From 8fd6910ca490dcdaa3b5109f5522aad23ed44632 Mon Sep 17 00:00:00 2001
From: Uwe Rathmann <Uwe.Rathmann@tigertal.de>
Date: Wed, 10 Apr 2019 19:39:06 +0200
Subject: [PATCH] manually scaling textures according to window coordinates

---
 src/controls/QskSkinlet.cpp  | 51 +++++++++++++++++++-----------------
 src/nodes/QskGraphicNode.cpp |  4 +--
 src/nodes/QskGraphicNode.h   |  2 +-
 src/nodes/QskTextureNode.cpp |  4 +--
 4 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/src/controls/QskSkinlet.cpp b/src/controls/QskSkinlet.cpp
index b3a9451e..4d559ee6 100644
--- a/src/controls/QskSkinlet.cpp
+++ b/src/controls/QskSkinlet.cpp
@@ -57,37 +57,43 @@ static inline QSGNode* qskFindNodeByFlag( QSGNode* parent, int nodeRole )
     return nullptr;
 }
 
-static qreal qskDevicePixelRatio( const QskSkinnable* skinnable )
-{
-    if ( auto control = skinnable->owningControl() )
-    {
-        if ( auto window = control->window() )
-            return window->effectiveDevicePixelRatio();
-    }
-
-    return qGuiApp->devicePixelRatio();
-}
-
 static inline QSGNode* qskUpdateGraphicNode(
     const QskSkinnable* skinnable, QSGNode* node,
     const QskGraphic& graphic, const QskColorFilter& colorFilter,
-    const QRect& rect )
+    const QRectF& rect )
 {
     if ( rect.isEmpty() )
         return nullptr;
 
     auto mode = QskTextureRenderer::OpenGL;
 
-    const auto control = skinnable->owningControl();
-    if ( control && control->testControlFlag( QskControl::PreferRasterForTextures ) )
-        mode = QskTextureRenderer::Raster;
-
     auto graphicNode = static_cast< QskGraphicNode* >( node );
     if ( graphicNode == nullptr )
         graphicNode = new QskGraphicNode();
 
-    const qreal ratio = qskDevicePixelRatio( skinnable );
-    const QRect r( rect.x(), rect.y(), ratio * rect.width(), ratio * rect.height() );
+    QRectF r = rect;
+
+    if ( const auto control = skinnable->owningControl() )
+    {
+        if ( control->testControlFlag( QskControl::PreferRasterForTextures ) )
+            mode = QskTextureRenderer::Raster;
+
+        if ( auto window = control->window() )
+        {
+            /*
+               Aligning the rect according to scene coordinates, so that
+               we don't run into rounding issues downstream, where values
+               will be floored/ceiled ending up with a slightly different
+               aspect ratio.
+             */
+            const QRectF sceneRect(
+                control->mapToScene( r.topLeft() ),
+                r.size() * window->effectiveDevicePixelRatio() );
+
+            r = qskInnerRect( sceneRect );
+            r.moveTopLeft( control->mapFromScene( r.topLeft() ) );
+        }
+    }
 
     graphicNode->setGraphic( graphic, colorFilter, mode, r );
 
@@ -538,12 +544,10 @@ QSGNode* QskSkinlet::updateGraphicNode(
     if ( graphic.isNull() )
         return nullptr;
 
-    const QSizeF scaledSize = graphic.defaultSize().scaled(
+    const QSizeF size = graphic.defaultSize().scaled(
         rect.size(), Qt::KeepAspectRatio );
 
-    const QRect r = qskAlignedRect( qskInnerRect( rect ),
-        int( scaledSize.width() ), int( scaledSize.height() ), alignment );
-
+    const QRectF r = qskAlignedRectF( rect, size.width(), size.height(), alignment );
     return qskUpdateGraphicNode( skinnable, node, graphic, colorFilter, r );
 }
 
@@ -555,8 +559,7 @@ QSGNode* QskSkinlet::updateGraphicNode(
     if ( graphic.isNull() )
         return nullptr;
 
-    return qskUpdateGraphicNode( skinnable, node,
-        graphic, colorFilter, rect.toAlignedRect() );
+    return qskUpdateGraphicNode( skinnable, node, graphic, colorFilter, rect );
 }
 
 #include "moc_QskSkinlet.cpp"
diff --git a/src/nodes/QskGraphicNode.cpp b/src/nodes/QskGraphicNode.cpp
index 56419623..e4ff34b1 100644
--- a/src/nodes/QskGraphicNode.cpp
+++ b/src/nodes/QskGraphicNode.cpp
@@ -47,7 +47,7 @@ QskGraphicNode::~QskGraphicNode()
 
 void QskGraphicNode::setGraphic(
     const QskGraphic& graphic, const QskColorFilter& colorFilter,
-    QskTextureRenderer::RenderMode renderMode, const QRect& rect )
+    QskTextureRenderer::RenderMode renderMode, const QRectF& rect )
 {
     bool isTextureDirty = ( QskTextureNode::textureId() == 0 );
 
@@ -70,7 +70,7 @@ void QskGraphicNode::setGraphic(
     if ( isTextureDirty )
     {
         const uint textureId = QskTextureRenderer::createTextureFromGraphic(
-            renderMode, rect.size(), graphic, colorFilter, Qt::IgnoreAspectRatio );
+            renderMode, rect.size().toSize(), graphic, colorFilter, Qt::IgnoreAspectRatio );
 
         QskTextureNode::setTextureId( textureId );
     }
diff --git a/src/nodes/QskGraphicNode.h b/src/nodes/QskGraphicNode.h
index e039d5be..3c139adf 100644
--- a/src/nodes/QskGraphicNode.h
+++ b/src/nodes/QskGraphicNode.h
@@ -19,7 +19,7 @@ class QSK_EXPORT QskGraphicNode : public QskTextureNode
     ~QskGraphicNode() override;
 
     void setGraphic( const QskGraphic&, const QskColorFilter&,
-        QskTextureRenderer::RenderMode, const QRect& );
+        QskTextureRenderer::RenderMode, const QRectF& );
 
   private:
     void setTextureId( int ) = delete;
diff --git a/src/nodes/QskTextureNode.cpp b/src/nodes/QskTextureNode.cpp
index 53dfe5d0..5051ad0d 100644
--- a/src/nodes/QskTextureNode.cpp
+++ b/src/nodes/QskTextureNode.cpp
@@ -316,11 +316,9 @@ void QskTextureNode::updateTexture()
         r.setBottom( 0 );
     }
 
-#if 1
     const qreal ratio = qskDevicePixelRatio();
-    const QRect rect( d->rect.x(), d->rect.y(),
+    const QRectF rect( d->rect.x(), d->rect.y(),
         d->rect.width() / ratio, d->rect.height() / ratio );
-#endif
 
     QSGGeometry::updateTexturedRectGeometry( &d->geometry, rect, r );
 }