Refactors HWNDPhotobooth into NativeViewPhotobooth and...

chrome/browser/views/tabs/hwnd_photobooth.cc

-// Copyright (c) 2006-2008 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 "app/gfx/canvas.h"
-#include "base/gfx/point.h"
-#include "chrome/browser/tab_contents/tab_contents.h"
-#include "chrome/browser/views/tabs/hwnd_photobooth.h"
-#include "third_party/skia/include/core/SkBitmap.h"
-#include "views/widget/widget_win.h"
-
-namespace {
-
-static BOOL CALLBACK MonitorEnumProc(HMONITOR monitor, HDC monitor_dc,
-                                     RECT* monitor_rect, LPARAM data) {
-  gfx::Point* point = reinterpret_cast<gfx::Point*>(data);
-  if (monitor_rect->right > point->x() && monitor_rect->bottom > point->y()) {
-    point->set_x(monitor_rect->right);
-    point->set_y(monitor_rect->bottom);
-  }
-  return TRUE;
-}
-
-gfx::Point GetCaptureWindowPosition() {
-  // Since the capture window must be visible to be painted, it must be opened
-  // off screen to avoid flashing. But if it is opened completely off-screen
-  // (e.g. at 0xFFFFx0xFFFF) then on Windows Vista it will not paint even if it
-  // _is_ visible. So we need to find the right/bottommost monitor, and
-  // position it so that 1x1 pixel is on-screen on that monitor which is enough
-  // to convince Vista to paint it. Don't ask why this is so - this appears to
-  // be a regression over XP.
-  gfx::Point point(0, 0);
-  EnumDisplayMonitors(NULL, NULL, &MonitorEnumProc,
-                      reinterpret_cast<LPARAM>(&point));
-  return gfx::Point(point.x() - 1, point.y() - 1);
-}
-
-}
-
-///////////////////////////////////////////////////////////////////////////////
-// HWNDPhotobooth, public:
-
-HWNDPhotobooth::HWNDPhotobooth(HWND initial_hwnd)
-    : capture_window_(NULL),
-      current_hwnd_(initial_hwnd) {
-  DCHECK(IsWindow(current_hwnd_));
-  CreateCaptureWindow(initial_hwnd);
-}
-
-HWNDPhotobooth::~HWNDPhotobooth() {
-  // Detach the attached HWND. The creator of the photo-booth is responsible
-  // for destroying it.
-  ReplaceHWND(NULL);
-  capture_window_->Close();
-}
-
-void HWNDPhotobooth::ReplaceHWND(HWND new_hwnd) {
-  if (IsWindow(current_hwnd_) &&
-      GetParent(current_hwnd_) == capture_window_->GetNativeView()) {
-    // We need to hide the window too, so it doesn't show up in the TaskBar or
-    // be parented to the desktop.
-    ShowWindow(current_hwnd_, SW_HIDE);
-    SetParent(current_hwnd_, NULL);
-  }
-  current_hwnd_ = new_hwnd;
-
-  if (IsWindow(new_hwnd)) {
-    // Insert the TabContents into the capture window.
-    SetParent(current_hwnd_, capture_window_->GetNativeView());
-
-    // Show the window (it may not be visible). This is the only safe way of
-    // doing this. ShowWindow does not work.
-    SetWindowPos(current_hwnd_, NULL, 0, 0, 0, 0,
-                 SWP_DEFERERASE | SWP_NOACTIVATE | SWP_NOCOPYBITS |
-                     SWP_NOOWNERZORDER | SWP_NOSENDCHANGING | SWP_NOZORDER |
-                     SWP_SHOWWINDOW | SWP_NOSIZE);
-  }
-}
-
-void HWNDPhotobooth::PaintScreenshotIntoCanvas(
-    gfx::Canvas* canvas,
-    const gfx::Rect& target_bounds) {
-  // Our contained window may have been re-parented. Make sure it belongs to
-  // us until someone calls ReplaceHWND(NULL).
