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, 59 insertions, 0 deletions

diff --git a/src/codec/SkWebpCodec.h b/src/codec/SkWebpCodec.h
index 93b60f646e..f4c7910ee6 100644
--- a/src/codec/SkWebpCodec.h
+++ b/src/codec/SkWebpCodec.h
@@ -11,9 +11,12 @@
 #include "SkCodec.h"
 #include "SkColorSpace.h"
 #include "SkEncodedImageFormat.h"
+#include "SkFrameHolder.h"
 #include "SkImageInfo.h"
 #include "SkTypes.h"
 
+#include <vector>
+
 class SkStream;
 extern "C" {
     struct WebPDemuxer;
@@ -37,6 +40,11 @@ protected:
     bool onDimensionsSupported(const SkISize&) override;
 
     bool onGetValidSubset(SkIRect* /* desiredSubset */) const override;
+
+    int onGetFrameCount() override;
+    bool onGetFrameInfo(int, FrameInfo*) const override;
+    int onGetRepetitionCount() override;
+
 private:
     SkWebpCodec(int width, int height, const SkEncodedInfo&, sk_sp<SkColorSpace>, SkStream*,
                 WebPDemuxer*, sk_sp<SkData>);
@@ -47,6 +55,57 @@ private:
     // This should not be freed until the decode is completed.
     sk_sp<SkData> fData;
 
+    class Frame : public SkFrame {
+    public:
+        Frame(int i, bool alpha)
+            : INHERITED(i)
+            , fReportsAlpha(alpha)
+        {}
+        Frame(Frame&& other)
+            : INHERITED(other.frameId())
+            , fReportsAlpha(other.fReportsAlpha)
+        {}
+
+    protected:
+        bool onReportsAlpha() const override {
+            return fReportsAlpha;
+        }
+
+    private:
+        const bool fReportsAlpha;
+
+        typedef SkFrame INHERITED;
+    };
+
+    class FrameHolder : public SkFrameHolder {
+    public:
+        ~FrameHolder() override {}
+        void setScreenSize(int w, int h) {
+            fScreenWidth = w;
+            fScreenHeight = h;
+        }
+        Frame* appendNewFrame(bool hasAlpha);
+        const Frame* frame(int i) const;
+        int size() const {
+            return static_cast<int>(fFrames.size());
+        }
+        void reserve(int size) {
+            fFrames.reserve(size);
+        }
+
+    protected:
+        const SkFrame* onGetFrame(int i) const override;
+
+    private:
+        std::vector<Frame> fFrames;
+    };
+
+    FrameHolder fFrameHolder;
+    // Set to true if WebPDemuxGetFrame fails. This only means
+    // that we will cap the frame count to the frames that
+    // succeed.
+    bool        fFailed;
+
     typedef SkCodec INHERITED;
 };
 #endif // SkWebpCodec_DEFINED