Track positions of dimensions in image files

third_party/WebKit/Source/platform/image-decoders/gif/GIFImageReader.cpp

 /* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
@@ skipping 445 matching lines @@
                     reader.getConsecutiveData(currentComponentPosition, 5, readBuffer));
 
             // This is the height and width of the "screen" or frame into which
             // images are rendered. The individual images can be smaller than
             // the screen size and located with an origin anywhere within the
             // screen.
             // Note that we don't inform the client of the size yet, as it might
             // change after we read the first frame's image header.
             m_screenWidth = GETINT16(currentComponent);
             m_screenHeight = GETINT16(currentComponent + 2);
-
+            m_client->setSizeOffsetOptimized(currentComponentPosition + 4);
             const size_t globalColorMapColors = 2 << (currentComponent[4] & 0x07);
 
             if ((currentComponent[4] & 0x80) && globalColorMapColors > 0) { /* global map */
                 m_globalColorMap.setTablePositionAndSize(dataPosition, globalColorMapColors);
                 GETN(BYTES_PER_COLORMAP_ENTRY * globalColorMapColors, GIFGlobalColormap);
                 break;
             }
 
             GETN(1, GIFImageStart);
             break;
@@ skipping 205 matching lines @@
             // the image size to allow the frame to be visible.  We can't do
             // this on subsequent frames because the rest of the decoding
             // infrastructure assumes the image size won't change as we
             // continue decoding, so any subsequent frames that are even
             // larger will be cropped.
             // Luckily, handling just the first frame is sufficient to deal
             // with most cases, e.g. ones where the image size is erroneously
             // set to zero, since usually the first frame completely fills
             // the image.
             if (currentFrameIsFirstFrame()) {
+                bool updated = (m_screenHeight < yOffset + height || m_screenWidth < yOffset + width);
+                if (updated)
+                    m_client->setSizeOffsetOptimized(0);
+                m_client->setSizeOffset(currentComponentPosition + 8);
                 m_screenHeight = std::max(m_screenHeight, yOffset + height);
                 m_screenWidth = std::max(m_screenWidth, xOffset + width);
             }
 
             // Inform the client of the final size.
             if (!m_sentSizeToClient && m_client && !m_client->setSize(m_screenWidth, m_screenHeight))
                 return false;
             m_sentSizeToClient = true;
 
             if (query == GIFImageDecoder::GIFSizeQuery) {
@@ skipping 138 matching lines @@
     rowIter = rowBuffer.begin();
     rowsRemaining = m_frameContext->height();
 
     // Clearing the whole suffix table lets us be more tolerant of bad data.
     for (int i = 0; i < clearCode; ++i) {
         suffix[i] = i;
         suffixLength[i] = 1;
     }
     return true;
 }