative drawing: when the first user re-enters the drawing interface, the system does not simply load a static image, but rather loads structured drawing data (including coordinate data recorded according to the drawing time sequence, brush parameters, color information, etc.) based on local storage. The system reverse-engineers the complete historical drawing trajectory and real-time status (such as brush thickness before exiting, current drawing layer, filled area, etc.) to ensure that the restored drawing content is completely consistent with that before exiting. This avoids content misalignment when the second user supplements the drawing due to the first user's progress being interrupted, ensuring the smooth progress of the two-person collaborative process. From the perspective of protecting the integrity of the work, the local storage and reverse restoration of structured data can accurately reproduce drawing details, such as the line direction, gradient color transition, and local eraser marks during the user's drawing process. These can all be accurately restored without image distortion or loss of details due to data storage or restoration deviations, providing a basic guarantee for the quality of the final collaborative work. From the perspective of system robustness, the entire drawing system has the fault tolerance capability to cope with sudden abnormal scenarios. It does not rely on remote servers to store intermediate drawing data in real time, reducing the dependence on network stability. Even in weak network or network outage environments, the user's drawing progress can still be effectively protected, greatly improving the reliability and stability of the system in complex usage scenarios. This lays a key technical foundation for the practical implementation and large-scale application of the two-person collaborative drawing function.

[0019] Furthermore, the screenshot processing precisely aligns the screenshot area with the drawing area by calibrating camera parameters, capturing a complete blended image of the drawn content and background resources as the corresponding image. Specifically: The process involves: obtaining the pixel reference parameters of the drawing area, including the starting pixel coordinates of the top-left corner and the ending pixel coordinates of the bottom-right corner in the game screen coordinate system, as well as the actual pixel width and height of the drawing area; configuring the camera's viewport parameters, matching the starting coordinates of the camera viewport with the starting pixel coordinates of the top-left corner of the drawing area, and setting the width and height of the camera viewport to match the actual pixel width and height, thus initially aligning the camera's viewport coverage with the pixel range of the drawing area; calibrating the camera's projection parameters, calculating the orthogonality of the camera based on the actual pixel height of the drawing area and the current device's screen pixel density; adjusting the camera's world coordinate position, setting the camera's position in the game world coordinate system to the world coordinates corresponding to the geometric center pixel coordinates of the drawing area, ensuring that each pixel within the drawing area is in the center of the camera's visible range, preventing edge pixels from being clipped due to viewport offset; and verifying the overlap accuracy using Cocos. The Creator engine's pixel reading interface collects pixel data from the edge of the camera viewport and determines whether it is completely consistent with the pixel coordinates of the corresponding edge of the drawing area. If not, the viewport parameters are readjusted until the overlap accuracy meets the preset threshold. If so, the screenshot processing is completed.

[0020] In this embodiment, the present invention addresses the scenario where the first user exits the drawing process midway. Through local persistent storage of drawing data objects and a reverse restoration mechanism of historical drawing trajectories and states, it achieves multiple key technical effects, significantly compensating for the robustness shortcomings and user experience deficiencies of existing drawing technologies in collaborative scenarios. From a user experience perspective, it completely solves the core pain point of losing all drawing progress when exiting midway in traditional drawing processes. Whether due to device crashes, unexpected power outages, temporary network interruptions, or the user actively closing the drawing interface, structured drawing data objects, including coordinate data recorded according to the drawing sequence, brush thickness parameters, color fill information, and erasure marks, are stably retained through local persistence (such as the device's local file system or a lightweight database). When the user re-enters the drawing interface, there is no need to repeat time-consuming drawing operations from scratch, greatly reducing the user's time cost and operational redundancy, effectively avoiding the frustration caused by lost progress, and significantly improving the user's willingness and persistence in participating in two-person collaborative drawing. From the perspective of collaborative continuity, this invention provides key progress anchors for two-person collaborative drawing: the reverse restoration based on locally stored data is not simply loading static images, but accurately reproducing historical drawing trajectories (such as the direction of lines and turning details) and real-time states (such as the brush working mode before exiting, the color transition levels of completed drawing areas, and the residual state of the image after partial erasure), ensuring that the restored drawing content is completely consistent with the state before the user exits midway, without problems such as image gaps or detail deviations; this means that when the second user loads the content drawn by the first user later, they can supplement their creation based on complete and accurate previous drawing results, completely avoiding the interruption of the two-person collaborative process or the misalignment of content connection caused by the first user's lost progress, ensuring the smoothness and continuity of the entire collaborative drawing process. From the perspective of artwork integrity, the precise storage and reverse restoration of structured drawing data can reproduce every minute detail of the drawing process. Whether it's the accuracy of fine line trajectories, the naturalness of gradient color transitions, or the smoothness of the edges after partial erasure, everything can be accurately restored. Data storage or restoration deviations will not lead to image distortion or loss of key creative details, laying a solid foundation for the final high-quality, highly complete artwork generated through collaborative work between two people. From the perspective of system robustness, this invention enables the drawing system to cope with unexpected abnormal scenarios: it eliminates the need to rely on remote servers for real-time storage of intermediate drawing data, reducing dependence on network stability. Even in complex environments such as weak or offline networks, the user's drawing progress can still be effectively protected. Simultaneously, the logic of local data storage and reverse restoration is independent of the cloud synchronization process, preventing cloud failures from affecting the local drawing scene. This significantly improves the system's reliability and resilience in diverse usage scenarios, providing key technical support for the practical application of collaborative drawing functions on different devices and in different network environments.

