[vlc-devel] [3.0 PATCH 1/2] qt: create another indirection X11 window

[remi at remlab.net]

From: Rémi Denis-Courmont <remi at remlab.net>

The main window may be destroyed before the video window. This notably
occurs if the user requests to close the main UI via window decorations.
While Qt allows those requests to be rejected, doing so would
reintroduce obnoxious bug #4606.

The Qt-X11 display connection will be closed as well as it belongs to
the QApplication instance.

This creates a separate window belonging to a separate display
connection, and which is not tied to the QApplication and QMainWindow
instances. Unfortunately, this adds yet another connection to the X11
display server in the VLC process in addition to QApplication's and the
video display's. And that connection won't process events.

Refs #21875.
---
 .../gui/qt/components/interface_widgets.cpp   |  4 +-
 modules/gui/qt/qt.cpp                         | 64 ++++++++++++++++++-
 2 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/modules/gui/qt/components/interface_widgets.cpp b/modules/gui/qt/components/interface_widgets.cpp
index ced7d9f8c7..74e82eab58 100644
--- a/modules/gui/qt/components/interface_widgets.cpp
+++ b/modules/gui/qt/components/interface_widgets.cpp
@@ -228,13 +228,15 @@ QSize VideoWidget::physicalSize() const
     return current_size;
 }
 
+void WindowResized(vout_window_t *, const QSize&);
+
 void VideoWidget::reportSize()
 {
     if( !p_window )
         return;
 
     QSize size = physicalSize();
-    vout_window_ReportSize( p_window, size.width(), size.height() );
+    WindowResized(p_window, size);
 }
 
 /* Set the Widget to the correct Size */
diff --git a/modules/gui/qt/qt.cpp b/modules/gui/qt/qt.cpp
index cbd197750a..6e7056b10b 100644
--- a/modules/gui/qt/qt.cpp
+++ b/modules/gui/qt/qt.cpp
@@ -361,6 +361,7 @@ static void Abort( void *obj )
 
 #if defined (QT5_HAS_X11)
 # include <vlc_xlib.h>
+# include <QX11Info>
 
 static void *ThreadXCB( void *data )
 {
@@ -708,6 +709,10 @@ static void ShowDialog( intf_thread_t *p_intf, int i_dialog_event, int i_arg,
  */
 static int WindowControl( vout_window_t *, int i_query, va_list );
 
+#ifdef QT5_HAS_X11
+static Display *dpy;
+#endif
+
 static int WindowOpen( vout_window_t *p_wnd, const vout_window_cfg_t *cfg )
 {
     if( cfg->is_standalone )
@@ -740,15 +745,61 @@ static int WindowOpen( vout_window_t *p_wnd, const vout_window_cfg_t *cfg )
     MainInterface *p_mi = p_intf->p_sys->p_mi;
     msg_Dbg( p_wnd, "requesting video window..." );
 
+#ifdef QT5_HAS_X11
+    Window xid;
+
+    if (QX11Info::isPlatformX11())
+    {
+        dpy = XOpenDisplay(NULL);
+        if (unlikely(dpy == NULL))
+            return VLC_EGENERIC;
+
+        int snum = DefaultScreen(dpy);
+        unsigned long black = BlackPixel(dpy, snum);
+
+        xid = XCreateSimpleWindow(dpy, RootWindow(dpy, snum),
+                                  0, 0, cfg->width, cfg->height,
+                                  0, black, black);
+    }
+#endif
+
     if( !p_mi->getVideo( p_wnd, cfg->width, cfg->height, cfg->is_fullscreen ) )
+    {
+#ifdef QT5_HAS_X11
+        if (QX11Info::isPlatformX11())
+            XCloseDisplay(dpy);
+#endif
         return VLC_EGENERIC;
+    }
 
+#ifdef QT5_HAS_X11
+    if (QX11Info::isPlatformX11())
+    {
+        XReparentWindow(dpy, xid, p_wnd->handle.xid, 0, 0);
+        XMapWindow(dpy, xid);
+        XSync(dpy, True);
+        p_wnd->handle.xid = xid;
+    }
+#endif
     p_wnd->info.has_double_click = true;
     p_wnd->control = WindowControl;
     p_wnd->sys = (vout_window_sys_t*)p_mi;
     return VLC_SUCCESS;
 }
 
+void WindowResized(vout_window_t *wnd, const QSize& size)
+{
+#ifdef QT5_HAS_X11
+    if (QX11Info::isPlatformX11())
+    {
+        XResizeWindow(dpy, wnd->handle.xid, size.width(), size.height());
+        XClearWindow(dpy, wnd->handle.xid);
+        XSync(dpy, True);
+    }
+#endif
+    vout_window_ReportSize(wnd, size.width(), size.height());
+}
+
 static int WindowControl( vout_window_t *p_wnd, int i_query, va_list args )
 {
     MainInterface *p_mi = (MainInterface *)p_wnd->sys;
@@ -779,8 +830,15 @@ static void WindowClose( vout_window_t *p_wnd )
     if (unlikely(!active))
     {
         msg_Warn (p_wnd, "video already released");
-        return;
     }
-    msg_Dbg (p_wnd, "releasing video...");
-    p_mi->releaseVideo();
+    else
+    {
+        msg_Dbg(p_wnd, "releasing video...");
+        p_mi->releaseVideo();
+    }
+
+#if defined (QT5_HAS_X11)
+    if (QX11Info::isPlatformX11())
+        XCloseDisplay(dpy);
+#endif
 }
-- 
2.30.0