From e67b3f1fdc15d1d28dce8d445e1632fb441abb17 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 5 Mar 2021 15:51:17 +0300
Subject: [PATCH] Add ui slider element

---
 .../psemek/ui/default_element_factory.hpp     |   1 +
 libs/ui/include/psemek/ui/element_factory.hpp |   2 +
 libs/ui/include/psemek/ui/slider.hpp          |  55 ++++++++
 libs/ui/include/psemek/ui/style.hpp           |   2 +
 libs/ui/source/default_element_factory.cpp    |  85 +++++++++++++
 libs/ui/source/element_factory.cpp            |   2 +
 libs/ui/source/slider.cpp                     | 118 ++++++++++++++++++
 libs/ui/source/style.cpp                      |   3 +
 todo.md                                       |   1 -
 9 files changed, 268 insertions(+), 1 deletion(-)
 create mode 100644 libs/ui/include/psemek/ui/slider.hpp
 create mode 100644 libs/ui/source/slider.cpp

diff --git a/libs/ui/include/psemek/ui/default_element_factory.hpp b/libs/ui/include/psemek/ui/default_element_factory.hpp
index ed0fce96..fc3174d8 100644
--- a/libs/ui/include/psemek/ui/default_element_factory.hpp
+++ b/libs/ui/include/psemek/ui/default_element_factory.hpp
@@ -25,6 +25,7 @@ namespace psemek::ui
 		std::shared_ptr<button> make_button() override;
 		std::shared_ptr<frame> make_frame() override;
 		std::shared_ptr<window> make_window(std::string caption) override;
+		std::shared_ptr<slider> make_slider() override;
 
 	private:
 		psemek_declare_pimpl
diff --git a/libs/ui/include/psemek/ui/element_factory.hpp b/libs/ui/include/psemek/ui/element_factory.hpp
index d56e6ab6..24bd1dbe 100644
--- a/libs/ui/include/psemek/ui/element_factory.hpp
+++ b/libs/ui/include/psemek/ui/element_factory.hpp
@@ -8,6 +8,7 @@
 #include <psemek/ui/grid_layout.hpp>
 #include <psemek/ui/image_view.hpp>
 #include <psemek/ui/rich_image_view.hpp>
+#include <psemek/ui/slider.hpp>
 
 #include <psemek/gfx/texture.hpp>
 
@@ -26,6 +27,7 @@ namespace psemek::ui
 		virtual std::shared_ptr<grid_layout> make_grid_layout();
 		virtual std::shared_ptr<image_view> make_image_view(std::shared_ptr<gfx::texture_2d> image);
 		virtual std::shared_ptr<rich_image_view> make_rich_image_view(std::shared_ptr<gfx::texture_2d> image);
+		virtual std::shared_ptr<slider> make_slider();
 
 		virtual ~element_factory() {}
 	};
diff --git a/libs/ui/include/psemek/ui/slider.hpp b/libs/ui/include/psemek/ui/slider.hpp
new file mode 100644
index 00000000..c5e0d7c0
--- /dev/null
+++ b/libs/ui/include/psemek/ui/slider.hpp
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <psemek/ui/element.hpp>
+
+#include <functional>
+
+namespace psemek::ui
+{
+
+	struct slider
+		: element
+	{
+		bool on_event(mouse_move const & e) override;
+		bool on_event(mouse_click const & e) override;
+		bool on_event(mouse_wheel const & e) override;
+
+		virtual geom::interval<int> value_range() const { return value_range_; }
+		virtual void set_value_range(geom::interval<int> i);
+
+		virtual int value() const { return value_; }
+		virtual void set_value(int v);
+
+		using on_value_changed_callback = std::function<void(int)>;
+
+		void on_value_changed(on_value_changed_callback callback);
+
+	protected:
+		enum class state_t
+		{
+			normal,
+			mouseover,
+			mousedown,
+		};
+
+		virtual state_t state() const { return state_; }
+
+		virtual void on_state_changed(state_t /* old */) {}
+
+		virtual geom::interval<float> slider_range() const;
+
+	private:
+		geom::interval<int> value_range_{0, 100};
+		int value_ = 0;
+
+		state_t state_ = state_t::normal;
+		std::optional<int> mouse_x_;
+
+		on_value_changed_callback callback_;
+
+		void post_value_changed();
+
+		int compute_value(int x) const;
+	};
+
+}
diff --git a/libs/ui/include/psemek/ui/style.hpp b/libs/ui/include/psemek/ui/style.hpp
index f3bed65d..b55e2598 100644
--- a/libs/ui/include/psemek/ui/style.hpp
+++ b/libs/ui/include/psemek/ui/style.hpp
@@ -20,6 +20,8 @@ namespace psemek::ui
 		std::optional<gfx::color_rgba> border_color;
 		std::optional<int> border_width;
 
