Query animation status instead of storing it

This makes it a lot easier to support more than one possible animation
in the same layer.

src/contextmenu.cpp

@@ -22,7 +22,6 @@ struct ContextMenu::MenuOption {
 ContextMenu::ContextMenu(GMenu2X &gmenu2x, Menu &menu)
 	: gmenu2x(gmenu2x)
 	, menu(menu)
-	, fadeAlpha(0)
 	, selected(0)
 {
 	Translator &tr = gmenu2x.tr;
@@ -95,24 +94,20 @@ ContextMenu::ContextMenu(GMenu2X &gmenu2x, Menu &menu)
 
 	// Init background fade animation.
 	tickStart = SDL_GetTicks();
-	startAnimating();
+	fadeAlpha = 0;
 }
 
-void ContextMenu::runAnimations()
+bool ContextMenu::runAnimations()
 {
 	if (fadeAlpha < 200) {
 		const long tickNow = SDL_GetTicks();
 		fadeAlpha = intTransition(0, 200, tickStart, 500, tickNow);
-		if (fadeAlpha == 200) {
-			stopAnimating();
-		}
 	}
+	return fadeAlpha < 200;
 }
 
 void ContextMenu::paint(Surface &s)
 {
-	runAnimations();
-
 	Font *font = gmenu2x.font;
 
 	// Darken background.

src/contextmenu.h

@@ -21,6 +21,7 @@ public:
 	ContextMenu(GMenu2X &gmenu2x, Menu &menu);
 
 	// Layer implementation:
+	virtual bool runAnimations();
 	virtual void paint(Surface &s);
 	virtual bool handleButtonPress(InputManager::Button button);
 	virtual bool handleTouchscreen(Touchscreen &ts);
@@ -28,8 +29,6 @@ public:
 private:
 	struct MenuOption;
 
-	void runAnimations();
-
 	GMenu2X &gmenu2x;
 	Menu &menu;
 	std::vector<std::shared_ptr<MenuOption>> options;

src/gmenu2x.cpp

@@ -591,24 +591,21 @@ void GMenu2X::main() {
 
 	bool quit = false;
 	while (!quit) {
-		// Check whether any layers are animating and remove dismissed layers
-		// from the stack.
-		bool animating = false;
+		// Remove dismissed layers from the stack.
 		for (auto it = layers.begin(); it != layers.end(); ) {
-			auto layer = *it;
-			switch (layer->getStatus()) {
-				case Layer::Status::DISMISSED:
-					it = layers.erase(it);
-					break;
-				case Layer::Status::ANIMATING:
-					animating = true;
-					// fall through
-				case Layer::Status::PASSIVE:
-					++it;
-					break;
+			if ((*it)->getStatus() == Layer::Status::DISMISSED) {
+				it = layers.erase(it);
+			} else {
+				++it;
 			}
 		}
 
+		// Run animations.
+		bool animating = false;
+		for (auto layer : layers) {
+			animating |= layer->runAnimations();
+		}
+
 		// Paint layers.
 		for (auto layer : layers) {
 			layer->paint(*s);

src/layer.h

@@ -16,10 +16,16 @@ class Touchscreen;
  */
 class Layer {
 public:
-	enum class Status { PASSIVE, ANIMATING, DISMISSED };
+	enum class Status { DISMISSED, NORMAL };
 
 	virtual ~Layer() {}
 
+	/**
+	 * Perform one frame worth of animation.
+	 * Returns true iff there are any animations in progress.
+	 */
+	virtual bool runAnimations() { return false; }
+
 	/**
 	 * Paints this layer on the given surface.
 	 */
@@ -50,22 +56,8 @@ protected:
 		status = Status::DISMISSED;
 	}
 
-	/**
-	 * Request that this layer be repainted every frame.
-	 */
-	void startAnimating() {
-		if (status == Status::PASSIVE) status = Status::ANIMATING;
-	}
-
-	/**
-	 * Request that this layer be repainted only after an event.
-	 */
-	void stopAnimating() {
-		if (status == Status::ANIMATING) status = Status::PASSIVE;
-	}
-
 private:
-	Status status = Status::PASSIVE;
+	Status status = Status::NORMAL;
 };
 
 #endif // LAYER_H

src/menu.cpp

@@ -171,18 +171,14 @@ void Menu::calcSectionRange(int &leftSection, int &rightSection) {
 			rightSection - numSections + 1);
 }
 
-void Menu::runAnimations() {
+bool Menu::runAnimations() {
 	if (sectionAnimation.isRunning()) {
 		sectionAnimation.step();
-		if (!sectionAnimation.isRunning()) {
-			stopAnimating();
-		}
 	}
+	return sectionAnimation.isRunning();
 }
 
 void Menu::paint(Surface &s) {
-	runAnimations();
-
 	const uint width = s.width(), height = s.height();
 	Font &font = *gmenu2x->font;
 	SurfaceCollection &sc = gmenu2x->sc;
@@ -371,13 +367,11 @@ vector<Link*> *Menu::sectionLinks(int i) {
 
 void Menu::decSectionIndex() {
 	sectionAnimation.adjust(-1 << 16);
-	startAnimating();
 	setSectionIndex(iSection - 1);
 }
 
 void Menu::incSectionIndex() {
 	sectionAnimation.adjust(1 << 16);
-	startAnimating();
 	setSectionIndex(iSection + 1);
 }
 

src/menu.h

@@ -65,8 +65,6 @@ private:
 
 	Animation sectionAnimation;
 
-	void runAnimations();
-
 	/**
 	 * Determine which section headers are visible.
 	 * The output values are relative to the middle section at 0.
@@ -127,6 +125,7 @@ public:
 	void skinUpdated();
 
 	// Layer implementation:
+	virtual bool runAnimations();
 	virtual void paint(Surface &s);
 	virtual bool handleButtonPress(InputManager::Button button);
 	virtual bool handleTouchscreen(Touchscreen &ts);