Implement webview.captureVisibleRegion()

content/browser/readback_request_helpers.cc

Index: content/browser/readback_request_helpers.cc
diff --git a/content/browser/readback_request_helpers.cc b/content/browser/readback_request_helpers.cc
new file mode 100644
index 0000000000000000000000000000000000000000..75c1a9abdc26fba11b417bb0aa87ac4519f073ae
--- /dev/null
+++ b/content/browser/readback_request_helpers.cc
@@ -0,0 +1,164 @@
+// Copyright 2016 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.
+
+#include "content/browser/readback_request_helpers.h"
+
+#include "base/callback_helpers.h"
+#include "base/memory/ref_counted.h"
+#include "cc/output/copy_output_result.h"
+#include "cc/resources/single_release_callback.h"
+#include "content/browser/compositor/image_transport_factory.h"
+#include "content/common/gpu/client/gl_helper.h"
+#include "skia/ext/image_operations.h"
+#include "skia/ext/refptr.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkColorFilter.h"
+#include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/effects/SkLumaColorFilter.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace content {
+
+void CopyFromCompositingSurfaceFinished(
+    const ReadbackRequestCallback& callback,
+    scoped_ptr<cc::SingleReleaseCallback> release_callback,
+    scoped_ptr<SkBitmap> bitmap,
+    scoped_ptr<SkAutoLockPixels> bitmap_pixels_lock,
+    bool result) {
+  bitmap_pixels_lock.reset();
+
+  gpu::SyncToken sync_token;
+  if (result) {
+    GLHelper* gl_helper = ImageTransportFactory::GetInstance()->GetGLHelper();
+    if (gl_helper)
+      gl_helper->GenerateSyncToken(&sync_token);
+  }
+  const bool lost_resource = !sync_token.HasData();
+  release_callback->Run(sync_token, lost_resource);
+
+  callback.Run(*bitmap, result ? READBACK_SUCCESS : READBACK_FAILED);
+}
+
+void PrepareTextureCopyOutputResult(const gfx::Size& dst_size_in_pixel,
+                                    const SkColorType color_type,
+                                    const ReadbackRequestCallback& callback,
+                                    scoped_ptr<cc::CopyOutputResult> result) {
+  DCHECK(result->HasTexture());
+  base::ScopedClosureRunner scoped_callback_runner(
+      base::Bind(callback, SkBitmap(), READBACK_FAILED));
+
+  // TODO(siva.gunturi): We should be able to validate the format here using
+  // GLHelper::IsReadbackConfigSupported before we processs the result.
+  // See crbug.com/415682 and crbug.com/415131.
+  scoped_ptr<SkBitmap> bitmap(new SkBitmap);
+  if (!bitmap->tryAllocPixels(SkImageInfo::Make(
+          dst_size_in_pixel.width(), dst_size_in_pixel.height(), color_type,
+          kOpaque_SkAlphaType))) {
+    scoped_callback_runner.Reset(
+        base::Bind(callback, SkBitmap(), READBACK_BITMAP_ALLOCATION_FAILURE));
+    return;
+  }
+
+  ImageTransportFactory* factory = ImageTransportFactory::GetInstance();
+  GLHelper* gl_helper = factory->GetGLHelper();
+  if (!gl_helper)
+    return;
+
+  scoped_ptr<SkAutoLockPixels> bitmap_pixels_lock(
+      new SkAutoLockPixels(*bitmap));
+  uint8_t* pixels = static_cast<uint8_t*>(bitmap->getPixels());
+
+  cc::TextureMailbox texture_mailbox;
+  scoped_ptr<cc::SingleReleaseCallback> release_callback;
+  result->TakeTexture(&texture_mailbox, &release_callback);
+  DCHECK(texture_mailbox.IsTexture());
+
+  ignore_result(scoped_callback_runner.Release());
+
+  gl_helper->CropScaleReadbackAndCleanMailbox(
+      texture_mailbox.mailbox(), texture_mailbox.sync_token(), result->size(),
+      gfx::Rect(result->size()), dst_size_in_pixel, pixels, color_type,
+      base::Bind(&CopyFromCompositingSurfaceFinished, callback,
+                 base::Passed(&release_callback), base::Passed(&bitmap),
+                 base::Passed(&bitmap_pixels_lock)),
+      GLHelper::SCALER_QUALITY_GOOD);
+}
+
+void PrepareBitmapCopyOutputResult(const gfx::Size& dst_size_in_pixel,
+                                   const SkColorType preferred_color_type,
+                                   const ReadbackRequestCallback& callback,
+                                   scoped_ptr<cc::CopyOutputResult> result) {
+  SkColorType color_type = preferred_color_type;
+  if (color_type != kN32_SkColorType && color_type != kAlpha_8_SkColorType) {
+    // Switch back to default colortype if format not supported.
+    color_type = kN32_SkColorType;
+  }
+  DCHECK(result->HasBitmap());
+  scoped_ptr<SkBitmap> source = result->TakeBitmap();
+  DCHECK(source);
+  SkBitmap scaled_bitmap;
+  if (source->width() != dst_size_in_pixel.width() ||
+      source->height() != dst_size_in_pixel.height()) {
+    scaled_bitmap = skia::ImageOperations::Resize(
+        *source, skia::ImageOperations::RESIZE_BEST, dst_size_in_pixel.width(),
+        dst_size_in_pixel.height());
+  } else {
+    scaled_bitmap = *source;
+  }
+  if (color_type == kN32_SkColorType) {
+    DCHECK_EQ(scaled_bitmap.colorType(), kN32_SkColorType);
+    callback.Run(scaled_bitmap, READBACK_SUCCESS);
+    return;
+  }
+  DCHECK_EQ(color_type, kAlpha_8_SkColorType);
+  // The software path currently always returns N32 bitmap regardless of the
+  // |color_type| we ask for.
+  DCHECK_EQ(scaled_bitmap.colorType(), kN32_SkColorType);
+  // Paint |scaledBitmap| to alpha-only |grayscale_bitmap|.
+  SkBitmap grayscale_bitmap;
+  bool success = grayscale_bitmap.tryAllocPixels(
+      SkImageInfo::MakeA8(scaled_bitmap.width(), scaled_bitmap.height()));
+  if (!success) {
+    callback.Run(SkBitmap(), READBACK_BITMAP_ALLOCATION_FAILURE);
+    return;
+  }
+  SkCanvas canvas(grayscale_bitmap);
+  SkPaint paint;
+  skia::RefPtr<SkColorFilter> filter =
+      skia::AdoptRef(SkLumaColorFilter::Create());
+  paint.setColorFilter(filter.get());
+  canvas.drawBitmap(scaled_bitmap, SkIntToScalar(0), SkIntToScalar(0), &paint);
+  callback.Run(grayscale_bitmap, READBACK_SUCCESS);
+}
+
+void CopyFromCompositingSurfaceHasResult(
+    const gfx::Size& dst_size_in_pixel,
+    const SkColorType color_type,
+    const ReadbackRequestCallback& callback,
+    scoped_ptr<cc::CopyOutputResult> result) {
+  if (result->IsEmpty() || result->size().IsEmpty()) {
+    callback.Run(SkBitmap(), READBACK_FAILED);
+    return;
+  }
+
+  gfx::Size output_size_in_pixel;
+  if (dst_size_in_pixel.IsEmpty())
+    output_size_in_pixel = result->size();
+  else
+    output_size_in_pixel = dst_size_in_pixel;
+
+  if (result->HasTexture()) {
+    // GPU-accelerated path
+    PrepareTextureCopyOutputResult(output_size_in_pixel, color_type, callback,
+                                   std::move(result));
+    return;
+  }
+
+  DCHECK(result->HasBitmap());
+  // Software path
+  PrepareBitmapCopyOutputResult(output_size_in_pixel, color_type, callback,
+                                std::move(result));
+}
+
+}  // namespace content