src/chrome/browser/ui/views/panels/taskbar_window_thumbnailer_win.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/ui/views/panels/taskbar_window_thumbnailer_win.h"
   6
   7 #include <dwmapi.h>
   8
   9 #include "base/logging.h"
  10 #include "base/win/scoped_hdc.h"
  11 #include "skia/ext/image_operations.h"
  12 #include "ui/gfx/canvas.h"
  13 #include "ui/gfx/gdi_util.h"
  14
  15 namespace {
  16
  17 HBITMAP GetNativeBitmapFromSkBitmap(const SkBitmap& bitmap) {
  18   int width = bitmap.width();
  19   int height = bitmap.height();
  20
  21   BITMAPV4HEADER native_bitmap_header;
  22   gfx::CreateBitmapV4Header(width, height, &native_bitmap_header);
  23
  24   HDC dc = ::GetDC(NULL);
  25   void* bits;
  26   HBITMAP native_bitmap = ::CreateDIBSection(dc,
  27       reinterpret_cast<BITMAPINFO*>(&native_bitmap_header),
  28       DIB_RGB_COLORS,
  29       &bits,
  30       NULL,
  31       0);
  32   DCHECK(native_bitmap);
  33   ::ReleaseDC(NULL, dc);
  34   bitmap.copyPixelsTo(bits, width * height * 4, width * 4);
  35   return native_bitmap;
  36 }
  37
  38 void EnableCustomThumbnail(HWND hwnd, bool enable) {
  39   BOOL enable_value = enable;
  40   ::DwmSetWindowAttribute(hwnd,
  41                           DWMWA_FORCE_ICONIC_REPRESENTATION,
  42                           &enable_value,
  43                           sizeof(enable_value));
  44   ::DwmSetWindowAttribute(hwnd,
  45                           DWMWA_HAS_ICONIC_BITMAP,
  46                           &enable_value,
  47                           sizeof(enable_value));
  48 }
  49
  50 }  // namespace
  51
  52
  53 TaskbarWindowThumbnailerWin::TaskbarWindowThumbnailerWin(
  54     HWND hwnd, TaskbarWindowThumbnailerDelegateWin* delegate)
  55     : hwnd_(hwnd),
  56       delegate_(delegate) {
  57   ui::HWNDSubclass::AddFilterToTarget(hwnd_, this);
  58 }
  59
  60 TaskbarWindowThumbnailerWin::~TaskbarWindowThumbnailerWin() {
  61   ui::HWNDSubclass::RemoveFilterFromAllTargets(this);
  62 }
  63
  64 void TaskbarWindowThumbnailerWin::Start() {
  65   EnableCustomThumbnail(hwnd_, true);
  66 }
  67
  68 void TaskbarWindowThumbnailerWin::Stop() {
  69   capture_bitmap_.reset();
  70   EnableCustomThumbnail(hwnd_, false);
  71 }
  72
  73 void TaskbarWindowThumbnailerWin::CaptureSnapshot() {
  74   if (!capture_bitmap_)
  75     capture_bitmap_.reset(CaptureWindowImage());
  76 }
  77
  78 void TaskbarWindowThumbnailerWin::InvalidateSnapshot() {
  79   capture_bitmap_.reset();
  80
  81   // The snapshot feeded to the system could be cached. Invalidate it.
  82   ::DwmInvalidateIconicBitmaps(hwnd_);
  83 }
  84
  85 void TaskbarWindowThumbnailerWin::ReplaceWindow(HWND new_hwnd) {
  86   // Stop serving the custom thumbnail for the old window.
  87   EnableCustomThumbnail(hwnd_, false);
  88   ui::HWNDSubclass::RemoveFilterFromAllTargets(this);
  89
  90   hwnd_ = new_hwnd;
  91
  92   // Start serving the custom thumbnail to the new window.
  93   ui::HWNDSubclass::AddFilterToTarget(hwnd_, this);
  94   EnableCustomThumbnail(hwnd_, true);
  95 }
  96
  97 bool TaskbarWindowThumbnailerWin::FilterMessage(HWND hwnd,
  98                                                 UINT message,
  99                                                 WPARAM w_param,
 100                                                 LPARAM l_param,
 101                                                 LRESULT* l_result) {
 102   DCHECK_EQ(hwnd_, hwnd);
 103   switch (message) {
 104     case WM_DWMSENDICONICTHUMBNAIL:
 105       return OnDwmSendIconicThumbnail(HIWORD(l_param),
 106                                       LOWORD(l_param),
 107                                       l_result);
 108     case WM_DWMSENDICONICLIVEPREVIEWBITMAP:
 109       return OnDwmSendIconicLivePreviewBitmap(l_result);
 110   }
 111   return false;
 112 }
 113
 114 bool TaskbarWindowThumbnailerWin::OnDwmSendIconicThumbnail(
 115     int width, int height, LRESULT* l_result) {
 116   CaptureSnapshot();
 117
 118   SkBitmap* thumbnail_bitmap = capture_bitmap_.get();
 119
 120   // Scale the image if needed.
