From c51ab381da0e86d2b4714560a8c100ebd1a0d66e Mon Sep 17 00:00:00 2001
From: David Edmundson <kde@davidedmundson.co.uk>
Date: Mon, 8 Apr 2024 11:42:08 +0100
Subject: [PATCH] deferred apply

When we get a configure event defer applying it until all pending
callbacks are processsed. This ensures we only only process configure
events that match the last thing we requested.
---
 src/qwaylandlayersurface.cpp | 43 ++++++++++++++++++++++++++----------
 src/qwaylandlayersurface_p.h |  6 ++---
 2 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/src/qwaylandlayersurface.cpp b/src/qwaylandlayersurface.cpp
index d7c9538..743c303 100644
--- a/src/qwaylandlayersurface.cpp
+++ b/src/qwaylandlayersurface.cpp
@@ -67,13 +67,15 @@ QWaylandLayerSurface::QWaylandLayerSurface(QWaylandLayerShellIntegration *shell,
     });
 
     setDesiredSize(window->windowContentGeometry().size());
+    requestWaylandSync();
 }
 
 QWaylandLayerSurface::~QWaylandLayerSurface()
 {
-    if (m_waitForSyncCallback) {
-        wl_callback_destroy(m_waitForSyncCallback);
+    for (auto syncCallback: m_waitForSyncCallbacks) {
+        wl_callback_destroy(syncCallback);
     }
+    m_waitForSyncCallbacks.clear();
     destroy();
 }
 
@@ -89,6 +91,13 @@ void QWaylandLayerSurface::zwlr_layer_surface_v1_configure(uint32_t serial, uint
     ack_configure(serial);
     m_pendingSize = QSize(width, height);
 
+    // because configure lacks a way to match it up with our resize requests
+    // we apply it only when our callback sync is complete
+    if (!m_waitForSyncCallbacks.isEmpty()) {
+        m_hasPendingConfigureToApply = true;
+        return;
+    }
+
     if (!m_configured) {
         m_configured = true;
         applyConfigure();
@@ -98,6 +107,7 @@ void QWaylandLayerSurface::zwlr_layer_surface_v1_configure(uint32_t serial, uint
         // are not painting to the window.
         window()->applyConfigureWhenPossible();
     }
+
 }
 
 void QWaylandLayerSurface::attachPopup(QtWaylandClient::QWaylandShellSurface *popup)
@@ -229,27 +239,36 @@ const wl_callback_listener QWaylandLayerSurface::syncCallbackListener = {
         Q_UNUSED(time);
         wl_callback_destroy(callback);
         QWaylandLayerSurface *layerSurface = static_cast<QWaylandLayerSurface *>(data);
-        layerSurface->m_waitForSyncCallback = nullptr;
-        layerSurface->sendExpose();
+        layerSurface->m_waitForSyncCallbacks.removeOne(callback);
+        layerSurface->handleWaylandSyncDone();
     }
 };
 
 void QWaylandLayerSurface::requestWaylandSync()
 {
-    if (m_waitForSyncCallback) {
-        return;
-    }
-
-    m_waitForSyncCallback = wl_display_sync(m_window->display()->wl_display());
-    wl_callback_add_listener(m_waitForSyncCallback, &syncCallbackListener, this);
+    auto syncCallback = wl_display_sync(m_window->display()->wl_display());
+    m_waitForSyncCallbacks.append(syncCallback);
+    wl_callback_add_listener(syncCallback, &syncCallbackListener, this);
 }
 
 void QWaylandLayerSurface::handleWaylandSyncDone()
 {
-    if (!window()->isExposed()) {
+    if (!window()->window()->isVisible() || !m_waitForSyncCallbacks.isEmpty()) {
         return;
     }
-    sendExpose();
+
+    if (m_hasPendingConfigureToApply) {
+        m_hasPendingConfigureToApply = false;
+        if (!m_configured) {
+            m_configured = true;
+            applyConfigure();
+            sendExpose();
+        } else {
+            // Later configures are resizes, so we have to queue them up for a time when we
+            // are not painting to the window.
+            window()->applyConfigureWhenPossible();
+        }
+    }
 }
 
 void QWaylandLayerSurface::sendExpose()
diff --git a/src/qwaylandlayersurface_p.h b/src/qwaylandlayersurface_p.h
index dee81e1..a34a47a 100644
--- a/src/qwaylandlayersurface_p.h
+++ b/src/qwaylandlayersurface_p.h
@@ -30,7 +30,7 @@ public:
 
     bool isExposed() const override
     {
-        return m_configured && !m_waitForSyncCallback;
+        return m_configured && m_waitForSyncCallbacks.isEmpty();
     }
     void attachPopup(QtWaylandClient::QWaylandShellSurface *popup) override;
 
@@ -64,11 +64,11 @@ private:
 
     bool m_configured = false;
     bool m_configuring = false;
+    bool m_hasPendingConfigureToApply = false;
 
     static const wl_callback_listener syncCallbackListener;
-    struct wl_callback *m_waitForSyncCallback = nullptr;
+    QList<struct wl_callback*> m_waitForSyncCallbacks;
 };
-
 }
 
 #endif