From ea068abeacd509b752284cee255220643132ee5c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20K=C3=A5re=20Alsaker?= <john.kare.alsaker@gmail.com>
Date: Mon, 6 Nov 2023 09:54:28 +0100
Subject: [PATCH] Don't let hidden views contribute to the parent's rect

---
 src/context.rs            | 12 +++++-------
 src/view.rs               | 29 ++++++++++++++++++-----------
 src/views/clip.rs         | 10 +---------
 src/views/virtual_list.rs | 10 ++--------
 4 files changed, 26 insertions(+), 35 deletions(-)

diff --git a/src/context.rs b/src/context.rs
index 65ab09b9..d06f7333 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1326,18 +1326,16 @@ impl<'a> LayoutCx<'a> {
     /// - invoking any attached context::ResizeListeners
     ///
     /// Returns the bounding rect that encompasses this view and its children
-    pub fn compute_view_layout(&mut self, view: &mut dyn View) -> Rect {
+    pub fn compute_view_layout(&mut self, view: &mut dyn View) -> Option<Rect> {
         let id = view.id();
         if self.app_state().is_hidden(id) {
-            return Rect::ZERO;
+            self.app_state_mut().view_state(id).layout_rect = Rect::ZERO;
+            return None;
         }
 
         self.save();
 
-        let layout = self
-            .app_state()
-            .get_layout(id)
-            .unwrap_or(taffy::layout::Layout::new());
+        let layout = self.app_state().get_layout(id).unwrap();
         let origin = Point::new(layout.location.x as f64, layout.location.y as f64);
         let parent_viewport = self.viewport.map(|rect| {
             rect.with_origin(Point::new(
@@ -1401,7 +1399,7 @@ impl<'a> LayoutCx<'a> {
 
         self.restore();
 
-        layout_rect
+        Some(layout_rect)
     }
 
     pub(crate) fn get_resize_listener(&mut self, id: Id) -> Option<&mut ResizeListener> {
diff --git a/src/view.rs b/src/view.rs
index 951315dc..81463a68 100644
--- a/src/view.rs
+++ b/src/view.rs
@@ -201,17 +201,7 @@ pub trait View {
 
     /// Responsible for computing the layout of the view's children.
     fn compute_layout(&mut self, cx: &mut LayoutCx) -> Option<Rect> {
-        let mut layout_rect: Option<Rect> = None;
-        self.for_each_child_mut(&mut |child| {
-            let child_layout = cx.compute_view_layout(child);
-            if let Some(rect) = layout_rect {
-                layout_rect = Some(rect.union(child_layout));
-            } else {
-                layout_rect = Some(child_layout);
-            }
-            false
-        });
-        layout_rect
+        default_compute_layout(self, cx)
     }
 
     /// Implement this to handle events and to pass them down to children
@@ -236,6 +226,23 @@ pub trait View {
     }
 }
 
+/// Computes the layout of the view's children, if any.
+pub fn default_compute_layout<V: View + ?Sized>(view: &mut V, cx: &mut LayoutCx) -> Option<Rect> {
+    let mut layout_rect: Option<Rect> = None;
+    view.for_each_child_mut(&mut |child| {
+        let child_layout = cx.compute_view_layout(child);
+        if let Some(child_layout) = child_layout {
+            if let Some(rect) = layout_rect {
+                layout_rect = Some(rect.union(child_layout));
+            } else {
+                layout_rect = Some(child_layout);
+            }
+        }
+        false
+    });
+    layout_rect
+}
+
 pub(crate) fn paint_bg(
     cx: &mut PaintCx,
     computed_style: &Style,
diff --git a/src/views/clip.rs b/src/views/clip.rs
index 43ba40a5..3763d544 100644
--- a/src/views/clip.rs
+++ b/src/views/clip.rs
@@ -1,4 +1,4 @@
-use kurbo::{Rect, Size};
+use kurbo::Size;
 
 use crate::{id::Id, view::View};
 
@@ -38,14 +38,6 @@ impl View for Clip {
         "Clip".into()
     }
 
-    fn layout(&mut self, cx: &mut crate::context::LayoutCx) -> taffy::prelude::Node {
-        cx.layout_node(self.id, true, |cx| vec![cx.layout_view(&mut self.child)])
-    }
-
-    fn compute_layout(&mut self, cx: &mut crate::context::LayoutCx) -> Option<Rect> {
-        Some(cx.compute_view_layout(&mut self.child))
-    }
-
     fn paint(&mut self, cx: &mut crate::context::PaintCx) {
         cx.save();
         let style = cx.get_builtin_style(self.id);
diff --git a/src/views/virtual_list.rs b/src/views/virtual_list.rs
index a18221ac..510bb77b 100644
--- a/src/views/virtual_list.rs
+++ b/src/views/virtual_list.rs
@@ -8,7 +8,7 @@ use taffy::{prelude::Node, style::Dimension};
 use crate::{
     context::LayoutCx,
     id::Id,
-    view::{ChangeFlags, View},
+    view::{self, ChangeFlags, View},
 };
 
 use super::{apply_diff, diff, Diff, DiffOpAdd, FxIndexSet, HashRun};
@@ -340,13 +340,7 @@ impl<V: View + 'static, T> View for VirtualList<V, T> {
             self.set_viewport.set(viewport);
         }
 
-        let mut layout_rect = Rect::ZERO;
-        for child in &mut self.children {
-            if let Some((child, _)) = child.as_mut() {
-                layout_rect = layout_rect.union(cx.compute_view_layout(child));
-            }
-        }
-        Some(layout_rect)
+        view::default_compute_layout(self, cx)
     }
 }