[0021] Furthermore, the network communication protocol adopts the TCP / IP protocol suite, and the error retransmission mechanism is implemented based on the sliding window protocol. Specifically, in the TCP / IP protocol suite, the transport layer uses the TCP protocol to transmit the drawing completion status data. Before state synchronization, a reliable connection is established between the first user terminal and the second user terminal, and between the terminal and the remote server through a TCP three-way handshake, ensuring the connection-oriented and sequential nature of data transmission. The status data includes the first user's drawing completion identifier, the storage address of the first image on the remote server, and a data checksum. The data length is controlled at 128 and 512 bytes to adapt to the lightweight state synchronization requirements. The initial size of the sliding window protocol's sending window is set to 2 and 4 data segments, respectively. The window size matches the sending window; the window size is dynamically adjusted based on the current network bandwidth and latency: if the round-trip time of data transmission does not exceed the preset round-trip time threshold and there is no packet loss, the sending window size increases by the first gradient, such as 50%; if the round-trip time of data transmission exceeds the preset round-trip time threshold or packet loss is detected, the sending window size decreases by the preset second gradient, such as halving, to balance transmission efficiency and reliability; if the sending end receives a data verification pass flag for the target state data returned by the receiving end within the timeout retransmission period, it is determined that the state synchronization is successful; if the sending end does not receive a data verification pass flag for the target state data returned by the receiving end within the timeout retransmission period, it is determined that the state synchronization has failed and a retransmission process is triggered.

[0022] In this embodiment, through layered design and dynamic adaptation logic, highly reliable, efficient, and adaptable technical support is provided for the state synchronization of dual-user theme drawing. The overall technical effect is reflected in four core dimensions: communication reliability assurance, transmission efficiency optimization, network environment adaptation, and continuity maintenance of the collaborative process. From the perspective of underlying communication reliability assurance, the transport layer adopts the TCP protocol and establishes connections between the first user terminal and the second user terminal, and between the terminal and the remote server through a three-way handshake. This completely avoids the risk of data loss and out-of-order transmission in connectionless transmission, ensuring that the drawing completion status data (including drawing completion identifier, image storage address, and data verification code) has connection-oriented stability and sequential transmission during transmission, laying a solid foundation for state synchronization from the source of the connection. From the perspective of transmission efficiency and lightweight adaptation, the length of the status data is strictly controlled to 128 and 512 bytes, which not only fully covers the core information necessary for collaboration but also minimizes the data's occupation of network bandwidth, avoiding transmission delays caused by excessive data volume. This precisely matches the lightweight synchronization needs of dual-user collaboration to quickly perceive the other party's drawing progress, allowing the second user to obtain the first user's completion status in a timely manner, significantly reducing collaboration waiting time. From the perspective of network environment... From a dynamic adaptation perspective, the dynamic adjustment logic based on the sliding window protocol achieves a balance between efficiency and reliability: the initial design of sending windows for 2 or 4 data segments and matching receiving windows ensures smooth data transmission during the initial network connection phase; when network conditions are good (round-trip time does not exceed the threshold and there is no packet loss), the window size is increased in 50% increments to fully utilize high-quality network resources, improve transmission rates, and accelerate state synchronization; when network fluctuations occur (round-trip time exceeds the limit or packet loss occurs), the window size is reduced by half in increments to alleviate network congestion by reducing the amount of data transmitted per transmission, avoid exacerbating packet loss, and make the mechanism flexible. It adapts to different scenarios such as stable WiFi and weak mobile networks. From the perspective of the continuity of the collaboration process, the judgment logic of timeout retransmission forms a closed loop to remedy transmission failure: if the sending end receives the verification pass flag within the timeout retransmission period, it confirms that the synchronization is successful and avoids invalid waiting; if it does not receive it, it triggers the retransmission process to prevent the loss of state data due to occasional network fluctuations. It ensures that the second user will not be unable to load the drawing content of the first user due to a single transmission failure, and completely avoids the problem of the first user completing the drawing but the second user not being aware of it, which leads to the interruption of collaboration. It provides key communication guarantee for the smooth progress of two-person collaborative drawing.

