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  1. Qt
  2. QTBUG-48279

Touchscreen capabilities not correctly detected

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    Description

      The multitouch input is broken on touchscreens which are not correctly parsed for capabilities.

      Without the position capability the "touchinteraction" example like any other "touch" based application gets stuck.
      The Qt qpa/xinput debug output

      qt.qpa.input.devices: input device  ELAN Touchscreen
      qt.qpa.input.devices:    has 7 buttons
      qt.qpa.input.devices:    has valuator "Abs X" recognized? true
      qt.qpa.input.devices:    has valuator "Abs Y" recognized? true
      qt.qpa.input.devices:    has valuator "Rel Horiz Scroll" recognized? true
      qt.qpa.input.devices:    has valuator "Rel Vert Scroll" recognized? true
      qt.qpa.input.devices:    it's a scrolling device
      qt.qpa.input.devices:    has touch class with mode 1
      qt.qpa.input.devices:    it's a touchscreen with type 0 capabilities 0x0 max touch points 15
      

      The output of xinput looks like

      $ xinput --list --long 9
      ELAN Touchscreen                        	id=9	[slave  pointer  (2)]
      	Reporting 6 classes:
      		Class originated from: 9. Type: XIButtonClass
      		Buttons supported: 7
      		Button labels: "Button Left" "Button Middle" "Button Right" "Button Wheel Up" "Button Wheel Down" "Button Horiz Wheel Left" "Button Horiz Wheel Right"
      		Button state:
      		Class originated from: 9. Type: XIValuatorClass
      		Detail for Valuator 0:
      		  Label: Abs X
      		  Range: 0.000000 - 65535.000000
      		  Resolution: 0 units/m
      		  Mode: absolute
      		  Current value: 990.000000
      		Class originated from: 9. Type: XIValuatorClass
      		Detail for Valuator 1:
      		  Label: Abs Y
      		  Range: 0.000000 - 65535.000000
      		  Resolution: 0 units/m
      		  Mode: absolute
      		  Current value: 409.000000
      		Class originated from: 9. Type: XIValuatorClass
      		Detail for Valuator 2:
      		  Label: Rel Horiz Scroll
      		  Range: -1.000000 - -1.000000
      		  Resolution: 0 units/m
      		  Mode: relative
      		Class originated from: 9. Type: XIValuatorClass
      		Detail for Valuator 3:
      		  Label: Rel Vert Scroll
      		  Range: -1.000000 - -1.000000
      		  Resolution: 0 units/m
      		  Mode: relative
      		Class originated from: 9. Type: XITouchClass
      		Touch mode: direct
      		Max number of touches: 15
      

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            srutledg Shawn Rutledge
            wbremer Wolfgang Bremer
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              Updated:
              Resolved:

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