Return raw (unencoded) bytes in Image.toByteData() (#5008)
Building image encoding into the engine bloated the
binary size. This change will return raw bytes, and
callers who use this functionality can take on the
dependency on image encoding in their apps (via a
Dart package or a platform plugin).
Fixes https://github.com/flutter/flutter/issues/16537
diff --git a/lib/ui/painting.dart b/lib/ui/painting.dart
index 02c4b49..96af472 100644
--- a/lib/ui/painting.dart
+++ b/lib/ui/painting.dart
@@ -1196,80 +1196,6 @@
}
}
-/// An encoding format to use with the [Image.toByteData].
-class EncodingFormat {
- /// PNG format.
- ///
- /// A loss-less compression format for images. This format is well suited for
- /// images with hard edges, such as screenshots or sprites, and images with
- /// text. Transparency is supported. The PNG format supports images up to
- /// 2,147,483,647 pixels in either dimension, though in practice available
- /// memory provides a more immediate limitation on maximum image size.
- ///
- /// PNG images normally use the `.png` file extension and the `image/png` MIME
- /// type.
- ///
- /// See also:
- ///
- /// * <https://en.wikipedia.org/wiki/Portable_Network_Graphics>, the Wikipedia page on PNG.
- /// * <https://tools.ietf.org/rfc/rfc2083.txt>, the PNG standard.
- const EncodingFormat.png()
- : _format = _pngFormat,
- _quality = 0;
-
- /// JPEG format.
- ///
- /// This format, strictly speaking called JFIF, is a lossy compression
- /// graphics format that can handle images up to 65,535 pixels in either
- /// dimension. The [quality] metric is a value in the range 0 to 100 that
- /// controls the compression ratio. Values in the range of about 50 to 90 are
- /// somewhat reasonable; values above 95 increase the file size with little
- /// noticeable improvement to the quality, values below 50 drop the quality
- /// substantially.
- ///
- /// This format is well suited for photographs. It is very poorly suited for
- /// images with hard edges or text. It does not support transparency.
- ///
- /// JPEG images normally use the `.jpeg` file extension and the `image/jpeg`
- /// MIME type.
- ///
- /// See also:
- ///
- /// * <https://en.wikipedia.org/wiki/JPEG>, the Wikipedia page on JPEG.
- const EncodingFormat.jpeg({int quality = 80})
- : _format = _jpegFormat,
- _quality = quality;
-
- /// WebP format.
- ///
- /// The WebP format supports both lossy and lossless compression; however, the
- /// [Image.toByteData] method always uses lossy compression when [webp] is
- /// specified. The [quality] metric is a value in the range 0 to 100 that
- /// controls the compression ratio; higher values result in better quality but
- /// larger file sizes, and vice versa. WebP images are limited to 16,383
- /// pixels in each direction (width and height).
- ///
- /// WebP images normally use the `.webp` file extension and the `image/webp`
- /// MIME type.
- ///
- /// See also:
- ///
- /// * <https://en.wikipedia.org/wiki/WebP>, the Wikipedia page on WebP.
- const EncodingFormat.webp({int quality = 80})
- : _format = _webpFormat,
- _quality = quality;
-
- final int _format;
- final int _quality;
-
- // Be conservative with the formats we expose. It is easy to add new formats
- // in future but difficult to remove.
- // These values must be kept in sync with the logic in ToSkEncodedImageFormat.
- static const int _jpegFormat = 0;
- static const int _pngFormat = 1;
- static const int _webpFormat = 2;
-}
-
/// Opaque handle to raw decoded image data (pixels).
///
/// To obtain an [Image] object, use [instantiateImageCodec].
@@ -1291,20 +1217,20 @@
/// Converts the [Image] object into a byte array.
///
- /// The [format] is encoding format to be used.
+ /// The image bytes will be RGBA form, 8 bits per channel, row-primary.
///
- /// Returns a future which complete with the binary image data (e.g a PNG or JPEG binary data) or
- /// an error if encoding fails.
- Future<ByteData> toByteData({EncodingFormat format: const EncodingFormat.jpeg()}) {
+ /// Returns a future that completes with the binary image data or an error
+ /// if encoding fails.
+ Future<ByteData> toByteData() {
return _futurize((_Callback<ByteData> callback) {
- return _toByteData(format._format, format._quality, (Uint8List encoded) {
- callback(encoded.buffer.asByteData());
+ return _toByteData((Uint8List encoded) {
+ callback(encoded?.buffer?.asByteData());
});
});
}
/// Returns an error message on failure, null on success.
