Remove clip_rect_margin (#8366)

* Closes https://github.com/emilk/egui/issues/5605
 
It has been zero by default for a few months now, and I do not wish to
support it. It was always an ugly hack, and it is no longer needed.

crates/egui/src/containers/resize.rs

@@ -289,16 +289,16 @@ impl Resize {
             Rect::from_min_size(position, state.desired_size)
         };
 
-        let mut content_clip_rect = inner_rect.expand(ui.visuals().clip_rect_margin);
+        let mut content_clip_rect = inner_rect;
 
         // If we pull the resize handle to shrink, we want to TRY to shrink it.
         // After laying out the contents, we might be much bigger.
         // In those cases we don't want the clip_rect to be smaller, because
         // then we will clip the contents of the region even thought the result gets larger. This is simply ugly!
         // So we use the memory of last_content_size to make the clip rect large enough.
-        content_clip_rect.max = content_clip_rect.max.max(
-            inner_rect.min + state.last_content_size + Vec2::splat(ui.visuals().clip_rect_margin),
-        );
+        content_clip_rect.max = content_clip_rect
+            .max
+            .max(inner_rect.min + state.last_content_size);
 
         content_clip_rect = content_clip_rect.intersect(ui.clip_rect()); // Respect parent region
 

crates/egui/src/containers/scroll_area.rs

@@ -810,12 +810,11 @@ impl ScrollArea {
 
         {
             // Clip the content, but only when we really need to:
-            let clip_rect_margin = ui.visuals().clip_rect_margin;
             let mut content_clip_rect = ui.clip_rect();
             for d in 0..2 {
                 if direction_enabled[d] {
-                    content_clip_rect.min[d] = inner_rect.min[d] - clip_rect_margin;
-                    content_clip_rect.max[d] = inner_rect.max[d] + clip_rect_margin;
+                    content_clip_rect.min[d] = inner_rect.min[d];
+                    content_clip_rect.max[d] = inner_rect.max[d];
                 } else {
                     // Nice handling of forced resizing beyond the possible:
                     content_clip_rect.max[d] = ui.clip_rect().max[d] - current_bar_use[d];
@@ -1306,8 +1305,6 @@ impl Prepared {
                 // * 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;
             }
 
@@ -1575,9 +1572,7 @@ fn paint_fade_areas_impl(ui: &Ui, inner_rect: Rect, content_size: Vec2, offset:
 
     let overflow = content_size - inner_rect.size();
 
-    let paint_rect = inner_rect
-        .intersect(ui.min_rect())
-        .expand(ui.visuals().clip_rect_margin);
+    let paint_rect = inner_rect.intersect(ui.min_rect());
 
     // Top fade: animate opacity based on how far we've scrolled down.
     if 0.0 < offset.y {

crates/egui/src/style.rs

@@ -1074,12 +1074,6 @@ pub struct Visuals {
     /// How the text cursor acts.
     pub text_cursor: TextCursorStyle,
 
-    /// Allow widgets to paint this much outside the scroll area rect.
-    ///
-    /// Legacy. Should not be used anymore.
-    /// Use [`crate::ScrollArea::content_margin`] instead.
-    pub clip_rect_margin: f32,
-
     /// Show a background behind buttons.
     pub button_frame: bool,
 
@@ -1534,7 +1528,6 @@ impl Visuals {
 
             text_cursor: Default::default(),
 
-            clip_rect_margin: 0.0,
             button_frame: true,
             collapsing_header_frame: false,
             indent_has_left_vline: true,
@@ -2297,7 +2290,6 @@ impl Visuals {
 
             text_cursor,
 
-            clip_rect_margin,
             button_frame,
             collapsing_header_frame,
             indent_has_left_vline,
@@ -2484,8 +2476,6 @@ impl Visuals {
 
         ui.collapsing("Misc", |ui| {
             ui.add(Slider::new(resize_corner_size, 0.0..=20.0).text("resize_corner_size"));
-            ui.add(Slider::new(clip_rect_margin, 0.0..=20.0).text("clip_rect_margin"));
-
             ui.checkbox(button_frame, "Button has a frame");
             ui.checkbox(collapsing_header_frame, "Collapsing header has a frame");
             ui.checkbox(

crates/egui_demo_lib/src/demo/scrolling.rs

@@ -340,10 +340,8 @@ impl crate::View for ScrollTo {
                     ui.scroll_to_cursor(Some(Align::BOTTOM));
                 }
 
-                let margin = ui.visuals().clip_rect_margin;
-
-                let current_scroll = ui.clip_rect().top() - ui.min_rect().top() + margin;
-                let max_scroll = ui.min_rect().height() - ui.clip_rect().height() + 2.0 * margin;
+                let current_scroll = ui.clip_rect().top() - ui.min_rect().top();
+                let max_scroll = ui.min_rect().height() - ui.clip_rect().height();
                 (current_scroll, max_scroll)
             })
             .inner;

crates/egui_extras/src/layout.rs

@@ -217,10 +217,7 @@ impl<'l> StripLayout<'l> {
         let mut child_ui = self.ui.new_child(ui_builder);
 
         if flags.clip {
-            let margin = egui::Vec2::splat(self.ui.visuals().clip_rect_margin);
-            let margin = margin.min(0.5 * self.ui.spacing().item_spacing);
-            let clip_rect = max_rect.expand2(margin);
-            child_ui.shrink_clip_rect(clip_rect);
+            child_ui.shrink_clip_rect(max_rect);
 
             if !child_ui.is_sizing_pass() {
                 // Better to truncate (if we can), rather than hard clipping: