Better UX when touch events aren't supported by Irrlicht device (#15288)

irr/include/IrrlichtDevice.h

@@ -193,6 +193,11 @@ public:
 	/** If this returns false, you should not do any rendering. */
 	virtual bool isWindowVisible() const { return true; };
 
+	//! Checks if the Irrlicht device supports touch events.
+	/** Intentionally doesn't check whether a touch input device is available
+	or similar. */
+	virtual bool supportsTouchEvents() const { return false; }
+
 	//! Get the current color format of the window
 	/** \return Color format of the window. */
 	virtual video::ECOLOR_FORMAT getColorFormat() const = 0;

irr/src/CIrrDeviceLinux.cpp

@@ -1205,6 +1205,17 @@ bool CIrrDeviceLinux::isWindowMaximized() const
 	return WindowMaximized;
 }
 
+//! Checks if the Irrlicht device supports touch events.
+bool CIrrDeviceLinux::supportsTouchEvents() const
+{
+#if defined(_IRR_LINUX_X11_XINPUT2_)
+	return true;
+#else
+	return false;
+#endif
+}
+
+
 //! returns color format of the window.
 video::ECOLOR_FORMAT CIrrDeviceLinux::getColorFormat() const
 {

irr/src/CIrrDeviceLinux.h

@@ -66,6 +66,9 @@ public:
 	//! returns last state from maximizeWindow() and restoreWindow()
 	bool isWindowMaximized() const override;
 
+	//! Checks if the Irrlicht device supports touch events.
+	bool supportsTouchEvents() const override;
+
 	//! returns color format of the window.
 	video::ECOLOR_FORMAT getColorFormat() const override;
 

irr/src/CIrrDeviceSDL.cpp

@@ -1293,6 +1293,12 @@ bool CIrrDeviceSDL::isWindowVisible() const
 	return !IsInBackground;
 }
 
+//! Checks if the Irrlicht device supports touch events.
+bool CIrrDeviceSDL::supportsTouchEvents() const
+{
+	return true;
+}
+
 //! returns if window is active. if not, nothing need to be drawn
 bool CIrrDeviceSDL::isWindowActive() const
 {

irr/src/CIrrDeviceSDL.h

@@ -93,6 +93,9 @@ public:
 	//! Checks if the window could possibly be visible.
 	bool isWindowVisible() const override;
 
+	//! Checks if the Irrlicht device supports touch events.
+	bool supportsTouchEvents() const override;
+
 	//! Get the position of this window on screen
 	core::position2di getWindowPosition() override;