From 66b926e0cf63da0765a3eb4b4b25bf2357d76e52 Mon Sep 17 00:00:00 2001
From: Stefan Csomor <csomor@advancedconcepts.ch>
Date: Fri, 30 May 2008 16:47:45 +0000
Subject: [PATCH] fixing a problem where CoreGraphics didn't correctly clip to
 an empty region

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@53845 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/mac/carbon/graphics.cpp | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/src/mac/carbon/graphics.cpp b/src/mac/carbon/graphics.cpp
index 2c9c1dad3d..0119269f1c 100755
--- a/src/mac/carbon/graphics.cpp
+++ b/src/mac/carbon/graphics.cpp
@@ -1345,9 +1345,6 @@ void wxMacCoreGraphicsContext::Init()
     m_cgContext = NULL;
     m_releaseContext = false;
     m_windowRef = NULL;
-
-    HIRect r = CGRectMake(0,0,0,0);
-    m_clipRgn.Set(HIShapeCreateWithRect(&r));
 }
 
 wxMacCoreGraphicsContext::wxMacCoreGraphicsContext( wxGraphicsRenderer* renderer, CGContextRef cgcontext ) : wxGraphicsContext(renderer)
@@ -1408,7 +1405,7 @@ void wxMacCoreGraphicsContext::EnsureIsValid()
         CGContextConcatCTM( m_cgContext, m_windowTransform );
 		CGContextSaveGState( m_cgContext );
 		m_releaseContext = true;
-		if ( !HIShapeIsEmpty(m_clipRgn) )
+		if ( (HIShapeRef) m_clipRgn != NULL )
 		{
             // the clip region is in device coordinates, so we convert this again to user coordinates
             wxMacCFRefHolder<HIMutableShapeRef> hishape ;
@@ -1416,7 +1413,17 @@ void wxMacCoreGraphicsContext::EnsureIsValid()
             CGPoint transformedOrigin = CGPointApplyAffineTransform( CGPointZero,m_windowTransform);
             HIShapeOffset( hishape, -transformedOrigin.x, -transformedOrigin.y );
 			HIShapeReplacePathInCGContext( hishape, m_cgContext );
-			CGContextClip( m_cgContext );
+            // if the shape is empty, HIShapeReplacePathInCGContext doesn't work
+            if ( HIShapeIsEmpty(hishape))
+            {
+                CGRect empty = CGRectMake( 0,0,0,0 );
+                CGContextClipToRect( m_cgContext, empty );
+            }
+            else
+            {
+                HIShapeReplacePathInCGContext( hishape, m_cgContext );
+                CGContextClip( m_cgContext );
+            }
 		}
 		CGContextSaveGState( m_cgContext );
 	}
@@ -1464,10 +1471,19 @@ void wxMacCoreGraphicsContext::Clip( const wxRegion &region )
 {
     if( m_cgContext )
     {
-        HIShapeRef shape = HIShapeCreateWithQDRgn( (RgnHandle) region.GetWXHRGN() );
-        HIShapeReplacePathInCGContext( shape, m_cgContext );
-        CGContextClip( m_cgContext );
-        CFRelease( shape );
+        wxMacCFRefHolder<HIShapeRef> shape;
+        shape = HIShapeCreateWithQDRgn( (RgnHandle) region.GetWXHRGN() );
+        // if the shape is empty, HIShapeReplacePathInCGContext doesn't work
+        if ( HIShapeIsEmpty(shape))
+        {
+            CGRect empty = CGRectMake( 0,0,0,0 );
+            CGContextClipToRect( m_cgContext, empty );
+        }
+        else
+        {
+            HIShapeReplacePathInCGContext( shape, m_cgContext );
+            CGContextClip( m_cgContext );
+        }
     }
     else
     {
@@ -1517,8 +1533,7 @@ void wxMacCoreGraphicsContext::ResetClip()
     }
     else
     {
-        HIRect r = CGRectMake(0,0,0,0);
-        m_clipRgn.Set(HIShapeCreateWithRect(&r));
+        m_clipRgn.Release();
     }
 }