COMMON: Add getSafeOverlayArea as OSystem function

This will let the GUI know where to put its widgets to avoid notches.

backends/graphics/graphics.h

@@ -25,6 +25,7 @@
 #include "common/system.h"
 #include "common/noncopyable.h"
 #include "common/keyboard.h"
+#include "common/rect.h"
 #include "common/rotationmode.h"
 
 #include "graphics/mode.h"
@@ -104,6 +105,13 @@ public:
 	virtual void copyRectToOverlay(const void *buf, int pitch, int x, int y, int w, int h) = 0;
 	virtual int16 getOverlayHeight() const = 0;
 	virtual int16 getOverlayWidth() const = 0;
+	virtual Common::Rect getSafeOverlayArea(int16 *width, int16 *height) const {
+		int16 w = getOverlayWidth(),
+			  h = getOverlayHeight();
+		if (width) *width = w;
+		if (height) *height = h;
+		return Common::Rect(w, h);
+	}
 	virtual float getHiDPIScreenFactor() const { return 1.0f; }
 
 	virtual bool showMouse(bool visible) = 0;

backends/modular-backend.cpp

@@ -253,6 +253,10 @@ int16 ModularGraphicsBackend::getOverlayWidth() const {
 	return _graphicsManager->getOverlayWidth();
 }
 
+Common::Rect ModularGraphicsBackend::getSafeOverlayArea(int16 *width, int16 *height) const {
+	return _graphicsManager->getSafeOverlayArea(width, height);
+}
+
 float ModularGraphicsBackend::getHiDPIScreenFactor() const {
 	return _graphicsManager->getHiDPIScreenFactor();
 }

backends/modular-backend.h

@@ -118,6 +118,7 @@ public:
 	void copyRectToOverlay(const void *buf, int pitch, int x, int y, int w, int h) override final;
 	int16 getOverlayHeight() const override final;
 	int16 getOverlayWidth() const override final;
+	Common::Rect getSafeOverlayArea(int16 *width, int16 *height) const override final;
 
 	float getHiDPIScreenFactor() const override final;
 

common/system.cpp

@@ -223,6 +223,14 @@ bool OSystem::setRotationMode(int rotation) {
 	return setRotationMode(Common::parseRotationMode(rotation));
 }
 
+Common::Rect OSystem::getSafeOverlayArea(int16 *width, int16 *height) const {
+	int16 w = getOverlayWidth(),
+		  h = getOverlayHeight();
+	if (width) *width = w;
+	if (height) *height = h;
+	return Common::Rect(w, h);
+}
+
 void OSystem::fatalError() {
 	quit();
 	exit(1);

common/system.h

@@ -1448,6 +1448,19 @@ public:
 	 */
 	virtual int16 getOverlayWidth() const = 0;
 
+	/**
+	 * Return the safe area for the overlay.
+	 * This area does not interfere with any system UI elements
+	 * such as the notch or home indicator on mobile devices.
+	 * Also returns the full overlay size.
+	 *
+	 * @param width   Returns the width of the overlay, if not nullptr
+	 * @param height  Returns the height of the overlay, if not nullptr
+	 *
+	 * @return The safe area in overlay coordinates.
+	 */
+	virtual Common::Rect getSafeOverlayArea(int16 *width = nullptr, int16 *height = nullptr) const;
+
 	/** @} */