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  1. Qt
  2. QTBUG-120206

QSGSoftwareInternalImageNode is always mirrored when the texture is a layer

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      but the layer can have mirroring disabled...

      The problem appears in such a case:

      1. QT_QUICK_BACKEND=software is used;
      2. Сustom effect implemented:
      // qml file
Item {
    ...

     layer.enabled: true
     layer.textureMirroring: ShaderEffectSource.NoMirroring
     layer.effect: CustomEffect {}

     ...
}

// custom effect cpp source
QSGNode *CustomEffect::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    ...

    // QQuickShaderEffectSource *m_source
    auto provider = m_source->textureProvider();
    auto texture = qobject_cast<QSGLayer *>(provider->texture());    
    auto node = static_cast<QSGInternalImageNode *>(oldNode);

    if (!node) {
        auto renderContext = QQuickItemPrivate::get(this)->sceneGraphRenderContext();
        node = context->createInternalImageNode(renderContext);
        node->setFlag(QSGNode::UsePreprocess);
        node->setTexture(texture);
        ...
     }

     ...
}

      The resulting effect is mirrored.

      I think QSGSoftwareInternalImageNode::update is missing a check for mirroring when setting the transform :

       

      void QSGSoftwareInternalImageNode::update()
{
    if (m_cachedMirroredPixmapIsDirty) {
        if (m_mirrorHorizontally || m_mirrorVertically || m_textureIsLayer) {
            QTransform transform((m_mirrorHorizontally ? -1 : 1), 0, 0,
                                 (m_textureIsLayer ? -1 : 1) * (m_mirrorVertically ? -1 : 1), 0, 0);
            m_cachedMirroredPixmap = pixmap().transformed(transform);
        } else {
            // Cleanup cached pixmap if necessary
            if (!m_cachedMirroredPixmap.isNull())
                m_cachedMirroredPixmap = QPixmap();
        }
        m_cachedMirroredPixmapIsDirty = false;
    }
}

      Everything works correctly if layer mirroring is checked, for example like this:

      if (m_mirrorHorizontally || m_mirrorVertically || (m_textureIsLayer && m_textureIsMirrored)) {
    ...

       

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            qt.team.graphics.and.multimedia Qt Graphics Team
            maksimshapovalov Maksim Shapovalov
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              Created:
              Updated:

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