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.
5 #include "chrome/browser/ui/views/tabs/native_view_photobooth_win.h"
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"
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);
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);
41 ///////////////////////////////////////////////////////////////////////////////
42 // NativeViewPhotoboothWin, public:
45 NativeViewPhotobooth* NativeViewPhotobooth::Create(
46 gfx::NativeView initial_view) {
47 return new NativeViewPhotoboothWin(initial_view);
50 NativeViewPhotoboothWin::NativeViewPhotoboothWin(HWND initial_hwnd)
51 : capture_window_(NULL),
52 current_hwnd_(initial_hwnd) {
53 DCHECK(IsWindow(current_hwnd_));
54 CreateCaptureWindow(initial_hwnd);
57 NativeViewPhotoboothWin::~NativeViewPhotoboothWin() {
58 // Detach the attached HWND. The creator of the photo-booth is responsible
61 capture_window_->Close();
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);
72 current_hwnd_ = new_hwnd;
74 if (IsWindow(new_hwnd)) {
75 // Insert the WebContents into the capture window.
76 SetParent(current_hwnd_, capture_window_->GetNativeView());
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);
87 void NativeViewPhotoboothWin::PaintScreenshotIntoCanvas(
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_);
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);
101 // Transfer the contents of the layered capture window to the screen-shot
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,
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();
119 ///////////////////////////////////////////////////////////////////////////////
120 // NativeViewPhotoboothWin, private:
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.
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.
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).
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.
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);
164 Replace(initial_hwnd);