Commit 7a5603fd authored by Peter Wu's avatar Peter Wu
Browse files

Refactor pixmap grabbing, add robustness

Do not go in an infinite loop when the root window cannot be captured
(bug 370303). Avoid crashing xcb_image_destroy by checking for NULL.

Split the getWindowPixmap into three logical methods depending on the
consumer: obtaining a pixmap from KWin, obtaining a pixmap from a single
window and obtaining a pixmap from a full screen. This enables some
optimizations, like obtaining a smaller area of the screen without
cropping. Additionally, it will make fixing HiDPI support easier.

Added robustness: if KWin somehow fails, now it will fallback to a
fullscreen capture instead of an null pixmap.

REVIEW: 129176
BUG: 370303
FIXED-IN: 16.12
parent aab52c83
......@@ -275,46 +275,75 @@ QPixmap X11ImageGrabber::blendCursorImage(const QPixmap &pixmap, int x, int y, i
return blendedPixmap;
QPixmap X11ImageGrabber::getWindowPixmap(xcb_window_t window, bool blendPointer)
QPixmap X11ImageGrabber::getPixmapFromDrawable(xcb_drawable_t drawableId, const QRect &rect)
xcb_connection_t *xcbConn = QX11Info::connection();
// first get geometry information for our drawable
xcb_get_geometry_cookie_t geomCookie = xcb_get_geometry_unchecked(xcbConn, window);
CScopedPointer<xcb_get_geometry_reply_t> geomReply(xcb_get_geometry_reply(xcbConn, geomCookie, NULL));
// then proceed to get an image
// proceed to get an image based on the geometry (in device pixels)
QScopedPointer<xcb_image_t, ScopedPointerXcbImageDeleter> xcbImage(
// if the image is null, this means we need to get the root image window
// and run a crop
// too bad, the capture failed.
if (xcbImage.isNull()) {
return getWindowPixmap(QX11Info::appRootWindow(), blendPointer)
.copy(geomReply->x, geomReply->y, geomReply->width, geomReply->height);
return QPixmap();
// now process the image
QPixmap nativePixmap = convertFromNative(;
return nativePixmap;
// finalize the grabbed pixmap where we know the absolute position
QPixmap X11ImageGrabber::postProcessPixmap(QPixmap pixmap, QRect rect, bool blendPointer)
if (!(blendPointer)) {
return nativePixmap;
// note: this may be the null pixmap if an error occurred.
return pixmap;
return blendCursorImage(pixmap, rect.x(), rect.y(), rect.width(), rect.height());
QPixmap X11ImageGrabber::getToplevelPixmap(QRect rect, bool blendPointer)
xcb_window_t rootWindow = QX11Info::appRootWindow();
// Treat a null rect as an alias for capturing fullscreen
if (!rect.isValid()) {
rect = getDrawableGeometry(rootWindow);
// now we blend in a pointer image
QPixmap nativePixmap = getPixmapFromDrawable(rootWindow, rect);
return postProcessPixmap(nativePixmap, rect, blendPointer);
QPixmap X11ImageGrabber::getWindowPixmap(xcb_window_t window, bool blendPointer)
xcb_connection_t *xcbConn = QX11Info::connection();
// first get geometry information for our window
xcb_get_geometry_cookie_t geomCookie = xcb_get_geometry_unchecked(xcbConn, window);
CScopedPointer<xcb_get_geometry_reply_t> geomReply(xcb_get_geometry_reply(xcbConn, geomCookie, NULL));
QRect rect(geomReply->x, geomReply->y, geomReply->width, geomReply->height);
// then proceed to get an image
QPixmap nativePixmap = getPixmapFromDrawable(window, rect);
// Translate window coordinates to global ones.
xcb_get_geometry_cookie_t geomRootCookie = xcb_get_geometry_unchecked(xcbConn, geomReply->root);
CScopedPointer<xcb_get_geometry_reply_t> geomRootReply(xcb_get_geometry_reply(xcbConn, geomRootCookie, NULL));
......@@ -324,7 +353,16 @@ QPixmap X11ImageGrabber::getWindowPixmap(xcb_window_t window, bool blendPointer)
CScopedPointer<xcb_translate_coordinates_reply_t> translateReply(
xcb_translate_coordinates_reply(xcbConn, translateCookie, NULL));
return blendCursorImage(nativePixmap, translateReply->dst_x,translateReply->dst_y, geomReply->width, geomReply->height);
// Adjust local to global coordinates.
rect.moveRight(rect.x() + translateReply->dst_x);
rect.moveTop(rect.y() + translateReply->dst_y);
// If the window capture failed, try to obtain one from the full screen.
if (nativePixmap.isNull()) {
return getToplevelPixmap(rect, blendPointer);
return postProcessPixmap(nativePixmap, rect, blendPointer);
