Bug 86600 - nsImageGTK::DrawToImage() was only updating the server side

pixmap.  Add code for the client side copy.  r=pavlov, sr=blizzard, a=asa

gfx/src/gtk/nsImageGTK.cpp

@@ -1720,6 +1720,101 @@ NS_IMETHODIMP nsImageGTK::DrawToImage(nsIImage* aDstImage,
 
   gdk_gc_unref(gc);
 
+  // need to copy the mImageBits in case we're rendered scaled
+  PRUint8 *scaledImage = 0, *scaledAlpha = 0;
+  PRUint8 *rgbPtr=0, *alphaPtr=0;
+  PRUint32 rgbStride, alphaStride;
+
+  if ((aDWidth != mWidth) || (aDHeight != mHeight)) {
+    // scale factor in DrawTo... start scaling
+    scaledImage = (PRUint8 *)nsMemory::Alloc(3*aDWidth*aDHeight);
+    if (!scaledImage)
+      return NS_ERROR_OUT_OF_MEMORY;
+
+    RectStretch(0, 0, mWidth-1, mHeight-1, 0, 0, aDWidth-1, aDHeight-1,
+                mImageBits, mRowBytes, scaledImage, 3*aDWidth, 24);
+
+    if (mAlphaDepth) {
+      if (mAlphaDepth==1)
+        alphaStride = (aDWidth+7)>>3;    // round to next byte
+      else
+        alphaStride = aDWidth;
+
+      scaledAlpha = (PRUint8 *)nsMemory::Alloc(alphaStride*aDHeight);
+      if (!scaledAlpha) {
+        nsMemory::Free(scaledImage);
+        return NS_ERROR_OUT_OF_MEMORY;
+      }
+
+      RectStretch(0, 0, mWidth-1, mHeight-1, 0, 0, aDWidth-1, aDHeight-1,
+                  mAlphaBits, mAlphaRowBytes, scaledAlpha, alphaStride,
+                  mAlphaDepth);
+    }
+    rgbPtr = scaledImage;
+    rgbStride = 3*aDWidth;
+    alphaPtr = scaledAlpha;
+  } else {
+    rgbPtr = mImageBits;
+    rgbStride = mRowBytes;
+    alphaPtr = mAlphaBits;
+    alphaStride = mAlphaRowBytes;
+  }
+
+  // now composite the two images together
+  switch (mAlphaDepth) {
+  case 1:
+    for (int y=0; y<aDHeight; y++) {
+      PRUint8 *dst = dest->mImageBits + (y+aDY)*dest->mRowBytes + 3*aDX;
+      PRUint8 *dstAlpha = dest->mAlphaBits + (y+aDY)*dest->mAlphaRowBytes;
+      PRUint8 *src = rgbPtr + y*rgbStride; 
+      PRUint8 *alpha = alphaPtr + y*alphaStride;
+      for (int x=0; x<aDWidth; x++, dst+=3, src+=3) {
+#define GET_BIT(rowptr, x) (rowptr[(x)>>3] &  (1<<(7-(x)&0x7)))
+#define SET_BIT(rowptr, x) (rowptr[(x)>>3] |= (1<<(7-(x)&0x7)))
+
+        // if this pixel is opaque then copy into the destination image
+        if (GET_BIT(alpha, x)) {
+          dst[0] = src[0];
+          dst[1] = src[1];
+          dst[2] = src[2];
+          SET_BIT(dstAlpha, aDX+x);
+        }
+
+#undef GET_BIT
+#undef SET_BIT
+      }
+    }
+    break;
+  case 8:
+    for (int y=0; y<aDHeight; y++) {
+      PRUint8 *dst = dest->mImageBits + (y+aDY)*dest->mRowBytes + 3*aDX;
+      PRUint8 *dstAlpha = 
+        dest->mAlphaBits + (y+aDY)*dest->mAlphaRowBytes + aDX;
+      PRUint8 *src = rgbPtr + y*rgbStride; 
+      PRUint8 *alpha = alphaPtr + y*alphaStride;
+      for (int x=0; x<aDWidth; x++, dst+=3, dstAlpha++, src+=3, alpha++) {
+
+        // blend this pixel over the destination image
+        unsigned val = *alpha;
+        MOZ_BLEND(dst[0], dst[0], src[0], val);
+        MOZ_BLEND(dst[1], dst[1], src[1], val);
+        MOZ_BLEND(dst[2], dst[2], src[2], val);
+        MOZ_BLEND(*dstAlpha, *dstAlpha, val, val);
+      }
+    }
+    break;
+  case 0:
+  default:
+    for (int y=0; y<aDHeight; y++)
+      memcpy(dest->mImageBits + (y+aDY)*dest->mRowBytes + 3*aDX, 
+             rgbPtr + y*rgbStride,
+             3*aDWidth);
+  }
+  if (scaledAlpha)
+    nsMemory::Free(scaledAlpha);
+  if (scaledImage)
+    nsMemory::Free(scaledImage);
+
   return NS_OK;
 }
 #endif