Binary Raster Operations

This section lists the binary raster-operation codes used by the GetROP2 and SetROP2 functions. Raster-operation codes define how GDI combines the bits from the selected pen with the bits in the destination bitmap.

Each raster-operation code represents a Boolean operation in which the values of the pixels in the selected pen and the destination bitmap are combined. Following are the two operands used in these operations:

Operand Meaning
P Selected pen
D Destination bitmap

The Boolean operators used in these operations follow:

Operator Meaning
a Bitwise AND
n Bitwise NOT (inverse)
o Bitwise OR
x Bitwise exclusive OR (XOR)

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 pen and the selected brush:

DPo

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 all possible outcomes resulting from the Boolean operation on two parameters (in this case, the pen and destination values). For example, the operation indexes for the DPo and DPan operations are shown in the following list:

P D DPo DPan
0 0 0 1
0 1 1 1
1 0 1 1
1 1 1 0

The following list outlines the drawing modes and the Boolean operations that they represent:

Raster operation Boolean operation
R2_BLACK 0
R2_COPYPEN P
R2_MASKNOTPEN DPna
R2_MASKPEN DPa
R2_MASKPENNOT PDna
R2_MERGENOTPEN DPno
R2_MERGEPEN DPo
R2_MERGEPENNOT PDno
R2_NOP D
R2_NOT Dn
R2_NOTCOPYPEN Pn
R2_NOTMASKPEN DPan
R2_NOTMERGEPEN DPon
R2_NOTXORPEN DPxn
R2_WHITE 1
R2_XORPEN DPx

For a monochrome device, GDI maps the value zero to black and the value 1 to white. If an application attempts to draw with a black pen on a white destination by using the available binary raster operations, the following results occur:

Raster operation Result
R2_BLACK Visible black line
R2_COPYPEN Visible black line
R2_MASKNOTPEN No visible line
R2_MASKPEN Visible black line
R2_MASKPENNOT Visible black line
R2_MERGENOTPEN No visible line
R2_MERGEPEN Visible black line
R2_MERGEPENNOT Visible black line
R2_NOP No visible line
R2_NOT Visible black line
R2_NOTCOPYPEN No visible line
R2_NOTMASKPEN No visible line
R2_NOTMERGEPEN Visible black line
R2_NOTXORPEN Visible black line
R2_WHITE No visible line
R2_XORPEN No visible line

For a color device, GDI uses RGB values to represent the colors of the pen and the destination. An RGB color value is a long integer that contains a red, a green, and a blue color field, each specifying the intensity of the given color. Intensities range from 0 through 255. The values are packed in the three low-order bytes of the long integer. The color of a pen is always a solid color, but the color of the destination may be a mixture of any two or three colors. If an application attempts to draw with a white pen on a blue destination by using the available binary raster operations, the following results occur:

Raster operation Result
R2_BLACK Visible black line
R2_COPYPEN Visible white line
R2_MASKNOTPEN Visible black line
R2_MASKPEN Invisible blue line
R2_MASKPENNOT Visible red/green line
R2_MERGENOTPEN Invisible blue line
R2_MERGEPEN Visible white line
R2_MERGEPENNOT Visible white line
R2_NOP Invisible blue line
R2_NOT Visible red/green line
R2_NOTCOPYPEN Visible black line
R2_NOTMASKPEN Visible red/green line
R2_NOTMERGEPEN Visible black line
R2_NOTXORPEN Invisible blue line
R2_WHITE Visible white line
R2_XORPEN Visible red/green line