chrome/browser/thumbnails/thumbnail_tab_helper.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/thumbnails/thumbnail_tab_helper.h"
   6
   7 #include "chrome/browser/browser_process.h"
   8 #include "chrome/browser/profiles/profile.h"
   9 #include "chrome/browser/thumbnails/thumbnail_service.h"
  10 #include "chrome/browser/thumbnails/thumbnail_service_factory.h"
  11 #include "chrome/browser/thumbnails/thumbnailing_algorithm.h"
  12 #include "chrome/browser/thumbnails/thumbnailing_context.h"
  13 #include "content/public/browser/browser_thread.h"
  14 #include "content/public/browser/notification_details.h"
  15 #include "content/public/browser/notification_source.h"
  16 #include "content/public/browser/notification_types.h"
  17 #include "content/public/browser/render_view_host.h"
  18 #include "content/public/browser/render_widget_host_view.h"
  19 #include "ui/gfx/color_utils.h"
  20 #include "ui/gfx/geometry/size_conversions.h"
  21 #include "ui/gfx/screen.h"
  22 #include "ui/gfx/scrollbar_size.h"
  23 #include "ui/gfx/skbitmap_operations.h"
  24
  25 #if defined(OS_WIN)
  26 #include "base/win/windows_version.h"
  27 #endif
  28
  29 DEFINE_WEB_CONTENTS_USER_DATA_KEY(ThumbnailTabHelper);
  30
  31 class SkBitmap;
  32
  33 // Overview
  34 // --------
  35 // This class provides a service for updating thumbnails to be used in
  36 // "Most visited" section of the new tab page. The service can be started
  37 // by StartThumbnailing(). The current algorithm of the service is as
  38 // simple as follows:
  39 //
  40 //    When a renderer is about to be hidden (this usually occurs when the
  41 //    current tab is closed or another tab is clicked), update the
  42 //    thumbnail for the tab rendered by the renderer, if needed. The
  43 //    heuristics to judge whether or not to update the thumbnail is
  44 //    implemented in ShouldUpdateThumbnail().
  45
  46 using content::RenderViewHost;
  47 using content::RenderWidgetHost;
  48 using content::WebContents;
  49
  50 using thumbnails::ClipResult;
  51 using thumbnails::ThumbnailingContext;
  52 using thumbnails::ThumbnailingAlgorithm;
  53
  54 namespace {
  55
  56 // Feed the constructed thumbnail to the thumbnail service.
  57 void UpdateThumbnail(const ThumbnailingContext& context,
  58                      const SkBitmap& thumbnail) {
  59   gfx::Image image = gfx::Image::CreateFrom1xBitmap(thumbnail);
  60   context.service->SetPageThumbnail(context, image);
  61   DVLOG(1) << "Thumbnail taken for " << context.url << ": "
  62            << context.score.ToString();
  63 }
  64
  65 void ProcessCapturedBitmap(scoped_refptr<ThumbnailingContext> context,
  66                            scoped_refptr<ThumbnailingAlgorithm> algorithm,
  67                            const SkBitmap& bitmap,
  68                            content::ReadbackResponse response) {
  69   if (response != content::READBACK_SUCCESS)
  70     return;
  71
  72   // On success, we must be on the UI thread (on failure because of shutdown we
  73   // are not on the UI thread).
  74   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  75
  76   algorithm->ProcessBitmap(context, base::Bind(&UpdateThumbnail), bitmap);
  77 }
  78
  79 void AsyncProcessThumbnail(content::WebContents* web_contents,
  80                            scoped_refptr<ThumbnailingContext> context,
  81                            scoped_refptr<ThumbnailingAlgorithm> algorithm) {
  82   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
  83   RenderWidgetHost* render_widget_host = web_contents->GetRenderViewHost();
  84   content::RenderWidgetHostView* view = render_widget_host->GetView();
  85   if (!view)
  86     return;
  87   if (!view->IsSurfaceAvailableForCopy())
  88     return;
  89
  90   gfx::Rect copy_rect = gfx::Rect(view->GetViewBounds().size());
  91   // Clip the pixels that will commonly hold a scrollbar, which looks bad in
  92   // thumbnails.
  93   int scrollbar_size = gfx::scrollbar_size();
  94   gfx::Size copy_size;
  95   copy_rect.Inset(0, 0, scrollbar_size, scrollbar_size);
  96
  97   if (copy_rect.IsEmpty())
  98     return;
  99
 100   ui::ScaleFactor scale_factor =
 101       ui::GetSupportedScaleFactor(
 102           ui::GetScaleFactorForNativeView(view->GetNativeView()));
 103   context->clip_result = algorithm->GetCanvasCopyInfo(
 104       copy_rect.size(),
 105       scale_factor,
 106       &copy_rect,
 107       &context->requested_copy_size);
 108   render_widget_host->CopyFromBackingStore(
 109       copy_rect,
 110       context->requested_copy_size,
 111       base::Bind(&ProcessCapturedBitmap, context, algorithm),
 112       kN32_SkColorType);
 113 }
 114
 115 }  // namespace
 116
 117 ThumbnailTabHelper::ThumbnailTabHelper(content::WebContents* contents)
 118     : content::WebContentsObserver(contents),
 119       enabled_(true),
 120       load_interrupted_(false) {
 121   // Even though we deal in RenderWidgetHosts, we only care about its
 122   // subclass, RenderViewHost when it is in a tab. We don't make thumbnails
 123   // for RenderViewHosts that aren't in tabs, or RenderWidgetHosts that
 124   // aren't views like select popups.
