Content-Aware Fill: preview at full resolution so it matches the result (#6530) (#6838)

crates/ui-egui/src/filter_dialog.rs

@@ -203,6 +203,9 @@ fn is_pixel_param_of(command: &str, key: &str) -> bool {
 /// Sharpen, Sharpen More, Sharpen Edges, Find Edges, Emboss and Despeckle use fixed one-pixel
 /// kernels with no size parameter, so a proxy changes their look: edges average away, making
 /// the sharpening and edge detection invisible. These must preview at full resolution (#3929).
+///
+/// Content-Aware Fill searches for matching patches, and the matches found on a reduced copy
+/// differ from those found at full size, so its preview would not show what OK writes (#6530).
 const FULL_RESOLUTION_PREVIEW: &[&str] = &[
     "filter.distort.ripple",
     "filter.stylize.diffuse",
@@ -225,6 +228,7 @@ const FULL_RESOLUTION_PREVIEW: &[&str] = &[
     "filter.stylize.findEdges",
     "filter.stylize.emboss",
     "filter.noise.despeckle",
+    "edit.contentAwareFill",
 ];
 
 /// Whether `command` with `params` previews at full resolution: [`FULL_RESOLUTION_PREVIEW`], every
@@ -2094,6 +2098,15 @@ mod tests {
         assert_eq!(preview_factor("image.mode.bitmap", &json!({"method": "threshold"}), 4), 4);
     }
 
+    /// #6530: the Content-Aware Fill preview runs at full resolution, for every Sampling choice,
+    /// because its patch search finds different matches on a reduced copy.
+    #[test]
+    fn content_aware_fill_previews_at_full_resolution() {
+        for params in [json!({}), json!({"sampling": "auto"}), json!({"sampling": "rectangular"})] {
+            assert_eq!(preview_factor("edit.contentAwareFill", &params, 4), 1, "{params}");
+        }
+    }
+
     /// #2063: proxy previews scaled what isn't a length (Tree's canvas fraction, Lens Correction's
     /// perspective), clamped negative lengths to +0.1 (Offset left/up), left Shadows/Highlights'
     /// radii in document pixels and rounded Mosaic's 10 px cells to 3 proxy px (12 px).