feat: implement wp_presentation_time protocol

src/seat/helper.cpp

@@ -2150,6 +2150,8 @@ void Helper::init(Treeland::Treeland *treeland)
     }
     if (!wlr_subcompositor_create(m_server->handle()))
         qCCritical(lcTlCore) << "Failed to create subcompositor";
+    if (!wlr_presentation_create(m_server->handle(), m_backend->handle(), 2))
+        qCCritical(lcTlCore) << "Failed to create presentation-time manager";
     if (!wlr_screencopy_manager_v1_create(m_server->handle()))
         qCCritical(lcTlCore) << "Failed to create screencopy manager";
     if (!wlr_ext_image_copy_capture_manager_v1_create(m_server->handle(), 1))

waylib/src/server/kernel/wlr_all.h

@@ -104,12 +104,13 @@
 #include <wlr/types/wlr_output_layout.h>
 #include <wlr/types/wlr_output_management_v1.h>
 #include <wlr/types/wlr_output_power_management_v1.h>
 #include <wlr/types/wlr_pointer.h>
 #include <wlr/types/wlr_pointer_constraints_v1.h>
 #include <wlr/types/wlr_pointer_gestures_v1.h>
+#include <wlr/types/wlr_presentation_time.h>
 #include <wlr/types/wlr_primary_selection.h>
 #include <wlr/types/wlr_primary_selection_v1.h>
 #include <wlr/types/wlr_relative_pointer_v1.h>
 #include <wlr/types/wlr_screencopy_v1.h>
 #include <wlr/types/wlr_seat.h>
 #include <wlr/types/wlr_session_lock_v1.h>

waylib/src/server/qtquick/woutputrenderwindow.cpp

@@ -1588,9 +1588,12 @@ void WOutputRenderWindowPrivate::doRender(wlr_output *needsFrameOutput,
             // transactions. It must not be suppressed merely because the
             // transaction itself scheduled the next frame.
             if (forceRender || Q_UNLIKELY(!i.first->framePending())) {
+                auto output = i.first->outputViewport()->output();
+                // Let consumers sample wp_presentation_time feedback (and other
+                // last-minute per-output work) before the output state is committed.
+                Q_EMIT q->outputAboutToCommit(output);
                 if (Q_LIKELY(i.first->commit(i.second))) {
                     // Make sure the output is still valid after commit
-                    auto output = i.first->outputViewport()->output();
                     if (Q_LIKELY(needsFrameOutput)) {
                         Q_ASSERT(output->handle() == needsFrameOutput);
                         if (committedOutputs.isEmpty())

waylib/src/server/qtquick/woutputrenderwindow.h

@@ -81,6 +81,11 @@ public Q_SLOTS:
     void initialized();
     void disableLayersChanged();
     void renderEnd(QList<QPointer<WOutput>> committedOutputs);
+    // Emitted synchronously right before each output's state is committed in
+    // doRender(). Compositors can use this to perform last-minute per-output
+    // work that must happen before wlr_output_commit_state(), e.g. sampling
+    // wp_presentation_time feedback via wlr_presentation_surface_textured_on_output().
+    void outputAboutToCommit(WAYLIB_SERVER_NAMESPACE::WOutput *output);
     void effectiveDevicePixelRatioChanged(qreal scale);
 
 private:

waylib/src/server/qtquick/wsurfaceitem.cpp

@@ -220,6 +220,8 @@ class Q_DECL_HIDDEN WSurfaceItemContentPrivate: public QQuickItemPrivate
 
         if (frameDoneConnection)
             QObject::disconnect(frameDoneConnection);
+        if (presentationConnection)
+            QObject::disconnect(presentationConnection);
 
         Q_ASSERT(!updateTextureConnection);
 
@@ -274,6 +276,8 @@ class Q_DECL_HIDDEN WSurfaceItemContentPrivate: public QQuickItemPrivate
 
         if (frameDoneConnection)
             QObject::disconnect(frameDoneConnection);
+        if (presentationConnection)
+            QObject::disconnect(presentationConnection);
         if (!q->window()) // maybe null due to item not fully initialized
             return;
 
@@ -290,6 +294,19 @@ class Q_DECL_HIDDEN WSurfaceItemContentPrivate: public QQuickItemPrivate
                                                            rendered = false;
                                                        }
                                                    }); // if signal is emitted from seperated rendering thread, default QueuedConnection is used
+
+            // Unlike frameDoneConnection (which tolerates a queued delivery), this
+            // connection MUST be synchronous: the feedback has to be sampled before
+            // wlr_output_commit_state() runs, so use Qt::DirectConnection explicitly.
+            presentationConnection = QObject::connect(rw, &WOutputRenderWindow::outputAboutToCommit,
+                                                       q, [this, q] (WOutput *output) {
+                                                           if (Q_LIKELY((rendered || q->isVisible()) && live)
+                                                               && surface &&
+                                                               output == surface->framePacingOutput()) {
+                                                               wlr_presentation_surface_textured_on_output(
+                                                                   surface->handle(), output->handle());
+                                                           }
+                                                       }, Qt::DirectConnection);
         } else {
             qCFatal(lcWlSurface) << "Needs a WOutputRenderWindow to render the WSurfaceItemContent, "
                                       "but the current window is:" << q->window();
@@ -358,6 +375,7 @@ class Q_DECL_HIDDEN WSurfaceItemContentPrivate: public QQuickItemPrivate
     qreal alphaModifier = 1.0;
 
     QMetaObject::Connection frameDoneConnection;
+    QMetaObject::Connection presentationConnection;
     mutable WSGTextureProvider *textureProvider = nullptr;
     BufferRef buffer;
     BufferRef pendingBuffer;
@@ -385,6 +403,8 @@ WSurfaceItemContent::~WSurfaceItemContent()
 
     if (d->frameDoneConnection)
         QObject::disconnect(d->frameDoneConnection);
+    if (d->presentationConnection)
+        QObject::disconnect(d->presentationConnection);
 
     //`d->window` will become nullptr in ~QQuickItem
     // Don't move this to private class