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[Olivier Tilloy <olivier.tilloy@xxxxxxxxxxxxx>]

I’ve now updated my branch to use the public SwipeArea component from
the UITK, and I’m still seeing an issue similar to the one originally
reported. I can reproduce it with a minimal standalone example:

import QtQuick 2.4
import Ubuntu.Components 1.3
import com.canonical.Oxide 1.11
WebView {
  url: "https://en.wikipedia.org/wiki/Ubuntu_(operating_system)"
  SwipeArea {
    direction: SwipeArea.Upwards
    onDraggingChanged: console.log("dragging:", dragging)
    onDistanceChanged: console.log("distance:", distance)
    anchors {
      left: parent.left
      right: parent.right
      bottom: parent.bottom
    }
    height: units.gu(2)
  }
}

I instrumented oxide to print a log statement every time a touch event
is detected, and when starting a drag even from the bottom edge, the
following happens:

qml: distance: 0
virtual void OxideQQuickWebView::touchEvent(QTouchEvent*) QTouchEvent(TouchBegin states: QFlags(0x1), 1 points: (TouchPoint(0 QRectF(599.979,1848.5 2.9974x2.9974) pressed)))
virtual void OxideQQuickWebView::touchEvent(QTouchEvent*) QTouchEvent(TouchUpdate states: QFlags(0x2), 1 points: (TouchPoint(0 QRectF(613.967,1676.09 2.9974x1.99827) moved)))
virtual void OxideQQuickWebView::touchEvent(QTouchEvent*) QTouchEvent(TouchUpdate states: QFlags(0x2), 1 points: (TouchPoint(0 QRectF(618.213,1623.12 4.99566x2.9974) moved)))
virtual void OxideQQuickWebView::touchEvent(QTouchEvent*) QTouchEvent(TouchUpdate states: QFlags(0x2), 1 points: (TouchPoint(0 QRectF(620.961,1507.47 2.9974x1.99827) moved)))
virtual void OxideQQuickWebView::touchEvent(QTouchEvent*) QTouchEvent(TouchUpdate states: QFlags(0x2), 1 points: (TouchPoint(0 QRectF(620.961,1492.02 2.9974x1.99827) moved)))
qml: dragging: true
qml: distance: 148.6371093749999
[…]
qml: distance: 513.631586442578
qml: dragging: false

It appears the webview is getting a TouchBegin event, followed by a
number of TouchUpdate events, before the SwipeArea even detects a drag.
When it does, events stop being sent to the webview, which as a
consequence never gets a TouchEnd event to match the first TouchBegin
event, leaving it in an inconsistent state.

** Summary changed:

- SwipeArea lets touch events through when a drag is detected
+ SwipeArea lets touch events through before a drag is detected

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Ubuntu.
https://bugs.launchpad.net/bugs/1459362

Title:
  SwipeArea lets touch events through before a drag is detected

Status in Oxide:
  New
Status in ubuntu-ui-toolkit package in Ubuntu:
  New
Status in webbrowser-app package in Ubuntu:
  New

Bug description:
  I recently build a branch of lp:webbrowser-app with the latest code
  drop for DirectionalDragArea from lp:unity8. The branch is there:
  lp:~osomon/webbrowser-app/update-dda.

  The DDA is used to detect a bottom edge drag over a WebView component,
  and display the tabs view accordingly. This works well, but often when
  a drag is detected the WebView under it gets a long press event, thus
  triggering the selection mechanism that it implements.

  According to Daniel with whom I discussed the issue prior to filing
  this bug:

  > Yes, the recognition parameters (and algorithm) were changed a bit.
  > So it's perfectly possible that what you consider a long press (don't
  > know how many milliseconds of pressed are needed for that) can happen
  > before the DirectionalDragArea reaches a decision on whether the gesture
  > is a directional drag gesture or not.

  The threshold duration for a long press to be detected by the WebView
  is 500ms.

  I’ve rebuilt my branch with DIRECTIONALDRAGAREA_DEBUG set to 1, and
  here is what I’m seeing when observing the issue:

  [DDA()] 10035 TouchBegin (id:8, state:pressed, scenePos:(268.503,917.002)) 
  [DDA()] WaitingForTouch -> Undecided
  [DDA()] Unowned 10072 TouchUpdate (id:8, state:moved, scenePos:(268.503,917.002)) 
  [DDA()] Sill within composition window. Let's wait more.
  [DDA()] Unowned 10089 TouchUpdate (id:8, state:moved, scenePos:(268.503,917.002)) 
  [DDA()] Sill within composition window. Let's wait more.
  [DDA()] Unowned 10106 TouchUpdate (id:8, state:moved, scenePos:(268.503,917.002)) 
  [DDA()]  movedFarEnoughAlongGestureAxis: scalarProjection=0, distanceThreshold=15.748
  [DDA()] Didn't move far enough yet. Let's wait more.
  [DDA()] Unowned 10123 TouchUpdate (id:8, state:moved, scenePos:(267.006,911.008)) 
  [DDA()]  movedFarEnoughAlongGestureAxis: scalarProjection=2.05677, distanceThreshold=15.748
  [DDA()] Didn't move far enough yet. Let's wait more.
  [DDA()] Unowned 10139 TouchUpdate (id:8, state:moved, scenePos:(267.505,891.706)) 
  [DDA()]  movedFarEnoughAlongGestureAxis: scalarProjection=21.3591, distanceThreshold=15.748
  [DDA()] grabbing touch
  [DDA()] Undecided -> Recognized
  [DDA()] 10150 TouchUpdate (id:8, state:moved, scenePos:(267.505,891.706)) 
  [DDA()] 10186 TouchUpdate (id:8, state:moved, scenePos:(268.503,845.866)) 
  [DDA()] 10215 TouchUpdate (id:8, state:moved, scenePos:(270.853,799.68)) 
  [DDA()] 10238 TouchUpdate (id:8, state:moved, scenePos:(271.996,774.151)) 
  [DDA()] 10248 TouchUpdate (id:8, state:moved, scenePos:(272.212,747.697)) 
  [DDA()] 10260 TouchUpdate (id:8, state:moved, scenePos:(274.196,721.618)) 
  [DDA()] 10288 TouchUpdate (id:8, state:moved, scenePos:(275.736,663.346)) 
  [DDA()] 10345 TouchUpdate (id:8, state:moved, scenePos:(278.203,582.836)) 
  [DDA()] 10465 TouchUpdate (id:8, state:moved, scenePos:(280.481,432.403)) 
  [DDA()] 10483 TouchUpdate (id:8, state:moved, scenePos:(281.486,382.402)) 
  [DDA()] 10501 TouchUpdate (id:8, state:moved, scenePos:(282.613,359.847)) 
  [DDA()] 10522 TouchUpdate (id:8, state:moved, scenePos:(283.838,335.342)) 
  [DDA()] 10532 TouchUpdate (id:8, state:moved, scenePos:(284.972,311.133)) 
  [DDA()] 10545 TouchUpdate (id:8, state:moved, scenePos:(286.124,288.236)) 
  [DDA()] 10590 TouchUpdate (id:8, state:moved, scenePos:(287.307,265.747)) 
  [DDA()] 10600 TouchUpdate (id:8, state:moved, scenePos:(288.466,228.588)) 
  [DDA()] 10601 TouchEnd (id:8, state:released, scenePos:(288.466,228.588)) 
  [DDA()] Recognized -> WaitingForTouch

  Let me know if I can provide more useful information.

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