window: auto-hide the cursor over the game window (#958)

* window: auto-hide the cursor over the game window

Hide the cursor when the game window is created and whenever the mouse
has been idle for two seconds; any mouse motion, button or wheel event
shows it again. Games that draw their own cursor (e.g. Blue Prince) no
longer show the host pointer on top of it.

Only real mouse input counts as activity: synthetic touch/pen mouse
events and zero-delta motion (sent by some platforms on focus or cursor
visibility changes) are ignored. The event loop only waits with a
timeout while the cursor is visible, so it still blocks indefinitely
once the cursor is hidden. The cursor is restored on shutdown.

Uses SDL_HideCursor/SDL_ShowCursor, which SDL implements for X11,
Wayland, Cocoa and Win32 and which only affect the cursor over the
emulator window.

Closes #282

* window: make cursor auto-hide optional in CLI and launcher

Co-authored-by: Anatolii Kucheruk <anatolii.kucheruk01@gmail.com>

---------

Co-authored-by: nmzik <Nmzik@mail.ru>
Co-authored-by: Anatolii Kucheruk <anatolii.kucheruk01@gmail.com>

src/common/emulatorConfig.cpp

@@ -72,6 +72,10 @@ bool FullscreenEnabled() {
 	return g_config->fullscreen_enabled;
 }
 
+bool HideCursorEnabled() {
+	return g_config->hide_cursor_enabled;
+}
+
 bool VrEnabled() {
 	return g_config->vr_enabled;
 }

src/common/emulatorConfig.h

@@ -53,6 +53,7 @@ struct ConfigOptions {
 	PresentMode            present_mode                = PresentMode::Mailbox;
 	int32_t                gpu_index                   = -1;
 	bool                   fullscreen_enabled          = false;
+	bool                   hide_cursor_enabled         = false;
 	bool                   vr_enabled                  = false;
 	bool                   amd_cpu_enabled             = false;
 	uint32_t               vblank_frequency            = 60;
@@ -93,6 +94,7 @@ uint32_t GetControllerVibrationIntensity();
 PresentMode GetPresentMode();
 int32_t GetGpuIndex();
 bool     FullscreenEnabled();
+bool     HideCursorEnabled();
 bool     VrEnabled();
 bool     AmdCpuEnabled();
 uint32_t GetVblankFrequency();

src/graphics/presentation/window/hostInput.cpp

@@ -72,6 +72,7 @@ struct Binding {
 };
 
 constexpr int              MOUSE_POLL_INTERVAL_MS = 33;
+constexpr uint64_t         CURSOR_IDLE_HIDE_MS    = 2000;
 constexpr std::string_view MOUSE_SENSITIVITY      = "MouseSensitivity=";
 
 struct MouseJoystickState {
@@ -81,7 +82,8 @@ struct MouseJoystickState {
 };
 
 MouseJoystickState g_mouse;
-SDL_Window*        g_mouse_window = nullptr;
+SDL_Window*        g_mouse_window   = nullptr;
+uint64_t           g_cursor_hide_at = 0;
 
 std::size_t ControlFromName(std::string_view name) {
 	const auto info = std::find_if(CONTROL_INFO.begin(), CONTROL_INFO.end(),
@@ -380,11 +382,31 @@ int PollMouse(uint64_t now_ms) {
 	return MOUSE_POLL_INTERVAL_MS;
 }
 
+bool IsCursorActivity(const SDL_Event& event) {
+	SDL_MouseID which;
+	switch (event.type) {
+		case SDL_EVENT_MOUSE_MOTION:
+			if (event.motion.xrel == 0.0f && event.motion.yrel == 0.0f) {
+				return false;
+			}
+			which = event.motion.which;
+			break;
+		case SDL_EVENT_MOUSE_BUTTON_DOWN:
+		case SDL_EVENT_MOUSE_BUTTON_UP: which = event.button.which; break;
+		case SDL_EVENT_MOUSE_WHEEL: which = event.wheel.which; break;
+		default: return false;
+	}
+	return which != SDL_TOUCH_MOUSEID && which != SDL_PEN_MOUSEID;
+}
+
 } // namespace
 
