From a8f51e93ac5fbfee79323899339c77e75bf58b72 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Tue, 8 Mar 2022 13:02:39 +0300
Subject: [PATCH] Add ui::selector (dropdown list component)

---
 libs/ui/include/psemek/ui/element_factory.hpp |   2 +
 libs/ui/include/psemek/ui/selector.hpp        |  50 +++++++
 libs/ui/source/element_factory.cpp            |   2 +
 libs/ui/source/selector.cpp                   | 126 ++++++++++++++++++
 4 files changed, 180 insertions(+)
 create mode 100644 libs/ui/include/psemek/ui/selector.hpp
 create mode 100644 libs/ui/source/selector.cpp

diff --git a/libs/ui/include/psemek/ui/element_factory.hpp b/libs/ui/include/psemek/ui/element_factory.hpp
index 7c34ec73..fd5b9a3b 100644
--- a/libs/ui/include/psemek/ui/element_factory.hpp
+++ b/libs/ui/include/psemek/ui/element_factory.hpp
@@ -15,6 +15,7 @@
 #include <psemek/ui/spinbox.hpp>
 #include <psemek/ui/scroller.hpp>
 #include <psemek/ui/progress_bar.hpp>
+#include <psemek/ui/selector.hpp>
 
 #include <psemek/gfx/texture.hpp>
 
@@ -47,6 +48,7 @@ namespace psemek::ui
 		virtual std::shared_ptr<button> make_arrow_button(int direction);
 		virtual std::shared_ptr<scroller> make_scroller();
 		virtual std::shared_ptr<progress_bar> make_progress_bar();
+		virtual std::shared_ptr<selector> make_selector();
 
 		virtual ~element_factory() {}
 	};
diff --git a/libs/ui/include/psemek/ui/selector.hpp b/libs/ui/include/psemek/ui/selector.hpp
new file mode 100644
index 00000000..68594cf1
--- /dev/null
+++ b/libs/ui/include/psemek/ui/selector.hpp
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <psemek/ui/element.hpp>
+#include <psemek/ui/container_impl.hpp>
+#include <psemek/ui/box_shape.hpp>
+
+namespace psemek::ui
+{
+
+	struct selector
+		: element
+	{
+		selector();
+
+		children_range children() const override { return container_.children(); }
+
+		struct shape const & shape() const override { return shape_; }
+
+		void reshape(geom::box<float, 2> const & box) override;
+
+		geom::box<float, 2> size_constraints() const override;
+
+		bool on_event(mouse_move const & e) override;
+		bool on_event(mouse_click const & e) override;
+
+		virtual std::size_t size() const;
+		virtual void resize(std::size_t size);
+		virtual void add(std::shared_ptr<element> child);
+		virtual std::shared_ptr<element> get(std::size_t index);
+
+		virtual std::optional<std::size_t> selected() const { return selected_; }
+		virtual void on_selected(std::function<void(std::size_t)> callback);
+
+	protected:
+
+		// extra distance between successive elements
+		virtual int y_extra() const { return 0; }
+
+		std::vector<geom::box<float, 2>> child_boxes_;
+
+	private:
+		container_impl container_;
+		box_shape shape_;
+
+		std::optional<std::size_t> selected_;
+
+		std::function<void(std::size_t)> callback_;
+	};
+
+}
diff --git a/libs/ui/source/element_factory.cpp b/libs/ui/source/element_factory.cpp
index 80dfc388..38336f56 100644
--- a/libs/ui/source/element_factory.cpp
+++ b/libs/ui/source/element_factory.cpp
@@ -121,4 +121,6 @@ namespace psemek::ui
 
 	std::shared_ptr<progress_bar> element_factory::make_progress_bar() { return nullptr; }
 
+	std::shared_ptr<selector> element_factory::make_selector() { return nullptr; }
+
 }
diff --git a/libs/ui/source/selector.cpp b/libs/ui/source/selector.cpp
new file mode 100644
index 00000000..2026a73a
--- /dev/null
+++ b/libs/ui/source/selector.cpp
@@ -0,0 +1,126 @@
+#include <psemek/ui/selector.hpp>
+
+#include <psemek/geom/contains.hpp>
+
+#include <stdexcept>
+
+namespace psemek::ui
+{
+
+	selector::selector()
+		: container_(this)
+	{}
+
+	void selector::reshape(geom::box<float, 2> const & box)
+	{
+		shape_.box = box;
+		child_boxes_.clear();
+
+		auto st = merged_own_style();
+
+		geom::interval<float> x_range = geom::shrink<float>(box[0], *st->inner_margin);
+
+		float y = box[1].min;
+
+		for (auto c : children())
+		{
+			float y_start = y;
+			y += *st->inner_margin;
+
+			if (c)
+			{
+				auto sc = c->size_constraints();
+				c->reshape({{x_range, {y, y + sc[1].min}}});
+				y += sc[1].min;
+			}
+
+			y += *st->inner_margin;
+
+			child_boxes_.push_back({{box[0], {y_start, y}}});
+
+			y += y_extra() * *st->scale;
+		}
+	}
+
+	geom::box<float, 2> selector::size_constraints() const
+	{
+		auto x_range = geom::interval<float>::full();
+
+		float y_sum = 0.f;
+
+		for (auto c : children())
+		{
+			if (!c) continue;
+
+			auto sc = c->size_constraints();
+			x_range &= sc[0];
+
+			y_sum += sc[1].min;
+		}
+
+		auto st = merged_own_style();
+
+		x_range += *st->inner_margin * 2.f;
+
+		y_sum += *st->inner_margin * 2.f * container_.size();
+		if (!container_.empty())
+			y_sum += *st->scale * y_extra() * static_cast<int>(container_.size() - 1);
+
+		return {{x_range, {y_sum, y_sum}}};
+	}
+
+	bool selector::on_event(mouse_move const & e)
+	{
+		auto const p = geom::cast<float>(e.position);
+
+		selected_ = std::nullopt;
+		for (std::size_t i = 0; i < child_boxes_.size(); ++i)
+		{
+			if (geom::contains(child_boxes_[i], p))
+			{
+				selected_ = i;
+				break;
+			}
+		}
+
+		return true;
+	}
+
+	bool selector::on_event(mouse_click const & e)
+	{
+		if (e.down && e.button == mouse_button::left && selected_ && callback_)
+		{
+			post([cb = callback_, i = *selected_]{ cb(i); });
+			return true;
+		}
+
+		return false;
+	}
+
+	std::size_t selector::size() const
+	{
+		return container_.size();
+	}
+
+	void selector::resize(std::size_t size)
+	{
+		container_.resize(size);
+	}
+
+	void selector::add(std::shared_ptr<element> child)
+	{
+		container_.add(child);
+	}
+
+	std::shared_ptr<element> selector::get(std::size_t index)
+	{
+		return container_.get(index);
+	}
+
+	void selector::on_selected(std::function<void(std::size_t)> callback)
+	{
+		callback_ = std::move(callback);
+	}
+
+
+}