CARROLL TOUCH
Appendix D - CTKERN Function Reference
Touch System Programmer’s Guide
D-31
SetTemporalFilterMode (14)
Description
This function sets the temporal filter mode.
Call with
AL
= 14 (function number).
BL
= Temporal filter mode.
00 =
Temporal filter disabled.
01 =
Temporal filter enabled.
Notes
When enabled, the temporal filter acts much like a low pass filter in the
time domain for all touch state transitions. You must specify a Spatial
Filter Box Size and a Temporal Filter Time.
When the stylus touches the screen the center of the spatial filter box is
set to the coordinates where the screen was first touched. The touch
state is set to “touched” and the touch coordinates set to the current
stylus location only after the stylus has remained in the spatial filter box
for the length of time specified by the Temporal Filter Time parameter.
If the stylus moves beyond the spatial filter box, the temporal filter
timer and the center of the spatial filter box are reset. The coordinates
are not updated until the stylus has once again remained in the spatial
filter box for the Temporal Filter Time. The coordinates associated with
the “not touched” state are still the exit point, but the touch state
becomes “not touched” only after the stylus is out of the screen for the
Temporal Filter Time. The touch state is set to “non-contiguous” only
after a non-contiguous stylus has been in the touch screen for the
Temporal Filter Time.
The Spatial Filter Box Size is specified as a percentage of the full screen
size. The valid range for this parameter is from 0% to 100% and the
default is 10%. This parameter specifies the width of the box. The
spatial filter box size is specified as a percentage rather than as an
absolute touch coordinate value because if it were specified as an
absolute value, the absolute size of the spatial filter box would vary if
the display resolution changed as a result of a change in the BIOS video
mode. Note that while the same percentage is used for both the x- and
y-axes, the absolute size of the box is not necessarily square. The box
instead has the same aspect ratio as the display. No correction for
display aspect ratio is performed.
Summary of Contents for TouchSystems CarrollTouch Prog
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Page 11: ...Table of Contents CARROLL TOUCH viii ...
Page 13: ...Table of Contents CARROLL TOUCH x ...
Page 17: ...Welcome CARROLL TOUCH xiv Touch System Programmer s Guide ...
Page 41: ...Chapter 3 General Programming Issues CARROLL TOUCH 3 12 Touch System Programmer s Guide ...
Page 57: ...Chapter 4 Smart Frame Protocol CARROLL TOUCH 4 16 Touch System Programmer s Guide ...
Page 237: ...Appendix D CTKERN Function Reference CARROLL TOUCH D 42 Touch System Programmer s Guide ...