From 80ea8b8b47c2bff79569b478a31dd2cf36f46b7a Mon Sep 17 00:00:00 2001
From: Elena Torro <elenatorro@gmail.com>
Date: Fri, 17 Apr 2026 11:36:40 +0200
Subject: [PATCH] wip

---
 render-wasm/src/render.rs          | 28 +++++++++++++++++++++++++++-
 render-wasm/src/render/surfaces.rs | 21 +++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/render-wasm/src/render.rs b/render-wasm/src/render.rs
index e1897ae09b..aab064509f 100644
--- a/render-wasm/src/render.rs
+++ b/render-wasm/src/render.rs
@@ -2794,8 +2794,13 @@ impl RenderState {
                     }
                 } else {
                     performance::begin_measure!("render_shape_tree::uncached");
+                    // At this point, interest-area tiles can still yield.
+                    let tile_is_visible = self
+                        .current_tile
+                        .is_some_and(|t| self.tile_viewbox.is_visible(&t));
+                    let can_stop = allow_stop && !tile_is_visible;
                     let (is_empty, early_return) = self
-                        .render_shape_tree_partial_uncached(tree, timestamp, allow_stop, false)?;
+                        .render_shape_tree_partial_uncached(tree, timestamp, can_stop, false)?;
 
                     if early_return {
                         return Ok(());
@@ -2866,6 +2871,18 @@ impl RenderState {
                         }));
                     }
                 }
+
+                // Only yield if the next tile is NOT visible.
+                let next_is_visible = self
+                    .current_tile
+                    .is_some_and(|t| self.tile_viewbox.is_visible(&t));
+
+                if allow_stop
+                    && !next_is_visible
+                    && performance::get_time() - timestamp > MAX_BLOCKING_TIME_MS
+                {
+                    return Ok(());
+                }
             } else {
                 should_stop = true;
             }
@@ -3043,6 +3060,15 @@ impl RenderState {
     }
 
     pub fn remove_cached_tile(&mut self, tile: tiles::Tile) {
+        let scale = self.get_scale();
+        let tile_size = tiles::get_tile_size(scale);
+        let doc_rect = skia::Rect::from_xywh(
+            tile.x() as f32 * tile_size,
+            tile.y() as f32 * tile_size,
+            tile_size,
+            tile_size,
+        );
+        self.surfaces.invalidate_atlas_rect(doc_rect);
         self.surfaces.remove_cached_tile_surface(tile);
     }
 
diff --git a/render-wasm/src/render/surfaces.rs b/render-wasm/src/render/surfaces.rs
index 3a1d20d900..3156841b82 100644
--- a/render-wasm/src/render/surfaces.rs
+++ b/render-wasm/src/render/surfaces.rs
@@ -297,6 +297,27 @@ impl Surfaces {
         self.atlas_size.width > 0 && self.atlas_size.height > 0
     }
 
+    /// Clears a document-space rect inside the persistent atlas. Called when
+    /// a tile cache entry is invalidated so that a zoom-out fast-mode preview
+    /// (which paints from the atlas) doesn't show the old pixels of deleted
+    /// or moved shapes. The cleared region becomes transparent; the next tile
+    /// render at any zoom will repopulate it via `blit_tile_image_into_atlas`.
+    pub fn invalidate_atlas_rect(&mut self, doc_rect: skia::Rect) {
+        if !self.has_atlas() || doc_rect.is_empty() {
+            return;
+        }
+        let scale = self.atlas_scale.max(0.01);
+        let atlas_rect = skia::Rect::from_xywh(
+            (doc_rect.left - self.atlas_origin.x) * scale,
+            (doc_rect.top - self.atlas_origin.y) * scale,
+            doc_rect.width() * scale,
+            doc_rect.height() * scale,
+        );
+        let mut paint = skia::Paint::default();
+        paint.set_blend_mode(skia::BlendMode::Clear);
+        self.atlas.canvas().draw_rect(atlas_rect, &paint);
+    }
+
     /// Draw the persistent atlas onto the target using the current viewbox transform.
     /// Intended for fast pan/zoom-out previews (avoids per-tile composition).
     pub fn draw_atlas_to_target(&mut self, viewbox: Viewbox, dpr: f32, background: skia::Color) {