ArcGIS engine 开发小小疑问 高分

是的，返回的是mapcontrol控件的X坐标的值，并且单位是IMapControl::MapUnits.；
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希望我的回答能够帮到你，祝学习进步！

是的
x is the X coordinate, in pixels, where the mouse button was pressed
referenced against the origin (0, 0) of the MapControl (the top left hand
corner).

y is the Y coordinate, in pixels, where the mouse button
was pressed referenced against the origin (0, 0) of the MapControl (the top left
hand corner).

mapX is the X coordinate, in map units, where the mouse button was
pressed referenced against the origin (bottom left hand corner) of the IMapControl2::Map. The values returned are in IMapControl2::MapUnits.

mapY is the Y coordinate, in map units, where the mouse button was
pressed referenced against the origin (bottom left hand corner) of the IMapControl2::Map. The values returned are in IMapControl2::MapUnits
参数x，y为屏幕坐标，以像素为单位；
参数mapX，mapY为地图坐标，为实际地图单位。
两者可以进行相互转换（需要自定义函数，我记得老师讲过）。