Ternary Raster Operations

Ternary raster operation codes define how the graphics device interface (GDI) combines the bits in a source bitmap with the bits in the destination bitmap. This topic lists the ternary raster-operation codes used by the BitBlt, PatBlt, and StretchBlt functions.

Each raster-operation code represents a Boolean operation in which the values of the pixels in the source, the selected brush, and the destination are combined. The following table shows the three operands used in these operations.

The following table shows the Boolean operators used in ternary raster operations.

All Boolean operations are presented in reverse Polish notation. For example, the following operation replaces the values of the pixels in the destination bitmap with a combination of the pixel values of the source and brush:

PSo 

The following operation combines the values of the pixels in the source and brush with the pixel values of the destination bitmap (there are alternative spellings of the same function, so although a particular spelling may not be in the list, an equivalent form would be):

DPSoo 

Each raster-operation code is a 32-bit integer whose high-order word is a Boolean operation index and whose low-order word is the operation code. The 16-bit operation index is a zero-extended, 8-bit value that represents the result of the Boolean operation on predefined brush, source, and destination values. For example, the operation indexes for the PSo and DPSoo operations are shown in the following table.

In this case, PSo has the operation index 00FC (read from the bottom up); DPSoo has the operation index 00FE. These values define the location of the corresponding raster-operation codes, as shown in the Raster-Operation Codes table below. The PSo operation is in line 252 (00FCh) of the table; DPSoo is in line 254 (00FEh).

The most commonly used raster operations have been given special names in the header file, Windows.h. You should use these names whenever possible in your applications.

When the source and destination bitmaps are monochrome, a bit value of 0 represents a black pixel and a bit value of 1 represents a white pixel. When the source and the destination bitmaps are color, those colors are represented with RGB values. For more information about RGB values, see RGB.

Raster-Operation Codes

See Also

Raster Operation Codes | Binary Raster Operations | BitBlt | PatBlt | StretchBlt | MAKEROP4

Last updated on Wednesday, April 13, 2005

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