Add animation support to SkWebpCodec

TBR=reed@google.com
(No change to the public API, but changed a header file)

SkWebpCodec:
- Implement onGetFrameCount, onGetFrameInfo, and onGetRepetitionCount
- Respect the alpha reported by libwebp. Although the spec states that
  it is only a hint, the libwebp encoder uses it properly. Respecting
  allows us to draw opaque images faster and decode them to 565. This
  also matches other SkCodecs (and Chromium).
- onGetPixels:
  - Decode the frame requested, recursively decoding required frame if
    necessary
  - When blending with a prior frame, use SkRasterPipeline

SkCodec:
- Move check for negative index to getFrameInfo
- Reset the colorXform if one is not needed

SkCodecAnimation:
- Add new blend enum, for WebP's (and APNG's) non-blending option

SkFrameHolder:
- New base classes for frames and the owner of the frames, allowing
  code sharing between SkWebpCodec and SkGifCodec (particularly for
  determining whether a frame has alpha and what frame it depends on)
- When moving items from SkGIFFrameContext, use Skia conventions (i.e.
  int instead of unsigned)
- Rename "delay time" to "duration", to match e.g. SkFrameInfo::
  fDuration

SkGifImageReader:
- Move pieces to SkFrameHolder, and adapt to changes made in the
  process
- Make setAlphaAndRequiredFrame (now on the base class SkFrameHolder)
  more general to support webp, and add support for frames that do not
  blend
- Change SkGIFFrameContext from a struct to a class, to match how we
  use the distinction elsewhere (i.e. struct is a small object with
  public fields)
- Rework hasTransparentPixel (now hasTransparency, since it returns true
  in some cases where there is not a transparent pixel) to better fit
  with the modified setAlphaAndRequiredFrame. Also be more consistent
  when there is no transparent pixel but no color map.
- Simplify an if condition that was previously simplified in 2d61e717
  but accidentally got reverted in a4db9be6

CodecAnimTest:
- Test new animated webp files
- Rearrange the test to more cleanly print alpha type mismatches for
  the first frame

resources:
- webp-animated.webp
  - animated webp from Chromium
- blendBG.webp
  - new webp file using bits of webp-animated-semitransparent4.webp
    from Chromium
  - tests required frame and alpha when using the non-blending mode
  - frames have the following properties:
    - Frame 0: no alpha, fills screen
    - Frame 1: alpha, fills screen
    - Frame 2: no alpha, fills screen
    - Frame 3: alpha, fills screen, blendBG
    - Frame 4: no alpha, fills screen, blendBG
    - Frame 5: alpha, blendBG
    - Frame 6: covers 4, has alpha, blendBG
  - also used to test decoding to 565 if the new frame data has alpha
    but blends onto an opaque frame

DM.cpp:
- Test animated images to non-native 8888 and unpremul

DMSrcSink.cpp:
- Do not test non-native 8888 decodes to f16 dst
- Test unpremul decodes to f16
- Copy a frame of an animated image prior to drawing, since in unpremul
  mode, the DM code will premultiply first.

Bug: skia: 3315
Change-Id: I4e55ae2ee5bc095b37a743bdcfac644be603b980
Reviewed-on: https://skia-review.googlesource.com/16707
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>

1 files changed, 25 insertions, 61 deletions

diff --git a/third_party/gif/SkGifImageReader.h b/third_party/gif/SkGifImageReader.h
index 4667f7963f..6c313e923b 100644
--- a/third_party/gif/SkGifImageReader.h
+++ b/third_party/gif/SkGifImageReader.h
@@ -47,6 +47,7 @@ class SkGifCodec;
 #include "SkCodecAnimation.h"
 #include "SkColorTable.h"
 #include "SkData.h"
+#include "SkFrameHolder.h"
 #include "SkImageInfo.h"
 #include "SkStreamBuffer.h"
 #include "../private/SkTArray.h"
@@ -85,7 +86,7 @@ enum SkGIFState {
     SkGIFConsumeComment
 };
 
-struct SkGIFFrameContext;
+class SkGIFFrameContext;
 class SkGIFColorMap;
 
 // LZW decoder state machine.
@@ -191,19 +192,15 @@ private:
     mutable sk_sp<SkColorTable> m_table;
 };
 
+class SkGifImageReader;
+
 // LocalFrame output state machine.
-struct SkGIFFrameContext : SkNoncopyable {
+class SkGIFFrameContext : public SkFrame {
 public:
-    SkGIFFrameContext(int id)
-        : m_frameId(id)
-        , m_xOffset(0)
-        , m_yOffset(0)
-        , m_width(0)
-        , m_height(0)
+    SkGIFFrameContext(SkGifImageReader* reader, int id)
+        : INHERITED(id)
+        , m_owner(reader)
         , m_transparentPixel(SkGIFColorMap::kNotFound)
-        , m_hasAlpha(false)
-        , m_disposalMethod(SkCodecAnimation::Keep_DisposalMethod)
-        , m_requiredFrame(kUninitialized)
         , m_dataSize(0)
         , m_progressiveDisplay(false)
         , m_interlaced(false)
@@ -226,31 +223,8 @@ public:
 
     bool decode(SkStreamBuffer*, SkGifCodec* client, bool* frameDecoded);
 