[0023] Furthermore, the timeout retransmission time is dynamically calculated based on the real-time measured round-trip delay. When an acknowledgment response is received from the receiver, the average round-trip delay is dynamically updated based on the newly measured round-trip delay sample and the old average round-trip delay. The initial value of the average round-trip delay is 200 milliseconds. The round-trip delay deviation is dynamically updated based on the old round-trip delay deviation, the newly measured round-trip delay, and the old average round-trip delay. Here, the timeout retransmission time = average round-trip delay + 4 × round-trip delay deviation; the new average round-trip delay = 0.875 × old average round-trip delay + 0.125 × newly measured round-trip delay; the new round-trip delay deviation = 0.75 × old round-trip delay deviation + 0.25 × |newly measured round-trip delay, old average round-trip delay|.

[0024] In this embodiment, through refined round-trip delay statistics and parameter iteration logic, a timeout determination basis that is both accurate and adaptable is provided for the state synchronization of dual-person theme drawing. Its technical effects can be described in detail from four dimensions: real-time adaptation, misjudgment avoidance, resource optimization, and collaboration guarantee. First, from the perspective of real-time adaptation, 200 milliseconds is used as the initial value of the average round-trip delay. This provides a reasonable timeout reference for the initial stage of network connection (avoiding blind waiting or false triggering when there is no initial data). Furthermore, through a weighted iteration formula, while preserving the stability of historical round-trip delay data (the high weight of 0.875 ensures that the average will not fluctuate significantly due to a single accidental fluctuation), the real-time changes of newly measured round-trip delay (0.875) are incorporated. A weight of 125 ensures rapid response to gradual changes in network conditions (such as the slow increase in round-trip latency when switching from stable WiFi to a weak mobile network), keeping the average value consistent with the actual transmission latency level of the current network. Secondly, from the perspective of avoiding false alarms, the calculation logic of the round-trip latency deviation accurately captures the fluctuation range of round-trip latency. When the network is stable (i.e., the round-trip latency fluctuation is small), the deviation value remains at a low level. However, when network jitter occurs (such as when the round-trip latency fluctuates due to 4G signal switching), the deviation value increases synchronously with the fluctuation range. Combined with the timeout retransmission time determination formula, the 4x deviation setting can statistically cover most normal round-trip latency fluctuations, accommodating occasional network latency peaks and effectively avoiding errors caused by round-trip latency fluctuations. The invention significantly reduces the false trigger rate of retransmissions by dynamically adjusting the timeout period to match the latency and fluctuation characteristics of the current network. Furthermore, from a resource optimization perspective, this invention avoids the problem of excessively short timeouts. If the timeout is fixed too short, even if data is still being transmitted normally, frequent false triggers of retransmissions will occur, causing network bandwidth to be occupied by duplicate data and exacerbating congestion. It also avoids the drawbacks of excessively long timeouts. If the timeout is fixed too long, when data is actually lost, a long wait is required before retransmission, causing the first user's drawing completion status to not be synchronized with the second user in a timely manner, delaying the collaboration progress. By dynamically adjusting the timeout period to match the current network latency and fluctuation characteristics, it minimizes the waste of network resources caused by invalid retransmissions, while ensuring that data is transmitted even when packet loss occurs. Timeliness of retransmission; Finally, from the perspective of ensuring two-person collaboration, precise timeout retransmission ensures that the first user's drawing completion status can be efficiently and reliably synchronized to the second user in complex network environments, such as home WiFi, outdoor mobile networks, and network signal switching scenarios. When the network is stable, the timeout is short, which can quickly confirm successful synchronization and allow the second user to load the first user's drawing image in time. When the network fluctuates, the timeout is reasonably extended as the deviation increases to avoid erroneous retransmissions. At the same time, it can trigger retransmission in time when there is actual packet loss, preventing the collaboration process from being interrupted due to status synchronization delays. Ultimately, it provides key time judgment support for the smooth progress of two-person collaborative drawing, significantly improving the stability of collaboration and user experience in cross-network scenarios.