 121   SkBitmap scaled_bitmap;
 122   if (capture_bitmap_->width() != width ||
 123       capture_bitmap_->height() != height) {
 124     double x_scale = static_cast<double>(width) / capture_bitmap_->width();
 125     double y_scale = static_cast<double>(height) / capture_bitmap_->height();
 126     double scale = std::min(x_scale, y_scale);
 127     width = capture_bitmap_->width() * scale;
 128     height = capture_bitmap_->height() * scale;
 129     scaled_bitmap = skia::ImageOperations::Resize(
 130         *capture_bitmap_, skia::ImageOperations::RESIZE_GOOD, width, height);
 131     thumbnail_bitmap = &scaled_bitmap;
 132   }
 133
 134   HBITMAP native_bitmap = GetNativeBitmapFromSkBitmap(*thumbnail_bitmap);
 135   ::DwmSetIconicThumbnail(hwnd_, native_bitmap, 0);
 136   ::DeleteObject(native_bitmap);
 137
 138   *l_result = 0;
 139   return true;
 140 }
 141
 142 bool TaskbarWindowThumbnailerWin::OnDwmSendIconicLivePreviewBitmap(
 143     LRESULT* l_result) {
 144   CaptureSnapshot();
 145
 146   HBITMAP native_bitmap = GetNativeBitmapFromSkBitmap(*capture_bitmap_);
 147   ::DwmSetIconicLivePreviewBitmap(hwnd_, native_bitmap, NULL, 0);
 148   ::DeleteObject(native_bitmap);
 149   *l_result = 0;
 150   return true;
 151 }
 152
 153 SkBitmap* TaskbarWindowThumbnailerWin::CaptureWindowImage() const {
 154   std::vector<HWND> snapshot_hwnds;
 155   if (delegate_)
 156     snapshot_hwnds = delegate_->GetSnapshotWindowHandles();
 157   if (snapshot_hwnds.empty())
 158     snapshot_hwnds.push_back(hwnd_);
 159
 160   int enclosing_x = 0;
 161   int enclosing_y = 0;
 162   int enclosing_right = 0;
 163   int enclosing_bottom = 0;
 164   for (std::vector<HWND>::const_iterator iter = snapshot_hwnds.begin();
 165        iter != snapshot_hwnds.end(); ++iter) {
 166     RECT bounds;
 167     if (!::GetWindowRect(*iter, &bounds))
 168       continue;
 169     if (iter == snapshot_hwnds.begin()) {
 170       enclosing_x = bounds.left;
 171       enclosing_y = bounds.top;
 172       enclosing_right = bounds.right;
 173       enclosing_bottom = bounds.bottom;
 174     } else {
 175       if (bounds.left < enclosing_x)
 176         enclosing_x = bounds.left;
 177       if (bounds.top < enclosing_y)
 178         enclosing_y = bounds.top;
 179       if (bounds.right > enclosing_right)
 180         enclosing_right = bounds.right;
 181       if (bounds.bottom > enclosing_bottom)
 182         enclosing_bottom = bounds.bottom;
 183     }
 184   }
 185
 186   int width = enclosing_right - enclosing_x;
 187   int height = enclosing_bottom - enclosing_y;
 188   if (!width || !height)
 189     return NULL;
 190
 191   gfx::Canvas canvas(gfx::Size(width, height), 1.0f, false);
 192   {
 193     skia::ScopedPlatformPaint scoped_platform_paint(canvas.sk_canvas());
 194     HDC target_dc = scoped_platform_paint.GetPlatformSurface();
 195     for (std::vector<HWND>::const_iterator iter = snapshot_hwnds.begin();
 196          iter != snapshot_hwnds.end(); ++iter) {
 197       HWND current_hwnd = *iter;
 198       RECT current_bounds;
 199       if (!::GetWindowRect(current_hwnd, &current_bounds))
 200         continue;
 201       base::win::ScopedGetDC source_dc(current_hwnd);
 202       ::BitBlt(target_dc,
 203                current_bounds.left - enclosing_x,
 204                current_bounds.top - enclosing_y,
 205                current_bounds.right - current_bounds.left,
 206                current_bounds.bottom - current_bounds.top,
 207                source_dc,
 208                0,
 209                0,
 210                SRCCOPY);
 211       ::ReleaseDC(current_hwnd, source_dc);
 212     }
 213   }
 214   return new SkBitmap(canvas.ExtractImageRep().sk_bitmap());
 215 }