bool X11ImageGrabber::isKWinAvailable()
......@@ -339,10 +377,20 @@ bool X11ImageGrabber::isKWinAvailable()
return false;
void X11ImageGrabber::KWinDBusScreenshotHelper(quint64 window)
void X11ImageGrabber::KWinDBusScreenshotHelper(quint64 pixmapId)
mPixmap = getWindowPixmap((xcb_window_t)window, false);
emit pixmapChanged(mPixmap);
// obtain width and height and grab an image (x and y are always zero for pixmaps)
QRect rect = getDrawableGeometry((xcb_drawable_t)pixmapId);
mPixmap = getPixmapFromDrawable((xcb_drawable_t)pixmapId, rect);
if (!mPixmap.isNull()) {
emit pixmapChanged(mPixmap);
// Cannot retrieve pixmap from KWin, just fallback to fullscreen capture. We
// could try to detect the original action (window under cursor or active
// window), but that is too complex for this edge case.
void X11ImageGrabber::rectangleSelectionCancelled()
......@@ -372,7 +420,7 @@ void X11ImageGrabber::rectangleSelectionConfirmed(const QPixmap &pixmap, const Q
void X11ImageGrabber::grabFullScreen()
mPixmap = getWindowPixmap(QX11Info::appRootWindow(), mCapturePointer);
mPixmap = getToplevelPixmap(QRect(), mCapturePointer);
emit pixmapChanged(mPixmap);
......@@ -382,7 +430,7 @@ void X11ImageGrabber::grabTransientWithParent()
// grab the image early
mPixmap = getWindowPixmap(QX11Info::appRootWindow(), false);
mPixmap = getToplevelPixmap(QRect(), false);
// now that we know we have a transient window, let's
// find other possible transient windows and the app window itself.
......@@ -543,7 +591,7 @@ void X11ImageGrabber::grabApplicationWindowHelper(xcb_window_t window)
KWindowInfo info(window, NET::WMFrameExtents);
if (info.valid()) {
QRect frameGeom = info.frameGeometry();
mPixmap = getWindowPixmap(QX11Info::appRootWindow(), mCapturePointer).copy(frameGeom);
mPixmap = getToplevelPixmap(frameGeom, mCapturePointer);
// fallback is window without the frame
......@@ -551,11 +599,11 @@ void X11ImageGrabber::grabApplicationWindowHelper(xcb_window_t window)
emit pixmapChanged(mPixmap);
QRect X11ImageGrabber::getApplicationWindowGeometry(xcb_window_t window)
QRect X11ImageGrabber::getDrawableGeometry(xcb_drawable_t drawable)
xcb_connection_t *xcbConn = QX11Info::connection();
xcb_get_geometry_cookie_t geomCookie = xcb_get_geometry_unchecked(xcbConn, window);
xcb_get_geometry_cookie_t geomCookie = xcb_get_geometry_unchecked(xcbConn, drawable);
CScopedPointer<xcb_get_geometry_reply_t> geomReply(xcb_get_geometry_reply(xcbConn, geomCookie, NULL));
return QRect(geomReply->x, geomReply->y, geomReply->width, geomReply->height);
......@@ -570,7 +618,7 @@ void X11ImageGrabber::grabCurrentScreen()
mPixmap = getWindowPixmap(QX11Info::appRootWindow(), mCapturePointer).copy(screenRect);
mPixmap = getToplevelPixmap(screenRect, mCapturePointer);
emit pixmapChanged(mPixmap);
......@@ -581,7 +629,7 @@ void X11ImageGrabber::grabCurrentScreen()
void X11ImageGrabber::grabRectangularRegion()
QuickEditor *editor = new QuickEditor(getWindowPixmap(QX11Info::appRootWindow(), false));
QuickEditor *editor = new QuickEditor(getToplevelPixmap(QRect(), false));
connect(editor, &QuickEditor::grabDone, this, &X11ImageGrabber::rectangleSelectionConfirmed);
connect(editor, &QuickEditor::grabCancelled, this, &X11ImageGrabber::rectangleSelectionCancelled);
......@@ -77,7 +77,10 @@ class X11ImageGrabber : public ImageGrabber
bool isKWinAvailable();
xcb_window_t getRealWindowUnderCursor();
void grabApplicationWindowHelper(xcb_window_t window);
QRect getApplicationWindowGeometry(xcb_window_t window);
QRect getDrawableGeometry(xcb_drawable_t drawable);
QPixmap postProcessPixmap(QPixmap pixmap, QRect rect, bool blendPointer);
QPixmap getPixmapFromDrawable(xcb_drawable_t drawableId, const QRect &rect);
QPixmap getToplevelPixmap(QRect rect, bool blendPointer);
QPixmap getWindowPixmap(xcb_window_t window, bool blendPointer);
QPixmap convertFromNative(xcb_image_t *xcbImage);
xcb_window_t getTransientWindowParent(xcb_window_t winId, QRect &outRect);
......@@ -90,7 +93,9 @@ template <typename T> using CScopedPointer = QScopedPointer<T, QScopedPointerPod
struct ScopedPointerXcbImageDeleter
static inline void cleanup(xcb_image_t *xcbImage) {
if (xcbImage) {
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment