2 files changed, 113 insertions, 14 deletions

diff --git a/ui.cpp b/ui.cpp
index 7b5128b..a3ed71b 100644
--- a/ui.cpp
+++ b/ui.cpp
@@ -706,6 +706,10 @@ void UI::Element::on_message(const Message& msg) {
 	(void)msg;
 }
 
+void UI::Element::on_add_child(Element* nch) {
+	(void)nch;
+}
+
 void UI::Element::on_render() {
 
 }
@@ -734,6 +738,7 @@ void UI::Element::add_child(Element* ch) {
 	}
 	ch->parent = this;
 	ui->layout_dirty = true;
+	on_add_child(ch);
 }
 
 void UI::Element::remove_child(Element* ch) {
@@ -821,12 +826,7 @@ void UI::Toolbar::on_render() {
 }
 
 UI::Button::Button(UI* ui, Element* parent, const char* label):
-	Element(ui, parent) {
-	text = dup_stringh(ui->heap, label);
-}
-
-UI::Button::~Button() {
-	heap_free(ui->heap, text);
+	Label(ui, parent, label) {
 }
 
 UI::Rect UI::Button::layout(const Rect& avail) {
@@ -988,3 +988,89 @@ void UI::Modal::bring_to_front() {
 	p->remove_child(this);
 	p->add_child(this);
 }
+
+UI::Tree::Tree(UI* ui, Element* parent, const char* label):
+	Element(ui, parent), collapsed(0), expandbtn(0), text(0) {
+	text = ui->create_element<Label>(this, label);
+}
+
+UI::Rect UI::Tree::layout(const Rect& avail) {
+	Rect cr(avail.x + ui_padding, avail.y, avail.w, avail.h);
+	Rect lr(0, avail.y, avail.w, avail.h);
+	Rect used(avail.x, avail.y, 0, 0);
+	Element* child;
+	Rect er = Rect(cr.x, cr.y, 0, 0);
+	if (expandbtn)
+		er = expandbtn->layout(cr);
+	lr.x = er.x + er.w + ui_padding;
+	Rect tr = text->layout(lr);
+	er.h += ui_padding;
+	used.h = er.h;
+	used.w = (tr.x + tr.w) - er.x;
+	cr.y += er.h;
+	cr.h -= er.h;
+	for (child = children; child; child = child->next) {
+		if (child == expandbtn || child == text) continue;
+		Rect r = child->layout(cr);
+		r.h += ui_padding;
+		cr.y += r.h;
+		cr.h -= r.h;
+		used.h += r.h;
+	}
+	used.h += ui_padding;
+	bound = used;
+	clip = used;
+	clip.clip(avail);
+	return bound;
+}
+
+void UI::Tree::on_render() {
+	if (collapsed) {
+		expandbtn->render();
+		text->render();
+	}
+}
+
+void UI::Tree::on_update() {
+	if (collapsed) {
+		expandbtn->update();
+		text->update();
+	}
+}
+
+void UI::Tree::on_add_child(Element* child) {
+	assert(collapsed == 0);
+	if (!expandbtn && text) {
+		expandbtn = (Button*)0x1;
+		expandbtn = ui->create_element<Button>(this, "-");
+		expandbtn->handler = [](Element* e, const Message& m) {
+			if (m.type == Message::Type::click) {
+				UI::Tree* t = (UI::Tree*)e->parent;
+				if (t->collapsed)
+					t->expand();
+				else
+					t->collapse();
+			}
+			return 0;
+		};
+	}
+	(void)child;
+}
+
+void UI::Tree::expand() {
+	children = collapsed;
+	collapsed = 0;
+	if (expandbtn)
+		expandbtn->set_text("-");
+}
+
+void UI::Tree::collapse() {
+	collapsed = children;
+	children = 0;
+	if (expandbtn)
+		expandbtn->set_text("+");
+}
+
+bool UI::Tree::is_leaf() const {
+	return children == 0 && collapsed == 0;
+}
diff --git a/ui.hpp b/ui.hpp
index adb1ba8..abb4f69 100644
--- a/ui.hpp
+++ b/ui.hpp
@@ -177,6 +177,7 @@ struct UI {
 		void update();
 		virtual void on_update();
 		virtual void on_render();
+		virtual void on_add_child(Element* nch);
 		virtual void on_message(const Message& msg);
 
 		void add_child(Element* ch);
@@ -204,14 +205,6 @@ struct UI {
 		void on_render() override;
 	};
 
-	struct Button : Element {
-		char* text;
-		Button(UI* ui, Element* parent, const char* label);
-		~Button();
-		Rect layout(const Rect& avail) override;
-		void on_render() override;
-	};
-
 	struct Label : Element {
 		char* text;
 		Label(UI* ui, Element* parent, const char* label);
@@ -222,6 +215,12 @@ struct UI {
 		void set_text(const char* s);
 	};
 
+	struct Button : Label {
+		Button(UI* ui, Element* parent, const char* label);
+		Rect layout(const Rect& avail) override;
+		void on_render() override;
+	};
+
 	struct Modal : Element {
 		Container* contents;
 		Toolbar* title_bar;
@@ -236,6 +235,20 @@ struct UI {
 		void on_update() override;
 		void bring_to_front();
 	};
+
+	struct Tree : Element {
+		Element* collapsed; /* <- children are moved here when it's collapsed so they stop layout'ing and rendering! */
+		Button* expandbtn;
+		Label* text;
+		Tree(UI* ui, Element* parent, const char* text);
+		Rect layout(const Rect& avail) override;
+		void on_render() override;
+		void on_update() override;
+		void on_add_child(Element* child) override;
+		void expand();
+		void collapse();
+		bool is_leaf() const;
+	};
 };
 
 #endif