[0025] Specifically, the retransmission process is as follows: During the first retransmission, the retransmitted data segment is marked as high-priority data and prioritizes the use of transmission bandwidth; after each retransmission, the timeout retransmission time is multiplied by a preset backoff coefficient, and the timeout retransmission timer is dynamically updated. The backoff coefficient is a variable that is dynamically adjusted according to the real-time network conditions, and its value ranges from 1.5 to 2.0. When the network packet loss rate or latency is detected to be higher than the preset threshold, a larger backoff coefficient is used, and vice versa; the cumulative number of retransmissions is counted in real time and compared with the preset maximum retransmission threshold; when the cumulative number of retransmissions reaches the maximum retransmission threshold and synchronization is still not successful, the sending end reports a status synchronization timeout to the local user, asks to check the network connection visualization prompt, and records the failure log. The remote server intervenes and pushes a notification to the second user terminal that the other party's drawing is complete and awaits confirmation, and suggests refreshing the page. At the same time, it triggers the server-side cached status data to be retried and pushed. If it still fails, the data status is marked as awaiting manual confirmation and the data is retained.

[0026] In this embodiment, through a layered and progressive refined design, the reliability of the synchronized drawing state of two users is guaranteed across all scenarios. Simultaneously, it achieves a synergistic improvement in network resource optimization and user experience. The overall technical effect is reflected in four dimensions: enhanced retransmission efficiency, network congestion avoidance, prevention of collaborative interruptions, and data security safeguards. From the perspective of prioritizing the first transmission, data segments are marked as high priority during the first retransmission. This ensures that core drawing completion status data, such as the first user's drawing result identifier and image storage address, are given priority in occupying transmission resources, even in scenarios with limited network bandwidth or multiple data transmission competition. This avoids bandwidth being squeezed out by low-priority data, leading to retransmission delays and significantly improving efficiency. This system improves the initial transmission success rate of critical information in complex network environments, reducing collaboration bottlenecks caused by resource contention. From a dynamic backoff adaptation perspective, it adjusts backoff coefficients in the range of 1.5 and 2.0 based on real-time network conditions (packet loss rate, latency), and updates timeout retransmission times through product processing. This creates an adaptive logic that becomes more cautious in poor network conditions and more efficient in good network conditions. When the network packet loss rate or latency exceeds a preset threshold, a larger backoff coefficient (1.8, 2.0, etc.) is used to extend the retransmission interval, preventing further network congestion caused by frequent retransmissions. When network conditions are good, a smaller backoff coefficient (1.5, 1.7, etc.) is used to shorten the retransmission interval, ensuring that lost data can be quickly retransmitted. This approach prevents network resource waste due to excessively short retransmission intervals while avoiding delays in collaboration due to excessively long intervals, achieving a dynamic balance between retransmission efficiency and network load. Regarding retransmission count control, real-time accumulation of retransmission counts and comparison with the maximum threshold effectively prevents long-term bandwidth occupation caused by unlimited retransmissions. Furthermore, when failure occurs after reaching the threshold, a multi-end feedback mechanism is triggered. This involves the sending end pushing a visual prompt to the local user indicating a synchronization timeout and requesting a network connection check, allowing the user to promptly identify the root cause of the problem and proactively troubleshoot (e.g., switching networks), and the remote server pushing a notification to the second user indicating that the drawing is complete and awaiting confirmation, suggesting a page refresh, to prevent the second user from being negatively impacted by information asymmetry. The system addresses the frustration of waiting for no response by combining technical safeguards with user guidance, minimizing the risk of disruption to the collaboration process. From a data security perspective, server intervention triggers a retry of pushing cached state data, and upon failure, the data is marked as awaiting manual confirmation and retained. This completely avoids the problem of permanent loss of drawing state data due to retransmission failures, ensuring that even in extreme network failure scenarios, critical drawing information for two-person collaboration can still be completely preserved. This provides a data foundation for subsequent manual intervention to restore collaboration (such as technical support assisting in data synchronization), significantly improving the resilience of two-person drawing state synchronization and building a solid technical defense for the smooth progress of cross-network and cross-device collaboration.

[0027] Furthermore, when the second user receives the first image after the screenshot has been processed, the first user can view the second user's drawing progress through a real-time synchronization interface. Both parties can add temporary collaborative annotations to the drawing area through the marking function. The annotation content is not included in the final work generation.

