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
(cherry picked from commit 4b9ecfd4f45501e4696f966c714fc2bcc43ce38b)
Reviewed-on: https://gerrit.libreoffice.org/14115
Tested-by: Julien Nabet <serval2412@yahoo.fr>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

2 files changed, 16 insertions, 9 deletions

diff --git a/vcl/source/gdi/bitmap3.cxx b/vcl/source/gdi/bitmap3.cxx
index 211516045adb..a99cd7705d2b 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 32ca3cc4412d..b995d0a1b021 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 );