ofEvents::did_notify() (#7773)

examples/events/notifyEventExample/src/main.cpp

@@ -0,0 +1,10 @@
+#include "ofApp.h"
+#include "ofMain.h"
+
+int main() {
+
+	ofGLWindowSettings settings;
+	auto window = ofCreateWindow(settings);
+	ofRunApp(window, std::make_shared<ofApp>());
+	ofRunMainLoop();
+}

examples/events/notifyEventExample/src/ofApp.cpp

@@ -0,0 +1,52 @@
+#include "ofApp.h"
+
+void ofApp::update() {
+
+	// you can check the state of a specific ofParameter
+	// (wrapper around it's own "hidden Event")
+	// no listeners/callbacks are required
+
+	if (size.didNotify()) {
+		ofLogNotice("new size") << size;
+	}
+
+	if (refresh.didNotify()) {
+		color = ofColor::fromHsb(ofRandom(360), 128, 128);
+		ofLogNotice("boosch") << color;
+	}
+
+	if (animate.didNotify()) { // this is the ofAbstractParameter::did_notify()
+		if (animate != animating) { // sanity check
+			animating = animate;
+			if (animating) {
+				ofLogNotice("stop animation");
+			} else {
+				ofLogNotice("begin animation");
+				size = 0;
+			}
+		}
+	}
+
+	if (auto what = params.parameterChangedE().did_notify()) { // this is the Events::did_notify()
+		// something happended in params, but you don't know what
+	}
+}
+
+void ofApp::draw() {
+	ofBackground(0);
+	if (animating) {
+		ofSetColor(color);
+		ofDrawCircle(ofGetWidth() / 2, ofGetHeight() / 2, size);
+		size = size + 1;
+		if (size > 100) size -= 100;
+	}
+	ofDrawBitmapString("<a> to toggle automation", 10, 10);
+	ofDrawBitmapString("<s> to randomize size", 10, 20);
+	ofDrawBitmapString("<c> to change color", 10, 30);
+}
+
+void ofApp::keyPressed(int key) {
+	if (key == 'a') animate = !animate;
+	if (key == 'r') size = ofRandom(50, 100);
+	if (key == 'c') refresh.trigger();
+}

examples/events/notifyEventExample/src/ofApp.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "ofMain.h"
+
+// note: this example, inspired by simpleEvents, is kept voluntarily
+// as small as possible to give a sense of the bare minimum requirements
+
+class ofApp : public ofBaseApp {
+
+	ofParameter<bool> animate { "animate", false };
+	ofParameter<void> refresh { "refresh" };
+	ofParameter<float> size { "size", 1.0f, 0.0f, 100.0f };
+	ofParameterGroup params { "myCallbacksAndSettings", animate, refresh, size };
+
+	bool animating { false };
+	ofColor color { ofColor::white };
+
+public:
+	void update() override;
+	void draw() override;
+	void keyPressed(int key) override;
+};

libs/openFrameworks/events/ofEvent.h

@@ -563,33 +563,38 @@ class ofEvent: public of::priv::BaseEvent<of::priv::Function<T,Mutex>,Mutex>{
 		 ofEvent<T,Mutex>::self->remove(*make_function(std::function<typename of::priv::callable_traits<TFunction>::function_type>(function), priority)->id);
 	}
 
-	inline bool notify(const void* sender, T & param){
-		if(ofEvent<T,Mutex>::self->enabled && !ofEvent<T,Mutex>::self->functions.empty()){
-			std::unique_lock<Mutex> lck(ofEvent<T,Mutex>::self->mtx);
-			auto functions_copy = ofEvent<T,Mutex>::self->functions;
-			lck.unlock();
-			for(auto & f: functions_copy){
-                if(f->notify(sender,param)){
-					return true;
-                }
-			}
+	/// \brief checks the state of the event
+	/// \returns true if the Event's state was notified since the last check
+	bool didNotify() {
+		if (notified_.load(std::memory_order_relaxed)) {
+			notified_.store(false, std::memory_order_seq_cst);
+			return true;
+		} else {
+			return false;
 		}
-		return false;
 	}
+	std::atomic<bool> notified_ { false };
 
-	inline bool notify(T & param){
-		if(ofEvent<T,Mutex>::self->enabled && !ofEvent<T,Mutex>::self->functions.empty()){
-			std::unique_lock<Mutex> lck(ofEvent<T,Mutex>::self->mtx);
-			auto functions_copy = ofEvent<T,Mutex>::self->functions;
-			lck.unlock();
-			for(auto & f: functions_copy){
-				if(f->notify(nullptr,param)){
-					return true;
+	inline bool notify(const void* sender, T & param) {
+		if (ofEvent<T,Mutex>::self->enabled) {
+			notified_.store(true, std::memory_order_relaxed);
+			if (!ofEvent<T,Mutex>::self->functions.empty()) {
+				std::unique_lock<Mutex> lck(ofEvent<T,Mutex>::self->mtx);
+				auto functions_copy = ofEvent<T,Mutex>::self->functions;
+				lck.unlock();
+				for (auto & f: functions_copy) {
+					if (f->notify(sender,param)) {
+						return true;
+					}
 				}
 			}
 		}
 		return false;
 	}
+
+	inline bool notify(T & param){
+		return this->notify(nullptr, param);
+	}
 };
 
 
@@ -721,32 +726,37 @@ class ofEvent<void,Mutex>: public of::priv::BaseEvent<of::priv::Function<void,Mu
 		 ofEvent<void,Mutex>::self->remove(*make_function(std::function<typename of::priv::callable_traits<TFunction>::function_type>(function),priority)->id);
 	}
 
+	/// \brief checks the state of the event
+	/// \returns true if the Event's state was notified since the last check
+	bool didNotify() {
+		if (notified_.load(std::memory_order_relaxed)) {
+			notified_.store(false, std::memory_order_seq_cst);
+			return true;
+		} else {
+			return false;
+		}
+	}
+	std::atomic<bool> notified_;
+
 	bool notify(const void* sender){
-		if(ofEvent<void,Mutex>::self->enabled && !ofEvent<void,Mutex>::self->functions.empty()){
-			std::unique_lock<Mutex> lck(ofEvent<void,Mutex>::self->mtx);
-			auto functions_copy = ofEvent<void,Mutex>::self->functions;
-			lck.unlock();
-			for(auto & f: functions_copy){
-				if(f->notify(sender)){
-					return true;
+		if(ofEvent<void,Mutex>::self->enabled) {
+			notified_.store(true, std::memory_order_relaxed);
+			if (!ofEvent<void,Mutex>::self->functions.empty()) {
+				std::unique_lock<Mutex> lck(ofEvent<void,Mutex>::self->mtx);
+				auto functions_copy = ofEvent<void,Mutex>::self->functions;
+				lck.unlock();
+				for (auto & f: functions_copy) {
+					if (f->notify(sender)) {
+						return true;
+					}
 				}
 			}
 		}
 		return false;
 	}
 
 	bool notify(){
-		if(ofEvent<void,Mutex>::self->enabled && !ofEvent<void,Mutex>::self->functions.empty()){
-			std::unique_lock<Mutex> lck(ofEvent<void,Mutex>::self->mtx);
-			auto functions_copy = ofEvent<void,Mutex>::self->functions;
-			lck.unlock();
-			for(auto & f: functions_copy){
-				if(f->notify(nullptr)){
-					return true;
-				}
-			}
-		}
-		return false;
+		return this->notify(nullptr);
 	}
 };