UI: Add enable preview button

Closes #1966

UI/forms/OBSBasic.ui

@@ -40,30 +40,102 @@
    <layout class="QVBoxLayout" name="verticalLayout">
     <item>
      <layout class="QHBoxLayout" name="horizontalLayout_2">
-      <item>
-       <widget class="QLabel" name="previewDisabledLabel">
-        <property name="sizePolicy">
-         <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
-          <horstretch>0</horstretch>
-          <verstretch>0</verstretch>
-         </sizepolicy>
-        </property>
-        <property name="contextMenuPolicy">
-         <enum>Qt::CustomContextMenu</enum>
-        </property>
-        <property name="text">
-         <string>Basic.Main.PreviewDisabled</string>
-        </property>
-        <property name="alignment">
-         <set>Qt::AlignCenter</set>
-        </property>
-       </widget>
-      </item>
       <item>
        <layout class="QHBoxLayout" name="previewLayout">
         <property name="spacing">
          <number>2</number>
         </property>
+        <item>
+         <widget class="QWidget" name="previewDisabledWidget" native="true">
+          <property name="sizePolicy">
+           <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+            <horstretch>0</horstretch>
+            <verstretch>0</verstretch>
+           </sizepolicy>
+          </property>
+          <layout class="QVBoxLayout" name="verticalLayout_7">
+           <item>
+            <spacer name="verticalSpacer_2">
+             <property name="orientation">
+              <enum>Qt::Vertical</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>20</width>
+               <height>40</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+           <item>
+            <widget class="QLabel" name="label">
+             <property name="sizePolicy">
+              <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+               <horstretch>0</horstretch>
+               <verstretch>0</verstretch>
+              </sizepolicy>
+             </property>
+             <property name="text">
+              <string>Basic.Main.PreviewDisabled</string>
+             </property>
+             <property name="alignment">
+              <set>Qt::AlignCenter</set>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <layout class="QHBoxLayout" name="horizontalLayout">
+             <item>
+              <spacer name="horizontalSpacer_2">
+               <property name="orientation">
+                <enum>Qt::Horizontal</enum>
+               </property>
+               <property name="sizeHint" stdset="0">
+                <size>
+                 <width>40</width>
+                 <height>20</height>
+                </size>
+               </property>
+              </spacer>
+             </item>
+             <item>
+              <widget class="QPushButton" name="enablePreviewButton">
+               <property name="text">
+                <string>Basic.Main.PreviewConextMenu.Enable</string>
+               </property>
+              </widget>
+             </item>
+             <item>
+              <spacer name="horizontalSpacer_3">
+               <property name="orientation">
+                <enum>Qt::Horizontal</enum>
+               </property>
+               <property name="sizeHint" stdset="0">
+                <size>
+                 <width>40</width>
+                 <height>20</height>
+                </size>
+               </property>
+              </spacer>
+             </item>
+            </layout>
+           </item>
+           <item>
+            <spacer name="verticalSpacer_3">
+             <property name="orientation">
+              <enum>Qt::Vertical</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>20</width>
+               <height>40</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+          </layout>
+         </widget>
+        </item>
         <item>
          <layout class="QVBoxLayout" name="previewTextLayout">
           <property name="spacing">
@@ -709,8 +781,8 @@
           <rect>
            <x>0</x>
            <y>0</y>
-           <width>16</width>
-           <height>28</height>
+           <width>28</width>
+           <height>16</height>
           </rect>
          </property>
          <property name="sizePolicy">

UI/window-basic-main.cpp

@@ -212,7 +212,7 @@ OBSBasic::OBSBasic(QWidget *parent)
 	api = InitializeAPIInterface(this);
 
 	ui->setupUi(this);
-	ui->previewDisabledLabel->setVisible(false);
+	ui->previewDisabledWidget->setVisible(false);
 
 	startingDockLayout = saveState();
 
@@ -381,6 +381,13 @@ OBSBasic::OBSBasic(QWidget *parent)
 		ui->previewLabel->setHidden(true);
 	else
 		ui->previewLabel->setHidden(!labels);
+
+	ui->previewDisabledWidget->setContextMenuPolicy(Qt::CustomContextMenu);
+	connect(ui->previewDisabledWidget,
+		SIGNAL(customContextMenuRequested(const QPoint &)), this,
+		SLOT(PreviewDisabledMenu(const QPoint &)));
+	connect(ui->enablePreviewButton, SIGNAL(clicked()), this,
+		SLOT(TogglePreview()));
 }
 
 static void SaveAudioDevice(const char *name, int channel, obs_data_t *parent,
@@ -5759,8 +5766,7 @@ void OBSBasic::on_program_customContextMenuRequested(const QPoint &)
 	popup.exec(QCursor::pos());
 }
 
-void OBSBasic::on_previewDisabledLabel_customContextMenuRequested(
-	const QPoint &pos)
+void OBSBasic::PreviewDisabledMenu(const QPoint &pos)
 {
 	QMenu popup(this);
 	delete previewProjectorMain;
@@ -6219,7 +6225,7 @@ void OBSBasic::EnablePreviewDisplay(bool enable)
 {
 	obs_display_set_enabled(ui->preview->GetDisplay(), enable);
 	ui->preview->setVisible(enable);
-	ui->previewDisabledLabel->setVisible(!enable);
+	ui->previewDisabledWidget->setVisible(!enable);
 }
 
 void OBSBasic::TogglePreview()

UI/window-basic-main.hpp

@@ -729,8 +729,7 @@ private slots:
 
 	void on_preview_customContextMenuRequested(const QPoint &pos);
 	void on_program_customContextMenuRequested(const QPoint &pos);
-	void
-	on_previewDisabledLabel_customContextMenuRequested(const QPoint &pos);
+	void PreviewDisabledMenu(const QPoint &pos);
 
 	void on_actionNewSceneCollection_triggered();
 	void on_actionDupSceneCollection_triggered();