PEGASUS: Add the Tracker class

engines/pegasus/input.cpp

@@ -267,4 +267,31 @@ bool InputHandler::wantsCursor() {
 	return false;
 }
 
+Tracker *Tracker::_currentTracker = 0;
+
+void Tracker::handleInput(const Input &input, const Hotspot *) {
+	if (stopTrackingInput(input))
+		stopTracking(input);
+	else if (isTracking())
+		continueTracking(input);
+}
+
+void Tracker::startTracking(const Input &) {
+	if (!isTracking()) {
+		_savedHandler = InputHandler::setInputHandler(this);
+		_currentTracker = this;
+	}
+}
+
+void Tracker::stopTracking(const Input &) {
+	if (isTracking()) {
+		_currentTracker = NULL;
+		InputHandler::setInputHandler(_savedHandler);
+	}
+}
+
+bool Tracker::isClickInput(const Input &input, const Hotspot *hotspot) {
+	return !isTracking() && InputHandler::isClickInput(input, hotspot);
+}
+
 } // End of namespace Pegasus

engines/pegasus/input.h

@@ -414,6 +414,41 @@ class InputHandler {
 	bool _allowInput;
 };
 
+
+/*
+
+	Tracker implements "dragging". A Tracker can receive a startTracking message,
+	which causes it to be the current tracker, as well as setting it up as the current
+	input handler. In addition, only one tracker can be tracking at a time, and no
+	other handler can be set up as the current handler until the track finishes. By
+	default, there is no next input handler for a Tracker, but this behavior can be
+	overridden if desired.
+
+*/
+
+class Tracker : public InputHandler {
+public:
+	Tracker() : InputHandler(0) {}
+	virtual ~Tracker();
+
+	virtual void handleInput(const Input &, const Hotspot *);
+	virtual bool stopTrackingInput(const Input &) { return false; }
+
+	virtual void startTracking(const Input &);
+	virtual void stopTracking(const Input &);
+	virtual void continueTracking(const Input &) {}
+
+	bool isTracking() { return this == _currentTracker; }
+	bool isClickInput(const Input &, const Hotspot *);
+
+	bool releaseInputFocus() { return !isTracking(); }
+
+protected:
+	static Tracker *_currentTracker;
+
+	InputHandler *_savedHandler;
+};
+
 } // End of namespace Pegasus
 
 #endif