Touchscreen cursor is running slower than pen at the touchscreen
Jörg Zywek
joerg.zywek at gmx.de
Sun Jul 2 10:00:39 UTC 2017
Hi,
I'm using Raspberry Pi 2B, actual Raspian Jessie (Jun 2017) and a eGalax
8" touchscreen. In general I've got the touchscreen working by modifying
the TransmissionMatrix to the following values:
Option "TransformationMatrix" "0 1 -0.001 -1 0 0.995 0 0 1"
(The display is rotated to 180 degrees by rotate instruction in the
/boot/config.txt file.)
The position of the shown cursor is quite exactly, if I point at the
middle of the screen. But when I move to right or to left the cursor
won't follow the pen exactly: the more I reach the right (or left)
margin of the display the cursor follows less. When I touch the right
border of the display, the cursor stands about 30 pixels left from the
physical position of the pen. At the left side it's just the opposite
behaviour. Moving up an down, the cursor "loses" about 50 pixels from
the physical position at the top or bottom of the display.
The strange values above (-0.0001 or 0.995) are incremental tries to
approach the correct behaviour. But I'm not sure, that it is the right
und promising path. And I can't find any reference manual what the
values of the TransformationMatrix are standing for. Can you help me or
give me a hint.
Best regards
Jörg
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