A method for dynamic loading display of electronic chart

Abstract

With the scale of electronic chart display system is larger and larger, function is stronger and stronger, safety and reliability are paid more and more attention. Therefore, it is of great significance to realize the rapid switching of the chart in the process of navigation. The invention is a method for dynamic loading display of electronic chart. The information of loading chart and the latitude and longitude range and scale information of chart interface after obtaining mouse event are analyzed respectively, and a method for effectively screening corresponding chart information and homonymic chart under the latitude and longitude range and scale range of current chart display interface is proposed. The latitude and longitude range and scale of the screen display interface are obtained by analyzing the code, the corresponding chart information is obtained, and the flowchart of dynamic loading of electronic chart is obtained. The method is verified by the experimental platform and the effect is shown. The invention can be widely used in the dynamic loading display of electronic chart in engineering.

Description

TECHNICAL FIELD

[0001] The application belongs to the application of electronic chart dynamic loading and display, mainly dynamically displaying different chart interfaces in different latitude and longitude sea areas, that is, displaying corresponding charts according to the current view latitude and longitude range changed by mouse zooming or dragging, achieving the effect of fast dynamic display of charts, improving the simplicity of chart interface operation and the dynamic readability of charts. BACKGROUND

[0002] The electronic chart is a digital chart mainly describing geographical information and navigation information of a sea area in a digital form. The electronic chart is highly valued because it has incomparable advantages over the traditional paper chart. The electronic chart system can automatically design a route, monitor a heading and track, automatically store a ship's track, re-demonstrate a historical voyage, automatically alarm during navigation, quickly query various information, dynamically display a ship in real time, and automatically correct thousands of charts in a few minutes. The sea environment is very complex and is accompanied by many uncertain factors. The current electronic chart loading technology needs to be manually operated by a navigation personnel. When entering a sea area, the chart of the sea area is displayed by manually loading the chart. Therefore, the navigation personnel cannot change the chart in a short time, which affects the quick and clear judgment of the situation around the ship. Therefore, searching for charts of different sea areas through mouse events is an effective means to quickly display charts. It can greatly improve the work efficiency of the navigation personnel, greatly improve the safety of all personnel and goods during marine navigation, and make the chart display interface more simple and beautiful and improve the operation experience.

[0003] The mouse event is an event entered by operating a mouse button and a scroll wheel. Running corresponding code can realize the functions corresponding to different operations. Therefore, the dynamic storage of electronic chart related information in different latitude and longitude ranges is realized by perfecting and implementing mouse dragging and scroll wheel events, so as to display corresponding charts. SUMMARY

[0004] In view of the deficiencies in the prior art, the application aims to provide an electronic chart dynamic display method in different latitude and longitude ranges through mouse events, so that only the corresponding information is stored when the chart is loaded for the first time, and the chart can be quickly displayed on the chart interface by mouse operation in subsequent use, without reloading the chart every time. To solve the above technical problems, the application adopts the following technical scheme:

[0005] A method for dynamically loading and displaying an electronic chart, comprising the following steps:

[0006] (1) By loading the chart menu item selection needs to display the chart file and parsing, get the selected chart file information, including the chart name, scale, latitude and longitude range, etc., and storage;

[0007] Chart file contains the information of each part of the chart, which can be defined, classified and drawn according to the information. Store these information to facilitate quick judgment when the interface display condition changes.

[0008] (2) Get the latitude and longitude range and scale of the chart display interface when the mouse is dragged or the mouse wheel is scrolled;

[0009] When the mouse event occurs, the latitude and longitude range and scale of the current display interface need to be recalculated.

[0010] When the mouse drag event occurs, the drag distance is calculated according to the mouse movement distance:

[0011] disX = (eUp.X-eDown.X)*LongLatX / screenX

[0012] disY = (eUp.Y-eDown.Y)*LongLatY / screenY

[0013] Where eUp is the screen coordinates when the mouse drag is completed and the key is lifted, eDown is the screen coordinates when the mouse drag starts and the key is pressed, LongLatX and longLatY are the longitude and latitude range before dragging, screenX and screenY are the screen pixel range, the geographical distance is obtained according to linear conversion, that is, the longitude distance disX and disY, then the longitude and latitude coordinates of the screen four corners are calculated according to the mouse drag distance and the drag direction. The interface scale will not change when the mouse is dragged.

