Support to custom the render target on the software renderer

Add QQuickRenderTarget::fromPaintDevice, aollow to get a
QQuickRendererTarget from the QPaintDevice object.

[ChangeLog][QtQuick] Added QQuickRenderTarget::fromPaintDevice,
Allowed to set the render target of QQuickWindow on the software
renderer.

Task-number: QTBUG-94075
Change-Id: I4946c25d2a6315cd8f9c12a7ac7ac4cf71d95361
Reviewed-by: Laszlo Agocs <[email protected]>
Reviewed-by: Qt CI Bot <[email protected]>

2 files changed, 25 insertions, 15 deletions

diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
index 4ddef6b4c2..eba7ce001d 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarecontext.cpp
@@ -218,8 +218,15 @@ QSGRendererInterface::ShaderSourceTypes QSGSoftwareContext::shaderSourceType() c
 
 void *QSGSoftwareContext::getResource(QQuickWindow *window, Resource resource) const
 {
-    if (resource == PainterResource && window && window->isSceneGraphInitialized())
-        return static_cast<QSGSoftwareRenderContext *>(QQuickWindowPrivate::get(window)->context)->m_activePainter;
+    if (!window)
+        return nullptr;
+
+    auto cd = QQuickWindowPrivate::get(window);
+
+    if (resource == PainterResource)
+        return window->isSceneGraphInitialized() ? static_cast<QSGSoftwareRenderContext *>(cd->context)->m_activePainter : nullptr;
+    else if (resource == RedirectPaintDevice)
+        return cd->redirect.rt.paintDevice;
 
     return nullptr;
 }
diff --git a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
index 12ffa0ef57..e56bacd187 100644
--- a/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
+++ b/src/quick/scenegraph/adaptations/software/qsgsoftwarerenderer.cpp
@@ -92,25 +92,28 @@ void QSGSoftwareRenderer::renderScene()
 
 void QSGSoftwareRenderer::render()
 {
-    if (!m_paintDevice && !m_backingStore)
+    if (!m_paintDevice && !m_backingStore && !m_rt.paintDevice)
         return;
 
-    // If there is a backingstore, set the current paint device
-    if (m_backingStore) {
+    QPaintDevice *paintDevice = m_paintDevice ? m_paintDevice : m_rt.paintDevice;
+    QBackingStore *backingStore = nullptr;
+    // If no paint device and there is a backingstore, set the current paint device
+    if (!paintDevice && m_backingStore) {
         // For HiDPI QBackingStores, the paint device is not valid
         // until begin() has been called. See: QTBUG-55875
         m_backingStore->beginPaint(QRegion());
-        m_paintDevice = m_backingStore->paintDevice();
+        paintDevice = m_backingStore->paintDevice();
         m_backingStore->endPaint();
+        backingStore = m_backingStore;
     }
 
     QElapsedTimer renderTimer;
 
     setBackgroundColor(clearColor());
     setBackgroundRect(QRect(0, 0,
-                            m_paintDevice->width() / m_paintDevice->devicePixelRatio(),
-                            m_paintDevice->height() / m_paintDevice->devicePixelRatio()),
-                     m_paintDevice->devicePixelRatio());
+                            paintDevice->width() / paintDevice->devicePixelRatio(),
+                            paintDevice->height() / paintDevice->devicePixelRatio()),
+                      paintDevice->devicePixelRatio());
 
     // Build Renderlist
     // The renderlist is created by visiting each node in the tree and when a
@@ -135,14 +138,14 @@ void QSGSoftwareRenderer::render()
     qint64 optimizeRenderListTime = renderTimer.restart();
 
     // If Rendering to a backingstore, prepare it to be updated
-    if (m_backingStore != nullptr) {
-        m_backingStore->beginPaint(updateRegion);
+    if (backingStore != nullptr) {
+        backingStore->beginPaint(updateRegion);
         // It is possible that a QBackingStore's paintDevice() will change
         // when begin() is called.
-        m_paintDevice = m_backingStore->paintDevice();
+        paintDevice = backingStore->paintDevice();
     }
 
-    QPainter painter(m_paintDevice);
+    QPainter painter(paintDevice);
     painter.setRenderHint(QPainter::Antialiasing);
     auto rc = static_cast<QSGSoftwareRenderContext *>(context());
     QPainter *prevPainter = rc->m_activePainter;
@@ -153,8 +156,8 @@ void QSGSoftwareRenderer::render()
     qint64 renderTime = renderTimer.elapsed();
 
     painter.end();
-    if (m_backingStore != nullptr)
-        m_backingStore->endPaint();
+    if (backingStore != nullptr)
+        backingStore->endPaint();
 
     rc->m_activePainter = prevPainter;
     qCDebug(lcRenderer) << "render" << m_flushRegion << buildRenderListTime << optimizeRenderListTime << renderTime;