A method of zooming and panning GDI electronic vector map based on mouse position

Abstract

A method for zooming and panning a GDI electronic vector map based on the mouse position. It includes establishing a map coordinate system and a screen coordinate system; establishing a reference rectangle, calculating the actual length and actual height of the reference rectangle, and the screen length and screen height, thereby establishing a mapping relationship between the map coordinate system and the screen coordinate system; obtaining the mouse wheel message, calculate the zoom factor; calculate the mouse translation factor according to the distance moved by the mouse; calculate the screen position of the new reference rectangle after zooming and translation according to the current position of the mouse, the zoom factor and the mouse translation factor, and realize the zooming and scaling of the reference rectangle Panning: Recalculate the screen coordinates of the vector map according to the reference rectangle to realize zooming and panning operations on the vector map. The invention can realize zooming and translation operations based on the center of the mouse on the GDI electronic vector map, and solves the problem of map drift during the zooming process. The method is simple to implement and has wide application prospects.

Description

technical field [0001] The invention belongs to the technical field of electronic vector map processing, in particular to a method for realizing zooming and panning of a GDI electronic vector map based on a mouse position. Background technique [0002] GDI (Graphics Device Interface) means a graphics device interface. Its main task is to be responsible for the information interaction between the Windows operating system and the drawing program, and to process the graphics output of all Windows applications. Compared with drawing engines such as OpenGL, GDI+, and Driect X, GDI has the advantages of high drawing efficiency and easy use, so it is widely used in drawing two-dimensional vector maps. However, GDI can only provide basic two-dimensional graphics drawing functions, but cannot provide two-dimensional graphics transformation functions, so it is difficult to realize advanced functions such as zooming and panning of electronic vector maps, while OpenGL, GDI+, Driect X, e...

AI Technical Summary

Problems solved by technology

However, GDI can only provide basic two-dimensional graphics drawing functions, but cannot provide two-dimensional graphics transformation functions, so it is difficult to realize advanced functions such as zooming and panning of electronic vector maps, while OpenGL, GDI+, Driect X, etc. all have related implementation functions

In addition, the existing GDI electronic vector map software uses the center point of the screen as a reference point to convert the pixel points of the drawing objects on the screen according to the zoom ratio when zooming, but the disadvantage is that the vector map will drift when zooming

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