When Windows calls the Enable function the first time, a graphics driver should initialize the members of the GDIINFO structure that contain information about the device's text-output capabilities. The following table identifies these members and their purpose:
| GDIINFO member | Purpose |
|---|---|
| dpText | Specifies the level of text support provided by the device. |
| dpRaster | Specifies whether or not the device supports the ExtTextOut and GetCharWidth functions. |
| dpCaps1 | Specifies whether or not the device is capable of drawing TrueType fonts as raster fonts.. |
If the device supports text output, it must set the appropriate members of the GDIINFO structure and support the following three functions: ExtTextOut and GetCharWidth.
The ExtTextOut function is called to draw a string of text on the device or to draw a string of text on a bitmap that's associated with the device. The GetCharWidth function is called to compute the width of a string of characters.
Enable, GDIINFO, ExtTextOut, GetCharWidth