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/tabs/native_view_photobooth_win.h" 6 7 #include "third_party/skia/include/core/SkBitmap.h" 8 #include "ui/gfx/canvas.h" 9 #include "ui/gfx/point.h" 10 #include "ui/gfx/rect.h" 11 #include "ui/views/widget/widget.h" 12 13 namespace { 14 15 static BOOL CALLBACK MonitorEnumProc(HMONITOR monitor, HDC monitor_dc, 16 RECT* monitor_rect, LPARAM data) { 17 gfx::Point* point = reinterpret_cast<gfx::Point*>(data); 18 if (monitor_rect->right > point->x() && monitor_rect->bottom > point->y()) { 19 point->set_x(monitor_rect->right); 20 point->set_y(monitor_rect->bottom); 21 } 22 return TRUE; 23 } 24 25 gfx::Point GetCaptureWindowPosition() { 26 // Since the capture window must be visible to be painted, it must be opened 27 // off screen to avoid flashing. But if it is opened completely off-screen 28 // (e.g. at 0xFFFFx0xFFFF) then on Windows Vista it will not paint even if it 29 // _is_ visible. So we need to find the right/bottommost monitor, and 30 // position it so that 1x1 pixel is on-screen on that monitor which is enough 31 // to convince Vista to paint it. Don't ask why this is so - this appears to 32 // be a regression over XP. 33 gfx::Point point(0, 0); 34 EnumDisplayMonitors(NULL, NULL, &MonitorEnumProc, 35 reinterpret_cast<LPARAM>(&point)); 36 return gfx::Point(point.x() - 1, point.y() - 1); 37 } 38 39 } // namespace 40 41 /////////////////////////////////////////////////////////////////////////////// 42 // NativeViewPhotoboothWin, public: 43 44 // static 45 NativeViewPhotobooth* NativeViewPhotobooth::Create( 46 gfx::NativeView initial_view) { 47 return new NativeViewPhotoboothWin(initial_view); 48 } 49 50 NativeViewPhotoboothWin::NativeViewPhotoboothWin(HWND initial_hwnd) 51 : capture_window_(NULL), 52 current_hwnd_(initial_hwnd) { 53 DCHECK(IsWindow(current_hwnd_)); 54 CreateCaptureWindow(initial_hwnd); 55 } 56 57 NativeViewPhotoboothWin::~NativeViewPhotoboothWin() { 58 // Detach the attached HWND. The creator of the photo-booth is responsible 59 // for destroying it. 60 Replace(NULL); 61 capture_window_->Close(); 62 } 63 64 void NativeViewPhotoboothWin::Replace(HWND new_hwnd) { 65 if (IsWindow(current_hwnd_) && 66 GetParent(current_hwnd_) == capture_window_->GetNativeView()) { 67 // We need to hide the window too, so it doesn't show up in the TaskBar or 68 // be parented to the desktop. 69 ShowWindow(current_hwnd_, SW_HIDE); 70 SetParent(current_hwnd_, NULL); 71 } 72 current_hwnd_ = new_hwnd; 73 74 if (IsWindow(new_hwnd)) { 75 // Insert the WebContents into the capture window. 76 SetParent(current_hwnd_, capture_window_->GetNativeView()); 77 78 // Show the window (it may not be visible). This is the only safe way of 79 // doing this. ShowWindow does not work. 80 SetWindowPos(current_hwnd_, NULL, 0, 0, 0, 0, 81 SWP_DEFERERASE | SWP_NOACTIVATE | SWP_NOCOPYBITS | 82 SWP_NOOWNERZORDER | SWP_NOSENDCHANGING | SWP_NOZORDER | 83 SWP_SHOWWINDOW | SWP_NOSIZE); 84 } 85 } 86 87 void NativeViewPhotoboothWin::PaintScreenshotIntoCanvas( 88 gfx::Canvas* canvas, 89 const gfx::Rect& target_bounds) { 90 // Our contained window may have been re-parented. Make sure it belongs to 91 // us until someone calls Replace(NULL). 92 if (IsWindow(current_hwnd_) && 93 GetParent(current_hwnd_) != capture_window_->GetNativeView()) { 94 Replace(current_hwnd_); 95 } 96 97 // We compel the contained HWND to paint now, synchronously. We do this to 98 // populate the device context with valid and current data. 99 RedrawWindow(current_hwnd_, NULL, NULL, RDW_INVALIDATE | RDW_UPDATENOW); 100 101 // Transfer the contents of the layered capture window to the screen-shot 102 // canvas' DIB. 103 HDC target_dc = canvas->BeginPlatformPaint(); 104 HDC source_dc = GetDC(current_hwnd_); 105 RECT window_rect = {0}; 106 GetWindowRect(current_hwnd_, &window_rect); 107 BitBlt(target_dc, target_bounds.x(), target_bounds.y(), 108 target_bounds.width(), target_bounds.height(), source_dc, 0, 0, 109 SRCCOPY); 110 // Windows screws up the alpha channel on all text it draws, and so we need 111 // to call makeOpaque _after_ the blit to correct for this. 112 skia::MakeOpaque(canvas->sk_canvas(), target_bounds.x(), 113 target_bounds.y(), target_bounds.width(), 114 target_bounds.height()); 115 ReleaseDC(current_hwnd_, source_dc); 116 canvas->EndPlatformPaint(); 117 } 118 119 /////////////////////////////////////////////////////////////////////////////// 120 // NativeViewPhotoboothWin, private: 121 122 void NativeViewPhotoboothWin::CreateCaptureWindow(HWND initial_hwnd) { 123 // Snapshotting a HWND is tricky - if the HWND is clipped (e.g. positioned 124 // partially off-screen) then just blitting from the HWND' DC to the capture 125 // bitmap would be incorrect, since the capture bitmap would show only the 126 // visible area of the HWND. 127 // 128 // The approach turns out to be to create a second layered window in 129 // hyperspace the to act as a "photo booth." The window is created with the 130 // size of the unclipped HWND, and we attach the HWND as a child, refresh the 131 // HWND' by calling |Paint| on it, and then blitting from the HWND's DC to 132 // the capture bitmap. This results in the entire unclipped HWND display 133 // bitmap being captured. 134 // 135 // The capture window must be layered so that Windows generates a backing 136 // store for it, so that blitting from a child window's DC produces data. If 137 // the window is not layered, because it is off-screen Windows does not 138 // retain its contents and blitting results in blank data. The capture window 139 // is a "basic" (1 level of alpha) layered window because that is the mode 140 // that supports having child windows (variable alpha layered windows do not 141 // support child HWNDs). 142 // 143 // This function sets up the off-screen capture window, and attaches the 144 // associated HWND to it. Note that the details are important here, see below 145 // for further comments. 146 // 147 RECT contents_rect; 148 GetClientRect(initial_hwnd, &contents_rect); 149 gfx::Point window_position = GetCaptureWindowPosition(); 150 gfx::Rect capture_bounds(window_position.x(), window_position.y(), 151 contents_rect.right - contents_rect.left, 152 contents_rect.bottom - contents_rect.top); 153 capture_window_ = new views::Widget; 154 views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP); 155 params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW; 156 params.bounds = capture_bounds; 157 capture_window_->Init(params); 158 // If the capture window isn't visible, blitting from the WebContents's 159 // HWND's DC to the capture bitmap produces blankness. 160 capture_window_->Show(); 161 SetLayeredWindowAttributes( 162 capture_window_->GetNativeView(), RGB(0xFF, 0xFF, 0xFF), 0xFF, LWA_ALPHA); 163 164 Replace(initial_hwnd); 165 } 166
