[canvaskit] Create an SkImage from a frame of an SkAnimatedImage

Flutter on the web wants to be able to extract arbitrary frames from
an animated image and pass those into functions like:
drawAtlas, drawImage, drawImageRect

This should allow that to happen w/o having to add lots of variants like
drawAnimatedImage. If this sticks, is drawAnimatedImage still useful?
(maybe it saves a copy?)

Change-Id: I99d7045c5dea61d0a1bd6d335c88e7517f2c4fc2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263020
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Mike Reed <reed@google.com>

RELEASE_NOTES.txt

@@ -8,6 +8,8 @@ Milestone 81
 
 <Insert new notes here- top is most recent.>
 
+  * Added SkAnimatedImage::getCurrentFrame()
+
   * Add support to create an SkSurface from an MTKView, with delayed acquisition of
     the MTLDrawable.
     Entry point: SkSurface::MakeFromMTKView

include/android/SkAnimatedImage.h

@@ -15,6 +15,7 @@
 #include "include/core/SkRect.h"
 
 class SkAndroidCodec;
+class SkImage;
 class SkPicture;
 
 /**
@@ -82,6 +83,13 @@ public:
      */
     int decodeNextFrame();
 
+    /**
+     *  Returns the current frame as an SkImage. The SkImage will not change
+     *  after it has been returned.
+     *  If there is no current frame, nullptr will be returned.
+     */
+    sk_sp<SkImage> getCurrentFrame();
+
     /**
      *  How long to display the current frame.
      *

modules/canvaskit/CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
    build.
  - Experimental Runtime shader available for custom builds.
  - WebP support.
+ - `SkAnimatedImage.getCurrentFrame` which returns an SkImage.
 
 ### Fixed
  - `CanvasKit.SaveLayerInitWithPrevious` and `CanvasKit.SaveLayerF16ColorType` constants.

modules/canvaskit/canvaskit_bindings.cpp

@@ -869,6 +869,7 @@ EMSCRIPTEN_BINDINGS(Skia) {
     class_<SkAnimatedImage>("SkAnimatedImage")
         .smart_ptr<sk_sp<SkAnimatedImage>>("sk_sp<SkAnimatedImage>")
         .function("decodeNextFrame", &SkAnimatedImage::decodeNextFrame)
+        .function("getCurrentFrame", &SkAnimatedImage::getCurrentFrame)
         .function("getFrameCount", &SkAnimatedImage::getFrameCount)
         .function("getRepetitionCount", &SkAnimatedImage::getRepetitionCount)
         .function("height",  optional_override([](SkAnimatedImage& self)->int32_t {

modules/canvaskit/tests/core.spec.js

@@ -271,6 +271,53 @@ describe('Core canvas behavior', function() {
         });
     });
 
+    it('can use various image filters on animated images', function(done) {
+        const imgPromise = fetch('/assets/flightAnim.gif')
+            .then((response) => response.arrayBuffer());
+        Promise.all([imgPromise, LoadCanvasKit]).then((values) => {
+            const gifData = values[0];
+            expect(gifData).toBeTruthy();
+            catchException(done, () => {
+                let img = CanvasKit.MakeAnimatedImageFromEncoded(gifData);
+                expect(img).toBeTruthy();
+                const surface = CanvasKit.MakeCanvasSurface('test');
+                expect(surface).toBeTruthy('Could not make surface');
+                if (!surface) {
+                    done();
+                    return;
+                }
+                img.decodeNextFrame();
+                img.decodeNextFrame();
+                const canvas = surface.getCanvas();
+                canvas.clear(CanvasKit.WHITE);
+                const paint = new CanvasKit.SkPaint();
+                paint.setAntiAlias(true);
+                paint.setColor(CanvasKit.Color(0, 255, 0, 1.0));
+                const redCF =  CanvasKit.SkColorFilter.MakeBlend(
+                        CanvasKit.Color(255, 0, 0, 0.1), CanvasKit.BlendMode.SrcOver);
+                const redIF = CanvasKit.SkImageFilter.MakeColorFilter(redCF, null);
+                const blurIF = CanvasKit.SkImageFilter.MakeBlur(8, 0.2, CanvasKit.TileMode.Decal, null);
+                const combined = CanvasKit.SkImageFilter.MakeCompose(redIF, blurIF);
+                paint.setImageFilter(combined);
+
+                const frame = img.getCurrentFrame();
+                canvas.drawImage(frame, 100, 50, paint);
+
+                surface.flush();
+
+                paint.delete();
+                redIF.delete();
+                redCF.delete();
+                blurIF.delete();
+                combined.delete();
+                frame.delete();
+                img.delete();
+
+                reportSurface(surface, 'animated_filters', done);
+            })();
+        });
+    });
+
     it('can use DecodeCache APIs', function(done) {
         LoadCanvasKit.then(catchException(done, () => {
             const initialLimit = CanvasKit.getDecodeCacheLimitBytes();

src/android/SkAnimatedImage.cpp

@@ -329,6 +329,9 @@ int SkAnimatedImage::decodeNextFrame() {
 }
 
 void SkAnimatedImage::onDraw(SkCanvas* canvas) {
+    // This SkBitmap may be reused later to decode the following frame. But Frame::init
+    // lazily copies the pixel ref if it has any other references. So it is safe to not
+    // do a deep copy here.
     auto image = SkMakeImageFromRasterBitmap(fDisplayFrame.fBitmap,
                                              kNever_SkCopyPixelsMode);
 
@@ -357,3 +360,11 @@ void SkAnimatedImage::onDraw(SkCanvas* canvas) {
 void SkAnimatedImage::setRepetitionCount(int newCount) {
     fRepetitionCount = newCount;
 }
+
+sk_sp<SkImage> SkAnimatedImage::getCurrentFrame() {
+    // This SkBitmap may be reused later to decode the following frame. But Frame::init
+    // lazily copies the pixel ref if it has any other references. So it is safe to not
+    // do a deep copy here.
+    return SkMakeImageFromRasterBitmap(fDisplayFrame.fBitmap,
+                                       kNever_SkCopyPixelsMode);
+}