Added ColorDepth change test with assertion to the Bitmap::Scale method

vcl/source/gdi/bitmap3.cxx

@@ -906,10 +906,13 @@ sal_Bool Bitmap::ImplConvertGhosted()
 
 sal_Bool Bitmap::Scale( const double& rScaleX, const double& rScaleY, sal_uLong nScaleFlag )
 {
+    bool bRetval(false);
+
 #ifdef DBG_UTIL
     // #121233# allow to test the different scalers in debug build with source
     // level debugger (change nNumber to desired action)
     static sal_uInt16 nNumber(0);
+    const sal_uInt16 nStartCount(GetBitCount());
 
     switch(nNumber)
     {
@@ -929,7 +932,7 @@ sal_Bool Bitmap::Scale( const double& rScaleX, const double& rScaleY, sal_uLong
     if(basegfx::fTools::equalZero(rScaleX) && basegfx::fTools::equalZero(rScaleY))
     {
         // no scale
-        return true;
+        bRetval = true;
     }
     else
     {
@@ -949,17 +952,17 @@ sal_Bool Bitmap::Scale( const double& rScaleX, const double& rScaleY, sal_uLong
             default:
             case BMP_SCALE_NONE :
             {
-                return false;
+                bRetval = false;
                 break;
             }
             case BMP_SCALE_FAST :
             {
-                return ImplScaleFast( rScaleX, rScaleY );
+                bRetval = ImplScaleFast( rScaleX, rScaleY );
                 break;
             }
             case BMP_SCALE_INTERPOLATE :
             {
-                return ImplScaleInterpolate( rScaleX, rScaleY );
+                bRetval = ImplScaleInterpolate( rScaleX, rScaleY );
                 break;
             }
             case BMP_SCALE_SUPER :
@@ -967,12 +970,12 @@ sal_Bool Bitmap::Scale( const double& rScaleX, const double& rScaleY, sal_uLong
                 if(GetSizePixel().Width() < 2 || GetSizePixel().Height() < 2)
                 {
                     // fallback to ImplScaleFast
-                    return ImplScaleFast( rScaleX, rScaleY );
+                    bRetval = ImplScaleFast( rScaleX, rScaleY );
                 }
                 else
                 {
                     // #121233# use method from symphony
-                    return ImplScaleSuper( rScaleX, rScaleY );
+                    bRetval = ImplScaleSuper( rScaleX, rScaleY );
                 }
                 break;
             }
@@ -980,35 +983,41 @@ sal_Bool Bitmap::Scale( const double& rScaleX, const double& rScaleY, sal_uLong
             {
                 const Lanczos3Kernel kernel;
 
-                return ImplScaleConvolution( rScaleX, rScaleY, kernel);
+                bRetval = ImplScaleConvolution( rScaleX, rScaleY, kernel);
                 break;
             }
             case BMP_SCALE_BICUBIC :
             {
                 const BicubicKernel kernel;
 
-                return ImplScaleConvolution( rScaleX, rScaleY, kernel );
+                bRetval = ImplScaleConvolution( rScaleX, rScaleY, kernel );
                 break;
             }
             case BMP_SCALE_BILINEAR :
             {
                 const BilinearKernel kernel;
 
-                return ImplScaleConvolution( rScaleX, rScaleY, kernel );
+                bRetval = ImplScaleConvolution( rScaleX, rScaleY, kernel );
                 break;
             }
             case BMP_SCALE_BOX :
             {
                 const BoxKernel kernel;
 
-                return ImplScaleConvolution( rScaleX, rScaleY, kernel );
+                bRetval = ImplScaleConvolution( rScaleX, rScaleY, kernel );
                 break;
             }
         }
     }
 
-    // should not happen
-    return false;
+#ifdef DBG_UTIL
+    if(bRetval && nStartCount != GetBitCount())
+    {
+        OSL_ENSURE(false, "Bitmap::Scale has changed the ColorDepth, this should *not* happen (!)");
+    }
+#endif
+
+    return bRetval;
 }
 
 // ------------------------------------------------------------------------