Resolves: fdo#87639 Image-filter Smooth crashes

regression from

commit 10e77ab3ff6f4314137acd6e2702a6e5c1ce1fae
Author: Thorsten Behrens <thb@documentfoundation.org>
Date:   Sun Nov 2 22:37:32 2014 +0100

coverity#1242508: swapped arguments

rename the variables to indicate which are source and
which are dest indexes and that the aNewBitmap
argument is always, and assert that it must be, of
equivalent rotated source to the Bitmap which has
ImplConvolutionPass called on it.

Change-Id: If9715b9f29655da66c6981c0f7cab3d89c528ed7

3 files changed, 16 insertions, 10 deletions

diff --git a/include/vcl/bitmap.hxx b/include/vcl/bitmap.hxx
index 0fe2afa4eda1..25842c6d53e6 100644
--- a/include/vcl/bitmap.hxx
+++ b/include/vcl/bitmap.hxx
@@ -807,7 +807,6 @@ public:
 
     SAL_DLLPRIVATE bool     ImplConvolutionPass(
                                 Bitmap& aNewBitmap,
-                                const int nNewSize,
                                 BitmapReadAccess* pReadAcc,
                                 int aNumberOfContributions,
                                 double* pWeights,
diff --git a/vcl/source/gdi/bitmap3.cxx b/vcl/source/gdi/bitmap3.cxx
index 83ce47fff5b0..2bd586f5f24c 100644
--- a/vcl/source/gdi/bitmap3.cxx
+++ b/vcl/source/gdi/bitmap3.cxx
@@ -2593,7 +2593,7 @@ bool Bitmap::Adjust( short nLuminancePercent, short nContrastPercent,
     return bRet;
 }
 
-bool Bitmap::ImplConvolutionPass(Bitmap& aNewBitmap, const int nNewSize, BitmapReadAccess* pReadAcc, int aNumberOfContributions, double* pWeights, int* pPixels, int* pCount)
+bool Bitmap::ImplConvolutionPass(Bitmap& aNewBitmap, BitmapReadAccess* pReadAcc, int aNumberOfContributions, double* pWeights, int* pPixels, int* pCount)
 {
     BitmapWriteAccess* pWriteAcc = aNewBitmap.AcquireWriteAccess();
 
@@ -2601,25 +2601,28 @@ bool Bitmap::ImplConvolutionPass(Bitmap& aNewBitmap, const int nNewSize, BitmapR
         return false;
 
     const int nHeight = GetSizePixel().Height();
+    assert(GetSizePixel().Height() == aNewBitmap.GetSizePixel().Width());
+    const int nWidth = GetSizePixel().Width();
+    assert(GetSizePixel().Width() == aNewBitmap.GetSizePixel().Height());
 
     BitmapColor aColor;
     double aValueRed, aValueGreen, aValueBlue;
     double aSum, aWeight;
     int aBaseIndex, aIndex;
 
-    for ( int y = 0; y < nHeight; y++ )
+    for (int nSourceY = 0; nSourceY < nHeight; ++nSourceY)
     {
-        for ( int x = 0; x < nNewSize; x++ )
+        for (int nSourceX = 0; nSourceX < nWidth; ++nSourceX)
         {
-            aBaseIndex = x * aNumberOfContributions;
+            aBaseIndex = nSourceX * aNumberOfContributions;
             aSum = aValueRed = aValueGreen = aValueBlue = 0.0;
 
-            for ( int j=0; j < pCount[x]; j++ )
+            for (int j = 0; j < pCount[nSourceX]; ++j)
             {
                 aIndex = aBaseIndex + j;
                 aSum += aWeight = pWeights[ aIndex ];
 
-                aColor = pReadAcc->GetColor( y, pPixels[ aIndex ] );
+                aColor = pReadAcc->GetColor(nSourceY, pPixels[aIndex]);
 
                 aValueRed += aWeight * aColor.GetRed();
                 aValueGreen += aWeight * aColor.GetGreen();
@@ -2630,7 +2633,11 @@ bool Bitmap::ImplConvolutionPass(Bitmap& aNewBitmap, const int nNewSize, BitmapR
                 (sal_uInt8) MinMax( aValueRed / aSum, 0, 255 ),
                 (sal_uInt8) MinMax( aValueGreen / aSum, 0, 255 ),
                 (sal_uInt8) MinMax( aValueBlue / aSum, 0, 255 ) );
-            pWriteAcc->SetPixel( y, x, aResultColor );
+
+            int nDestX = nSourceY;
+            int nDestY = nSourceX;
+
+            pWriteAcc->SetPixel(nDestY, nDestX, aResultColor);
         }
     }
     aNewBitmap.ReleaseAccess( pWriteAcc );
diff --git a/vcl/source/gdi/bitmap4.cxx b/vcl/source/gdi/bitmap4.cxx
index a18b9c26b71e..bb588b54d373 100644
--- a/vcl/source/gdi/bitmap4.cxx
+++ b/vcl/source/gdi/bitmap4.cxx
@@ -1099,7 +1099,7 @@ bool Bitmap::ImplSeparableBlurFilter(const double radius)
     // switch coordinates as convolution pass transposes result
     Bitmap aNewBitmap( Size( nHeight, nWidth ), 24 );
 
-    bool bResult = ImplConvolutionPass( aNewBitmap, nWidth, pReadAcc, aNumberOfContributions, pWeights, pPixels, pCount );
+    bool bResult = ImplConvolutionPass( aNewBitmap, pReadAcc, aNumberOfContributions, pWeights, pPixels, pCount );
 
     // Cleanup
     ReleaseAccess( pReadAcc );
@@ -1121,7 +1121,7 @@ bool Bitmap::ImplSeparableBlurFilter(const double radius)
 
     pReadAcc = AcquireReadAccess();
     aNewBitmap = Bitmap( Size( nWidth, nHeight ), 24 );
-    bResult = ImplConvolutionPass( aNewBitmap, nHeight, pReadAcc, aNumberOfContributions, pWeights, pPixels, pCount );
+    bResult = ImplConvolutionPass( aNewBitmap, pReadAcc, aNumberOfContributions, pWeights, pPixels, pCount );
 
     // Cleanup
     ReleaseAccess( pReadAcc );