[0028] In this embodiment, the present invention, through the bidirectional empowerment of real-time progress synchronization and temporary collaborative annotation, constructs an interactive system for collaborative drawing between two people, enabling information transparency and precise communication. Its technical effects deeply align with the core needs of two-person collaboration, specifically manifested in four key aspects: improved collaboration fluency, optimized communication efficiency, guaranteed work quality, and enhanced user experience. From the perspective of collaboration fluency, the first user can view the drawing progress of the second user after receiving the first image through a real-time synchronization interface, completely breaking down the information gaps in traditional two-person collaboration. The first user can clearly know whether the second user has started supplementing the drawing and the current drawing area without repeatedly asking or passively waiting. The system monitors the scope and progress of the drawing process (e.g., whether core elements have been completed or whether the process has entered the detail adjustment stage), avoiding blind waiting or repetitive communication due to information asymmetry. This allows for a virtuous cycle of visible progress and controllable pace in collaborative work, significantly improving efficiency. From a communication efficiency perspective, the system supports adding temporary collaborative annotations to the drawing area, providing a visually precise solution for collaborative communication. When both parties need to offer suggestions on the drawing content, such as thickening lines, adding elements matching the theme on the right, or confirming details like whether to retain a color transition effect, there's no need to rely on purely textual descriptions detached from the image, which can easily lead to misunderstandings due to vague wording. To address any issues, annotations (such as arrows or text labels) can be directly added to the corresponding areas of the drawing area. This allows for intuitive communication by clearly indicating where adjustments are needed, significantly reducing communication costs and the probability of misunderstandings. It ensures that both parties have a consistent understanding of the drawing direction and detail requirements. From a quality assurance perspective, excluding annotations from the final artwork is a key optimization. This setting fully leverages the communicative value of annotations during collaboration while technically preventing temporary communication markers from affecting the visual integrity and neatness of the final artwork. It avoids interference with the artwork's theme or visual redundancy due to residual annotations, thus guaranteeing the quality and presentation of the final collaborative work. No need for either party to spend extra time cleaning up annotations after drawing; from the perspective of enhanced user experience, real-time progress viewing extends the sense of participation for the first user (even after completing their own drawing, they can continue to follow the collaborative process, enhancing their sense of control over the overall work), while the temporary annotation function makes the collaboration between the two parties more interactive and tacit, getting rid of the mechanical nature of drawing with a single division of labor, giving the collaboration more flexible communication space, further enhancing the fun and user stickiness of two-person drawing, making the collaborative process not only the task of completing the work, but also an interactive experience, ultimately providing dual technical support for the smoothness, accuracy and user experience of two-person theme drawing collaboration.

[0029] Furthermore, the method for two people to complete a drawing on a certain theme and save the work also includes a drawing data encryption function: the drawing data object is encrypted in real time using the AES encryption algorithm when stored locally, and is transmitted via the HTTPS protocol during the upload to the remote server. The server uses an asymmetric encryption method to store the data key, ensuring the privacy and security of the user's drawing content.

[0030] In this embodiment, the present invention constructs a multi-layered, comprehensive privacy protection system for the core data of dual-person theme drawing through a full-link security design that includes local storage encryption, transmission process encryption, and server key encryption. Its technical effectiveness deeply covers key nodes in the data lifecycle, specifically reflected in four core dimensions: privacy and security assurance, enhanced user trust, technical compliance, and a balanced collaborative experience. From the perspective of local storage security, the drawing data object is processed in real-time using the AES encryption algorithm when persisted locally. AES, as an internationally recognized high-strength symmetric encryption standard, can irreversibly encrypt and protect structured drawing coordinate data, pen parameters, progress information, etc., even if... Even if a user's device is lost, illegally accessed, or locally stored files are stolen, a third party without the decryption key cannot crack the data content. This completely avoids the risk of privacy leaks caused by raw local data storage, such as unfinished sketches or personalized creative details being viewed illegally, thus building a solid first line of defense for data security. From a transmission security perspective, data is transmitted to the remote server using the HTTPS protocol. HTTPS encrypts and authenticates the transmitted data through the SSL / TLS protocol layer, preventing data from being intercepted, tampered with, or eavesdropped on by hackers during transmission. This ensures that core content such as the first user's screenshots and the second user's supplementary drawing data remains secure on both the terminal and the server. The system ensures complete and secure transmission across the network, while also preventing data leaks caused by users connecting to fake servers through server authentication, thus resolving security risks in cross-network transmission scenarios. From the perspective of server-side key security management, the server uses asymmetric encryption to store data keys. Asymmetric encryption separates the data keys from the actual drawing data through a public-key encryption and private-key decryption mechanism. Even if the server is attacked, the attacker only obtains the encrypted drawing data and cannot obtain the corresponding private key, thus preventing decryption. This also avoids the risk of total data loss due to a single key leak, as is present in symmetric encryption, providing a higher level of security for server-side data storage. From the perspective of user collaboration... From the perspective of balancing verification and trust, the end-to-end encryption design ensures privacy and security without increasing users' additional operational costs: the encryption and decryption processes are completed automatically in the background, allowing both users to confidently engage in collaborative creation without worrying about the leakage or misuse of personalized drawing content. At the same time, the security guarantee enhances users' trust in the collaborative system. Especially for drawing content containing personal creativity and personalized expression, the privacy and security guarantee can significantly increase users' willingness to participate in two-person collaboration. It also complies with data security compliance requirements, such as relevant personal information protection regulations. Ultimately, it achieves a synergy between security protection and collaborative experience, providing key technical support for the privacy and security and healthy collaborative ecosystem of two-person themed drawing.