 void HostInputInit(SDL_Window* window) {
 	GetInputMap();
 	g_mouse_window = window;
+	if (Config::HideCursorEnabled()) {
+		g_cursor_hide_at = SDL_GetTicks() + CURSOR_IDLE_HIDE_MS;
+	}
 }
 
 void HostInputShutdown() {
@@ -393,7 +415,11 @@ void HostInputShutdown() {
 		CenterMouseStick();
 		g_mouse = {};
 	}
-	g_mouse_window = nullptr;
+	g_mouse_window   = nullptr;
+	g_cursor_hide_at = 0;
+	if (Config::HideCursorEnabled()) {
+		SDL_ShowCursor();
+	}
 }
 
 void HostInputKey(int key_code, bool down) {
@@ -429,20 +455,36 @@ void HostInputToggleMouseToJoystick() {
 }
 
 bool HostInputWaitEvent(SDL_Event* event) {
-	bool has_event;
+	int timeout = -1;
 	if (!g_mouse.enabled || SDL_GetKeyboardFocus() != g_mouse_window) {
 		g_mouse.next_poll = 0;
 		CenterMouseStick();
-		has_event = SDL_WaitEvent(event);
-		if (!has_event) {
-			EXIT("%s\n", SDL_GetError());
-		}
 	} else {
 		if (g_mouse.next_poll == 0) {
 			SDL_GetRelativeMouseState(nullptr, nullptr);
 			g_mouse.next_poll = SDL_GetTicks() + MOUSE_POLL_INTERVAL_MS;
 		}
-		has_event = SDL_WaitEventTimeout(event, PollMouse(SDL_GetTicks()));
+		timeout = PollMouse(SDL_GetTicks());
+	}
+
+	if (g_cursor_hide_at != 0) {
+		const auto now_ms = SDL_GetTicks();
+		const int  cursor_timeout =
+		    now_ms < g_cursor_hide_at ? static_cast<int>(g_cursor_hide_at - now_ms) : 0;
+		timeout = timeout < 0 ? cursor_timeout : std::min(timeout, cursor_timeout);
+	}
+	const bool has_event = SDL_WaitEventTimeout(event, timeout);
+
+	if (Config::HideCursorEnabled()) {
+		const auto now_ms = SDL_GetTicks();
+		if (has_event && !g_mouse.enabled && IsCursorActivity(*event) &&
+		    SDL_GetWindowFromEvent(event) == g_mouse_window) {
+			SDL_ShowCursor();
+			g_cursor_hide_at = now_ms + CURSOR_IDLE_HIDE_MS;
+		} else if (g_cursor_hide_at != 0 && now_ms >= g_cursor_hide_at) {
+			SDL_HideCursor();
+			g_cursor_hide_at = 0;
+		}
 	}
 
 	if (has_event && event->type == SDL_EVENT_WINDOW_FOCUS_LOST &&

src/launcher/forms/configuration_edit_dialog.ui

@@ -173,6 +173,12 @@
           <property name="text"><string>Enable tessellation support (experimental)</string></property>
          </widget>
         </item>
+        <item row="8" column="1">
+         <widget class="QCheckBox" name="checkBox_hide_cursor">
+          <property name="toolTip"><string>Hide the host cursor after 2 seconds without mouse activity</string></property>
+          <property name="text"><string>Auto-hide cursor</string></property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </item>