-  if (IsWindow(current_hwnd_) &&
-      GetParent(current_hwnd_) != capture_window_->GetNativeView()) {
-    ReplaceHWND(current_hwnd_);
-  }
-
-  // We compel the contained HWND to paint now, synchronously. We do this to
-  // populate the device context with valid and current data.
-  RedrawWindow(current_hwnd_, NULL, NULL, RDW_INVALIDATE | RDW_UPDATENOW);
-
-  // Transfer the contents of the layered capture window to the screen-shot
-  // canvas' DIB.
-  HDC target_dc = canvas->beginPlatformPaint();
-  HDC source_dc = GetDC(current_hwnd_);
-  RECT window_rect = {0};
-  GetWindowRect(current_hwnd_, &window_rect);
-  BitBlt(target_dc, target_bounds.x(), target_bounds.y(),
-         target_bounds.width(), target_bounds.height(), source_dc, 0, 0,
-         SRCCOPY);
-  // Windows screws up the alpha channel on all text it draws, and so we need
-  // to call makeOpaque _after_ the blit to correct for this.
-  canvas->getTopPlatformDevice().makeOpaque(target_bounds.x(),
-                                            target_bounds.y(),
-                                            target_bounds.width(),
-                                            target_bounds.height());
-  ReleaseDC(current_hwnd_, source_dc);
-  canvas->endPlatformPaint();
-}
-
-///////////////////////////////////////////////////////////////////////////////
-// HWNDPhotobooth, private:
-
-void HWNDPhotobooth::CreateCaptureWindow(HWND initial_hwnd) {
-  // Snapshotting a HWND is tricky - if the HWND is clipped (e.g. positioned
-  // partially off-screen) then just blitting from the HWND' DC to the capture
-  // bitmap would be incorrect, since the capture bitmap would show only the
-  // visible area of the HWND.
-  //
-  // The approach turns out to be to create a second layered window in
-  // hyperspace the to act as a "photo booth." The window is created with the
-  // size of the unclipped HWND, and we attach the HWND as a child, refresh the
-  // HWND' by calling |Paint| on it, and then blitting from the HWND's DC to
-  // the capture bitmap. This results in the entire unclipped HWND display
-  // bitmap being captured.
-  //
-  // The capture window must be layered so that Windows generates a backing
-  // store for it, so that blitting from a child window's DC produces data. If
-  // the window is not layered, because it is off-screen Windows does not
-  // retain its contents and blitting results in blank data. The capture window
-  // is a "basic" (1 level of alpha) layered window because that is the mode
-  // that supports having child windows (variable alpha layered windows do not
-  // support child HWNDs).
-  //
-  // This function sets up the off-screen capture window, and attaches the
-  // associated HWND to it. Note that the details are important here, see below
-  // for further comments.
-  //
-  CRect contents_rect;
-  GetClientRect(initial_hwnd, &contents_rect);
-  gfx::Point window_position = GetCaptureWindowPosition();
-  gfx::Rect capture_bounds(window_position.x(), window_position.y(),
-                           contents_rect.Width(), contents_rect.Height());
-  capture_window_ = new views::WidgetWin;
-  capture_window_->set_window_style(WS_POPUP);
-  // WS_EX_TOOLWINDOW ensures the capture window doesn't produce a Taskbar
-  // button.
-  capture_window_->set_window_ex_style(WS_EX_LAYERED | WS_EX_TOOLWINDOW);
-  capture_window_->Init(NULL, capture_bounds, false);
-  // If the capture window isn't visible, blitting from the TabContents'
-  // HWND's DC to the capture bitmap produces blankness.
-  capture_window_->Show();
-  SetLayeredWindowAttributes(
-      capture_window_->GetNativeView(), RGB(0xFF, 0xFF, 0xFF), 0xFF, LWA_ALPHA);
-
-  ReplaceHWND(initial_hwnd);
-}