[0031] Furthermore, the method for two people to complete a drawing on a certain theme and save the work also includes a drawing permission control function: after the first user completes the drawing, the drawing area can be locked to restrict the second user's permission to modify the drawing content, and only allow supplementary drawing in the specified extension area. The locked state can be lifted through negotiation between the two parties.

[0032] In this embodiment, a three-tiered design—protection of creative rights, clear collaboration boundaries, and a flexible negotiation mechanism—builds a controllable and orderly interactive framework for collaborative two-person theme drawing. Its technical effectiveness deeply aligns with the core need for balancing personalized creation and collaborative supplementation in two-person collaboration, specifically reflected in four key dimensions: ensuring creative integrity, improving collaboration efficiency, enhancing interactive flexibility, and maintaining stable work quality. From the perspective of protecting creative rights, the first user can set a locked drawing area after completing their drawing, technically preventing the second user from accidentally manipulating (such as accidentally erasing key lines or modifying core colors) or maliciously altering the content. This is especially beneficial for the first user's carefully designed... The locking mechanism preserves the core elements of the theme (such as the main structure and distinctive patterns in a bottle opener theme) and retains the creator's intent and details, preventing the destruction of previous creative work due to uncontrolled permissions and effectively protecting the creator's work and creative autonomy. From a clear perspective of collaboration boundaries, the restriction that only supplementary drawing is allowed in designated extended areas defines a clear division of creative tasks for two-person collaboration. The first user's locked area is the basic creation area, and the second user's designated extended area is the supplementary creation area. Both parties do not need to repeatedly communicate the operable scope, allowing the second user to directly focus on creating in the extended area (such as adding decorative elements or background scenes next to the bottle opener), thus avoiding the need for repeated communication regarding the operable scope. The design avoids the confusion caused by ambiguous scope (such as a second user accidentally overlaying content in the main area, resulting in visual redundancy), but it also ensures an orderly connection between the core and supplementary elements in dual-user creation, guaranteeing consistency between the collaborative direction and the theme. From the perspective of enhanced interactive flexibility, the design of unlocking the locked state through mutual agreement breaks the rigid limitation of one-way locking, allowing for dynamic adaptation in collaboration. If the first user later finds that their drawing needs fine-tuning, or the second user believes that key details need to be added to the locked area to perfect the theme, both parties can negotiate to unlock the area. This avoids creative limitations caused by overly rigid locking (such as incomplete theme expression) and reflects the equality and communication of collaboration, making access control more flexible. The system transforms from a mechanical constraint into a flexible tool that serves collaborative needs. In terms of maintaining consistent work quality, this feature reduces ineffective communication and operational conflicts during collaboration through permission control (such as eliminating arguments about whether certain content can be modified or where to add it), allowing both parties to focus more on the creation itself. At the same time, the design of locking the core area and guiding the supplementary area ensures that the core style and details of the work are established by the first user, and the supplementary content of the second user revolves around the core, avoiding the disjointed style of the picture due to the difference in creative direction between the two parties. Ultimately, it achieves a collaborative effect of personalized creation without conflict and more efficient collaborative supplementation, significantly improving the interactive experience of dual-person drawing and the integrity and consistency of the final work.

[0033] Furthermore, the method for two people to complete a drawing on a certain theme and save the work also includes a work version rollback function: the remote server stores the first image, the second image and the complete version of the final work. Users can trigger the version rollback operation to restore the work state at any drawing stage. The rollback process supports comparing and viewing the drawing differences between different versions.