+		std::optional<gfx::color_rgba> axis_color;
+
 		std::optional<geom::vector<int, 2>> shadow_offset;
 		std::optional<gfx::color_rgba> shadow_color;
 
diff --git a/libs/ui/source/default_element_factory.cpp b/libs/ui/source/default_element_factory.cpp
index 7733a068..c2c8caab 100644
--- a/libs/ui/source/default_element_factory.cpp
+++ b/libs/ui/source/default_element_factory.cpp
@@ -310,6 +310,86 @@ namespace psemek::ui
 			element * children_[3];
 		};
 
+		struct slider_impl
+			: slider
+		{
+			struct shape const & shape() const override { return shape_; }
+
+			void reshape(geom::box<float, 2> const & bbox)
+			{
+				shape_.box = bbox;
+			}
+
+			geom::box<float, 2> size_constraints() const
+			{
+				static float const inf = std::numeric_limits<float>::infinity();
+				return {{{button_width(), inf}, {button_height(), inf}}};
+			}
+
+			void draw(painter & p) const
+			{
+				auto st = merged_style();
+
+				geom::box<float, 2> ab;
+				ab[0] = shape_.box[0];
+				ab[1] = geom::expand(geom::interval<float>::singleton(shape_.box[1].center()), axis_width() / 2.f);
+
+				gfx::color_rgba c = *st->fg_color;
+				if (state() == state_t::mouseover)
+					c = *st->highlight_color;
+				else if (state() == state_t::mousedown)
+					c = *st->action_color;
+
+				auto const r = slider_range();
+
+				float x = geom::lerp(r, geom::unlerp<float>(geom::cast<float>(value_range()), value()));
+
+				geom::box<float, 2> sb;
+				sb[0] = geom::expand(geom::interval<float>::singleton(x), button_width() / 2.f);
+				sb[1] = geom::expand(geom::interval<float>::singleton(shape_.box[1].center()), button_height() / 2.f);
+
+				if (*st->shadow_offset != geom::vector{0, 0})
+				{
+					auto off = geom::cast<float>(*st->shadow_offset);
+					p.draw_rect(ab + off, *st->shadow_color);
+					p.draw_rect(sb + off, *st->shadow_color);
+				}
+
+				p.draw_rect(ab, *st->axis_color);
+				if (*st->border_width != 0)
+					p.draw_rect(sb, *st->border_color);
+				p.draw_rect(geom::shrink(sb, 1.f * (*st->border_width)), c);
+			}
+
+		protected:
+
+			geom::interval<float> slider_range() const override
+			{
+				return geom::shrink(shape_.box[0], button_width() / 2.f);
+			}
+
+		private:
+			box_shape shape_;
+
+			int button_width() const
+			{
+				auto st = merged_style();
+				return *st->outer_margin;
+			}
+
+			int button_height() const
+			{
+				auto st = merged_style();
+				return 3 * (*st->outer_margin);
+			}
+
+			int axis_width() const
+			{
+				auto st = merged_style();
+				return *st->inner_margin;
+			}
+		};
+
 	}
 
 	struct default_element_factory::impl
@@ -350,4 +430,9 @@ namespace psemek::ui
 		return r;
 	}
 
+	std::shared_ptr<slider> default_element_factory::make_slider()
+	{
+		return std::make_shared<slider_impl>();
+	}
+
 }
diff --git a/libs/ui/source/element_factory.cpp b/libs/ui/source/element_factory.cpp
index 5608114a..2e671a59 100644
--- a/libs/ui/source/element_factory.cpp
+++ b/libs/ui/source/element_factory.cpp
@@ -73,4 +73,6 @@ namespace psemek::ui
 		return i;
 	}
 
