From 3faccd125679451308ee6a417bd9a81238ad5a23 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Fri, 5 Mar 2021 23:13:57 +0300
Subject: [PATCH] Default ui element factory supports arrow buttons

---
 .../psemek/ui/default_element_factory.hpp     |  7 ++
 libs/ui/source/default_element_factory.cpp    | 88 ++++++++++++++++++-
 2 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/libs/ui/include/psemek/ui/default_element_factory.hpp b/libs/ui/include/psemek/ui/default_element_factory.hpp
index d012bc91..17e98bf5 100644
--- a/libs/ui/include/psemek/ui/default_element_factory.hpp
+++ b/libs/ui/include/psemek/ui/default_element_factory.hpp
@@ -18,6 +18,13 @@ namespace psemek::ui
 		std::shared_ptr<window> make_window(std::string caption) override;
 		std::shared_ptr<slider> make_slider() override;
 
+		// directions:
+		// 0 - up
+		// 1 - down
+		// 2 - left
+		// 3 - right
+		std::shared_ptr<button> make_arrow_button(int direction);
+
 	private:
 		psemek_declare_pimpl
 	};
diff --git a/libs/ui/source/default_element_factory.cpp b/libs/ui/source/default_element_factory.cpp
index d25145a0..b44f0a3f 100644
--- a/libs/ui/source/default_element_factory.cpp
+++ b/libs/ui/source/default_element_factory.cpp
@@ -5,7 +5,6 @@
 
 #include <psemek/ui/resources/cross_red_16x16_png.hpp>
 
-
 namespace psemek::ui
 {
 
@@ -395,6 +394,88 @@ namespace psemek::ui
 			}
 		};
 
+		struct arrow_button_impl
+			: button
+		{
+			arrow_button_impl(int direction)
+				: direction_{direction}
+			{}
+
+			geom::box<float, 2> size_constraints() const override
+			{
+				auto b = button::size_constraints();
+
+				auto st = merged_style();
+				b[0].min = *st->ref_height / 2.f;
+				b[1].min = *st->ref_height / 2.f;
+
+				return b;
+			}
+
+			struct shape const & shape() const override
+			{
+				return shape_;
+			}
+
+			void reshape(geom::box<float, 2> const & box) override
+			{
+				shape_.box = box;
+
+				switch (direction_)
+				{
+				case 0:
+					triangle_[0] = box.corner(0.f, 1.f);
+					triangle_[1] = box.corner(1.f, 1.f);
+					triangle_[2] = box.corner(0.5f, 0.f);
+					break;
+				case 1:
+					triangle_[0] = box.corner(0.f, 0.f);
+					triangle_[1] = box.corner(1.f, 0.f);
+					triangle_[2] = box.corner(0.5f, 1.f);
+					break;
+				case 2:
+					triangle_[0] = box.corner(1.f, 0.f);
+					triangle_[1] = box.corner(1.f, 1.f);
+					triangle_[2] = box.corner(0.f, 0.5f);
+					break;
+				case 3:
+					triangle_[0] = box.corner(0.f, 0.f);
+					triangle_[1] = box.corner(0.f, 1.f);
+					triangle_[2] = box.corner(1.f, 0.5f);
+					break;
+				default:
+					throw std::runtime_error("Unknown arrow button direction");
+				}
+
+				if (geom::volume(triangle_[0], triangle_[1], triangle_[2]) < 0.f)
+					std::swap(triangle_[1], triangle_[2]);
+			}
+
+			void draw(painter &p) const override
+			{
+				auto st = merged_style();
+
+				if (*st->shadow_offset != geom::vector{0, 0})
+					p.draw_triangle(triangle_ + geom::cast<float>(*st->shadow_offset), *st->shadow_color);
+
+				geom::vector off{0.f, 0.f};
+				if (state() == state_t::mousedown)
+					off = geom::cast<float>(*st->action_offset);
+
+				gfx::color_rgba color = *st->fg_color;
+				if (state() == state_t::mouseover)
+					color = *st->highlight_color;
+				else if (state() == state_t::mousedown)
+					color = *st->action_color;
+				p.draw_triangle(triangle_ + off, color);
+			}
+
+		private:
+			int const direction_;
+			box_shape shape_;
+			geom::triangle<geom::point<float, 2>> triangle_;
+		};
+
 	}
 
 	struct default_element_factory::impl
@@ -440,4 +521,9 @@ namespace psemek::ui
 		return std::make_shared<slider_impl>();
 	}
 
+	std::shared_ptr<button> default_element_factory::make_arrow_button(int direction)
+	{
+		return std::make_shared<arrow_button_impl>(direction);
+	}
+
 }