From 361ef9fd7a5859a09d1b7ccee7deaa8dd9b9285a Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Thu, 5 Jan 2023 04:54:01 +0300
Subject: [PATCH] Add default scroller implementation

---
 libs/ui/source/default_element_factory.cpp | 54 +++++++++++++++++++++-
 libs/ui/source/scroller.cpp                | 23 ++++-----
 2 files changed, 61 insertions(+), 16 deletions(-)

diff --git a/libs/ui/source/default_element_factory.cpp b/libs/ui/source/default_element_factory.cpp
index b33a9781..0e94e7b7 100644
--- a/libs/ui/source/default_element_factory.cpp
+++ b/libs/ui/source/default_element_factory.cpp
@@ -946,6 +946,58 @@ namespace psemek::ui
 			button * dec_button_;
 		};
 
+		struct scroller_impl
+			: scroller
+		{
+			void draw(struct painter & painter) const override
+			{
+				auto st = merged_own_style();
+
+				auto draw_box = [&](geom::box<float, 2> box, state_t state, float position, int dimension)
+				{
+					float h = height();
+
+					box[dimension].max -= h;
+					float origin = geom::lerp(box[dimension], position);
+					box[dimension] = {origin, origin + h};
+
+					gfx::color_rgba color;
+					if (state == state_t::normal)
+						color = *st->fg_color;
+					else if (state == state_t::mouseover)
+						color = *st->highlight_color;
+					else
+					{
+						color = *st->action_color;
+						box += geom::cast<float>(*st->action_offset);
+					}
+
+					if (*st->shadow_offset != geom::vector{0, 0})
+						painter.draw_rect(box + geom::cast<float>(*st->shadow_offset), *st->shadow_color);
+					painter.draw_rect(box, color);
+				};
+
+				if (horizontal_scroll())
+					draw_box(horizontal_box(), horizontal_state_, position(direction::horizontal), 0);
+
+				if (vertical_scroll())
+					draw_box(vertical_box(), vertical_state_, position(direction::vertical), 1);
+
+				scroller::draw(painter);
+			}
+
+		protected:
+			float width() const override
+			{
+				return 10.f;
+			}
+
+			float height() const
+			{
+				return 50.f;
+			}
+		};
+
 		struct selector_impl
 			: selector
 		{
@@ -1083,7 +1135,7 @@ namespace psemek::ui
 
 	std::shared_ptr<scroller> default_element_factory::make_scroller()
 	{
-		return std::make_shared<scroller>();
+		return std::make_shared<scroller_impl>();
 	}
 
 	std::shared_ptr<selector> default_element_factory::make_selector()
diff --git a/libs/ui/source/scroller.cpp b/libs/ui/source/scroller.cpp
index 5338c12c..b94ceb87 100644
--- a/libs/ui/source/scroller.cpp
+++ b/libs/ui/source/scroller.cpp
@@ -48,15 +48,8 @@ namespace psemek::ui
 					if (!child_)
 						return false;
 
-					auto sc = child_->size_constraints();
-
 					float c = geom::unlerp<float>(box[0], e.position[0]);
-					c = geom::clamp(c, {0.f, 1.f});
-
-					auto old = shift_tgt_;
-					shift_tgt_[0] = shape_.box[0].length() / 2.f - c * sc[0].min;
-					clamp_shift();
-					on_scroll(shift_tgt_ - old);
+					set_position(direction::horizontal, geom::clamp(c, {0.f, 1.f}), true);
 				}
 				break;
 			}
@@ -82,15 +75,9 @@ namespace psemek::ui
 					if (!child_)
 						return false;
 
-					auto sc = child_->size_constraints();
-
 					float c = geom::unlerp<float>(box[1], e.position[1]);
 					c = geom::clamp(c, {0.f, 1.f});
-
-					auto old = shift_tgt_;
-					shift_tgt_[1] = shape_.box[1].length() / 2.f - c * sc[1].min;
-					clamp_shift();
-					on_scroll(shift_tgt_ - old);
+					set_position(direction::vertical, geom::clamp(c, {0.f, 1.f}), true);
 				}
 				break;
 			}
@@ -317,6 +304,8 @@ namespace psemek::ui
 		if (dir == direction::vertical && !vertical_scroll())
 			return;
 
+		auto old_shift = shift_tgt_;
+
 		int dim = (dir == direction::horizontal) ? 0 : 1;
 
 		auto child_box = child_->shape().bbox();
@@ -329,8 +318,12 @@ namespace psemek::ui
 			child_area[0] -= width() * *st->scale;
 
 		shift_tgt_[dim] = position * (child_area[dim] - child_box[dim].length());
+		clamp_shift();
+
 		if (!animate)
 			shift_[dim] = shift_tgt_[dim];
+
+		on_scroll(shift_tgt_ - old_shift);
 	}
 
 	void scroller::update(float dt)