UI: Add ability to lock preview

Adds the ability to lock the preview so sources can't be edited.  This
feature is typically used in the case where the user wants to prevent
accidentally clicking and dragging on sources.

obs/data/locale/en-US.ini

@@ -324,6 +324,7 @@ Basic.MainMenu.Edit.Undo="&Undo"
 Basic.MainMenu.Edit.Redo="&Redo"
 Basic.MainMenu.Edit.UndoAction="&Undo $1"
 Basic.MainMenu.Edit.RedoAction="&Redo $1"
+Basic.MainMenu.Edit.LockPreview="&Lock Preview"
 Basic.MainMenu.Edit.Transform="&Transform"
 Basic.MainMenu.Edit.Transform.EditTransform="&Edit Transform..."
 Basic.MainMenu.Edit.Transform.ResetTransform="&Reset Transform"

obs/forms/OBSBasic.ui

@@ -7,7 +7,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>957</width>
+    <width>1110</width>
     <height>724</height>
    </rect>
   </property>
@@ -804,7 +804,7 @@
     <rect>
      <x>0</x>
      <y>0</y>
-     <width>957</width>
+     <width>1110</width>
      <height>21</height>
     </rect>
    </property>
@@ -875,6 +875,7 @@
     </widget>
     <addaction name="transformMenu"/>
     <addaction name="orderMenu"/>
+    <addaction name="actionLockPreview"/>
     <addaction name="separator"/>
     <addaction name="actionAdvAudioProperties"/>
    </widget>
@@ -1310,6 +1311,14 @@
     <string>Basic.MainMenu.View.StatusBar</string>
    </property>
   </action>
+  <action name="actionLockPreview">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Basic.MainMenu.Edit.LockPreview</string>
+   </property>
+  </action>
  </widget>
  <customwidgets>
   <customwidget>

obs/window-basic-main.cpp

@@ -374,6 +374,8 @@ void OBSBasic::Save(const char *file)
 			ui->transitionDuration->value(), transitions,
 			scene, curProgramScene);
 
+	obs_data_set_bool(saveData, "preview_locked", ui->preview->Locked());
+
 	if (!obs_data_save_json_safe(saveData, file, "tmp", "bak"))
 		blog(LOG_ERROR, "Could not save scene data to %s", file);
 
@@ -607,6 +609,10 @@ retryScene:
 
 	RefreshQuickTransitions();
 
+	bool previewLocked = obs_data_get_bool(data, "preview_locked");
+	ui->preview->SetLocked(previewLocked);
+	ui->actionLockPreview->setChecked(previewLocked);
+
 	obs_data_release(data);
 
 	if (!opt_starting_scene.empty())
@@ -2958,6 +2964,12 @@ void OBSBasic::CreateSourcePopupMenu(QListWidgetItem *item, bool preview)
 		if (IsPreviewProgramMode())
 			action->setEnabled(false);
 
+		action = popup.addAction(
+				QTStr("Basic.MainMenu.Edit.LockPreview"),
+				this, SLOT(on_actionLockPreview_triggered()));
+		action->setCheckable(true);
+		action->setChecked(ui->preview->Locked());
+
 		previewProjector = new QMenu(QTStr("PreviewProjector"));
 		AddProjectorMenuMonitors(previewProjector, this,
 				SLOT(OpenPreviewProjector()));
@@ -4306,3 +4318,9 @@ void OBSBasic::on_toggleStatusBar_toggled(bool visible)
 	config_set_bool(App()->GlobalConfig(), "BasicWindow",
 			"ShowStatusBar", visible);
 }
+
+void OBSBasic::on_actionLockPreview_triggered()
+{
+	ui->preview->ToggleLocked();
+	ui->actionLockPreview->setChecked(ui->preview->Locked());
+}

obs/window-basic-main.hpp

@@ -460,6 +460,8 @@ private slots:
 	void on_actionMoveToTop_triggered();
 	void on_actionMoveToBottom_triggered();
 
+	void on_actionLockPreview_triggered();
+
 	void on_streamButton_clicked();
 	void on_recordButton_clicked();
 	void on_settingsButton_clicked();

obs/window-basic-preview.cpp

@@ -379,6 +379,11 @@ void OBSBasicPreview::GetStretchHandleData(const vec2 &pos)
 
 void OBSBasicPreview::mousePressEvent(QMouseEvent *event)
 {
+	if (locked) {
+		OBSQTDisplay::mousePressEvent(event);
+		return;
+	}
+
 	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
 	float pixelRatio = main->devicePixelRatio();
 	float x = float(event->x()) - main->previewX / pixelRatio;
@@ -451,6 +456,11 @@ void OBSBasicPreview::ProcessClick(const vec2 &pos)
 
 void OBSBasicPreview::mouseReleaseEvent(QMouseEvent *event)
 {
+	if (locked) {
+		OBSQTDisplay::mouseReleaseEvent(event);
+		return;
+	}
+
 	if (mouseDown) {
 		vec2 pos = GetMouseEventPos(event);
 
@@ -941,6 +951,9 @@ void OBSBasicPreview::StretchItem(const vec2 &pos)
 
 void OBSBasicPreview::mouseMoveEvent(QMouseEvent *event)
 {
+	if (locked)
+		return;
+
 	if (mouseDown) {
 		vec2 pos = GetMouseEventPos(event);
 
@@ -1076,6 +1089,9 @@ bool OBSBasicPreview::DrawSelectedItem(obs_scene_t *scene,
 
 void OBSBasicPreview::DrawSceneEditing()
 {
+	if (locked)
+		return;
+
 	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
 
 	gs_effect_t    *solid = obs_get_base_effect(OBS_EFFECT_SOLID);

obs/window-basic-preview.hpp

@@ -45,6 +45,7 @@ private:
 	bool         mouseMoved     = false;
 	bool         mouseOverItems = false;
 	bool         cropping       = false;
+	bool         locked         = false;
 
 	static vec2 GetMouseEventPos(QMouseEvent *event);
 	static bool DrawSelectedItem(obs_scene_t *scene, obs_sceneitem_t *item,
@@ -80,6 +81,10 @@ public:
 
 	void DrawSceneEditing();
 
+	inline void SetLocked(bool newLockedVal) {locked = newLockedVal;}
+	inline void ToggleLocked() {locked = !locked;}
+	inline bool Locked() const {return locked;}
+
 	/* use libobs allocator for alignment because the matrices itemToScreen
 	 * and screenToItem may contain SSE data, which will cause SSE
 	 * instructions to crash if the data is not aligned to at least a 16