[0034] In this embodiment, the present invention provides multi-dimensional support for collaborative theme drawing by two people through its technical design of full-stage data retention, flexible state recovery, and visual difference comparison. This support includes fault tolerance, collaborative review, and creative optimization. Its technical effects deeply align with the core needs of two-person collaboration: process controllability, traceable modifications, and superior results. Specifically, this is reflected in four key aspects: improved collaborative fault tolerance, optimized communication efficiency, guaranteed creative quality, and enhanced user experience. From the perspective of collaborative fault tolerance, the remote server completely stores the first image drawn by the first user, the second image drawn by the second user, and the full version data of the final merged work. This completely solves the pain point of irreversible modification errors in traditional collaborations, even if the second user accidentally damages the first image during supplementary drawing. The core element of the project remains the ability for both parties to adjust the direction of their work if they are dissatisfied with the final style. This can be achieved by triggering a version rollback, precisely restoring the project to any drawing stage. For example, it can preserve only the initial state of the first image or revert to a semi-finished state where the second user was drawing, eliminating the need to start from scratch. This significantly reduces the cost of errors in collaboration and provides a safe space for trial and error in collaborative creation. From a communication efficiency perspective, the rollback process allows for comparison of drawing differences between different versions, making the modification trajectory of the collaboration completely transparent. For instance, the first user can clearly see the additional drawing content and color adjustments made by the second user based on the first image. The second user can also compare the final work with their own second image after layer merging, avoiding the need for further adjustments. To address communication ambiguity caused by unclear details of the other party's modifications (e.g., an invalid inquiry about which part you just changed), both parties can directly discuss and adjust solutions based on a comparison of differences, significantly improving the focus and efficiency of collaborative communication. From a quality assurance perspective, the version rollback function provides the possibility of comparing multiple solutions for work optimization. When there are disagreements on the drawing direction, such as disputes over the style of background elements added by a second user, different versions can be reviewed for a direct comparison to determine which solution better fits the theme requirements. This avoids deviations in work style due to the inability to go back and revisit previous versions. Furthermore, by reviewing each stage of the version, creative ideas can be clarified, and details can be optimized. For example, if smoother lines are found in a certain stage, adjustments can be made based on that after going back, thus contributing to the final product. Higher quality collaborative works; from the perspective of enhanced user experience, full-version data retention and flexible retrospection give users a sense of control over the creative process. The first user can review the creative progress of the second user, and the second user can also trace the original design logic of the first image. This process-visible experience not only enhances the interactivity of two-person collaboration, but also meets the user's need to record the creative process. For example, if they want to show the complete collaborative creation process later, the complete storage on the server side also avoids the problem of version unrecoverable due to local data loss, further strengthening the user's trust in the collaborative system. Ultimately, it forms a collaborative closed loop where mistakes can be recovered, processes are traceable, and solutions can be compared, laying a solid technical foundation for the smooth progress of two-person theme drawing and the output of high-quality results.

[0035] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CDs, ROMs, optical storage, etc.) containing computer-usable program code.

[0036] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0037] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0038] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0039] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0040] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for two people to complete a drawing on a specific theme and save the artwork, characterized in that, Includes the following steps: Based on the theme content, the drawing boundaries and size are set, and the exclusive drawing areas for the first user and the second user are initialized. The drawing areas support cross-device adaptation. The first user performs drawing operations within their designated drawing area using the graphics drawing component. The real-time coordinate data generated during the drawing process is stored in a local array according to the drawing sequence, forming a structured drawing data object. After the first user completes the drawing, the first image is taken as a screenshot and then uploaded to a remote server for encrypted storage. After the remote server confirms that the screenshot processing and the first image are successfully stored, it synchronizes the drawing completion status of the first user to the second user through the network communication protocol. The synchronization process includes error detection and retransmission mechanisms. The second user receives the drawing completion status, obtains the first image after screenshot processing from the remote server, and performs image adaptation processing, which includes scaling, translation, rotation, and resolution adaptation adjustment of the first image. The second user supplements the drawing of the first image after image adaptation processing, and then performs screenshot processing to generate the second image and uploads it to the remote server. Once both the first and second users have finished drawing, layer blending and overall adaptation are performed on the first and second images to generate the final artwork.

2. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, If the first user exits the drawing process midway, the drawing data object is saved through local persistent storage. When the first user re-enters the drawing interface, the historical drawing trajectory and status are restored based on the locally stored data.

3. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, The screenshot processing precisely aligns the screenshot area with the drawing area by calibrating camera parameters, and captures a complete fused image of the drawn content and background resources as the corresponding image. Specifically: Obtain the pixel reference parameters of the drawing area, which include the starting pixel coordinates of the upper left corner and the ending pixel coordinates of the lower right corner of the drawing area in the game screen coordinate system, the actual pixel width of the drawing area and the actual pixel height of the drawing area; Configure the camera's viewport parameters, making the starting coordinates of the camera viewport correspond one-to-one with the starting pixel coordinates of the upper left corner of the drawing area, and setting the width and height of the camera viewport to correspond to the actual pixel width and actual pixel height, respectively. The camera's projection parameters are calibrated, and the orthogonality of the camera is calculated based on the actual pixel height of the drawing area and the current screen pixel density of the device. Adjust the world coordinate position of the camera, set the position of the camera in the game world coordinate system to the world coordinates corresponding to the geometric center pixel coordinates of the drawing area, so that each pixel in the drawing area is in the center of the camera's visible range, and avoids edge pixels being clipped due to viewport offset. Collect pixel data from the edge of the camera viewport and determine whether it is completely consistent with the pixel coordinates of the corresponding edge of the drawing area; Otherwise, readjust the viewport parameters until the overlap accuracy meets the preset threshold. If so, the screenshot process is complete.

4. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, The network communication protocol adopts the TCP / IP protocol suite, and the error retransmission mechanism is implemented based on the sliding window protocol, specifically including: In the TCP / IP protocol suite, the transport layer uses the TCP protocol to transmit the drawing completion status data. Before state synchronization, a reliable connection is established between the first user terminal and the second user terminal, and between the terminal and the remote server through a TCP three-way handshake, to ensure the connection-oriented and sequential nature of data transmission. The status data includes the first user's drawing completion identifier, the storage address of the first image on the remote server, and the data checksum. The window size is dynamically adjusted based on the current network bandwidth and latency: if the round-trip time of data transmission does not exceed the preset round-trip time threshold and there is no packet loss, the sending window size increases according to the preset first gradient. If the round-trip time of data transmission exceeds the preset round-trip time threshold or packet loss is detected, the sending window size is reduced according to the preset second gradient. When the sending end receives a data verification pass flag for the target state data returned by the receiving end within the timeout retransmission period, it is determined that the state synchronization is successful. If the sending end does not receive a data verification pass flag for the target status data from the receiving end within the timeout retransmission period, it is determined that the status synchronization has failed and the retransmission process is triggered.

5. The method for two people to complete a drawing on a certain theme and save the work as described in claim 4, characterized in that, The timeout retransmission time is dynamically calculated based on the real-time measured round-trip delay. When an acknowledgment response is received from the receiving end, the round-trip delay average is dynamically updated based on the newly measured round-trip delay sample and the old round-trip delay average; the round-trip delay deviation is dynamically updated based on the old round-trip delay deviation, the newly measured round-trip delay, and the old round-trip delay average.

6. The method for two people to complete a drawing on a certain theme and save the work as described in claim 4, characterized in that, The retransmission process is as follows: During the first retransmission, the retransmitted data segment is marked as high-priority data and will occupy the transmission bandwidth first. After each retransmission, the timeout retransmission time is processed using a preset backoff coefficient, and the timeout retransmission timer is dynamically updated. The cumulative number of retransmissions is counted in real time and compared with the preset maximum retransmission threshold. When the cumulative number of retransmissions reaches the maximum retransmission threshold and synchronization is still unsuccessful, the sending end provides a visual prompt to the local user and records a failure log. At the same time, it triggers a retry to push the cached status data on the server side. If it still fails, the data status is marked as pending manual confirmation and the data is retained.

7. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, When the second user receives the first image after the screenshot processing, the first user can view the second user's drawing progress through the real-time synchronization interface. Both parties can add temporary collaborative annotations in the drawing area through the marking function. The annotation content is not included in the final work generation.

8. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, It also includes a drawing data encryption function: the drawing data object is encrypted in real time using the AES encryption algorithm when stored locally, and is transmitted via the HTTPS protocol during the upload to the remote server. The server uses an asymmetric encryption method to store the data key, ensuring the privacy and security of the user's drawing content.

9. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, It also includes drawing permission control function: after the first user completes the drawing, the drawing area can be locked to restrict the second user's permission to modify the drawing content, and only allow supplementary drawing in the specified extension area. The locked state can be lifted through negotiation between the two parties.

10. The method for two people to complete a drawing on a certain theme and save the work as described in claim 1, characterized in that, The system also includes a version rollback function: the remote server stores the first image, the second image, and the complete version of the final work. Users can trigger the version rollback operation to restore the state of the work at any drawing stage. The rollback process supports comparing and viewing the drawing differences between different versions.

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