Windows 3.1 Device Drivers (ddag31qh.hlp) (Table of Contents; Topic list)
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SET_SCREEN_ANGLE
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#define SET_SCREEN_ANGLE 4105 
short Control(lpDevice, SET_SCREEN_ANGLE, lpAngle, NULL)
LPPDEVICE lpDevice;
LPINT lpAngle;
 
The SET_SCREEN_ANGLE escape sets the current screen angle to the desired
angle and enables an application to simulate the tilting of a photographic
mask in producing a separation for a particular primary color.
 
Four-color process separation is the process of separating the colors
comprising an image into four component primaries: cyan, magenta, yellow,
and black. The image is then reproduced by overprinting each primary. In
traditional four-color process printing, half-tone images for each of the
four primaries are photographed against a mask tilted to a particular angle.
Tilting the mask in this manner minimizes unwanted moire patterns caused by
overprinting two or more colors.
 
Parameter  Description
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lpDevice   Points to a PDEVICE structure specifying the destination device.
 
lpAngle    Points to a 16-bit variable specifying the desired screen angle
           in tenths of a degree. The angle is measured counterclockwise.
 
Return Value
 
This escape returns the previous screen angle.
 
Comments
 
The default screen angle is defined by the device driver.
 
See Also
 
PDEVICE