- String _toByteData(int format, int quality, _Callback<Uint8List> callback) native 'Image_toByteData';
+ String _toByteData(_Callback<Uint8List> callback) native 'Image_toByteData';
/// Release the resources used by this object. The object is no longer usable
/// after this method is called.
diff --git a/lib/ui/painting/image.cc b/lib/ui/painting/image.cc
index a1b9b45..4704a9a 100644
--- a/lib/ui/painting/image.cc
+++ b/lib/ui/painting/image.cc
@@ -32,10 +32,8 @@
CanvasImage::~CanvasImage() = default;
-Dart_Handle CanvasImage::toByteData(int format,
- int quality,
- Dart_Handle callback) {
- return EncodeImage(this, format, quality, callback);
+Dart_Handle CanvasImage::toByteData(Dart_Handle callback) {
+ return GetImageBytes(this, callback);
}
void CanvasImage::dispose() {
diff --git a/lib/ui/painting/image.h b/lib/ui/painting/image.h
index aeec2a0..3c6620f 100644
--- a/lib/ui/painting/image.h
+++ b/lib/ui/painting/image.h
@@ -31,7 +31,7 @@
int height() { return image_.get()->height(); }
- Dart_Handle toByteData(int format, int quality, Dart_Handle callback);
+ Dart_Handle toByteData(Dart_Handle callback);
void dispose();
diff --git a/lib/ui/painting/image_encoding.cc b/lib/ui/painting/image_encoding.cc
index f010fce..952e77e 100644
--- a/lib/ui/painting/image_encoding.cc
+++ b/lib/ui/painting/image_encoding.cc
@@ -8,6 +8,7 @@
#include <utility>
#include "flutter/common/task_runners.h"
+#include "flutter/glue/trace_event.h"
#include "flutter/lib/ui/painting/image.h"
#include "flutter/lib/ui/ui_dart_state.h"
#include "lib/fxl/build_config.h"
@@ -17,6 +18,7 @@
#include "lib/tonic/typed_data/uint8_list.h"
#include "third_party/skia/include/core/SkEncodedImageFormat.h"
#include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkSurface.h"
using tonic::DartInvoke;
using tonic::DartPersistentValue;
@@ -41,65 +43,70 @@
}
}
-sk_sp<SkData> EncodeImage(sk_sp<SkImage> image,
- SkEncodedImageFormat format,
- int quality) {
+sk_sp<SkData> GetImageBytesAsRGBA(sk_sp<SkImage> image) {
+ TRACE_EVENT0("flutter", __FUNCTION__);
+
if (image == nullptr) {
return nullptr;
}
- return image->encodeToData(format, quality);
+
+ // Copy the GPU image snapshot into CPU memory.
+ auto cpu_snapshot = image->makeRasterImage();
+ if (!cpu_snapshot) {
+ FXL_LOG(ERROR) << "Pixel copy failed.";
+ return nullptr;
+ }
+
+ SkPixmap pixmap;
+ if (!cpu_snapshot->peekPixels(&pixmap)) {
+ FXL_LOG(ERROR) << "Pixel address is not available.";
+ return nullptr;
+ }
+
+ if (pixmap.colorType() != kRGBA_8888_SkColorType) {
+ TRACE_EVENT0("flutter", "ConvertToRGBA");
+
+ // Convert the pixel data to N32 to adhere to our API contract.
+ const auto image_info = SkImageInfo::MakeN32Premul(image->width(),
+ image->height());
+ auto surface = SkSurface::MakeRaster(image_info);
+ surface->writePixels(pixmap, 0, 0);
+ if (!surface->peekPixels(&pixmap)) {
+ FXL_LOG(ERROR) << "Pixel address is not available.";
+ return nullptr;
+ }
+ ASSERT(pixmap.colorType() == kRGBA_8888_SkColorType);
+
+ const size_t pixmap_size = pixmap.computeByteSize();
+ return SkData::MakeWithCopy(pixmap.addr32(), pixmap_size);
+ } else {
+ const size_t pixmap_size = pixmap.computeByteSize();
+ return SkData::MakeWithCopy(pixmap.addr32(), pixmap_size);
+ }
}
-void EncodeImageAndInvokeDataCallback(
+void GetImageBytesAndInvokeDataCallback(
std::unique_ptr<DartPersistentValue> callback,
sk_sp<SkImage> image,
- SkEncodedImageFormat format,
- int quality,
fxl::RefPtr<fxl::TaskRunner> ui_task_runner) {
- sk_sp<SkData> encoded = EncodeImage(std::move(image), format, quality);
+ sk_sp<SkData> buffer = GetImageBytesAsRGBA(std::move(image));
ui_task_runner->PostTask(
- fxl::MakeCopyable([callback = std::move(callback), encoded]() mutable {
- InvokeDataCallback(std::move(callback), std::move(encoded));
+ fxl::MakeCopyable([callback = std::move(callback), buffer]() mutable {
+ InvokeDataCallback(std::move(callback), std::move(buffer));
}));
}
-SkEncodedImageFormat ToSkEncodedImageFormat(int format) {
- // Map the formats exposed in flutter to formats supported in Skia.
