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Fix WindowCapturerWin to capture window decorations after window size changes.

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DWM doesn't update window decorations in bitmap captured
from GetWindowDC(). Work it around by calling PrintWindow()
after each resize (which somehow affects what's later
captured from GetWindowDC()). That solution avoids the
downsides of PrintWindow() (namely flickering) while still
allowing to capture window decorations correctly.

BUG=crbug.com/289759
R=alexeypa@chromium.org

Review URL: https://webrtc-codereview.appspot.com/2295004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4847 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
sergeyu@chromium.org 2013-09-25 22:56:59 +00:00
parent 3fdeddb59a
commit becbefaee6
1 changed files with 19 additions and 6 deletions
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25
webrtc/modules/desktop_capture/window_capturer_win.cc
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@ -107,6 +107,8 @@ class WindowCapturerWin : public WindowCapturer {
HMODULE dwmapi_library_;
DwmIsCompositionEnabledFunc is_composition_enabled_func_;
DesktopSize previous_size_;
DISALLOW_COPY_AND_ASSIGN(WindowCapturerWin);
};
@ -151,6 +153,7 @@ bool WindowCapturerWin::SelectWindow(WindowId id) {
if (!IsWindow(window) || !IsWindowVisible(window) || IsIconic(window))
return false;
window_ = window;
previous_size_.set(0, 0);
return true;
}
@ -206,13 +209,21 @@ void WindowCapturerWin::Capture(const DesktopRegion& region) {
// window is occluded. PrintWindow() is slower but lets rendering the window
// contents to an off-screen device context when Aero is not available.
// PrintWindow() is not supported by some applications.
//
// If Aero is enabled, we prefer BitBlt() because it's faster and avoids
// window flickering. Otherwise, we prefer PrintWindow() because BitBlt() may
// render occluding windows on top of the desired window.
//
// When composition is enabled the DC returned by GetWindowDC() doesn't always
// have window frame rendered correctly. Windows renders it only once and then
// caches the result between captures. We hack it around by calling
// PrintWindow() whenever window size changes - it somehow affects what we
// get from BitBlt() on the subsequent captures.
if (!IsAeroEnabled())
if (!IsAeroEnabled() ||
(!previous_size_.is_empty() && !previous_size_.equals(frame->size()))) {
result = PrintWindow(window_, mem_dc, 0);
}
// Aero is enabled or PrintWindow() failed, use BitBlt.
if (!result) {
@ -220,15 +231,17 @@ void WindowCapturerWin::Capture(const DesktopRegion& region) {
window_dc, 0, 0, SRCCOPY);
}
SelectObject(mem_dc, NULL);
DeleteDC(mem_dc);
ReleaseDC(window_, window_dc);
previous_size_ = frame->size();
if (!result) {
LOG(LS_ERROR) << "Both PrintWindow() and BitBlt() failed.";
frame.reset();
}
SelectObject(mem_dc, NULL);
DeleteDC(mem_dc);
ReleaseDC(window_, window_dc);
callback_->OnCaptureCompleted(frame.release());
}