From d2f36a0a58c0ce3acd53a39226dd3b77d892d527 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?H=C3=A9ctor=20Ram=C3=B3n=20Jim=C3=A9nez?= <hector@hecrj.dev>
Date: Sun, 17 Aug 2025 00:58:37 +0200
Subject: [PATCH] Resize base layer in `Stack` before drawing

---
 core/src/renderer.rs          | 4 ++--
 core/src/renderer/null.rs     | 2 +-
 graphics/src/layer.rs         | 5 ++++-
 renderer/src/fallback.rs      | 4 ++--
 runtime/src/user_interface.rs | 4 +---
 tiny_skia/src/lib.rs          | 4 ++--
 wgpu/src/lib.rs               | 4 ++--
 7 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/core/src/renderer.rs b/core/src/renderer.rs
index 53f59303..84d48304 100644
--- a/core/src/renderer.rs
+++ b/core/src/renderer.rs
@@ -60,8 +60,8 @@ pub trait Renderer {
     /// Fills a [`Quad`] with the provided [`Background`].
     fn fill_quad(&mut self, quad: Quad, background: impl Into<Background>);
 
-    /// Clears all of the recorded primitives in the [`Renderer`].
-    fn clear(&mut self);
+    /// Resets the [`Renderer`] to start drawing in the `new_bounds` from scratch.
+    fn reset(&mut self, new_bounds: Rectangle);
 }
 
 /// A polygon with four sides.
diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 2251e527..60c87a81 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -16,7 +16,7 @@ impl Renderer for () {
 
     fn end_transformation(&mut self) {}
 
-    fn clear(&mut self) {}
+    fn reset(&mut self, _new_bounds: Rectangle) {}
 
     fn fill_quad(
         &mut self,
diff --git a/graphics/src/layer.rs b/graphics/src/layer.rs
index 4f4219fd..dbab0192 100644
--- a/graphics/src/layer.rs
+++ b/graphics/src/layer.rs
@@ -158,12 +158,15 @@ impl<T: Layer> Stack<T> {
 
     /// Clears the layers of the [`Stack`], allowing reuse.
     ///
+    /// It resizes the base layer bounds to the `new_bounds`.
+    ///
     /// This will normally keep layer allocations for future drawing operations.
-    pub fn clear(&mut self) {
+    pub fn reset(&mut self, new_bounds: Rectangle) {
         for layer in self.layers[..self.active_count].iter_mut() {
             layer.reset();
         }
 
+        self.layers[0].resize(new_bounds);
         self.current = 0;
         self.active_count = 1;
         self.previous.clear();
diff --git a/renderer/src/fallback.rs b/renderer/src/fallback.rs
index 79e22c77..411b5862 100644
--- a/renderer/src/fallback.rs
+++ b/renderer/src/fallback.rs
@@ -46,8 +46,8 @@ where
         delegate!(self, renderer, renderer.fill_quad(quad, background.into()));
     }
 
-    fn clear(&mut self) {
-        delegate!(self, renderer, renderer.clear());
+    fn reset(&mut self, new_bounds: Rectangle) {
+        delegate!(self, renderer, renderer.reset(new_bounds));
     }
 
     fn start_layer(&mut self, bounds: Rectangle) {
diff --git a/runtime/src/user_interface.rs b/runtime/src/user_interface.rs
index 95e7574f..482ffafa 100644
--- a/runtime/src/user_interface.rs
+++ b/runtime/src/user_interface.rs
@@ -482,10 +482,8 @@ where
         style: &renderer::Style,
         cursor: mouse::Cursor,
     ) {
-        // TODO: Move to shell level (?)
-        renderer.clear();
-
         let viewport = Rectangle::with_size(self.bounds);
+        renderer.reset(viewport);
 
         let base_cursor = match &self.overlay {
             None
diff --git a/tiny_skia/src/lib.rs b/tiny_skia/src/lib.rs
index 8f343277..bc379981 100644
--- a/tiny_skia/src/lib.rs
+++ b/tiny_skia/src/lib.rs
@@ -225,8 +225,8 @@ impl core::Renderer for Renderer {
         layer.draw_quad(quad, background.into(), transformation);
     }
 
-    fn clear(&mut self) {
-        self.layers.clear();
+    fn reset(&mut self, new_bounds: Rectangle) {
+        self.layers.reset(new_bounds);
     }
 }
 
diff --git a/wgpu/src/lib.rs b/wgpu/src/lib.rs
index b5af87b7..4361d605 100644
--- a/wgpu/src/lib.rs
+++ b/wgpu/src/lib.rs
@@ -648,8 +648,8 @@ impl core::Renderer for Renderer {
         layer.draw_quad(quad, background.into(), transformation);
     }
 
-    fn clear(&mut self) {
-        self.layers.clear();
+    fn reset(&mut self, new_bounds: Rectangle) {
+        self.layers.reset(new_bounds);
     }
 }