Fix QML item is missing if its parent's clip property is true

If using QQuickRenderTarget to the QQuickWindow, and set true in
QQuickRenderTarget::setMirrorVertically, the QQuickWindow will
apply flip Y to the matrix with native NDC, this behovior is
wrong, If QRhi::isYUpInNDC is true, must ensure the
QSGAbstractRenderer::projectionMatrixWithNativeNDC is following
QSGAbstractRenderer::projectionMatrix, otherwise must ensure its
flip Y relative to QSGAbstractRenderer::projectionMatrix.

Fixes: QTBUG-116587
Change-Id: I12b5f6e37ed5bad8656cf46bf1a25e534db24b62
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit e898c06759b5c5a6138fac6f9a2cb31388ea3da9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 51 insertions, 30 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index a1a9c01ced..23da3e8dcc 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -626,13 +626,6 @@ void QQuickWindowPrivate::renderSceneGraph()
     emit q->beforeRendering();
     runAndClearJobs(&beforeRenderingJobs);
 
-    QSGAbstractRenderer::MatrixTransformFlags matrixFlags;
-    bool flipY = rhi ? !rhi->isYUpInNDC() : false;
-    if (!customRenderTarget.isNull() && customRenderTarget.mirrorVertically())
-        flipY = !flipY;
-    if (flipY)
-        matrixFlags |= QSGAbstractRenderer::MatrixTransformFlipY;
-
     const qreal devicePixelRatio = q->effectiveDevicePixelRatio();
     QSize pixelSize;
     if (redirect.rt.renderTarget)
@@ -647,7 +640,16 @@ void QQuickWindowPrivate::renderSceneGraph()
     renderer->setDevicePixelRatio(devicePixelRatio);
     renderer->setDeviceRect(QRect(QPoint(0, 0), pixelSize));
     renderer->setViewportRect(QRect(QPoint(0, 0), pixelSize));
-    renderer->setProjectionMatrixToRect(QRectF(QPointF(0, 0), pixelSize / devicePixelRatio), matrixFlags);
+
+    QSGAbstractRenderer::MatrixTransformFlags matrixFlags;
+    bool flipY = rhi ? !rhi->isYUpInNDC() : false;
+    if (!customRenderTarget.isNull() && customRenderTarget.mirrorVertically())
+        flipY = !flipY;
+    if (flipY)
+        matrixFlags |= QSGAbstractRenderer::MatrixTransformFlipY;
+
+    const QRectF rect(QPointF(0, 0), pixelSize / devicePixelRatio);
+    renderer->setProjectionMatrixToRect(rect, matrixFlags, rhi && !rhi->isYUpInNDC());
 
     context->renderNextFrame(renderer);
 
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
index a51521eeaa..bb374f8aaa 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
@@ -193,15 +193,7 @@ QRect QSGAbstractRenderer::viewportRect() const
  */
 void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect)
 {
-    QMatrix4x4 matrix;
-    matrix.ortho(rect.x(),
-                 rect.x() + rect.width(),
-                 rect.y() + rect.height(),
-                 rect.y(),
-                 1,
-                 -1);
-    setProjectionMatrix(matrix);
-    setProjectionMatrixWithNativeNDC(matrix);
+    setProjectionMatrixToRect(rect, {}, false);
 }
 
 /*!
@@ -217,24 +209,49 @@ void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect)
  */
 void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags)
 {
+    setProjectionMatrixToRect(rect, flags, flags.testFlag(MatrixTransformFlipY));
+}
+
+/*!
+    Convenience method that calls setProjectionMatrix() with an
+    orthographic matrix generated from \a rect.
+
+    Set MatrixTransformFlipY in \a flags when the graphics API uses Y down in
+    its normalized device coordinate system (for example, Vulkan).
+
+    Convenience method that calls setProjectionMatrixWithNativeNDC() with an
+    orthographic matrix generated from \a rect.
+
+    Set true to \a nativeNDCFlipY to flip the Y axis relative to
+    projection matrix in its normalized device coordinate system.
+
+    \sa setProjectionMatrix(), projectionMatrix()
+    \sa setProjectionMatrixWithNativeNDC(), projectionMatrixWithNativeNDC()
+
+    \since 6.7
+ */
+void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags,
+                                                    bool nativeNDCFlipY)
+{
     const bool flipY = flags.testFlag(MatrixTransformFlipY);
+
+    const float left = rect.x();
+    const float right = rect.x() + rect.width();
+    float bottom = rect.y() + rect.height();
+    float top = rect.y();
+
+    if (flipY)
+        std::swap(top, bottom);
+
     QMatrix4x4 matrix;
-    matrix.ortho(rect.x(),
-                 rect.x() + rect.width(),
-                 flipY ? rect.y() : rect.y() + rect.height(),
-                 flipY ? rect.y() + rect.height() : rect.y(),
-                 1,
-                 -1);
+    matrix.ortho(left, right, bottom, top, 1, -1);
     setProjectionMatrix(matrix);
 
-    if (flipY) {
+    if (nativeNDCFlipY) {
+        std::swap(top, bottom);
+
         matrix.setToIdentity();
-        matrix.ortho(rect.x(),
-                     rect.x() + rect.width(),
-                     rect.y() + rect.height(),
-                     rect.y(),
-                     1,
-                     -1);
+        matrix.ortho(left, right, bottom, top, 1, -1);
     }
     setProjectionMatrixWithNativeNDC(matrix);
 }
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h b/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
index ec2cb66662..81263111cb 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer_p.h
@@ -61,6 +61,8 @@ public:
 
     void setProjectionMatrixToRect(const QRectF &rect);
     void setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags);
+    void setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags,
+                                   bool nativeNDCFlipY);
     void setProjectionMatrix(const QMatrix4x4 &matrix);
     void setProjectionMatrixWithNativeNDC(const QMatrix4x4 &matrix);
     QMatrix4x4 projectionMatrix() const;