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  1. Qt
  2. QTBUG-28799

Using a Rectangle as source gives binding loop detected + errors

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Details

    • Bug
    • Resolution: Duplicate
    • P2: Important
    • 5.0.1
    • 5.0.0
    • None
    • I;m using Windows 7 x64 with stock Qt 5.0.0 as is downloadable on qt-project.org. Developing in QtCreator and i have visual studio 2010 express installed for the compiler.

    Description

      Hi,

      When i'm trying to use one of the quite cool effects from http://qt-project.org/doc/qt-5.0/qtgraphicaleffects/qmlmodule-qtgraphicaleffects1-qtgraphicaleffects-1-0.html on a Rectangle element then i'm getting binding loop errors.

      Example snippet:

      import QtQuick 2.0
      import QtQuick.Particles 2.0
      import QtGraphicalEffects 1.0

      Rectangle {
      width: 800
      height: 600
      color: "black"

      Rectangle

      { id: dest width: 200 height: 200 color: "blue" }

      Rectangle

      { id: source width: 200 height: 200 color: "red" }

      Blend

      { anchors.fill: source source: source foregroundSource: dest }

      }

      But there is more. If i try to do the http://qt-project.org/doc/qt-5.0/qtgraphicaleffects/qml-qtgraphicaleffects1-thresholdmask.html effect, set an image as "maskSource" and a rectangle as "source" then it doesn't work.

      Till here the errors are the same for both issues:
      file:///F:/Qt/Qt5.0.0/5.0.0/msvc2010/qml/QtGraphicalEffects/ThresholdMask.qml:182:5: QML SourceProxy: Binding loop detected for property "output"
      file:///F:/Qt/Qt5.0.0/5.0.0/msvc2010/qml/QtGraphicalEffects/ThresholdMask.qml:177:5: QML SourceProxy: Binding loop detected for property "output"

      But in the blend case the output is correct. In the Mask case the output isn't. Now if i "hackfix" this issue by opening "ThresholdMask.qml" and changing the line:
      property variant source: sourceProxy.output
      to
      property variant source: rootItem.source

      then the effect works just as i would expect it to work, but my console gets spammed with one message:
      ShaderEffect: source or provider missing when binding textures

      If you fix the binding loop the next issue will likely be:
      ShaderEffect: source or provider missing when binding textures

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            sletta Gunnar Sletta
            markg85 Mark
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            Dates

              Created:
              Updated:
              Resolved:

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