在Windows应用程序中，只要进行绘图，就要使用GDI坐标系统。Windows提供了几种映射方式，每一种映射都对应着一种坐标系。例如，绘制图形 时，必须给出图形各个点在客户区的位置，其位置用x　和y两个坐标表示，x　表示横坐标，y表示纵坐标。在所有的GDI绘制函数中，这些坐标使用的是一种 “逻辑单位”。当GDI函数将结果输出送到某个物理设备上时，Windows将逻辑坐标转换成设备坐标（如屏幕或打印机的像素点）-In Windows applications, as long as for graphics, it is necessary to use the GDI Coordinate System. Windows provides several mapping methods, each of which corresponds with a map coordinate system. For example, graphics rendering, the graphics must be given in various areas in the customer location, the location of the two with x and y coordinates, x that the abscissa, y that the longitudinal coordinates. In all GDI drawing function, which coordinates the use of a " logical unit."　When the GDI output function to the results when a physical device, Windows will be the logical coordinates into device coordinates (such as screen or printer pixels)