From f05a8d5458522c4468116cdf5909ab370e8f6005 Mon Sep 17 00:00:00 2001
From: rustbasic <127506429+rustbasic@users.noreply.github.com>
Date: Sat, 29 Jun 2024 11:38:24 +0900
Subject: [PATCH] Update scroll_area.rs

---
 crates/egui/src/containers/scroll_area.rs | 65 +++++++++++------------
 1 file changed, 31 insertions(+), 34 deletions(-)

diff --git a/crates/egui/src/containers/scroll_area.rs b/crates/egui/src/containers/scroll_area.rs
index 536b3c33a94..da7004ba06f 100644
--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -793,14 +793,7 @@ impl Prepared {
 
         let content_size = content_ui.min_size();
 
-        let scroll_delta = content_ui
-            .ctx()
-            .frame_state_mut(|state| std::mem::take(&mut state.scroll_delta));
-
         for d in 0..2 {
-            // FrameState::scroll_delta is inverted from the way we apply the delta, so we need to negate it.
-            let mut delta = -scroll_delta[d];
-
             // We always take both scroll targets regardless of which scroll axes are enabled. This
             // is to avoid them leaking to other scroll areas.
             let scroll_target = content_ui
@@ -808,6 +801,13 @@ impl Prepared {
                 .frame_state_mut(|state| state.scroll_target[d].take());
 
             if scroll_enabled[d] {
+                let scroll_delta = content_ui
+                    .ctx()
+                    .frame_state_mut(|state| std::mem::take(&mut state.scroll_delta[d]));
+
+                // FrameState::scroll_delta is inverted from the way we apply the delta, so we need to negate it.
+                let mut delta = -scroll_delta;
+
                 delta += if let Some((target_range, align)) = scroll_target {
                     let min = content_ui.min_rect().min[d];
                     let clip_rect = content_ui.clip_rect();
@@ -963,16 +963,30 @@ impl Prepared {
             let inner_margin = show_factor * scroll_style.bar_inner_margin;
             let outer_margin = show_factor * scroll_style.bar_outer_margin;
 
+            let mut max_cross = outer_rect.max[1 - d] - outer_margin;
+            if ui.clip_rect().max[1 - d] < max_cross + outer_margin {
+                // Move the scrollbar so it is visible. This is needed in some cases.
+                // For instance:
+                // * When we have a vertical-only scroll area in a top level panel,
+                //   and that panel is not wide enough for the contents.
+                // * When one ScrollArea is nested inside another, and the outer
+                //   is scrolled so that the scroll-bars of the inner ScrollArea (us)
+                //   is outside the clip rectangle.
+                // Really this should use the tighter clip_rect that ignores clip_rect_margin, but we don't store that.
+                // clip_rect_margin is quite a hack. It would be nice to get rid of it.
+                max_cross = ui.clip_rect().max[1 - d] - outer_margin;
+            }
+
             // top/bottom of a horizontal scroll (d==0).
             // left/rigth of a vertical scroll (d==1).
-            let mut cross = if scroll_style.floating {
+            let cross = if scroll_style.floating {
                 let max_bar_rect = if d == 0 {
-                    outer_rect.with_min_y(outer_rect.max.y - scroll_style.allocated_width())
+                    outer_rect.with_min_y(max_cross - scroll_style.bar_width)
                 } else {
-                    outer_rect.with_min_x(outer_rect.max.x - scroll_style.allocated_width())
+                    outer_rect.with_min_x(max_cross - scroll_style.bar_width)
                 };
-                let is_hovering_bar_area = is_hovering_outer_rect
-                    && ui.rect_contains_pointer(max_bar_rect)
+                let is_hovering_bar_area = (is_hovering_outer_rect
+                    && ui.rect_contains_pointer(max_bar_rect))
                     || state.scroll_bar_interaction[d];
                 let is_hovering_bar_area_t = ui
                     .ctx()
@@ -983,39 +997,22 @@ impl Prepared {
                         is_hovering_bar_area_t,
                     );
 
-                let max_cross = outer_rect.max[1 - d] - outer_margin;
                 let min_cross = max_cross - width;
                 Rangef::new(min_cross, max_cross)
             } else {
-                let min_cross = inner_rect.max[1 - d] + inner_margin;
-                let max_cross = outer_rect.max[1 - d] - outer_margin;
+                let min_cross = max_cross - scroll_style.bar_width;
                 Rangef::new(min_cross, max_cross)
             };
 
-            if ui.clip_rect().max[1 - d] < cross.max + outer_margin {
-                // Move the scrollbar so it is visible. This is needed in some cases.
-                // For instance:
-                // * When we have a vertical-only scroll area in a top level panel,
-                //   and that panel is not wide enough for the contents.
-                // * When one ScrollArea is nested inside another, and the outer
-                //   is scrolled so that the scroll-bars of the inner ScrollArea (us)
-                //   is outside the clip rectangle.
-                // Really this should use the tighter clip_rect that ignores clip_rect_margin, but we don't store that.
-                // clip_rect_margin is quite a hack. It would be nice to get rid of it.
-                let width = cross.max - cross.min;
-                cross.max = ui.clip_rect().max[1 - d] - outer_margin;
-                cross.min = cross.max - width;
-            }
-
             let outer_scroll_rect = if d == 0 {
                 Rect::from_min_max(
-                    pos2(inner_rect.left(), cross.min),
-                    pos2(inner_rect.right(), cross.max),
+                    pos2(inner_rect.left(), cross.min - inner_margin),
+                    pos2(inner_rect.right(), cross.max + outer_margin),
                 )
             } else {
                 Rect::from_min_max(
-                    pos2(cross.min, inner_rect.top()),
-                    pos2(cross.max, inner_rect.bottom()),
+                    pos2(cross.min - inner_margin, inner_rect.top()),
+                    pos2(cross.max + outer_margin, inner_rect.bottom()),
                 )
             };