From bcd8ed3042ca79533f5226c4b6324c97a17ef76f Mon Sep 17 00:00:00 2001
From: zeljko <zeljko@lazarus-ide.org>
Date: Thu, 18 Feb 2010 08:56:30 +0000
Subject: [PATCH] Qt: check for clip rect size before image drawing. fixes
 #15622 and #15684

git-svn-id: trunk@23730 -
---
 lcl/interfaces/qt/qtobjects.pas | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lcl/interfaces/qt/qtobjects.pas b/lcl/interfaces/qt/qtobjects.pas
index 69201195fb..606b98d865 100644
--- a/lcl/interfaces/qt/qtobjects.pas
+++ b/lcl/interfaces/qt/qtobjects.pas
@@ -2818,6 +2818,7 @@ procedure TQtDeviceContext.drawImage(targetRect: PRect;
       mask: QImageH; maskRect: PRect; flags: QtImageConversionFlags = QtAutoColor);
 var
   LocalRect: TRect;
+  R: TRect;
   APixmap, ATemp: QPixmapH;
   AMask: QBitmapH;
   ScaledImage: QImageH;
@@ -2826,6 +2827,17 @@ begin
   Write('TQtDeviceContext.drawImage() ');
   {$endif}
   LocalRect := targetRect^;
+  R := getClipRegion.getBoundingRect;
+  {cannot draw on empty rect - no bounding rect}
+  if IsRectEmpty(R) then
+    exit;
+
+  {if clip region is smaller than target rect then
+   target rect should be clip rect}
+  if ((R.Right - R.Left) < (LocalRect.Right - LocalRect.Left)) and
+    ((R.Bottom - R.Top) < (LocalRect.Bottom - LocalRect.Top)) then
+    LocalRect := R;
+
   if mask <> nil then
   begin
     // TODO: check maskRect
@@ -2856,7 +2868,6 @@ begin
      results with RGB32 images on Linux and Win32 if DstRect <> sourceRect.
      Explanation: Look at #11713 linux & win screenshoots.
      Note: This is slower operation than QImage_scaled() we used before.}
-
     if not EqualRect(LocalRect, sourceRect^) and
       (QImage_format(Image) = QImageFormat_RGB32) then
     begin