Client: Improve support of zxdg_output_v1 version 3

by applying recommendations regarding the deprecated events

Change-Id: Ic462b1be83a1241f01f3fc909fa803615781ed2e
Reviewed-by: David Edmundson <davidedmundson@kde.org>

src/3rdparty/wayland/protocols/xdg-output/xdg-output-unstable-v1.xml

@@ -35,12 +35,12 @@
     Typically, the global compositor space on a desktop system is made of
     a contiguous or overlapping set of rectangular regions.
 
-    Some of the information provided in this protocol might be identical
+    The logical_position and logical_size events defined in this protocol
-    to their counterparts already available from wl_output, in which case
+    might provide information identical to their counterparts already
-    the information provided by this protocol should be preferred to their
+    available from wl_output, in which case the information provided by this
-    equivalent in wl_output. The goal is to move the desktop specific
+    protocol should be preferred to their equivalent in wl_output. The goal is
-    concepts (such as output location within the global compositor space,
+    to move the desktop specific concepts (such as output location within the
-    the connector name and types, etc.) out of the core wl_output protocol.
+    global compositor space, etc.) out of the core wl_output protocol.
 
     Warning! The protocol described in this file is experimental and
     backward incompatible changes may be made. Backward compatible
@@ -117,10 +117,6 @@
 	The logical_size event describes the size of the output in the
 	global compositor space.
 
-	For example, a surface without any buffer scale, transformation
-	nor rotation set, with the size matching the logical_size will
-	have the same size as the corresponding output when displayed.
-
 	Most regular Wayland clients should not pay attention to the
 	logical size and would rather rely on xdg_shell interfaces.
 
@@ -131,14 +127,14 @@
 
 	For example, for a wl_output mode 3840×2160 and a scale factor 2:
 
-	- A compositor not scaling the surface buffers will advertise a
+	- A compositor not scaling the monitor viewport in its compositing space
-	  logical size of 3840×2160,
+	  will advertise a logical size of 3840×2160,
 
-	- A compositor automatically scaling the surface buffers will
+	- A compositor scaling the monitor viewport with scale factor 2 will
 	  advertise a logical size of 1920×1080,
 
-	- A compositor using a fractional scale of 1.5 will advertise a
+	- A compositor scaling the monitor viewport using a fractional scale of
-	  logical size to 2560×1620.
+	  1.5 will advertise a logical size of 2560×1440.
 
 	For example, for a wl_output mode 1920×1080 and a 90 degree rotation,
 	the compositor will advertise a logical size of 1080x1920.
@@ -155,7 +151,7 @@
 	   summary="height in global compositor space"/>
     </event>
 
-    <event name="done">
+    <event name="done" deprecated-since="3">
       <description summary="all information about the output have been sent">
 	This event is sent after all other properties of an xdg_output
 	have been sent.
@@ -191,6 +187,9 @@
 	xdg_output_manager.get_xdg_output). This event is only sent once per
 	xdg_output, and the name does not change over the lifetime of the
 	wl_output global.
+
+        This event is deprecated, instead clients should use wl_output.name.
+        Compositors must still support this event.
       </description>
       <arg name="name" type="string" summary="output name"/>
     </event>
@@ -212,6 +211,9 @@
 	For objects of version 2 and lower, this event is only sent once per
 	xdg_output, and the description does not change over the lifetime of
 	the wl_output global.
+
+	This event is deprecated, instead clients should use
+	wl_output.description. Compositors must still support this event.
       </description>
       <arg name="description" type="string" summary="output description"/>
     </event>

src/plugins/platforms/wayland/qwaylandscreen.cpp

@@ -60,9 +60,10 @@ uint QWaylandScreen::requiredEvents() const
     uint ret = OutputDoneEvent;
 
     if (mWaylandDisplay->xdgOutputManager()) {
-        if (mWaylandDisplay->xdgOutputManager()->version() >= 2)
+        if (mWaylandDisplay->xdgOutputManager()->version() >= ZXDG_OUTPUT_V1_NAME_SINCE_VERSION)
             ret |= XdgOutputNameEvent;
 
+        // For objects version 3 onwards, zxdg_output_v1.done is deprecated.
         if (mWaylandDisplay->xdgOutputManager()->version() < 3)
             ret |= XdgOutputDoneEvent;
     }
@@ -387,12 +388,23 @@ void QWaylandScreen::zxdg_output_v1_name(const QString &name)
     if (Q_UNLIKELY(mInitialized))
         qCWarning(lcQpaWayland) << "zxdg_output_v1.name received after output has been initialized, this is most likely a bug in the compositor";
 
+    if (Q_UNLIKELY(mProcessedEvents & XdgOutputNameEvent)) {
+        qCWarning(lcQpaWayland) << "zxdg_output_v1.name received more than once, this is most likely a bug in the compositor";
+        return;
+    }
+
+    // This event is deprecated, instead clients should use wl_output.name.
+    if (!(mProcessedEvents & OutputNameEvent)) {
+        if (!name.isEmpty())
             mOutputName = name;
+    }
+
     mProcessedEvents |= XdgOutputNameEvent;
 }
 
 void QWaylandScreen::updateXdgOutputProperties()
 {
+    Q_ASSERT(mInitialized);
     Q_ASSERT(zxdg_output_v1::isInitialized());
     QWindowSystemInterface::handleScreenGeometryChange(screen(), geometry(), geometry());
 }