From 315a021fbd5398c7720d0ce5d29436ca8fdc448c Mon Sep 17 00:00:00 2001
From: sekelsenmat <sekelsenmat@lazarus-ide.org>
Date: Sun, 28 Jan 2007 14:48:40 +0000
Subject: [PATCH] Small improvements on coordinate handling on Qt's
 StretchDraw.

git-svn-id: trunk@10524 -
---
 lcl/interfaces/qt/qtobjects.pas | 25 +++++++++++++++++++++++++
 lcl/interfaces/qt/qtwinapi.inc  | 16 ++++++++++------
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/lcl/interfaces/qt/qtobjects.pas b/lcl/interfaces/qt/qtobjects.pas
index e32f768a2a..022823fed4 100644
--- a/lcl/interfaces/qt/qtobjects.pas
+++ b/lcl/interfaces/qt/qtobjects.pas
@@ -203,6 +203,7 @@ type
     function RestoreDCData(DCData: PQtDCData): boolean;
     procedure DebugClipRect(const msg: string);
     procedure setImage(AImage: TQtImage);
+    procedure CorrectCoordinates(var ARect: TRect);
   public
     { Qt functions }
     procedure drawPoint(x1: Integer; y1: Integer);
@@ -842,6 +843,30 @@ begin
   Widget := QPainter_Create(vImage);
 end;
 
+{------------------------------------------------------------------------------
+  Function: TQtDeviceContext.CorrectCoordinates
+  Params:  None
+  Returns: Nothing
+  
+  If you draw an image with negative coordinates
+ (for example x: -50 y: -50 w: 100 h: 100), the result is not well
+ defined in Qt, and could well be: (x: 0 y: 0 w: 100 h: 100)
+  This method corrects the coordinates, cutting the result, so we draw:
+ (x: 0 y: 0 w: 50 h: 50)
+ ------------------------------------------------------------------------------}
+procedure TQtDeviceContext.CorrectCoordinates(var ARect: TRect);
+var
+  Buffer: Integer;
+begin
+  if ARect.Left < 0 then ARect.Left := 0;
+
+  if ARect.Top < 0 then ARect.Top := 0;
+
+{  if ARect.Right > MaxRight then ARect.Right := MaxRight;
+
+  if ARect.Bottom > MaxBottom then ARect.Bottom := MaxBottom;}
+end;
+
 {------------------------------------------------------------------------------
   Function: TQtDeviceContext.CreateDCData
   Params:  None
diff --git a/lcl/interfaces/qt/qtwinapi.inc b/lcl/interfaces/qt/qtwinapi.inc
index 7238cdec32..57896d1a4b 100644
--- a/lcl/interfaces/qt/qtwinapi.inc
+++ b/lcl/interfaces/qt/qtwinapi.inc
@@ -2641,12 +2641,6 @@ var
   SrcRect, DstRect: TRect;
   Image: QImageH;
 begin
-  DstRect := Bounds(X, Y, Width, Height);
-
-  SrcRect := Bounds(XSrc, YSrc, SrcWidth, SrcHeight);
-  
-  Image := TQtDeviceContext(SrcDC).vImage;
-
   {$ifdef VerboseQtWinAPI}
     WriteLn('[WinAPI StretchMaskBlt]',
      ' DestDC:', dbghex(DestDC),
@@ -2658,6 +2652,16 @@ begin
      ' WSrc:', dbgs(SrcWidth), ' HSrc:', dbgs(SrcHeight));
   {$endif}
 
+  DstRect := Bounds(X, Y, Width, Height);
+
+  SrcRect := Bounds(XSrc, YSrc, SrcWidth, SrcHeight);
+  
+  Image := TQtDeviceContext(SrcDC).vImage;
+
+  TQtDeviceContext(DestDC).CorrectCoordinates(DstRect);
+
+  TQtDeviceContext(DestDC).CorrectCoordinates(SrcRect);
+
   TQtDeviceContext(DestDC).drawImage(@DstRect, Image, @SrcRect);
 
   Result := True;