Add support to click touchpad using back button on other controllers

Takes the back button and allows the user to change the behavior of how it clicks the touchpad. The current options are left, right, center, and none.

src/common/config.cpp

@@ -41,6 +41,7 @@ static std::string logFilter;
 static std::string logType = "async";
 static std::string userName = "shadPS4";
 static std::string updateChannel;
+static std::string backButtonBehavior = "Touchpad Left";
 static bool useSpecialPad = false;
 static int specialPadClass = 1;
 static bool isDebugDump = false;
@@ -123,6 +124,10 @@ std::string getUpdateChannel() {
     return updateChannel;
 }
 
+std::string getBackButtonBehavior() {
+    return backButtonBehavior;
+}
+
 bool getUseSpecialPad() {
     return useSpecialPad;
 }
@@ -275,6 +280,10 @@ void setUpdateChannel(const std::string& type) {
     updateChannel = type;
 }
 
+void setBackButtonBehavior(const std::string& type) {
+    backButtonBehavior = type;
+}
+
 void setUseSpecialPad(bool use) {
     useSpecialPad = use;
 }
@@ -435,6 +444,7 @@ void load(const std::filesystem::path& path) {
         }
         isShowSplash = toml::find_or<bool>(general, "showSplash", true);
         isAutoUpdate = toml::find_or<bool>(general, "autoUpdate", false);
+        backButtonBehavior = toml::find_or<std::string>(general, "backButtonBehavior", "Touchpad Left");
     }
 
     if (data.contains("Input")) {
@@ -533,6 +543,7 @@ void save(const std::filesystem::path& path) {
     data["General"]["updateChannel"] = updateChannel;
     data["General"]["showSplash"] = isShowSplash;
     data["General"]["autoUpdate"] = isAutoUpdate;
+    data["General"]["backButtonBehavior"] = backButtonBehavior;
     data["Input"]["useSpecialPad"] = useSpecialPad;
     data["Input"]["specialPadClass"] = specialPadClass;
     data["GPU"]["screenWidth"] = screenWidth;
@@ -591,6 +602,7 @@ void setDefaultValues() {
     } else {
         updateChannel = "Nightly";
     }
+    backButtonBehavior = "Touchpad Left";
     useSpecialPad = false;
     specialPadClass = 1;
     isDebugDump = false;

src/common/config.h

@@ -20,6 +20,7 @@ std::string getLogFilter();
 std::string getLogType();
 std::string getUserName();
 std::string getUpdateChannel();
+std::string getBackButtonBehavior();
 
 bool getUseSpecialPad();
 int getSpecialPadClass();
@@ -54,6 +55,7 @@ void setLanguage(u32 language);
 void setNeoMode(bool enable);
 void setUserName(const std::string& type);
 void setUpdateChannel(const std::string& type);
+void setBackButtonBehavior(const std::string& type);
 
 void setUseSpecialPad(bool use);
 void setSpecialPadClass(int type);

src/qt_gui/settings_dialog.cpp

@@ -151,6 +151,10 @@ SettingsDialog::SettingsDialog(std::span<const QString> physical_devices, QWidge
             Config::setBGMvolume(val);
             BackgroundMusicPlayer::getInstance().setVolume(val);
         });
+
+        connect(ui->backButtonBehaviorComboBox, &QComboBox::currentTextChanged, this, [](const QString& text) {
+            Config::setBackButtonBehavior(text.toStdString());
+        });
     }
 
     // GPU TAB
@@ -258,6 +262,8 @@ void SettingsDialog::LoadValuesFromConfig() {
         }
     }
     ui->updateComboBox->setCurrentText(QString::fromStdString(updateChannel));
+
+    ui->backButtonBehaviorComboBox->setCurrentText(QString::fromStdString(Config::getBackButtonBehavior()));
 }
 
 void SettingsDialog::InitializeEmulatorLanguages() {

src/qt_gui/settings_dialog.ui

@@ -442,20 +442,64 @@
            </layout>
           </item>
           <item>
-           <spacer name="horizontalSpacer">
+           <layout class="QVBoxLayout" name="ControllerTabLayoutRight" stretch="1">
-            <property name="orientation">
+            <item>
-             <enum>Qt::Orientation::Horizontal</enum>
+             <widget class="QGroupBox" name="ControllerGroupBox">
-            </property>
+              <property name="sizePolicy">
-            <property name="sizeType">
+               <sizepolicy hsizetype="MinimumExpanding" vsizetype="Preferred">
-             <enum>QSizePolicy::Policy::Expanding</enum>
+                <horstretch>0</horstretch>
-            </property>
+                <verstretch>0</verstretch>
-            <property name="sizeHint" stdset="0">
+               </sizepolicy>
-             <size>
+              </property>
-              <width>0</width>
+              <property name="title">
-              <height>0</height>
+               <string>Controller Settings</string>
-             </size>
+              </property>
-            </property>
+              <widget class="QGroupBox" name="backButtonBehaviorGroupBox">
-           </spacer>
+               <property name="geometry">
+                <rect>
+                 <x>12</x>
+                 <y>30</y>
+                 <width>241</width>
+                 <height>65</height>
+                </rect>
+               </property>
+               <property name="title">
+                <string>Back Button Behavior</string>
+               </property>
+               <widget class="QComboBox" name="backButtonBehaviorComboBox">
+                <property name="geometry">
+                 <rect>
+                  <x>12</x>
+                  <y>30</y>
+                  <width>217</width>
+                  <height>28</height>
+                 </rect>
+                </property>
+                <item>
+                 <property name="text">
+                  <string>Touchpad Left</string>
+                 </property>
+                </item>
+                <item>
+                 <property name="text">
+                  <string>Touchpad Right</string>
+                 </property>
+                </item>
+                <item>
+                 <property name="text">
+                  <string>Touchpad Center</string>
+                 </property>
+                </item>
+                <item>
+                 <property name="text">
+                  <string>None</string>
+                 </property>
+                </item>
+               </widget>
+              </widget>
+             </widget>
+            </item>
+           </layout>
           </item>
          </layout>
         </item>

src/sdl_window.cpp

@@ -330,7 +330,17 @@ void WindowSDL::onGamepadEvent(const SDL_Event* event) {
     case SDL_EVENT_GAMEPAD_BUTTON_UP:
         button = sdlGamepadToOrbisButton(event->gbutton.button);
         if (button != 0) {
-            controller->CheckButton(0, button, event->type == SDL_EVENT_GAMEPAD_BUTTON_DOWN);
+            if (event->gbutton.button == SDL_GAMEPAD_BUTTON_BACK) {
+                std::string backButtonBehavior = Config::getBackButtonBehavior();
+                if (backButtonBehavior != "None") {
+                    float x = backButtonBehavior == "Touchpad Left" ? 0.25f : (backButtonBehavior == "Touchpad Right" ? 0.75f : 0.5f);
+                    // trigger a touchpad event so that the touchpad emulation for back button works
+                    controller->SetTouchpadState(0, true, x, 0.5f);
+                    controller->CheckButton(0, button, event->type == SDL_EVENT_GAMEPAD_BUTTON_DOWN);
+                }
+            } else {
+                controller->CheckButton(0, button, event->type == SDL_EVENT_GAMEPAD_BUTTON_DOWN);
+            }
         }
         if (SDL_GetCursor() != NULL) {
             SDL_HideCursor();