From 5779680e1d142b3bccbd9a05adf14b3115b829cc Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 5 Feb 2022 12:43:21 +0300
Subject: [PATCH] Fix ui::slider behavior if reshape occurs while user is
 changing value

---
 libs/ui/include/psemek/ui/slider.hpp |  2 ++
 libs/ui/source/slider.cpp            | 11 +++++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/libs/ui/include/psemek/ui/slider.hpp b/libs/ui/include/psemek/ui/slider.hpp
index 00ef3528..0669d5db 100644
--- a/libs/ui/include/psemek/ui/slider.hpp
+++ b/libs/ui/include/psemek/ui/slider.hpp
@@ -49,12 +49,14 @@ namespace psemek::ui
 
 		state_t state_ = state_t::normal;
 		std::optional<geom::point<int, 2>> mouse_;
+		std::optional<geom::interval<float>> drag_range_;
 
 		on_value_changed_callback callback_;
 
 		void post_value_changed();
 
 		int compute_value(int x) const;
+		int compute_value(int x, geom::interval<float> const & range) const;
 	};
 
 }
diff --git a/libs/ui/source/slider.cpp b/libs/ui/source/slider.cpp
index 18204d55..ec440bef 100644
--- a/libs/ui/source/slider.cpp
+++ b/libs/ui/source/slider.cpp
@@ -25,7 +25,7 @@ namespace psemek::ui
 			break;
 		case state_t::mousedown:
 			if (mouse_)
-				set_value(compute_value((*mouse_)[0]));
+				set_value(compute_value((*mouse_)[0], *drag_range_));
 			break;
 		}
 
@@ -44,7 +44,10 @@ namespace psemek::ui
 			{
 				state_ = state_t::mousedown;
 				if (mouse_)
-					set_value(compute_value((*mouse_)[0]));
+				{
+					drag_range_ = slider_range();
+					set_value(compute_value((*mouse_)[0], *drag_range_));
+				}
 				on_state_changed(state_t::mouseover);
 				return true;
 			}
@@ -56,6 +59,7 @@ namespace psemek::ui
 					state_ = state_t::mouseover;
 				else
 					state_ = state_t::normal;
+				drag_range_ = std::nullopt;
 				on_state_changed(state_t::mousedown);
 				return true;
 			}
@@ -116,9 +120,8 @@ namespace psemek::ui
 			});
 	}
 
-	int slider::compute_value(int x) const
+	int slider::compute_value(int x, geom::interval<float> const & range) const
 	{
-		auto const range = slider_range();
 		return std::round(geom::unlerp(range, x * 1.f) * value_range_.length()) + value_range_.min;
 	}