A few minor cleanups of the MultiFrameCodec

lib/ui/painting/image_generator_apng.h

@@ -128,7 +128,7 @@ class APNGImageGenerator : public ImageGenerator {
     // X offset of this image when composited. Only applicable to frames.
     unsigned int x_offset;
 
-    // X offset of this image when composited. Only applicable to frames.
+    // Y offset of this image when composited. Only applicable to frames.
     unsigned int y_offset;
   };
 

lib/ui/painting/multi_frame_codec.cc

@@ -54,39 +54,6 @@ static void InvokeNextFrameCallback(
                      tonic::ToDart(decode_error)});
 }
 
-// Copied the source bitmap to the destination. If this cannot occur due to
-// running out of memory or the image info not being compatible, returns false.
-static bool CopyToBitmap(SkBitmap* dst,
-                         SkColorType dstColorType,
-                         const SkBitmap& src) {
-  SkPixmap srcPM;
-  if (!src.peekPixels(&srcPM)) {
-    return false;
-  }
-
-  SkBitmap tmpDst;
-  SkImageInfo dstInfo = srcPM.info().makeColorType(dstColorType);
-  if (!tmpDst.setInfo(dstInfo)) {
-    return false;
-  }
-
-  if (!tmpDst.tryAllocPixels()) {
-    return false;
-  }
-
-  SkPixmap dstPM;
-  if (!tmpDst.peekPixels(&dstPM)) {
-    return false;
-  }
-
-  if (!srcPM.readPixels(dstPM)) {
-    return false;
-  }
-
-  dst->swap(tmpDst);
-  return true;
-}
-
 std::pair<sk_sp<DlImage>, std::string>
 MultiFrameCodec::State::GetNextFrameImage(
     fml::WeakPtr<GrDirectContext> resourceContext,
@@ -113,25 +80,20 @@ MultiFrameCodec::State::GetNextFrameImage(
 
   const int requiredFrameIndex =
       frameInfo.required_frame.value_or(SkCodec::kNoFrame);
-  std::optional<unsigned int> prior_frame_index = std::nullopt;
 
   if (requiredFrameIndex != SkCodec::kNoFrame) {
     // We are here when the frame said |disposal_method| is
     // `DisposalMethod::kKeep` or `DisposalMethod::kRestorePrevious` and
     // |requiredFrameIndex| is set to ex-frame or ex-ex-frame.
-    if (lastRequiredFrame_ == nullptr) {
+    if (!lastRequiredFrame_.has_value()) {
       FML_DLOG(INFO)
           << "Frame " << nextFrameIndex_ << " depends on frame "
           << requiredFrameIndex
           << " and no required frames are cached. Using blank slate instead.";
     } else {
       // Copy the previous frame's output buffer into the current frame as the
       // starting point.
-      if (lastRequiredFrame_->getPixels() &&
-          CopyToBitmap(&bitmap, lastRequiredFrame_->colorType(),
-                       *lastRequiredFrame_)) {
-        prior_frame_index = requiredFrameIndex;
-      }
+      bitmap.writePixels(lastRequiredFrame_->pixmap());
     }
   }
 
@@ -151,7 +113,7 @@ MultiFrameCodec::State::GetNextFrameImage(
   const bool restore_previous_frame =
       frameInfo.disposal_method ==
       SkCodecAnimation::DisposalMethod::kRestorePrevious;
-  const bool previous_frame_available = !!lastRequiredFrame_;
+  const bool previous_frame_available = lastRequiredFrame_.has_value();
 
   // Store the current frame in `lastRequiredFrame_` if the frame's disposal
   // method indicates we should do so.
@@ -167,7 +129,7 @@ MultiFrameCodec::State::GetNextFrameImage(
       (previous_frame_available && !restore_previous_frame)) {
     // Replace the stored frame. The `lastRequiredFrame_` will get used as the
     // starting backdrop for the next frame.
-    lastRequiredFrame_ = std::make_unique<SkBitmap>(bitmap);
+    lastRequiredFrame_ = bitmap;
     lastRequiredFrameIndex_ = nextFrameIndex_;
   }
 

lib/ui/painting/multi_frame_codec.h

@@ -53,7 +53,7 @@ class MultiFrameCodec : public Codec {
     // thread.
     int nextFrameIndex_;
     // The last decoded frame that's required to decode any subsequent frames.
-    std::unique_ptr<SkBitmap> lastRequiredFrame_;
+    std::optional<SkBitmap> lastRequiredFrame_;
 
     // The index of the last decoded required frame.
     int lastRequiredFrameIndex_ = -1;