🐛 Fix inner strokes black background effect

render-wasm/src/render.rs

@@ -19,7 +19,7 @@ use options::RenderOptions;
 use surfaces::{SurfaceId, Surfaces};
 
 use crate::performance;
-use crate::shapes::{modified_children_ids, Corners, Shape, StructureEntry, Type};
+use crate::shapes::{modified_children_ids, Corners, Shape, StrokeKind, StructureEntry, Type};
 use crate::tiles::{self, TileRect, TileViewbox, TileWithDistance};
 use crate::uuid::Uuid;
 use crate::view::Viewbox;
@@ -441,6 +441,13 @@ impl RenderState {
                         self.fonts.font_collection(),
                     );
                     shadows::render_text_drop_shadows(self, &shape, &stroke_paragraphs, antialias);
+                    if stroke.kind == StrokeKind::Inner {
+                        // Inner strokes must be rendered on the Fills surface because their blend modes
+                        // (e.g., SrcATop, DstOver) rely on the text fill already being present underneath.
+                        // Rendering them on a separate surface would break this blending and result in incorrect visuals as
+                        // black color background.
+                        text::render(self, &shape, &stroke_paragraphs, None, None);
+                    } else {
                         text::render(
                             self,
                             &shape,
@@ -448,6 +455,7 @@ impl RenderState {
                             Some(SurfaceId::Strokes),
                             None,
                         );
+                    }
                     shadows::render_text_inner_shadows(self, &shape, &stroke_paragraphs, antialias);
                 }
 

render-wasm/src/render/text.rs

@@ -8,13 +8,19 @@ pub fn render(
     surface_id: Option<SurfaceId>,
     paint: Option<skia::Paint>,
 ) {
+    let use_save_layer = paint.is_some();
     let mask_paint = paint.unwrap_or_default();
     let mask = SaveLayerRec::default().paint(&mask_paint);
     let canvas = render_state
         .surfaces
         .canvas(surface_id.unwrap_or(SurfaceId::Fills));
 
+    // Skip save_layer when no custom paint is provided to avoid isolating content unnecessarily.
+    // This ensures inner strokes and fills can blend correctly on the same surface.
+    if use_save_layer {
         canvas.save_layer(&mask);
+    }
+
     for group in paragraphs {
         let mut offset_y = 0.0;
         for skia_paragraph in group {
@@ -23,5 +29,7 @@ pub fn render(
             offset_y += skia_paragraph.height();
         }
     }
+    if use_save_layer {
         canvas.restore();
+    }
 }