Microsoft KB Archive/74402

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Microsoft Windows GDI Defines Monochrome Bitmap Format

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Q74402

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The information in this article applies to:


 * Microsoft Windows Device Development Kit (DDK) for Windows, versions 3.0, 3.1

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SUMMARY
In the Microsoft Windows graphical environment, a display driver can generally define its own color bitmap format based on the particular hardware it supports. However, a display driver cannot define its own monochrome bitmap format. The Windows graphics device interface (GDI) defines the monochrome bitmap format as follows: each byte contains 8 pixels with the most significant bit representing the left-most pixel. For example, to activate the pixel at the upper-left corner of the bitmap, set bit 7 of the first bitmap byte to 1.

Due to hardware design, it might be more convenient to define the monochrome bitmap format in some other fashion. However, Windows requires the particular monochrome bitmap format described above.

MORE INFORMATION
The main reason that the monochrome bitmap format cannot be redefined is to enforce a common standard across all devices. Windows can render a bitmap in this format on any display or any raster printer device.

GDI assumes the monochrome format for device-independent bitmap (DIB) simulations, StretchBlt simulations, and to allow Windows to select a monochrome bitmap in any device context regardless of the color resolution.

Additional query words: 3.00 3.10 DDKDISPLAY

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