Expand window scale factors up to 8×

5× is just about the highest factor useful for a 3840×2160 (“4K”)
monitor with games running in 320×200 mode.  7680×4320 (“8K”) monitors
are also on the market and the higher scale factors should be useful
for them too.

src/qt/languages/en-US.po

@@ -76,6 +76,24 @@ msgstr "1.&5x"
 msgid "&2x"
 msgstr "&2x"
 
+msgid "&3x"
+msgstr "&3x"
+
+msgid "&4x"
+msgstr "&4x"
+
+msgid "&5x"
+msgstr "&5x"
+
+msgid "&6x"
+msgstr "&6x"
+
+msgid "&7x"
+msgstr "&7x"
+
+msgid "&8x"
+msgstr "&8x"
+
 msgid "Filter method"
 msgstr "Filter method"
 

src/qt/qt_mainwindow.cpp

@@ -416,12 +416,36 @@ MainWindow::MainWindow(QWidget *parent) :
     case 3:
         ui->action2x->setChecked(true);
         break;
+    case 4:
+        ui->action3x->setChecked(true);
+        break;
+    case 5:
+        ui->action4x->setChecked(true);
+        break;
+    case 6:
+        ui->action5x->setChecked(true);
+        break;
+    case 7:
+        ui->action6x->setChecked(true);
+        break;
+    case 8:
+        ui->action7x->setChecked(true);
+        break;
+    case 9:
+        ui->action8x->setChecked(true);
+        break;
     }
     actGroup = new QActionGroup(this);
     actGroup->addAction(ui->action0_5x);
     actGroup->addAction(ui->action1x);
     actGroup->addAction(ui->action1_5x);
     actGroup->addAction(ui->action2x);
+    actGroup->addAction(ui->action3x);
+    actGroup->addAction(ui->action4x);
+    actGroup->addAction(ui->action5x);
+    actGroup->addAction(ui->action6x);
+    actGroup->addAction(ui->action7x);
+    actGroup->addAction(ui->action8x);
     switch (video_filter_method) {
     case 0:
         ui->actionNearest->setChecked(true);
@@ -1765,6 +1789,12 @@ static void update_scaled_checkboxes(Ui::MainWindow* ui, QAction* selected) {
     ui->action1x->setChecked(ui->action1x == selected);
     ui->action1_5x->setChecked(ui->action1_5x == selected);
     ui->action2x->setChecked(ui->action2x == selected);
+    ui->action3x->setChecked(ui->action3x == selected);
+    ui->action4x->setChecked(ui->action4x == selected);
+    ui->action5x->setChecked(ui->action5x == selected);
+    ui->action6x->setChecked(ui->action6x == selected);
+    ui->action7x->setChecked(ui->action7x == selected);
+    ui->action8x->setChecked(ui->action8x == selected);
 
     reset_screen_size();
     device_force_redraw();
@@ -1794,6 +1824,36 @@ void MainWindow::on_action2x_triggered() {
     update_scaled_checkboxes(ui, ui->action2x);
 }
 
+void MainWindow::on_action3x_triggered() {
+    scale = 4;
+    update_scaled_checkboxes(ui, ui->action3x);
+}
+
+void MainWindow::on_action4x_triggered() {
+    scale = 5;
+    update_scaled_checkboxes(ui, ui->action4x);
+}
+
+void MainWindow::on_action5x_triggered() {
+    scale = 6;
+    update_scaled_checkboxes(ui, ui->action5x);
+}
+
+void MainWindow::on_action6x_triggered() {
+    scale = 7;
+    update_scaled_checkboxes(ui, ui->action6x);
+}
+
+void MainWindow::on_action7x_triggered() {
+    scale = 8;
+    update_scaled_checkboxes(ui, ui->action7x);
+}
+
+void MainWindow::on_action8x_triggered() {
+    scale = 9;
+    update_scaled_checkboxes(ui, ui->action8x);
+}
+
 void MainWindow::on_actionNearest_triggered() {
     video_filter_method = 0;
     ui->actionLinear->setChecked(false);

src/qt/qt_mainwindow.hpp

@@ -81,6 +81,12 @@ private slots:
     void on_action1x_triggered();
     void on_action1_5x_triggered();
     void on_action2x_triggered();
+    void on_action3x_triggered();
+    void on_action4x_triggered();
+    void on_action5x_triggered();
+    void on_action6x_triggered();
+    void on_action7x_triggered();
+    void on_action8x_triggered();
     void on_actionLinear_triggered();
     void on_actionNearest_triggered();
     void on_actionFullScreen_int_triggered();

src/qt/qt_mainwindow.ui

@@ -118,6 +118,12 @@
      <addaction name="action1x"/>
      <addaction name="action1_5x"/>
      <addaction name="action2x"/>
+     <addaction name="action3x"/>
+     <addaction name="action4x"/>
+     <addaction name="action5x"/>
+     <addaction name="action6x"/>
+     <addaction name="action7x"/>
+     <addaction name="action8x"/>
     </widget>
     <widget class="QMenu" name="menuFilter_method">
      <property name="title">
@@ -478,6 +484,54 @@
     <string>&amp;2x</string>
    </property>
   </action>
+  <action name="action3x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;3x</string>
+   </property>
+  </action>
+  <action name="action4x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;4x</string>
+   </property>
+  </action>
+  <action name="action5x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;5x</string>
+   </property>
+  </action>
+  <action name="action6x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;6x</string>
+   </property>
+  </action>
+  <action name="action7x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;7x</string>
+   </property>
+  </action>
+  <action name="action8x">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>&amp;8x</string>
+   </property>
+  </action>
   <action name="actionNearest">
    <property name="checkable">
     <bool>true</bool>