Use SkJpegEncoder in WebKit platform

third_party/WebKit/Source/platform/image-encoders/ImageEncoder.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ImageEncoder_h
+#define ImageEncoder_h
+
+#include "platform/PlatformExport.h"
+#include "platform/wtf/Vector.h"
+#include "third_party/skia/include/core/SkStream.h"
+#include "third_party/skia/include/encode/SkJpegEncoder.h"
+#include "third_party/skia/include/encode/SkPngEncoder.h"
+
+namespace blink {
+
+class VectorWStream : public SkWStream {
+ public:
+  VectorWStream(Vector<unsigned char>* dst) : dst_(dst) {
+    DCHECK(dst_);
+    DCHECK_EQ(0UL, dst->size());
+  }
+
+  bool write(const void* buffer, size_t size) override {
+    dst_->Append((const unsigned char*)buffer, size);
+    return true;
+  }
+
+  size_t bytesWritten() const override { return dst_->size(); }
+
+ private:
+  // Does not have ownership.
+  Vector<unsigned char>* dst_;
+};
+
+class PLATFORM_EXPORT ImageEncoder {
+ public:
+  static bool Encode(Vector<unsigned char>* dst,

[f(malita), 2017/05/16 21:09:46]

I was actually thinking encode() would be non-static, like encodeRows().  Then
you don't need two version and can avoid passing the options here.  You'd have
to create a ImageEncoder on stack, but that's not a big deal.

[...]

Ah, scratch that - I see SkEncoder doesn't have an encode() virtual.

[msarett1, 2017/05/17 02:26:59]

Acknowledged.

+                     const SkPixmap& src,
+                     const SkJpegEncoder::Options&);
+
+  static bool Encode(Vector<unsigned char>* dst,
+                     const SkPixmap& src,
+                     const SkPngEncoder::Options&);
+
+  static std::unique_ptr<ImageEncoder> Make(Vector<unsigned char>* dst,

[f(malita), 2017/05/16 21:09:46]

Nit: "Create" is the common factory name in Blink.

[msarett1, 2017/05/17 02:26:59]

Done.

+                                            const SkPixmap& src,
+                                            const SkJpegEncoder::Options&);
+
+  static std::unique_ptr<ImageEncoder> Make(Vector<unsigned char>* dst,

[f(malita), 2017/05/16 21:09:46]

Ditto.

[msarett1, 2017/05/17 02:26:59]

Done.

+                                            const SkPixmap& src,
+                                            const SkPngEncoder::Options&);
+
+  bool encodeRows(int numRows) { return encoder_->encodeRows(numRows); }
+
+  /**
+   *  If quality is in [0, 1], this will simply convert to a [0, 100]
+   *  integer scale (which is what is used by libjpeg-turbo).
+   *
+   *  Otherwise, this will return the default value.
+   */
+  static int ComputeJpegQuality(double quality);
+
+ private:
+  ImageEncoder(Vector<unsigned char>* dst) : dst_(dst) {}
+
+  VectorWStream dst_;
+  std::unique_ptr<SkEncoder> encoder_;
+};
+};
+
+#endif