[0014] When the mouse wheel sliding event occurs, the longitude and latitude coordinates of the screen four corners are calculated according to the wheel sliding:

[0015] dis1X = (UpLeft.X-e.X)*n

[0016] dis1Y = (UpLeft.Y-e.Y)*n

[0017] dis2X = (DownRight.X-e.X)*n

[0018] dis2Y = (DownRight.Y-e.Y)*n

[0019] Wherein, e is the latitude and longitude coordinates of the mouse wheel stop point, UpLeft is the latitude and longitude coordinates of the upper left corner of the screen before the wheel slides, DownRight is the latitude and longitude coordinates of the lower right corner of the screen before the wheel slides, dis1 is the latitude and longitude distance from the stop point to the upper left corner of the screen, dis2 is the latitude and longitude distance from the stop point to the lower right corner of the screen, and the distance is enlarged or reduced by a certain zoom factor n factor every time the wheel slides. Then, the latitude and longitude coordinates of the upper left corner or the lower right corner of the screen after the wheel slides are calculated according to the latitude and longitude of the stop point and the latitude and longitude distance from the upper left corner or the lower right corner of the screen, so that the latitude and longitude range of the interface is obtained. The scale of the interface is also proportional to the zoom factor n.

[0020] (3) Obtain the corresponding chart information that meets the latitude and longitude and scale range of the chart display interface, and filter out the chart file information that best meets the current display interface;

[0021] All chart file information is traversed to determine whether its latitude and longitude and scale range are within the interface display range. If so, mark this information as displayable chart information. When multiple charts meet the range, filter out the chart information that best meets the conditions and mark it as displayable, and mark the rest as non-displayable.

[0022] (4) Obtain the same-named electronic chart corresponding to the chart information within the display range and display it on the chart interface, and update the menu bar information;

[0023] All electronic charts are traversed. If there is an electronic chart with the same name as the marked displayable chart name, the electronic chart is displayed and drawn, and the chart information displayed on the current interface is updated in the menu bar.

[0024] (5) The timer refreshes to obtain dynamic information and redraws the chart.

[0025] The advantages and positive effects of the present application are:

[0026] (1) The present application highlights the advantages of quickly replacing electronic charts and performing dynamic reading. It does not rely on complete prior knowledge and fully utilizes language programming and running effect analysis.

[0027] (2) The proposed method can solve the safety problem of not being able to quickly replace charts in the face of sudden changes in the variable marine environment, and can provide quick, accurate and efficient judgment for mariners, improving operation fluency, interface aesthetics, work efficiency and navigation safety.

[0028] (3) The implementation of the present method can be realized by language programming in an electronic chart display system without introducing additional equipment.

[0029] (4) The method is verified through a large number of experiments and effectively improves the reliability of the method. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is an electronic chart dynamic loading flowchart in the specific embodiment of the present application;

[0031] Figure 2 is a screen longitude and latitude range map obtained after mouse dragging in the specific embodiment of the present application;

[0032] Figure 3 is a screen longitude and latitude range and scale map obtained after mouse wheel sliding in the specific embodiment of the present application;

[0033] Figure 4 is a map of filtering the chart information meeting the display interface in the specific embodiment of the present application;

[0034] Figure 5 is a map of obtaining the same-name electronic chart file in the specific embodiment of the present application;

[0035] Figure 6 is a map before mouse dragging in the specific embodiment of the present application;

[0036] Figure 7 is a map after mouse dragging in the specific embodiment of the present application;

[0037] Figure 8 is a map before mouse wheel sliding in the specific embodiment of the present application;

[0038] Figure 9 is a map after mouse wheel sliding in the specific embodiment of the present application; DETAILED DESCRIPTION

[0039] The present example takes the electronic chart dynamic loading conversion as the research object, and describes the embodiment of the present application in detail. In view of the characteristics that the marine environment and the navigation trip are developing towards diversification, automation and complication, the dynamic readable demand of the system is analyzed through language programming, the dynamic loading of the electronic chart after the change of the chart display interface when the mouse event occurs is realized, and the simple operation, readability and high efficiency of the electronic chart system are improved.

