Working on UI

src/UiManager.cpp

@@ -821,6 +821,7 @@ namespace ZL {
 		);
 		buttons.clear();
 		textButtons.clear();
+		allInteractives.clear();
 		sliders.clear();
 		textViews.clear();
 		textFields.clear();
@@ -1066,9 +1067,11 @@ namespace ZL {
 	void UiManager::collectButtonsAndSliders(const std::shared_ptr<UiNode>& node) {
 		if (node->button) {
 			buttons.push_back(node->button);
+			allInteractives.push_back(node->button);
 		}
 		if (node->textButton) {
 			textButtons.push_back(node->textButton);
+			allInteractives.push_back(node->textButton);
 		}
 		if (node->slider) {
 			sliders.push_back(node->slider);
@@ -1191,6 +1194,7 @@ namespace ZL {
 		prev.root = root;
 		prev.buttons = buttons;
 		prev.textButtons = textButtons;
+		prev.allInteractives = allInteractives;
 		prev.sliders = sliders;
 		prev.textViews = textViews;
 		prev.textFields = textFields;
@@ -1255,6 +1259,7 @@ namespace ZL {
 		root = s.root;
 		buttons = s.buttons;
 		textButtons = s.textButtons;
+		allInteractives = s.allInteractives;
 		sliders = s.sliders;
 		textViews = s.textViews;
 		textFields = s.textFields;
@@ -1646,22 +1651,22 @@ namespace ZL {
 
 
 	void UiManager::onTouchDown(int64_t fingerId, int x, int y) {
-		for (auto& b : buttons) {
-			if (b->state != ButtonState::Disabled)
-			{
-				if (b->getClickZoneRect().containsConsideringBorder((float)x, (float)y, b->border)) {
+		// Iterate allInteractives in reverse DFS order: later-declared elements have higher priority.
+		// At most one button or textButton is pressed per touch.
+		for (auto it = allInteractives.rbegin(); it != allInteractives.rend(); ++it) {
+			if (std::holds_alternative<std::shared_ptr<UiButton>>(*it)) {
+				auto& b = std::get<std::shared_ptr<UiButton>>(*it);
+				if (b->state != ButtonState::Disabled &&
+					b->getClickZoneRect().containsConsideringBorder((float)x, (float)y, b->border)) {
 					b->state = ButtonState::Pressed;
 					pressedButtons[fingerId] = b;
 					if (b->onPress) b->onPress(b->name);
-					break; // a single finger can only press one button
+					break;
 				}
-			}
-		}
-
-		for (auto& tb : textButtons) {
-			if (tb->state != ButtonState::Disabled)
-			{
-				if (tb->getClickZoneRect().containsConsideringBorder((float)x, (float)y, tb->border)) {
+			} else {
+				auto& tb = std::get<std::shared_ptr<UiTextButton>>(*it);
+				if (tb->state != ButtonState::Disabled &&
+					tb->getClickZoneRect().containsConsideringBorder((float)x, (float)y, tb->border)) {
 					tb->state = ButtonState::Pressed;
 					pressedTextButtons[fingerId] = tb;
 					if (tb->onPress) tb->onPress(tb->name);