JPEGImageDecoder RGB565 and downsample support and related Skia imagegenerator changes

third_party/WebKit/Source/platform/image-decoders/ImageFrame.cpp

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008, 2009 Google, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 28 matching lines @@
     , m_premultiplyAlpha(true)
     , m_pixelsChanged(false)
     , m_requiredPreviousFrameIndex(kNotFound)
 {
 }
 
 ImageFrame& ImageFrame::operator=(const ImageFrame& other)
 {
     if (this == &other)
         return *this;
-
     m_bitmap = other.m_bitmap;
     // Keep the pixels locked since we will be writing directly into the
     // bitmap throughout this object's lifetime.
     m_bitmap.lockPixels();
     // Be sure to assign this before calling setStatus(), since setStatus() may
     // call notifyBitmapIfPixelsChanged().
     m_pixelsChanged = other.m_pixelsChanged;
     setMemoryAllocator(other.allocator());
     setOriginalFrameRect(other.originalFrameRect());
     setStatus(other.status());
@@ skipping 27 matching lines @@
 bool ImageFrame::copyBitmapData(const ImageFrame& other)
 {
     if (this == &other)
         return true;
 
     m_hasAlpha = other.m_hasAlpha;
     m_bitmap.reset();
     return other.m_bitmap.copyTo(&m_bitmap, other.m_bitmap.colorType());
 }
 
-bool ImageFrame::setSize(int newWidth, int newHeight)
+bool ImageFrame::setSize(int newWidth, int newHeight, ColorType bitmapType)
 {
-    // setSize() should only be called once, it leaks memory otherwise.
-    ASSERT(!width() && !height());
+    // shouldn't be called with the same size, though not a problem if it happens
+    ASSERT(m_bitmap.isNull() || hasSize(IntSize(newWidth, newHeight), bitmapType));
+    if (bitmapType == RGBA8888) {
+        m_bitmap.setInfo(SkImageInfo::MakeN32Premul(newWidth, newHeight));
+    } else if (bitmapType == RGB565) {
+        m_bitmap.setInfo(SkImageInfo::Make(newWidth, newHeight, kRGB_565_SkColorType, kOpaque_SkAlphaType));
+    } else {
+        ASSERT(false);
+    }
 
-    m_bitmap.setInfo(SkImageInfo::MakeN32Premul(newWidth, newHeight));
     if (!m_bitmap.tryAllocPixels(m_allocator, 0))
         return false;
 
     zeroFillPixelData();

[scroggo_chromium, 2015/10/28 19:08:47]

This will erase the background to black, in the case of 565. If the entire image
is available, we'll write over it, but if the image is only partially available,
we'll end up with black at the bottom instead of transparent. (I know we skip
565 in this CL if allDataReceived is not true, but I assume it's possible that
all the data was received but the image itself was incomplete. If that happens,
we'll report that the image decoder has failed, which prevents it from doing any
more work, but does not appear to prevent any callers from drawing that bitmap.)
I don't know whether such a change is good, bad, or indifferent, but we should
be aware of it.

In addition, this will set m_hasAlpha to true, which I think you do not want to
do (maybe it gets set back to false later, so it does not matter).

[aleksandar.stojiljkovic, 2015/10/29 13:06:42]

The initial idea was to let image generators decode partial to 8888 until it is
successful. By that time, we would know:
- if image is complete
- for png, if it really has alpha so that it can be decoded to 565 (next time
there is a request to decode it).
Not handling here the case that there once was complete data and for some reason
it is not complete anymore. Can it happen?
Will clean this part about alpha. Thanks.
 

     return true;
 }
 
 const SkBitmap& ImageFrame::bitmap() const
 {
     return m_bitmap;
 }
 
 bool ImageFrame::hasAlpha() const
 {
@@ skipping 27 matching lines @@
 void ImageFrame::zeroFillFrameRect(const IntRect& rect)
 {
     if (rect.isEmpty())
         return;
 
     m_bitmap.eraseArea(rect, SkColorSetARGB(0, 0, 0, 0));
     setHasAlpha(true);
 }
 
 } // namespace blink