src/launcher/include/configuration.h

@@ -119,6 +119,7 @@ public:
 	PresentMode            present_mode                = PresentMode::Mailbox;
 	int                    gpu_index                   = -1;
 	bool                   fullscreen_enabled          = false;
+	bool                   hide_cursor_enabled         = false;
 	bool                   readback_linear_images      = false;
 	bool                   tessellation_enabled        = false;
 	int                    vblank_frequency            = 60;
@@ -150,6 +151,7 @@ public:
 		present_mode                = other.present_mode;
 		gpu_index                   = other.gpu_index;
 		fullscreen_enabled          = other.fullscreen_enabled;
+		hide_cursor_enabled         = other.hide_cursor_enabled;
 		readback_linear_images      = other.readback_linear_images;
 		tessellation_enabled        = other.tessellation_enabled;
 		vblank_frequency            = other.vblank_frequency;
@@ -196,6 +198,7 @@ public:
 		KYTY_CFG_SET(present_mode);
 		KYTY_CFG_SET(gpu_index);
 		KYTY_CFG_SET(fullscreen_enabled);
+		KYTY_CFG_SET(hide_cursor_enabled);
 		KYTY_CFG_SET(readback_linear_images);
 		KYTY_CFG_SET(tessellation_enabled);
 		KYTY_CFG_SET(vblank_frequency);
@@ -238,6 +241,7 @@ public:
 			present_mode = PresentMode::Mailbox;
 		}
 		KYTY_CFG_GET(fullscreen_enabled);
+		KYTY_CFG_GET(hide_cursor_enabled);
 		KYTY_CFG_GET(readback_linear_images);
 		KYTY_CFG_GET(tessellation_enabled);
 		vblank_frequency = s->value("vblank_frequency", vblank_frequency).toInt();

src/launcher/src/configurationEditDialog.cpp

@@ -273,6 +273,7 @@ void ConfigurationEditDialog::Init(const Configuration& info) {
 	    info.gpu_index >= 0 && info.gpu_index < m_ui->comboBox_gpu->count() - 1 ? info.gpu_index + 1
 	                                                                            : 0);
 	m_ui->checkBox_fullscreen->setChecked(info.fullscreen_enabled);
+	m_ui->checkBox_hide_cursor->setChecked(info.hide_cursor_enabled);
 	m_ui->checkBox_readback->setChecked(info.readback_linear_images);
 	m_ui->checkBox_tessellation->setChecked(info.tessellation_enabled);
 	m_ui->spinBox_vblank_frequency->setValue(info.vblank_frequency);
@@ -425,6 +426,7 @@ static void UpdateInfo(Configuration& info, Ui::ConfigurationEditDialog& ui, boo
 	    TextToEnum<Configuration::PresentMode>(ui.comboBox_present_mode->currentText());
 	info.gpu_index                 = ui.comboBox_gpu->currentIndex() - 1;
 	info.fullscreen_enabled        = ui.checkBox_fullscreen->isChecked();
+	info.hide_cursor_enabled       = ui.checkBox_hide_cursor->isChecked();
 	info.readback_linear_images    = ui.checkBox_readback->isChecked();
 	info.tessellation_enabled      = ui.checkBox_tessellation->isChecked();
 	info.vblank_frequency          = ui.spinBox_vblank_frequency->value();

src/launcher/src/mainDialog.cpp

@@ -240,6 +240,9 @@ static QStringList CreateEmulatorArgs(const Configuration& info) {
 	if (info.fullscreen_enabled) {
 		args << "--fullscreen";
 	}
+	if (info.hide_cursor_enabled) {
+		args << "--hide-cursor";
+	}
 	args << "--readback-linear-images" << BoolArg(info.readback_linear_images);
 	if (info.tessellation_enabled) {
 		args << "--tessellation";

src/main.cpp

@@ -61,6 +61,8 @@ static void PrintUsage() {
 	::printf(
 	    "  --gpu <index>                        Vulkan physical device index. Default: auto.\n");
 	::printf("  --fullscreen                         Run in borderless desktop fullscreen.\n");
+	::printf(
+	    "  --hide-cursor                        Hide the cursor after 2 s idle. Default: off.\n");
 	::printf("  --vr                                 Enable the virtual VR headset.\n");
 	::printf("  --amd-cpu                            Apply AMD CPU instruction patches.\n");
 	::printf("  --vblank-frequency <num>             Virtual vblank frequency. Default: 60.\n");
@@ -205,6 +207,11 @@ static bool ParseArgs(int argc, char* argv[], RunOptions& options, bool& show_he
 			continue;
 		}
 
+		if (arg == "--hide-cursor") {
+			options.config.hide_cursor_enabled = true;
+			continue;
+		}
+
 		if (arg == "--vr") {
 			options.config.vr_enabled = true;
 			continue;