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Dimensions

The graphics origin is always the top left hand corner of a window. Dimensions are a problem in a multi-platform application, since display and character widths will change from machine to machine, even more so than for different PC display boards. At the moment wxWindows uses pixels; MS Windows tackles the problem by using 'dialog units' based on the size of the standard system font. To avoid this problem when creating panel items, wxWindows provides automatic left to right, top to bottom item layout (similar to XView), in addition to absolute positioning, in which case, portability is up to the discretion of the programmer.

A canvas has a mapping mode associated with it, which determines the meaning of dimensions in subsequent graphics operations. Drawing may be done using various units including mm, 1/10 mm, pixels and points. Mapping modes other than pixels cannot be relied upon, however; future versions of wxWindows may support mapping modes better, and allow a change of graphics origin.