Specifications

CARROLL TOUCH Appendix D - CTKERN Function Reference
Touch System Programmer’s Guide D-29
SetScalingParameters (9)
Description
This function sets the scaling parameters that CTKERN uses to scale
the calibrated touch coordinates, overriding the parameters that are in
effect at the time that this function is called.
Call with
AL = 9 (function number).
CX = Segment of four-word buffer that holds the scaling data
structure.
DX = Offset of four-word buffer that holds the scaling data
structure.
Scaling data structure:
WORD Upper Left X
WORD Upper Left Y
WORD Lower Right X
WORD Lower Right Y
Notes
This function lets you set the scaling parameters to arbitrary values that
are not related to the Xres and Yres parameters in any calibration table
entry. The scaling mode should be set to fixed when using this function.
If the scaling mode is set to automatic, the next video mode change
causes the scaling parameters to be overwritten by the scaling
parameters that correspond to the calibration table entry for that video
mode.
The default origin for the Touch Coordinate Reports is the upper left
corner. This default origin may be changed by setting the upper left
value of an axis to a value greater than that for the lower right value for
that axis. For example, if the scaling parameters are set to:
Upper left x = 0
Upper left y = 0
Lower right x = 639
Lower right y = 479
The screen reports 0, 0 when the upper left corner is touched and 639,
479 when the lower right corner is touched, and linearly scaled
coordinates in between.