An application can create custom patterns by using bit maps or characters and symbols from an image font. When designing custom patterns, consider that the operating system uses only the first eight bits in the first eight rows, starting with the lower-left corner of the bit map. The cell size of an image font used as a fill pattern might be too large to include the complete character or symbol.
An application can change the appearance of a fill pattern by changing its alignment in an area primitive with GpiSetPatternRefPoint. When the default reference point is set, the operating system aligns the lower-left corner of the fill pattern with the point (0,0) in the application's world space and begins filling the area. If an application adjusts the pattern reference point to (3,2), The operating system aligns the lower-left corner of the fill pattern with the point (3,2) in the application's world space and begins filling the area. By moving the reference point from (0,0) to (3,2), the fill pattern appears shifted up two pels and to the right three pels.