-    int frameId() const { return m_frameId; }
-    void setRect(unsigned x, unsigned y, unsigned width, unsigned height)
-    {
-        m_xOffset = x;
-        m_yOffset = y;
-        m_width = width;
-        m_height = height;
-    }
-    SkIRect frameRect() const { return SkIRect::MakeXYWH(m_xOffset, m_yOffset, m_width, m_height); }
-    unsigned xOffset() const { return m_xOffset; }
-    unsigned yOffset() const { return m_yOffset; }
-    unsigned width() const { return m_width; }
-    unsigned height() const { return m_height; }
     int transparentPixel() const { return m_transparentPixel; }
     void setTransparentPixel(int pixel) { m_transparentPixel = pixel; }
-    bool hasAlpha() const { return m_hasAlpha; }
-    void setHasAlpha(bool alpha) { m_hasAlpha = alpha; }
-    SkCodecAnimation::DisposalMethod getDisposalMethod() const { return m_disposalMethod; }
-    void setDisposalMethod(SkCodecAnimation::DisposalMethod disposalMethod) { m_disposalMethod = disposalMethod; }
-
-    int getRequiredFrame() const {
-        SkASSERT(this->reachedStartOfData());
-        return m_requiredFrame;
-    }
-    void setRequiredFrame(int req) { m_requiredFrame = req; }
 
     unsigned delayTime() const { return m_delayTime; }
     void setDelayTime(unsigned delay) { m_delayTime = delay; }
@@ -274,24 +248,14 @@ public:
     const SkGIFColorMap& localColorMap() const { return m_localColorMap; }
     SkGIFColorMap& localColorMap() { return m_localColorMap; }
 
-    bool reachedStartOfData() const { return m_requiredFrame != kUninitialized; }
+protected:
+    bool onReportsAlpha() const override;
 
 private:
-    static constexpr int kUninitialized = -2;
+    // Unowned pointer to the object that owns this frame.
+    const SkGifImageReader* m_owner;
 
-    int m_frameId;
-    unsigned m_xOffset;
-    unsigned m_yOffset; // With respect to "screen" origin.
-    unsigned m_width;
-    unsigned m_height;
     int m_transparentPixel; // Index of transparent pixel. Value is kNotFound if there is no transparent pixel.
-    // Cached value, taking into account:
-    // - m_transparentPixel
-    // - frameRect
-    // - previous required frame
-    bool m_hasAlpha;
-    SkCodecAnimation::DisposalMethod m_disposalMethod; // Restore to background, leave in place, etc.
-    int m_requiredFrame;
     int m_dataSize;
 
     bool m_progressiveDisplay; // If true, do Haeberli interlace hack.
@@ -309,9 +273,11 @@ private:
     bool m_isComplete;
     bool m_isHeaderDefined;
     bool m_isDataSizeDefined;
+
+    typedef SkFrame INHERITED;
 };
 
-class SkGifImageReader final : public SkNoncopyable {
+class SkGifImageReader final : public SkFrameHolder {
 public:
     // This takes ownership of stream.
     SkGifImageReader(SkStream* stream)
@@ -319,8 +285,6 @@ public:
         , m_state(SkGIFType)
         , m_bytesToConsume(6) // Number of bytes for GIF type, either "GIF87a" or "GIF89a".
         , m_version(0)
-        , m_screenWidth(0)
-        , m_screenHeight(0)
         , m_loopCount(cLoopCountNotSeen)
         , m_streamBuffer(stream)
         , m_parseCompleted(false)
@@ -335,9 +299,6 @@ public:
 
     void setClient(SkGifCodec* client) { m_client = client; }
 
-    unsigned screenWidth() const { return m_screenWidth; }
-    unsigned screenHeight() const { return m_screenHeight; }
-
     // Option to pass to parse(). All enums are negative, because a non-negative value is used to
     // indicate that the Reader should parse up to and including the frame indicated.
     enum SkGIFParseQuery {
@@ -408,6 +369,16 @@ public:
 
     bool firstFrameSupportsIndex8() const { return m_firstFrameSupportsIndex8; }
 
+    // Helper function that returns whether an SkGIFFrameContext has transparency.
+    // This method is sometimes called before creating one/parsing its color map,
+    // so it cannot rely on SkGIFFrameContext::transparentPixel or ::localColorMap().
+    bool hasTransparency(int transPix, bool hasLocalColorMap, int localMapColors) const;
+
+protected:
+    const SkFrame* onGetFrame(int i) const override {
+        return static_cast<const SkFrame*>(this->frameContext(i));
+    }
+
 private:
     // Requires that one byte has been buffered into m_streamBuffer.
     unsigned char getOneByte() const {
@@ -415,11 +386,6 @@ private:
     }
 
     void addFrameIfNecessary();
-    // Must be called *after* the SkGIFFrameContext's color table (if any) has been parsed.
-    void setAlphaAndRequiredFrame(SkGIFFrameContext*);
-    // This method is sometimes called before creating a SkGIFFrameContext, so it cannot rely
-    // on SkGIFFrameContext::localColorMap().
-    bool hasTransparentPixel(int frameIndex, bool hasLocalColorMap, int localMapColors);
     bool currentFrameIsFirstFrame() const
     {
         return m_frames.empty() || (m_frames.size() == 1u && !m_frames[0]->isComplete());
@@ -434,8 +400,6 @@ private:
 
     // Global (multi-image) state.
     int m_version; // Either 89 for GIF89 or 87 for GIF87.
-    unsigned m_screenWidth; // Logical screen width & height.
-    unsigned m_screenHeight;
     SkGIFColorMap m_globalColorMap;
 
     static constexpr int cLoopCountNotSeen = -2;