[0040] To make the purpose and technical scheme of the present application clearer, the specific implementation steps of the present application are described in detail below in combination with the drawings.

[0041] Reference Figure 1 The implementation steps are as follows:

[0042] (1) obtaining the information of the stored chart file;

[0043] ① Open the chart loading pop-up window and click the Load Chart menu item

[0044] ② Select the chart file to be displayed and parse it

[0045] ③ Get the current chart file information, including the chart name, scale, latitude and longitude range, and store it in the collection_s57Infos of the chart information class

[0046] (2) Get the latitude and longitude range and scale of the chart display interface when the mouse event changes;

[0047] If the mouse event is dragging, refer to Figure 2 , the steps are:

[0048] ① Calculate the longitude distance num and latitude distance num2 of the drag

[0049] ② Calculate the latitude and longitude range of the display interface after dragging

[0050] The longitude range of the world map is -180° ~ +180°, and the latitude range is -90° ~ +90°.

[0051] If the latitude and longitude distance of the drag is within this range:

[0052] The latitude and longitude range of the current display interface_upLeftPos, _downRightPos is simply added and subtracted with the latitude and longitude distance num and num2. If the latitude and longitude distance num and num2 are negative, the latitude and longitude values displayed by the current interface will be larger than before dragging; if the latitude and longitude distance num and num2 are positive, the latitude and longitude values displayed by the current interface will be smaller than before dragging.

[0053] If the drag distance is not within the above range:

[0054] When dragging to the right: there will be a -180° offset in the longitude distance, and after linear superposition, the longitude range of the display interface will change;

[0055] When dragging to the left: there will be a 360° offset in the longitude distance, and after linear superposition, the longitude range of the display interface will change;

[0056] When dragging upwards: there will be a -90° offset in the latitude distance, and after linear superposition, the latitude range of the display interface will change;

[0057] When dragging downwards: there will be a 90° offset in the latitude distance, and after linear superposition, the latitude range of the display interface will change;

[0058] If the mouse event is a scroll wheel slide, refer toFigure 3 Then the steps are:

[0059] ①Calculate the longitude and latitude distance of the mouse stay point and the four corners of the screen

[0060] Where num is the longitude distance of the stay point from the four corners of the screen, and num2 is the latitude distance of the stay point from the four corners of the screen.

[0061] ②Calculate the longitude and latitude distance after the scroll wheel slides

[0062] When the scroll wheel slides once, it will be enlarged or reduced by a certain scale scale, and the longitude and latitude distance of the mouse stay point from the four corners of the screen will also be scaled by this scale. Specifically, when the mouse wheel is enlarged, the enlargement factor scale is 0.5, and the longitude and latitude distance will be reduced by 0.5 times each time; when the mouse wheel is reduced, the reduction factor scale is 2, and the longitude and latitude distance will be increased by 2 times each time.

[0063] ③Calculate the longitude and latitude coordinates of the four corners of the screen according to the longitude and latitude distance after the scroll wheel slides and the longitude and latitude coordinates of the mouse stay point, so as to obtain the longitude and latitude range after the scroll wheel slides

[0064] When the scroll wheel slides, the longitude and latitude ES57V2d at the mouse stay point remains unchanged, and linear addition and subtraction according to the longitude and latitude of this point and the longitude and latitude distance from the four corners of the screen will obtain the longitude and latitude coordinates of the four corners of the screen, so as to obtain the longitude and latitude range of the screen after the mouse is enlarged or reduced.

[0065] (3) Obtain the corresponding chart information under the longitude and latitude and scale range of the chart display interface, refer to Figure 4 ;

[0066] ①Iterate through the chart information_s57Infos, compare the scale, longitude and latitude range in the chart information_s57Infos with the scale, longitude and latitude range of the display interface after the mouse event, and mark the IsLoadData of the chart information within the range as true, indicating that the chart information can be displayed, otherwise as false

[0067] ②Select the information in the multiple chart information that best fits the current screen range and mark it as true, and the rest as false

[0068] (4) Obtain the electronic chart corresponding to the chart information within the display range and display it in the chart interface, update the menu bar information, refer to Figure 5 ;

[0069] ① Traverse the chart information_s57Infos and the chart set_s57Maps, if the chart set_s57Maps contains the same name chart map, and the IsLoadData in the chart information_s57Infos is marked as true, indicating that the chart information is marked as displayable, then the chart map will be drawn and displayed; if the IsLoadDate in the chart information_s57Infos is marked as false, then remove the chart map; if the chart set_s57Maps does not contain the same name chart map, then add the chart map with the same name to the chart set_s57Maps for subsequent drawing and display.

