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Bug
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Resolution: Done
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P1: Critical
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5.15, 6.2.2
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None
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Linux/X11
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81bbd0b45a (qt/qtdeclarative/dev) 81bbd0b45a (qt/tqtc-qtdeclarative/dev) 5561df5ac4 (qt/qtdeclarative/6.2) 5561df5ac4 (qt/tqtc-qtdeclarative/6.2) 27daadc214 (qt/qtdeclarative/6.3) 684ed0323c (qt/tqtc-qtquickcontrols2/5.15)
Using QQuickNinePatch Image as a provider, an crash occurs on QQuickOpenGLShaderEffectMaterial::updateTextures() in qt5.15 and QSGRhiShaderEffectNode::preprocess() in Qt6.2.
The brief reason of this crash is that ShaderEffect is trying to use wrong texture invalidated already by wrong image source.
The major factors of this crash are
- use QQuickNinePatchImage.
- QQuickNinePatchImage's cache: false.
- use the QQuickNinePatchImage as a source of other Shader related object like ShaderEffect or OpacityMask or something.
- change the QQuickNinePatchImage's source to invalid image after running with valid image.
- after above, update them.
Test codes are below.
Window {
id: root
width: 640
height: 480
visible: true
title: qsTr("Hello World")
NinePatchImage {
id: np
source : "qrc://aaa.png" // any valid image.
cache: false
visible: false
}
/*
* this is for Qt6
ShaderEffect {
width: 300
height: 300
property variant source: np
property real amplitude: 0.04
property real frequency: 20
property real time: 0
fragmentShader: "content/shaders/wobble.frag.qsb" // any shader codes. this fragment shader code was from QtQuick ShaderEffect example
}
*/
// this is for Qt5
ShaderEffect {
width: 300
height: 300
property variant src: np
// any vertex shader
vertexShader: "
uniform highp mat4 qt_Matrix;
attribute highp vec4 qt_Vertex;
attribute highp vec2 qt_MultiTexCoord0;
varying highp vec2 coord;
void main() {
coord = qt_MultiTexCoord0;
gl_Position = qt_Matrix * qt_Vertex;
}"
// any fragment shader
fragmentShader: "
varying highp vec2 coord;
uniform sampler2D src;
uniform lowp float qt_Opacity;
void main() {
lowp vec4 tex = texture2D(src, coord);
gl_FragColor = vec4(vec3(dot(tex.rgb,
vec3(0.344, 0.5, 0.156))),
tex.a) * qt_Opacity;
}"
}
Timer{
running: true
interval: 2000
onTriggered: {
np.source =""
}
}
MouseArea {
anchors.fill: parent
onClicked: {
root.update();
}
}
}
If QQuickImage is used instead, these is no problem because QQuickImage updates provider's texture before checking invalidation of current texture while updating like this.
// qtdeclarative/src/quick/items/qquickimage.cpp QSGNode *QQuickImage::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *) { Q_D(QQuickImage); QSGTexture *texture = d->sceneGraphRenderContext()->textureForFactory(d->pix.textureFactory(), window()); // Copy over the current texture state into the texture provider... if (d->provider) { d->provider->m_smooth = d->smooth; d->provider->m_mipmap = d->mipmap; d->provider->updateTexture(texture); } if (!texture || width() <= 0 || height() <= 0) { delete oldNode; return nullptr; } // ... }
in QQuickNinePatchImage, however, provider's texture remains regardless whether current image is valid or not. it seems to cause dangling problem.