1 files changed, 12 insertions, 29 deletions

diff --git a/third_party/gif/SkGifImageReader.cpp b/third_party/gif/SkGifImageReader.cpp
index 990da5618b..658e08348f 100644
--- a/third_party/gif/SkGifImageReader.cpp
+++ b/third_party/gif/SkGifImageReader.cpp
@@ -96,6 +96,16 @@ mailing address.
 // Get a 16-bit value stored in little-endian format.
 #define GETINT16(p)   ((p)[1]<<8|(p)[0])
 
+namespace {
+    bool is_palette_index_valid(int transparentIndex) {
+        // -1 is a signal that there is no transparent index.
+        // Otherwise, it is encoded in 8 bits, and all 256 values are considered
+        // valid since a GIF may use an index outside of the palette to be
+        // transparent.
+        return transparentIndex >= 0;
+    }
+} // anonymous namespace
+
 // Send the data to the display front-end.
 void SkGIFLZWContext::outputRow(const unsigned char* rowBegin)
 {
@@ -752,9 +762,7 @@ SkCodec::Result SkGifImageReader::parse(SkGifImageReader::SkGIFParseQuery query)
             if (currentFrameIsFirstFrame()) {
                 const int transPix = m_frames.empty() ? SkGIFColorMap::kNotFound
                                                       : m_frames[0]->transparentPixel();
-                if (this->hasTransparency(transPix,
-                        isLocalColormapDefined, numColors))
-                {
+                if (is_palette_index_valid(transPix)) {
                     m_firstFrameHasAlpha = true;
                 } else {
                     const bool frameIsSubset = xOffset > 0 || yOffset > 0
@@ -846,30 +854,6 @@ SkCodec::Result SkGifImageReader::parse(SkGifImageReader::SkGIFParseQuery query)
     }
 }
 
-bool SkGifImageReader::hasTransparency(int transparentPixel, bool isLocalColormapDefined,
-                                       int localColors) const {
-    const int globalColors = m_globalColorMap.numColors();
-    if (!isLocalColormapDefined && globalColors == 0) {
-        // No color table for this frame, so it is completely transparent.
-        return true;
-    }
-
-    if (transparentPixel < 0) {
-        SkASSERT(SkGIFColorMap::kNotFound == transparentPixel);
-        return false;
-    }
-
-    if (isLocalColormapDefined) {
-        return transparentPixel < localColors;
-    }
-
-    // If there is a global color table, it will be parsed before reaching
-    // here. If its numColors is set, it will be defined.
-    SkASSERT(globalColors > 0);
-    SkASSERT(m_globalColorMap.isDefined());
-    return transparentPixel < globalColors;
-}
-
 void SkGifImageReader::addFrameIfNecessary()
 {
     if (m_frames.empty() || m_frames.back()->isComplete()) {
@@ -899,8 +883,7 @@ bool SkGIFFrameContext::onReportsAlpha() const {
     // Note: We could correct these after decoding - i.e. some frames may turn out to be
     // independent and opaque if they do not use the transparent pixel, but that would require
     // checking whether each pixel used the transparent index.
-    return m_owner->hasTransparency(this->transparentPixel(),
-            m_localColorMap.isDefined(), m_localColorMap.numColors());
+    return is_palette_index_valid(this->transparentPixel());
 }
 
 void SkFrameHolder::setAlphaAndRequiredFrame(SkFrame* frame) {