Avoid changing function signature in public header

Change-Id: I0be124dfcafa2244531281ffd1ac6b559d82c604
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

5 files changed, 64 insertions, 10 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index cd620e3408..e00789be85 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -500,10 +500,10 @@ void QQuickWindowPrivate::renderSceneGraph(const QSize &size, const QSize &surfa
             renderer->setDeviceRect(rect);
             renderer->setViewportRect(rect);
             if (QQuickRenderControl::renderWindowFor(q)) {
-                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), size), false);
+                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), size));
                 renderer->setDevicePixelRatio(devicePixelRatio);
             } else {
-                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), rect.size()), false);
+                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), rect.size()));
                 renderer->setDevicePixelRatio(1);
             }
         } else {
@@ -520,7 +520,10 @@ void QQuickWindowPrivate::renderSceneGraph(const QSize &size, const QSize &surfa
             renderer->setDeviceRect(rect);
             renderer->setViewportRect(rect);
             const bool flipY = rhi ? !rhi->isYUpInNDC() : false;
-            renderer->setProjectionMatrixToRect(QRectF(QPoint(0, 0), logicalSize), flipY);
+            QSGAbstractRenderer::MatrixTransformFlags matrixFlags = 0;
+            if (flipY)
+                matrixFlags |= QSGAbstractRenderer::MatrixTransformFlipY;
+            renderer->setProjectionMatrixToRect(QRectF(QPoint(0, 0), logicalSize), matrixFlags);
             renderer->setDevicePixelRatio(devicePixelRatio);
         }
 
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
index 679ad1d445..62ed342244 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer.cpp
@@ -73,6 +73,22 @@ QT_BEGIN_NAMESPACE
  */
 
 /*!
+    \enum QSGAbstractRenderer::MatrixTransformFlag
+
+    Used with setProjectionMatrixToRect() to indicate the expectations towards
+    the generated projection matrix.
+
+    \value MatrixTransformFlipY The traditional assumption in Qt Quick is that
+    Y points up in the normalized device coordinate system. There is at least
+    one modern graphics API where this is not the case (Vulkan). This flag can
+    then be used to get a projection that is appropriate for such an API.
+
+    \sa setProjectionMatrixToRect()
+
+    \since 5.14
+ */
+
+/*!
     \fn void QSGAbstractRenderer::renderScene(GLuint fboId = 0)
 
     Render the scene to the specified \a fboId
@@ -224,14 +240,38 @@ QRect QSGAbstractRenderer::viewportRect() const
     Convenience method that calls setProjectionMatrix() with an
     orthographic matrix generated from \a rect.
 
-    \a flipY must be \c true when the graphics API uses Y down in its
-    normalized device coordinate system (for example, Vulkan), \c false
-    otherwise.
+    \note This function assumes that the graphics API uses Y up in its
+    normalized device coordinate system.
 
     \sa setProjectionMatrix(), projectionMatrix()
  */
-void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect, bool flipY)
+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);
+}
+
+/*!
+    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).
+
+    \sa setProjectionMatrix(), projectionMatrix()
+
+    \since 5.14
+ */
+void QSGAbstractRenderer::setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags)
 {
+    const bool flipY = flags.testFlag(MatrixTransformFlipY);
     QMatrix4x4 matrix;
     matrix.ortho(rect.x(),
                  rect.x() + rect.width(),
diff --git a/src/quick/scenegraph/coreapi/qsgabstractrenderer.h b/src/quick/scenegraph/coreapi/qsgabstractrenderer.h
index 08e600e0b8..1594352dab 100644
--- a/src/quick/scenegraph/coreapi/qsgabstractrenderer.h
+++ b/src/quick/scenegraph/coreapi/qsgabstractrenderer.h
@@ -63,6 +63,13 @@ public:
     Q_DECLARE_FLAGS(ClearMode, ClearModeBit)
     Q_FLAG(ClearMode)
 
+    enum MatrixTransformFlag
+    {
+        MatrixTransformFlipY = 0x01
+    };
+    Q_DECLARE_FLAGS(MatrixTransformFlags, MatrixTransformFlag)
+    Q_FLAG(MatrixTransformFlags)
+
     ~QSGAbstractRenderer() override;
 
     void setRootNode(QSGRootNode *node);
@@ -75,7 +82,8 @@ public:
     inline void setViewportRect(const QSize &size) { setViewportRect(QRect(QPoint(), size)); }
     QRect viewportRect() const;
 
-    void setProjectionMatrixToRect(const QRectF &rect, bool flipY = false);
+    void setProjectionMatrixToRect(const QRectF &rect);
+    void setProjectionMatrixToRect(const QRectF &rect, MatrixTransformFlags flags);
     void setProjectionMatrix(const QMatrix4x4 &matrix);
     void setProjectionMatrixWithNativeNDC(const QMatrix4x4 &matrix);
     QMatrix4x4 projectionMatrix() const;
diff --git a/src/quick/scenegraph/qsgopengllayer.cpp b/src/quick/scenegraph/qsgopengllayer.cpp
index 8db4cba58a..ae5032231d 100644
--- a/src/quick/scenegraph/qsgopengllayer.cpp
+++ b/src/quick/scenegraph/qsgopengllayer.cpp
@@ -408,7 +408,7 @@ void QSGOpenGLLayer::grab()
                     m_mirrorVertical ? m_rect.bottom() : m_rect.top(),
                     m_mirrorHorizontal ? -m_rect.width() : m_rect.width(),
                     m_mirrorVertical ? -m_rect.height() : m_rect.height());
-    m_renderer->setProjectionMatrixToRect(mirrored, false);
+    m_renderer->setProjectionMatrixToRect(mirrored);
     m_renderer->setClearColor(Qt::transparent);
 
     if (m_multisampling) {
diff --git a/src/quick/scenegraph/qsgrhilayer.cpp b/src/quick/scenegraph/qsgrhilayer.cpp
index 80ca40d50a..757410eded 100644
--- a/src/quick/scenegraph/qsgrhilayer.cpp
+++ b/src/quick/scenegraph/qsgrhilayer.cpp
@@ -388,7 +388,10 @@ void QSGRhiLayer::grab()
                           m_mirrorHorizontal ? -m_rect.width() : m_rect.width(),
                           m_mirrorVertical ? m_rect.height() : -m_rect.height());
     }
-    m_renderer->setProjectionMatrixToRect(mirrored, !m_rhi->isYUpInNDC());
+    QSGAbstractRenderer::MatrixTransformFlags matrixFlags = 0;
+    if (!m_rhi->isYUpInNDC())
+        matrixFlags |= QSGAbstractRenderer::MatrixTransformFlipY;
+    m_renderer->setProjectionMatrixToRect(mirrored, matrixFlags);
     m_renderer->setClearColor(Qt::transparent);
     m_renderer->setRenderTarget(m_rt);
     m_renderer->setCommandBuffer(m_context->currentFrameCommandBuffer());