+	std::shared_ptr<slider> element_factory::make_slider() { return nullptr; }
+
 }
diff --git a/libs/ui/source/slider.cpp b/libs/ui/source/slider.cpp
new file mode 100644
index 00000000..8fab1b55
--- /dev/null
+++ b/libs/ui/source/slider.cpp
@@ -0,0 +1,118 @@
+#include <psemek/ui/slider.hpp>
+
+namespace psemek::ui
+{
+
+	bool slider::on_event(mouse_move const & e)
+	{
+		bool const over = shape().contains(geom::cast<float>(e.position));
+		mouse_x_ = e.position[0];
+
+		switch (state_) {
+		case state_t::normal:
+			if (over)
+			{
+				state_ = state_t::mouseover;
+				on_state_changed(state_t::normal);
+			}
+			break;
+		case state_t::mouseover:
+			if (!over)
+			{
+				state_ = state_t::normal;
+				on_state_changed(state_t::mouseover);
+			}
+			break;
+		case state_t::mousedown:
+			if (mouse_x_)
+				set_value(compute_value(*mouse_x_));
+			break;
+		}
+
+		return false;
+	}
+
+	bool slider::on_event(mouse_click const & e)
+	{
+		if (e.button != mouse_button::left) return false;
+
+		switch (state_) {
+		case state_t::normal:
+			break;
+		case state_t::mouseover:
+			if (e.down)
+			{
+				state_ = state_t::mousedown;
+				if (mouse_x_)
+					set_value(compute_value(*mouse_x_));
+				on_state_changed(state_t::mouseover);
+				return true;
+			}
+			break;
+		case state_t::mousedown:
+			if (!e.down)
+			{
+				state_ = state_t::mouseover;
+				on_state_changed(state_t::mousedown);
+				return true;
+			}
+			break;
+		}
+
+		return false;
+	}
+
+	bool slider::on_event(mouse_wheel const & e)
+	{
+		if (state_ == state_t::mouseover)
+		{
+			set_value(value_ + e.delta);
+			return true;
+		}
+
+		return false;
+	}
+
+	void slider::set_value_range(geom::interval<int> i)
+	{
+		if (i.empty()) throw std::runtime_error("Empty value range for ui::slider");
+		value_range_ = i;
+		set_value(value_);
+	}
+
+	void slider::set_value(int v)
+	{
+		v = geom::clamp(v, value_range_);
+		if (value_ != v)
+		{
+			value_ = v;
+			post_value_changed();
+		}
+	}
+
+	void slider::on_value_changed(on_value_changed_callback callback)
+	{
+		callback_ = std::move(callback);
+		post_value_changed();
+	}
+
+	geom::interval<float> slider::slider_range() const
+	{
+		return shape().bbox()[0];
+	}
+
+	void slider::post_value_changed()
+	{
+		if (callback_)
+			post([cb = callback_, value = value_]{
+				cb(value);
+			});
+	}
+
+	int slider::compute_value(int x) const
+	{
+		auto const range = slider_range();
+		return std::round(geom::unlerp(range, x * 1.f) * value_range_.length()) + value_range_.min;
+	}
+
+}
diff --git a/libs/ui/source/style.cpp b/libs/ui/source/style.cpp
index 1f19a2c2..6de66d14 100644
--- a/libs/ui/source/style.cpp
+++ b/libs/ui/source/style.cpp
@@ -24,6 +24,7 @@ namespace psemek::ui
 		merge(dst.action_offset, src.action_offset);
 		merge(dst.border_color, src.border_color);
 		merge(dst.border_width, src.border_width);
+		merge(dst.axis_color, src.axis_color);
 		merge(dst.shadow_offset, src.shadow_offset);
 		merge(dst.shadow_color, src.shadow_color);
 		merge(dst.inner_margin, src.inner_margin);
@@ -47,6 +48,8 @@ namespace psemek::ui
 		s.border_color = {255, 255, 255, 255};
 		s.border_width = 3;
 
+		s.axis_color = {255, 255, 255, 255};
+
 		s.shadow_offset = {1, 1};
 		s.shadow_color = {0, 0, 0, 255};
 
diff --git a/todo.md b/todo.md
index 52eaccdb..9325f578 100644
--- a/todo.md
+++ b/todo.md
@@ -26,4 +26,3 @@
 	* grid layout quadratic optimization
 	* draggable window element
 	* screen children sorting
-	* slider element