- // See:
- // https://github.com/google/skia/blob/master/include/core/SkEncodedImageFormat.h
- switch (format) {
- case 0:
- return SkEncodedImageFormat::kJPEG;
- case 1:
- return SkEncodedImageFormat::kPNG;
- case 2:
- return SkEncodedImageFormat::kWEBP;
- default:
- /* NOTREACHED */
- return SkEncodedImageFormat::kWEBP;
- }
-}
-
} // namespace
-Dart_Handle EncodeImage(CanvasImage* canvas_image,
- int format,
- int quality,
- Dart_Handle callback_handle) {
+Dart_Handle GetImageBytes(CanvasImage* canvas_image,
+ Dart_Handle callback_handle) {
if (!canvas_image)
return ToDart("encode called with non-genuine Image.");
if (!Dart_IsClosure(callback_handle))
return ToDart("Callback must be a function.");
- SkEncodedImageFormat image_format = ToSkEncodedImageFormat(format);
-
- if (quality > 100)
- quality = 100;
- if (quality < 0)
- quality = 0;
-
auto callback = std::make_unique<DartPersistentValue>(
tonic::DartState::Current(), callback_handle);
sk_sp<SkImage> image = canvas_image->image();
@@ -107,11 +114,11 @@
const auto& task_runners = UIDartState::Current()->GetTaskRunners();
task_runners.GetIOTaskRunner()->PostTask(fxl::MakeCopyable(
- [callback = std::move(callback), image, image_format, quality,
+ [callback = std::move(callback), image,
ui_task_runner = task_runners.GetUITaskRunner()]() mutable {
- EncodeImageAndInvokeDataCallback(std::move(callback), std::move(image),
- image_format, quality,
- std::move(ui_task_runner));
+ GetImageBytesAndInvokeDataCallback(std::move(callback),
+ std::move(image),
+ std::move(ui_task_runner));
}));
return Dart_Null();
diff --git a/lib/ui/painting/image_encoding.h b/lib/ui/painting/image_encoding.h
index a121d59..5081bc4 100644
--- a/lib/ui/painting/image_encoding.h
+++ b/lib/ui/painting/image_encoding.h
@@ -11,10 +11,8 @@
class CanvasImage;
-Dart_Handle EncodeImage(CanvasImage* canvas_image,
- int format,
- int quality,
- Dart_Handle callback_handle);
+Dart_Handle GetImageBytes(CanvasImage* canvas_image,
+ Dart_Handle callback_handle);
} // namespace blink
diff --git a/testing/dart/encoding_test.dart b/testing/dart/encoding_test.dart
index 5fbbb4e..22c0a28 100644
--- a/testing/dart/encoding_test.dart
+++ b/testing/dart/encoding_test.dart
@@ -7,57 +7,81 @@
import 'dart:typed_data';
import 'dart:io';
-import 'package:test/test.dart';
+import 'package:flutter_test/flutter_test.dart';
import 'package:path/path.dart' as path;
+const int _kWidth = 10;
+const int _kRadius = 2;
+
+const Color _kBlack = const Color.fromRGBO(0, 0, 0, 1.0);
+const Color _kGreen = const Color.fromRGBO(0, 255, 0, 1.0);
+
void main() {
- final Image testImage = createSquareTestImage();
+ group('Image.toByteData', () {
+ test('Encode with default arguments', () async {
+ Image testImage = createSquareTestImage();
+ ByteData data = await testImage.toByteData();
+ expect(new Uint8List.view(data.buffer), getExpectedBytes());
+ });
- test('Encode with default arguments', () async {
- ByteData data = await testImage.toByteData();
- List<int> expected = readFile('square-80.jpg');
- expect(new Uint8List.view(data.buffer), expected);
- });
-
- test('Encode JPEG', () async {
- ByteData data = await testImage.toByteData(
- format: new EncodingFormat.jpeg(quality: 80));
- List<int> expected = readFile('square-80.jpg');
- expect(new Uint8List.view(data.buffer), expected);
- });
-
- test('Encode PNG', () async {
- ByteData data =
- await testImage.toByteData(format: new EncodingFormat.png());
- List<int> expected = readFile('square.png');
- expect(new Uint8List.view(data.buffer), expected);
- });
-
- test('Encode WEBP', () async {