[0070] ② Display and draw the chart in the chart set_s57Maps on the interface, and update the current display chart information in the menu bar

[0071] (5) The timer refreshes to obtain dynamic information and redraws the chart.

[0072] The chart will be refreshed every certain period of time, if a mouse event occurs, the latitude and longitude range and scale of the display interface will be recalculated, and the electronic chart that meets the display range will be filtered according to the chart information stored when the chart is first opened, and will be automatically drawn and displayed on the interface without reloading the chart every time.

[0073] Reference Figure 6 ,7,8,9, when the mouse drag event or mouse wheel sliding event occurs, the latitude and longitude range and scale of the current chart display interface change, the chart that meets the range will be displayed and drawn, and the chart information in the menu bar will be updated.

[0074] The above-described embodiments are only preferred specific implementations, and the examples are applied to help understand the method and core idea of the application, and from the implementation and actual effect of the examples, it can be seen that the application realizes dynamic loading of electronic charts, and through mouse operation, the electronic charts can be quickly switched without reloading the chart every time, which helps to improve the work efficiency of the operator, and greatly solves the safety problem caused by navigation in the changing marine environment. The technical solutions described in the foregoing embodiments and the equivalent replacement of part of the indicators should be included in the protection scope of the application.

Claims

1. A method for dynamic loading display of electronic chart, characterized in that, The dynamic loading display method comprises the following steps: (1) Obtain information of a stored chart file, including chart name, scale, latitude and longitude range, and store them; (2) Obtain a mouse event in response to a mouse event, calculate and update the latitude and longitude range and scale of the chart display interface, calculate the longitude distance and latitude distance of the drag according to the mouse movement distance; based on the world map latitude and longitude range constraint, combined with the boundary offset processing, finally calculate the accurate latitude and longitude range of the display interface after dragging; based on the direction of the scroll wheel sliding and the preset zoom factor, calculate the new value of the latitude and longitude distance of the mouse resting point from the four corners of the screen after scaling; then, taking the latitude and longitude coordinates of the mouse resting point as the reference, linearly calculate the accurate latitude and longitude coordinates of the four corners of the screen after the scroll wheel operation through the scaled latitude and longitude distance, so as to obtain the scaled interface latitude and longitude range; (3) Obtain the corresponding chart information under the latitude and longitude and scale range of the chart display interface, determine the current display interface latitude and longitude range and scale information, dynamically traverse the stored chart information; judge whether the scale of each chart information is suitable and whether its latitude and longitude range is consistent with the current display interface range; mark the chart information with the highest consistency as a displayable state, and mark the rest as a non-displayable state; according to the marking state, dynamically manage the chart set and update the display interface; (4) Timer refreshes to obtain dynamic information and redraws the chart, periodically obtains dynamic information and redraws it on the chart; after responding to the mouse event and completing the new interface range calculation, trigger step (3); thus, the entire interface update process is based on the mouse event results and the stored chart information, intelligently loads the chart within the display range, removes the chart outside the display range, and redraws the interface.

2. The method for dynamic loading display of electronic chart according to claim 1, characterized in that: The chart information screening method in step (3): ① Traverse the stored chart information, compare the scale and latitude and longitude range of each information with the current interface range, set the displayable mark for the chart information with high consistency, and set the non-displayable mark for the rest, wherein the displayable mark is set to true and the non-displayable mark is set to false; ② Dynamically manage the chart set and display based on the marking state: traverse the chart information and the currently loaded chart set - if the information is marked as true and the same name chart is in the set, draw and display; if the information is marked as false but the same name chart is in the set, remove this chart; if the same name chart is not in the set, add this chart to the set for subsequent drawing and display; ③ Update the chart display interface and menu bar: draw all charts in the chart set that meet the display range, and update the current display chart information in the menu bar.

Images