Fix for [ #193 ] viewer goes black if the window is dragged from one screen to another.

include/xstudio/ui/qml/qml_viewport.hpp

@@ -85,6 +85,7 @@ namespace ui {
             void keyReleaseEvent(QKeyEvent *event) override;
 
           public slots:
+            void initRenderer();
 
             void sync();
             void cleanup();
@@ -140,6 +141,7 @@ namespace ui {
             void hasOverlaysChanged();
 
           private:
+            void createRenderer();
             void releaseResources() override;
 
             void sendPointerEvent(EventType t, QMouseEvent *event, int force_modifiers = 0);
@@ -158,6 +160,7 @@ namespace ui {
             bool has_overlays_ = {true};
 
             caf::actor keypress_monitor_;
+            caf::actor m_playhead;
         };
 
     } // namespace qml

src/ui/qml/viewport/src/qml_viewport.cpp

@@ -64,13 +64,31 @@ int qtModifierToOurs(const Qt::KeyboardModifiers qt_modifiers) {
 QMLViewport::QMLViewport(QQuickItem *parent) : QQuickItem(parent), cursor_(Qt::ArrowCursor) {
 
     connect(this, &QQuickItem::windowChanged, this, &QMLViewport::handleWindowChanged);
-    static int index = 0;
-
-    renderer_actor = new QMLViewportRenderer(this);
 
     keypress_monitor_ = CafSystemObject::get_actor_system().registry().template get<caf::actor>(
         xstudio::keyboard_events);
 
+    connect(this, SIGNAL(visibleChanged()), this, SLOT(onVisibleChanged()));
+
+    setAcceptedMouseButtons(Qt::AllButtons);
+    setAcceptHoverEvents(true);
+
+    createRenderer();
+}
+
+void QMLViewport::initRenderer() {
+    if (!renderer_actor) {
+        spdlog::info("QMLViewport::initRenderer recreating renderer");
+        createRenderer();
+    }
+}
+
+void QMLViewport::createRenderer() {
+    if (renderer_actor)
+        return;
+
+    renderer_actor = new QMLViewportRenderer(this);
+
     connect(
         renderer_actor,
         SIGNAL(translationChanged()),
@@ -104,20 +122,40 @@ QMLViewport::QMLViewport(QQuickItem *parent) : QQuickItem(parent), cursor_(Qt::A
         this,
         SIGNAL(snapshotRequestResult(QString)));
 
-    connect(this, SIGNAL(visibleChanged()), this, SLOT(onVisibleChanged()));
-
-    setAcceptedMouseButtons(Qt::AllButtons);
-    setAcceptHoverEvents(true);
-
     if (renderer_actor)
         renderer_actor->visibleChanged(isVisible());
+
+    if (window()) {
+        connect(
+            window(),
+            &QQuickWindow::frameSwapped,
+            renderer_actor,
+            &QMLViewportRenderer::frameSwapped,
+            Qt::DirectConnection);
+
+        connect(
+            renderer_actor, &QMLViewportRenderer::doRedraw, window(), &QQuickWindow::update);
+
+        renderer_actor->setWindow(window());
+
+        // Reset connected state so sync() will reconnect the render loop signal
+        connected_ = false; 
+    }
+
+    // Restore state
+    renderer_actor->setIsQuickViewer(is_quickview_);
+    renderer_actor->setHasOverlays(has_overlays_);
+    if (m_playhead) renderer_actor->set_playhead(m_playhead);
+
+    emit nameChanged();
+    emit playheadUuidChanged(); // Ensure bindings update
 }
 
 QMLViewport::~QMLViewport() { delete renderer_actor; }
 
 void QMLViewport::handleWindowChanged(QQuickWindow *win) {
 
-    spdlog::debug("QMLViewport::handleWindowChanged");
+    spdlog::info("QMLViewport::handleWindowChanged");
     if (win) {
         // Send screen info for the first time
         QScreen *screen = win->screen();
@@ -137,6 +175,13 @@ void QMLViewport::handleWindowChanged(QQuickWindow *win) {
             &QMLViewport::cleanup,
             Qt::DirectConnection);
 
+        connect(
+            win,
+            &QQuickWindow::sceneGraphInitialized,
+            this,
+            &QMLViewport::initRenderer,
+            Qt::DirectConnection);
+
         connect(
             win,
             &QQuickWindow::screenChanged,
@@ -166,7 +211,18 @@ void QMLViewport::handleWindowChanged(QQuickWindow *win) {
 
 void QMLViewport::handleScreenChanged(QScreen *screen) {
 
-    spdlog::debug("QMLViewport::handleScreenChanged");
+    spdlog::info("QMLViewport::handleScreenChanged {}", StdFromQString(screen->name()));
+
+    // If we have a renderer, destroy and recreate it.
+    // This is necessary because on some platforms (macOS), moving screens can change
+    // the underlying OpenGL context/pixel format without firing sceneGraphInvalidated,
+    // leaving us with invalid shared resources (VAOs).
+    if (renderer_actor) {
+        spdlog::info("Forcing renderer recreation on screen change");
+        cleanup();
+        initRenderer();
+    }
+
     if (renderer_actor)
         renderer_actor->setScreenInfos(
             screen->name(),
@@ -258,7 +314,7 @@ void QMLViewport::setHasOverlays(const bool hasOverlays) {
 
 void QMLViewport::cleanup() {
 
-    spdlog::debug("QMLViewport::cleanup");
+    spdlog::info("QMLViewport::cleanup");
     if (renderer_actor) {
         // delete renderer_actor;
         delete renderer_actor;
@@ -522,8 +578,11 @@ void QMLViewport::setPlayhead(const QString actorAddress) {
     if (actorAddress != "") {
         caf::actor playhead =
             actorFromQString(CafSystemObject::get_actor_system(), actorAddress);
-        if (playhead && renderer_actor) {
-            renderer_actor->set_playhead(playhead);
+        if (playhead) {
+             m_playhead = playhead;
+             if (renderer_actor) {
+                 renderer_actor->set_playhead(playhead);
+             }
         } else {
             spdlog::warn(
                 "{} bad playhead actor address: {}",