extensions/browser/api/capture_web_contents_function.cc

// Copyright 2013 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 "extensions/browser/api/capture_web_contents_function.h"

#include "base/base64.h"
#include "base/strings/stringprintf.h"
#include "content/public/browser/render_widget_host.h"
#include "content/public/browser/render_widget_host_view.h"
#include "content/public/browser/web_contents.h"
#include "extensions/browser/extension_function.h"
#include "extensions/common/constants.h"
#include "ui/gfx/codec/jpeg_codec.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/display.h"
#include "ui/gfx/geometry/size_conversions.h"
#include "ui/gfx/screen.h"

using content::RenderWidgetHost;
using content::RenderWidgetHostView;
using content::WebContents;

namespace extensions {

using api::extension_types::ImageDetails;

bool CaptureWebContentsFunction::HasPermission() {
  return true;
}

bool CaptureWebContentsFunction::RunAsync() {
  EXTENSION_FUNCTION_VALIDATE(args_);

  context_id_ = extension_misc::kCurrentWindowId;
  args_->GetInteger(0, &context_id_);

  scoped_ptr<ImageDetails> image_details;
  if (args_->GetSize() > 1) {
    base::Value* spec = NULL;
    EXTENSION_FUNCTION_VALIDATE(args_->Get(1, &spec) && spec);
    image_details = ImageDetails::FromValue(*spec);
  }

  if (!IsScreenshotEnabled())
    return false;

  WebContents* contents = GetWebContentsForID(context_id_);
  if (!contents)
    return false;

  // The default format and quality setting used when encoding jpegs.
  const api::extension_types::ImageFormat kDefaultFormat =
      api::extension_types::IMAGE_FORMAT_JPEG;
  const int kDefaultQuality = 90;

  image_format_ = kDefaultFormat;
  image_quality_ = kDefaultQuality;

  if (image_details) {
    if (image_details->format != api::extension_types::IMAGE_FORMAT_NONE)
      image_format_ = image_details->format;
    if (image_details->quality.get())
      image_quality_ = *image_details->quality;
  }

  // TODO(miu): Account for fullscreen render widget?  http://crbug.com/419878
  RenderWidgetHostView* const view = contents->GetRenderWidgetHostView();
  RenderWidgetHost* const host = view ? view->GetRenderWidgetHost() : nullptr;
  if (!view || !host) {
    OnCaptureFailure(FAILURE_REASON_VIEW_INVISIBLE);
    return false;
  }

  // By default, the requested bitmap size is the view size in screen
  // coordinates.  However, if there's more pixel detail available on the
  // current system, increase the requested bitmap size to capture it all.
  const gfx::Size view_size = view->GetViewBounds().size();
  gfx::Size bitmap_size = view_size;
  const gfx::NativeView native_view = view->GetNativeView();
  gfx::Screen* const screen = gfx::Screen::GetScreenFor(native_view);
  const float scale =
      screen->GetDisplayNearestWindow(native_view).device_scale_factor();
  if (scale > 1.0f)
    bitmap_size = gfx::ScaleToCeiledSize(view_size, scale);

  host->CopyFromBackingStore(
      gfx::Rect(view_size),
      bitmap_size,
      base::Bind(&CaptureWebContentsFunction::CopyFromBackingStoreComplete,
                 this),
      kN32_SkColorType);
  return true;
}

void CaptureWebContentsFunction::CopyFromBackingStoreComplete(
    const SkBitmap& bitmap,
    content::ReadbackResponse response) {
  if (response == content::READBACK_SUCCESS) {
    OnCaptureSuccess(bitmap);
    return;
  }
  OnCaptureFailure(FAILURE_REASON_UNKNOWN);
}

void CaptureWebContentsFunction::OnCaptureSuccess(const SkBitmap& bitmap) {
  std::vector<unsigned char> data;
  SkAutoLockPixels screen_capture_lock(bitmap);
  bool encoded = false;
  std::string mime_type;
  switch (image_format_) {
    case api::extension_types::IMAGE_FORMAT_JPEG:
      encoded = gfx::JPEGCodec::Encode(
          reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
          gfx::JPEGCodec::FORMAT_SkBitmap,
          bitmap.width(),
          bitmap.height(),
          static_cast<int>(bitmap.rowBytes()),
          image_quality_,
          &data);
      mime_type = kMimeTypeJpeg;
      break;
    case api::extension_types::IMAGE_FORMAT_PNG:
      encoded =
          gfx::PNGCodec::EncodeBGRASkBitmap(bitmap,
                                            true,  // Discard transparency.
                                            &data);
      mime_type = kMimeTypePng;
      break;
    default:
      NOTREACHED() << "Invalid image format.";
  }

  if (!encoded) {
    OnCaptureFailure(FAILURE_REASON_ENCODING_FAILED);
    return;
  }

  std::string base64_result;
  base::StringPiece stream_as_string(reinterpret_cast<const char*>(data.data()),
                                     data.size());

  base::Base64Encode(stream_as_string, &base64_result);
  base64_result.insert(
      0, base::StringPrintf("data:%s;base64,", mime_type.c_str()));
  SetResult(new base::StringValue(base64_result));
  SendResponse(true);
}

}  // namespace extensions