UI: Don't transition if already transitioning (studio mode)

Closes obsproject/obs-studio#1304

UI/window-basic-main-transitions.cpp

@@ -254,6 +254,12 @@ void OBSBasic::TransitionStopped()
 		OBSSource scene = OBSGetStrongRef(swapScene);
 		if (scene)
 			SetCurrentScene(scene);
+
+		// Make sure we re-enable the transition button
+		if (transitionButton)
+			transitionButton->setEnabled(true);
+
+		EnableQuickTransitionWidgets();
 	}
 
 	if (api) {
@@ -294,7 +300,7 @@ void OBSBasic::TransitionToScene(OBSSource source, bool force, bool direct,
 		return;
 
 	OBSWeakSource lastProgramScene;
-	
+
 	if (usingPreviewProgram) {
 		lastProgramScene = programScene;
 		programScene = OBSGetWeakRef(source);
@@ -321,6 +327,12 @@ void OBSBasic::TransitionToScene(OBSSource source, bool force, bool direct,
 	OBSSource transition = obs_get_output_source(0);
 	obs_source_release(transition);
 
+	bool stillTransitioning = obs_transition_get_time(transition) < 1.0f;
+
+	// If actively transitioning, block new transitions from starting
+	if (usingPreviewProgram && stillTransitioning)
+		goto cleanup;
+
 	if (force) {
 		obs_transition_set(transition, source);
 		if (api)
@@ -355,6 +367,15 @@ void OBSBasic::TransitionToScene(OBSSource source, bool force, bool direct,
 			TransitionFullyStopped();
 	}
 
+	// If transition has begun, disable Transition button
+	if (usingPreviewProgram && stillTransitioning) {
+		if (transitionButton)
+			transitionButton->setEnabled(false);
+
+		DisableQuickTransitionWidgets();
+	}
+
+cleanup:
 	if (usingPreviewProgram && sceneDuplicationMode)
 		obs_scene_release(scene);
 }
@@ -725,7 +746,7 @@ void OBSBasic::CreateProgramOptions()
 	QHBoxLayout *mainButtonLayout = new QHBoxLayout();
 	mainButtonLayout->setSpacing(2);
 
-	QPushButton *transitionButton = new QPushButton(QTStr("Transition"));
+	transitionButton = new QPushButton(QTStr("Transition"));
 	QHBoxLayout *quickTransitions = new QHBoxLayout();
 	quickTransitions->setSpacing(2);
 
@@ -809,7 +830,7 @@ void OBSBasic::CreateProgramOptions()
 		menu.exec(QCursor::pos());
 	};
 
-	connect(transitionButton, &QAbstractButton::clicked,
+	connect(transitionButton.data(), &QAbstractButton::clicked,
 			this, &OBSBasic::TransitionClicked);
 	connect(addQuickTransition, &QAbstractButton::clicked, onAdd);
 	connect(configTransitions, &QAbstractButton::clicked, onConfig);
@@ -1124,6 +1145,48 @@ void OBSBasic::RefreshQuickTransitions()
 		AddQuickTransitionId(qt.id);
 }
 
+void OBSBasic::DisableQuickTransitionWidgets()
+{
+	if (!IsPreviewProgramMode())
+		return;
+
+	QVBoxLayout *programLayout =
+		reinterpret_cast<QVBoxLayout*>(programOptions->layout());
+
+	for (int idx = 0;; idx++) {
+		QLayoutItem *item = programLayout->itemAt(idx);
+		if (!item)
+			break;
+
+		QWidget *widget = item->widget();
+		if (!widget)
+			continue;
+
+		widget->setEnabled(false);
+	}
+}
+
+void OBSBasic::EnableQuickTransitionWidgets()
+{
+	if (!IsPreviewProgramMode())
+		return;
+
+	QVBoxLayout *programLayout =
+		reinterpret_cast<QVBoxLayout*>(programOptions->layout());
+
+	for (int idx = 0;; idx++) {
+		QLayoutItem *item = programLayout->itemAt(idx);
+		if (!item)
+			break;
+
+		QWidget *widget = item->widget();
+		if (!widget)
+			continue;
+
+		widget->setEnabled(true);
+	}
+}
+
 void OBSBasic::SetPreviewProgramMode(bool enabled)
 {
 	if (IsPreviewProgramMode() == enabled)

UI/window-basic-main.hpp

@@ -186,6 +186,7 @@ private:
 
 	QPointer<QMenu> startStreamMenu;
 
+	QPointer<QPushButton> transitionButton;
 	QPointer<QPushButton> replayBufferButton;
 
 	QScopedPointer<QSystemTrayIcon> trayIcon;
@@ -310,6 +311,8 @@ private:
 	obs_data_array_t *SaveQuickTransitions();
 	void ClearQuickTransitionWidgets();
 	void RefreshQuickTransitions();
+	void DisableQuickTransitionWidgets();
+	void EnableQuickTransitionWidgets();
 	void CreateDefaultQuickTransitions();
 
 	QMenu *CreatePerSceneTransitionMenu();