From 645c2a8dda0a858e67236c0d262fb167d0745f2f Mon Sep 17 00:00:00 2001
From: zeljan1 <zeljko@holobit.hr>
Date: Tue, 31 Dec 2024 22:50:25 +0100
Subject: [PATCH] Qt5, Qt6: fix bitBlt when device is scaled. issue #41299

---
 lcl/interfaces/qt5/qtwinapi.inc | 27 ++++++++++++++++++++-------
 lcl/interfaces/qt6/qtwinapi.inc | 27 ++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/lcl/interfaces/qt5/qtwinapi.inc b/lcl/interfaces/qt5/qtwinapi.inc
index d0be99a21a..578fcc68c8 100644
--- a/lcl/interfaces/qt5/qtwinapi.inc
+++ b/lcl/interfaces/qt5/qtwinapi.inc
@@ -6784,6 +6784,12 @@ var
     else
       QPixmap_copy(APixmap, ATempPixmap, 0, 0, QPixmap_width(APixmap), QPixmap_height(APixmap));
 
+    if (AMaskImg = nil) and QPixmap_isNull(ATempPixmap) then
+    begin
+      QPixmap_destroy(ATempPixmap);
+      exit;
+    end;
+
     if AMaskImg <> nil then
     begin
       // apply mask to pixmap
@@ -6794,8 +6800,8 @@ var
 
         if IsRectEmpty(MaskRect) or (MaskRect.Size <> DstRect.Size) then
         begin
-          if (QPixmap_width(ATempPixmap) < (DstRect.Right - DstRect.Left)) or
-            (QPixmap_Height(ATempPixmap) < (DstRect.Bottom - DstRect.Top)) then
+          if not QPixmap_isNull(ATempPixmap) and ((QPixmap_width(ATempPixmap) < (DstRect.Right - DstRect.Left)) or
+            (QPixmap_Height(ATempPixmap) < (DstRect.Bottom - DstRect.Top))) then
             QPixmap_scaled(AMaskPix, AScaledPix, QPixmap_width(ATempPixmap), QPixmap_height(ATempPixmap))
           else
             QPixmap_scaled(AMaskPix, AScaledPix, Width, Height);
@@ -6813,13 +6819,20 @@ var
       end;
     end;
 
-    if ARenderHint then
-      QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, True);
+    if not QPixmap_isNull(ATempPixmap) then
+    begin
+      if ARenderHint then
+        QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, True);
 
-    QPainter_drawPixmap(DstQDC.Widget, X, Y, Width, Height, ATempPixmap);
+      if (QPixmap_width(ATempPixmap) = Width) and (QPixmap_height(ATempPixmap) = Height) and (Rop = SRCCOPY) then
+      begin
+        QPainter_drawPixmap(DstQDC.Widget, X, Y, ATempPixmap);
+      end else
+        QPainter_drawPixmap(DstQDC.Widget, X, Y, Width, Height, ATempPixmap);
 
-    if ARenderHint then
-      QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, not ARenderHint);
+      if ARenderHint then
+        QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, not ARenderHint);
+    end;
 
     QPixmap_destroy(ATempPixmap);
   end;
diff --git a/lcl/interfaces/qt6/qtwinapi.inc b/lcl/interfaces/qt6/qtwinapi.inc
index 323721e0ae..854350365a 100644
--- a/lcl/interfaces/qt6/qtwinapi.inc
+++ b/lcl/interfaces/qt6/qtwinapi.inc
@@ -6845,6 +6845,12 @@ var
     else
       QPixmap_copy(APixmap, ATempPixmap, 0, 0, QPixmap_width(APixmap), QPixmap_height(APixmap));
 
+    if (AMaskImg = nil) and QPixmap_isNull(ATempPixmap) then
+    begin
+      QPixmap_destroy(ATempPixmap);
+      exit;
+    end;
+
     if AMaskImg <> nil then
     begin
       // apply mask to pixmap
@@ -6855,8 +6861,8 @@ var
 
         if IsRectEmpty(MaskRect) or (MaskRect.Size <> DstRect.Size) then
         begin
-          if (QPixmap_width(ATempPixmap) < (DstRect.Right - DstRect.Left)) or
-            (QPixmap_Height(ATempPixmap) < (DstRect.Bottom - DstRect.Top)) then
+          if not QPixmap_isNull(ATempPixmap) and ((QPixmap_width(ATempPixmap) < (DstRect.Right - DstRect.Left)) or
+            (QPixmap_Height(ATempPixmap) < (DstRect.Bottom - DstRect.Top))) then
             QPixmap_scaled(AMaskPix, AScaledPix, QPixmap_width(ATempPixmap), QPixmap_height(ATempPixmap))
           else
             QPixmap_scaled(AMaskPix, AScaledPix, Width, Height);
@@ -6874,13 +6880,20 @@ var
       end;
     end;
 
-    if ARenderHint then
-      QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, True);
+    if not QPixmap_isNull(ATempPixmap) then
+    begin
+      if ARenderHint then
+        QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, True);
 
-    QPainter_drawPixmap(DstQDC.Widget, X, Y, Width, Height, ATempPixmap);
+      if (QPixmap_width(ATempPixmap) = Width) and (QPixmap_height(ATempPixmap) = Height) and (Rop = SRCCOPY) then
+      begin
+        QPainter_drawPixmap(DstQDC.Widget, X, Y, ATempPixmap);
+      end else
+        QPainter_drawPixmap(DstQDC.Widget, X, Y, Width, Height, ATempPixmap);
 
-    if ARenderHint then
-      QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, not ARenderHint);
+      if ARenderHint then
+        QPainter_setRenderHint(DstQDC.Widget, QPainterSmoothPixmapTransform, not ARenderHint);
+    end;
 
     QPixmap_destroy(ATempPixmap);
   end;