[vlc-devel] [RFC PATCH] qt: Use XCB events to notify of a video widget resize

[Hugo Beauzée-Luyssen]

This obviously lacks support for wayland, and seems to be unrequired on
windows.
Ref #18211
---
 configure.ac                                    |  1 +
 modules/gui/qt/components/interface_widgets.cpp | 23 +++++++++++++++++++++++
 modules/gui/qt/components/interface_widgets.hpp |  8 ++++++++
 3 files changed, 32 insertions(+)

diff --git a/configure.ac b/configure.ac
index cc54fad48c..696ef77749 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3010,6 +3010,7 @@ AS_IF([test "${enable_xcb}" != "no"], [
   PKG_CHECK_MODULES(XCB_KEYSYMS, [xcb-keysyms >= 0.3.4], [have_xcb_keysyms="yes"], [
     AC_MSG_WARN([${XCB_KEYSYMS_PKG_ERRORS}. Hotkeys will not work.])
   ])
+  AC_DEFINE([HAVE_XCB], [1], [Define to 1 if XCB is available.])
 ])
 AM_CONDITIONAL([HAVE_XCB], [test "${have_xcb}" = "yes"])
 AM_CONDITIONAL([HAVE_XCB_KEYSYMS], [test "${have_xcb_keysyms}" = "yes"])
diff --git a/modules/gui/qt/components/interface_widgets.cpp b/modules/gui/qt/components/interface_widgets.cpp
index 081985dc2c..56869ff87d 100644
--- a/modules/gui/qt/components/interface_widgets.cpp
+++ b/modules/gui/qt/components/interface_widgets.cpp
@@ -53,6 +53,9 @@
 #if defined (QT5_HAS_X11)
 # include <X11/Xlib.h>
 # include <QX11Info>
+# if HAVE_XCB
+# include <xcb/xproto.h>
+#endif
 #endif
 #ifdef QT5_HAS_WAYLAND
 # include QPNI_HEADER
@@ -257,12 +260,32 @@ void VideoWidget::setSize( unsigned int w, unsigned int h )
     sync();
 }
 
+#if RESIZE_FROM_NATIVE_EVENTS
+bool VideoWidget::nativeEvent( const QByteArray& eventType, void* message, long* )
+{
+#if HAVE_XCB
+    if ( eventType == "xcb_generic_event_t" )
+    {
+        const xcb_generic_event_t* xev = reinterpret_cast<const xcb_generic_event_t*>( message );
+
+        if ( xev->response_type == XCB_CONFIGURE_NOTIFY )
+        {
+            msg_Err( p_intf, "COUCOU");
+            reportSize();
+        }
+    }
+#endif
+    // Let Qt handle that event in any case
+    return false;
+}
+#else
 void VideoWidget::resizeEvent( QResizeEvent *event )
 {
     QWidget::resizeEvent( event );
 
     reportSize();
 }
+#endif
 
 int VideoWidget::qtMouseButton2VLC( Qt::MouseButton qtButton )
 {
diff --git a/modules/gui/qt/components/interface_widgets.hpp b/modules/gui/qt/components/interface_widgets.hpp
index ca2926c49c..1a1dbdfe5c 100644
--- a/modules/gui/qt/components/interface_widgets.hpp
+++ b/modules/gui/qt/components/interface_widgets.hpp
@@ -45,6 +45,10 @@
 #include <QPropertyAnimation>
 #include <QLinkedList>
 
+#if HAVE_XCB
+# define RESIZE_FROM_NATIVE_EVENTS 1
+#endif
+
 class QMenu;
 class QSlider;
 class QWidgetAction;
@@ -69,7 +73,11 @@ protected:
         return NULL;
     }
 
+#if RESIZE_FROM_NATIVE_EVENTS
+    bool nativeEvent(const QByteArray &eventType, void *message, long *result) Q_DECL_OVERRIDE;
+#else
     virtual void resizeEvent(QResizeEvent *) Q_DECL_OVERRIDE;
+#endif
     void mousePressEvent(QMouseEvent *) Q_DECL_OVERRIDE;
     void mouseMoveEvent(QMouseEvent *) Q_DECL_OVERRIDE;
     void mouseReleaseEvent(QMouseEvent *) Q_DECL_OVERRIDE;
-- 
2.11.0