root/chrome/renderer/chrome_render_frame_observer.cc

DEFINITIONS

1. Downscale
2. OnMessageReceived
3. OnSetIsPrerendering
4. OnRequestThumbnailForContextNode
5. OnPrintNodeUnderContextMenu

// 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 "chrome/renderer/chrome_render_frame_observer.h"

#include "chrome/common/prerender_messages.h"
#include "chrome/common/print_messages.h"
#include "chrome/common/render_messages.h"
#include "chrome/renderer/prerender/prerender_helper.h"
#include "chrome/renderer/printing/print_web_view_helper.h"
#include "content/public/renderer/render_frame.h"
#include "skia/ext/image_operations.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/WebKit/public/platform/WebImage.h"
#include "third_party/WebKit/public/web/WebElement.h"
#include "third_party/WebKit/public/web/WebNode.h"

using blink::WebElement;
using blink::WebNode;

namespace {
// If the source image is null or occupies less area than
// |thumbnail_min_area_pixels|, we return the image unmodified.  Otherwise, we
// scale down the image so that the width and height do not exceed
// |thumbnail_max_size_pixels|, preserving the original aspect ratio.
SkBitmap Downscale(blink::WebImage image,
                   int thumbnail_min_area_pixels,
                   gfx::Size thumbnail_max_size_pixels) {
  if (image.isNull())
    return SkBitmap();

  gfx::Size image_size = image.size();

  if (image_size.GetArea() < thumbnail_min_area_pixels)
    return image.getSkBitmap();

  if (image_size.width() <= thumbnail_max_size_pixels.width() &&
      image_size.height() <= thumbnail_max_size_pixels.height())
    return image.getSkBitmap();

  gfx::SizeF scaled_size = image_size;

  if (scaled_size.width() > thumbnail_max_size_pixels.width()) {
    scaled_size.Scale(thumbnail_max_size_pixels.width() / scaled_size.width());
  }

  if (scaled_size.height() > thumbnail_max_size_pixels.height()) {
    scaled_size.Scale(
        thumbnail_max_size_pixels.height() / scaled_size.height());
  }

  return skia::ImageOperations::Resize(image.getSkBitmap(),
                                       skia::ImageOperations::RESIZE_GOOD,
                                       static_cast<int>(scaled_size.width()),
                                       static_cast<int>(scaled_size.height()));
}

}
ChromeRenderFrameObserver::ChromeRenderFrameObserver(
    content::RenderFrame* render_frame)
    : content::RenderFrameObserver(render_frame) {
}

ChromeRenderFrameObserver::~ChromeRenderFrameObserver() {
}

bool ChromeRenderFrameObserver::OnMessageReceived(const IPC::Message& message) {
  // Filter only.
  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP(ChromeRenderFrameObserver, message)
    IPC_MESSAGE_HANDLER(PrerenderMsg_SetIsPrerendering, OnSetIsPrerendering)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()
  if (handled)
    return false;

  IPC_BEGIN_MESSAGE_MAP(ChromeRenderFrameObserver, message)
    IPC_MESSAGE_HANDLER(ChromeViewMsg_RequestThumbnailForContextNode,
                        OnRequestThumbnailForContextNode)
    IPC_MESSAGE_HANDLER(PrintMsg_PrintNodeUnderContextMenu,
                        OnPrintNodeUnderContextMenu)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()

  return handled;
}

void ChromeRenderFrameObserver::OnSetIsPrerendering(bool is_prerendering) {
  if (is_prerendering) {
    // If the PrerenderHelper for this frame already exists, don't create it. It
    // can already be created for subframes during handling of
    // RenderFrameCreated, if the parent frame was prerendering at time of
    // subframe creation.
    if (prerender::PrerenderHelper::Get(render_frame()))
      return;

    // The PrerenderHelper will destroy itself either after recording histograms
    // or on destruction of the RenderView.
    new prerender::PrerenderHelper(render_frame());
  }
}

void ChromeRenderFrameObserver::OnRequestThumbnailForContextNode(
    int thumbnail_min_area_pixels,
    const gfx::Size& thumbnail_max_size_pixels) {
  WebNode context_node = render_frame()->GetContextMenuNode();
  SkBitmap thumbnail;
  gfx::Size original_size;
  if (!context_node.isNull() && context_node.isElementNode()) {
    blink::WebImage image = context_node.to<WebElement>().imageContents();
    original_size = image.size();
    thumbnail = Downscale(image,
                          thumbnail_min_area_pixels,
                          thumbnail_max_size_pixels);
  }
  Send(new ChromeViewHostMsg_RequestThumbnailForContextNode_ACK(
      routing_id(), thumbnail, original_size));
}

void ChromeRenderFrameObserver::OnPrintNodeUnderContextMenu() {
  printing::PrintWebViewHelper* helper =
      printing::PrintWebViewHelper::Get(render_frame()->GetRenderView());
  if (helper)
    helper->PrintNode(render_frame()->GetContextMenuNode());
}