- ByteData data = await testImage.toByteData(
- format: new EncodingFormat.webp(quality: 80));
- List<int> expected = readFile('square-80.webp');
- expect(new Uint8List.view(data.buffer), expected);
+ test('Handles greyscale images', () async {
+ Uint8List png = await new File('../resources/4x4.png').readAsBytes();
+ Completer<Image> completer = new Completer<Image>();
+ decodeImageFromList(png, (Image image) => completer.complete(image));
+ Image image = await completer.future;
+ ByteData data = await image.toByteData();
+ Uint8List bytes = data.buffer.asUint8List();
+ expect(bytes, hasLength(16));
+ expect(bytes, <int>[
+ 255, 255, 255, 255,
+ 127, 127, 127, 255,
+ 127, 127, 127, 255,
+ 0, 0, 0, 255,
+ ]);
+ });
});
}
Image createSquareTestImage() {
+ double width = _kWidth.toDouble();
+ double radius = _kRadius.toDouble();
+ double innerWidth = (_kWidth - 2 * _kRadius).toDouble();
+
PictureRecorder recorder = new PictureRecorder();
- Canvas canvas = new Canvas(recorder, new Rect.fromLTWH(0.0, 0.0, 10.0, 10.0));
+ Canvas canvas =
+ new Canvas(recorder, new Rect.fromLTWH(0.0, 0.0, width, width));
Paint black = new Paint()
..strokeWidth = 1.0
- ..color = const Color.fromRGBO(0, 0, 0, 1.0);
+ ..color = _kBlack;
Paint green = new Paint()
..strokeWidth = 1.0
- ..color = const Color.fromRGBO(0, 255, 0, 1.0);
+ ..color = _kGreen;
- canvas.drawRect(new Rect.fromLTWH(0.0, 0.0, 10.0, 10.0), black);
- canvas.drawRect(new Rect.fromLTWH(2.0, 2.0, 6.0, 6.0), green);
- return recorder.endRecording().toImage(10, 10);
+ canvas.drawRect(new Rect.fromLTWH(0.0, 0.0, width, width), black);
+ canvas.drawRect(
+ new Rect.fromLTWH(radius, radius, innerWidth, innerWidth), green);
+ return recorder.endRecording().toImage(_kWidth, _kWidth);
}
-List<int> readFile(fileName) {
- final file = new File(path.join('flutter', 'testing', 'resources', fileName));
- return file.readAsBytesSync();
+List<int> getExpectedBytes() {
+ int bytesPerChannel = 4;
+ List<int> result = new List<int>(_kWidth * _kWidth * bytesPerChannel);
+
+ fillWithColor(Color color, int min, int max) {
+ for (int i = min; i < max; i++) {
+ for (int j = min; j < max; j++) {
+ int offset = i * bytesPerChannel + j * _kWidth * bytesPerChannel;
+ result[offset] = color.red;
+ result[offset + 1] = color.green;
+ result[offset + 2] = color.blue;
+ result[offset + 3] = color.alpha;
+ }
+ }
+ }
+
+ fillWithColor(_kBlack, 0, _kWidth);
+ fillWithColor(_kGreen, _kRadius, _kWidth - _kRadius);
+
+ return result;
}
diff --git a/testing/dart/pubspec.yaml b/testing/dart/pubspec.yaml
index 43f35ec..2c79b49 100644
--- a/testing/dart/pubspec.yaml
+++ b/testing/dart/pubspec.yaml
@@ -1,3 +1,8 @@
name: engine_tests
dependencies:
- test: 0.12.15+4
+ flutter:
+ sdk: flutter
+dev_dependencies:
+ flutter_test:
+ sdk: flutter
+ path: any
diff --git a/testing/resources/4x4.png b/testing/resources/4x4.png
new file mode 100644
index 0000000..21b295a
--- /dev/null
+++ b/testing/resources/4x4.png
Binary files differ
diff --git a/testing/resources/square-80.jpg b/testing/resources/square-80.jpg
deleted file mode 100644
index 1140c33..0000000
--- a/testing/resources/square-80.jpg
+++ /dev/null
Binary files differ
diff --git a/testing/resources/square-80.webp b/testing/resources/square-80.webp
deleted file mode 100644
index fe3924c..0000000
--- a/testing/resources/square-80.webp
+++ /dev/null
Binary files differ
diff --git a/testing/resources/square.png b/testing/resources/square.png
deleted file mode 100644
index a042cec..0000000
--- a/testing/resources/square.png
+++ /dev/null
Binary files differ