 125   registrar_.Add(this,
 126                  content::NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED,
 127                  content::Source<WebContents>(contents));
 128 }
 129
 130 ThumbnailTabHelper::~ThumbnailTabHelper() {
 131 }
 132
 133 void ThumbnailTabHelper::Observe(int type,
 134                                  const content::NotificationSource& source,
 135                                  const content::NotificationDetails& details) {
 136   switch (type) {
 137     case content::NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED:
 138       RenderViewHostCreated(content::Details<RenderViewHost>(details).ptr());
 139       break;
 140
 141     case content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED:
 142       if (!*content::Details<bool>(details).ptr())
 143         WidgetHidden(content::Source<RenderWidgetHost>(source).ptr());
 144       break;
 145
 146     default:
 147       NOTREACHED() << "Unexpected notification type: " << type;
 148   }
 149 }
 150
 151 void ThumbnailTabHelper::RenderViewDeleted(
 152     content::RenderViewHost* render_view_host) {
 153   bool registered = registrar_.IsRegistered(
 154       this,
 155       content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
 156       content::Source<RenderWidgetHost>(render_view_host));
 157   if (registered) {
 158     registrar_.Remove(
 159         this,
 160         content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
 161         content::Source<RenderWidgetHost>(render_view_host));
 162   }
 163 }
 164
 165 void ThumbnailTabHelper::DidStartLoading() {
 166   load_interrupted_ = false;
 167 }
 168
 169 void ThumbnailTabHelper::NavigationStopped() {
 170   // This function gets called when the page loading is interrupted by the
 171   // stop button.
 172   load_interrupted_ = true;
 173 }
 174
 175 void ThumbnailTabHelper::UpdateThumbnailIfNecessary(
 176     WebContents* web_contents) {
 177   // Destroying a WebContents may trigger it to be hidden, prompting a snapshot
 178   // which would be unwise to attempt <http://crbug.com/130097>. If the
 179   // WebContents is in the middle of destruction, do not risk it.
 180   if (!web_contents || web_contents->IsBeingDestroyed())
 181     return;
 182   // Skip if a pending entry exists. WidgetHidden can be called while navigating
 183   // pages and this is not a time when thumbnails should be generated.
 184   if (web_contents->GetController().GetPendingEntry())
 185     return;
 186   const GURL& url = web_contents->GetURL();
 187   Profile* profile =
 188       Profile::FromBrowserContext(web_contents->GetBrowserContext());
 189
 190   scoped_refptr<thumbnails::ThumbnailService> thumbnail_service =
 191       ThumbnailServiceFactory::GetForProfile(profile);
 192
 193   // Skip if we don't need to update the thumbnail.
 194   if (thumbnail_service.get() == NULL ||
 195       !thumbnail_service->ShouldAcquirePageThumbnail(url)) {
 196     return;
 197   }
 198
 199   scoped_refptr<thumbnails::ThumbnailingAlgorithm> algorithm(
 200       thumbnail_service->GetThumbnailingAlgorithm());
 201
 202   scoped_refptr<ThumbnailingContext> context(new ThumbnailingContext(
 203       web_contents, thumbnail_service.get(), load_interrupted_));
 204   AsyncProcessThumbnail(web_contents, context, algorithm);
 205 }
 206
 207 void ThumbnailTabHelper::RenderViewHostCreated(
 208     content::RenderViewHost* renderer) {
 209   // NOTIFICATION_WEB_CONTENTS_RENDER_VIEW_HOST_CREATED is really a new
 210   // RenderView, not RenderViewHost, and there is no good way to get
 211   // notifications of RenderViewHosts. So just be tolerant of re-registrations.
 212   bool registered = registrar_.IsRegistered(
 213       this,
 214       content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
 215       content::Source<RenderWidgetHost>(renderer));
 216   if (!registered) {
 217     registrar_.Add(
 218         this,
 219         content::NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
 220         content::Source<RenderWidgetHost>(renderer));
 221   }
 222 }
 223
 224 void ThumbnailTabHelper::WidgetHidden(RenderWidgetHost* widget) {
 225   if (!enabled_)
 226     return;
 227   UpdateThumbnailIfNecessary(web_contents());
 228 }