On Fri, 18 Feb 2022 17:04:08 GMT, Alexander Scherbatiy <alex...@openjdk.org> wrote:
> Zoomed/Rotated with two fingers rectangle flickers (unexpectedly becomes > pretty small or large and then returns back to previous size several times > during zooming/rotating) on a Raspberry Pi with Touchscreen. > > The log with traced events shows that it is possible that only one > ABS_MT_POSITION_X or ABS_MT_POSITION_Y can be sent for a given slot. In this > case the corresponding omitted Y/X value is undefined and is assigned from > ABS_Y/X value. This produces incorrect result for slots different from 0. > > Example of the trace events log, enabled by > `-Dmonocle.input.traceEvents.verbose=true -Dmonocle.input.traceEvents=true` > flags: > > traceEvent: Processing EV_ABS ABS_MT_SLOT 1 [index=48] > traceEvent: Processing EV_ABS ABS_MT_TRACKING_ID 302 [index=64] > traceEvent: Processing EV_ABS ABS_MT_POSITION_X 399 [index=80] > traceEvent: Processing EV_ABS ABS_MT_POSITION_Y 272 [index=96] > traceEvent: Processing EV_KEY BTN_TOUCH 1 [index=112] > traceEvent: Read EV_ABS ABS_MT_SLOT 0 [index=176] > traceEvent: Read EV_ABS ABS_MT_POSITION_Y 315 [index=192] > traceEvent: Read EV_ABS ABS_Y 315 [index=208] > traceEvent: Read EV_SYN SYN_REPORT 0 [index=224] > > ... > > traceEvent: Read EV_ABS ABS_MT_SLOT 1 [index=320] > traceEvent: Read EV_ABS ABS_MT_POSITION_Y 271 [index=336] > traceEvent: Read EV_ABS ABS_X 552 [index=352] > traceEvent: Read EV_ABS ABS_Y 322 [index=368] > traceEvent: Read EV_SYN SYN_REPORT 0 [index=384] > > First both ABS_MT_POSITION_X/Y events with values x: 399 and y: 272 are > received for the slot 1. > Next only ABS_MT_POSITION_Y with y: 271 value is received (which implies that > the x value has not been changed) for the slot 1. > The x value is undefined in the > LinuxStatefulMultiTouchProcessor.processEvents() loop and is unexpectedly > assigned to the ABS_X 552 value which belongs to the slot 0. > > The fix skips setting ABS_X/Y values for slots different from 0. The fix also fixes the first use case described in the JDK-8087370 1. Consider you're touching the screen with two fingers, for example coordinates of one point is ~100,100 and second point is ~200,200. While still touching around the same points some events are reported with one or another point to be either 100,200 or 200,100. ------------- PR: https://git.openjdk.java.net/jfx/pull/737
