fix: Fix virtualizer drag and drop with layout gaps

Author: devongovett

packages/@react-stately/layout/src/GridLayout.ts

@@ -102,6 +102,7 @@ export class GridLayout<T, O extends GridLayoutOptions = GridLayoutOptions> exte
     // Compute the number of rows and columns needed to display the content
     let columns = Math.floor(visibleWidth / (minItemSize.width + minSpace.width));
     let numColumns = Math.max(1, Math.min(maxColumns, columns));
+    this.numColumns = numColumns;
 
     // Compute the available width (minus the space between items)
     let width = visibleWidth - (minSpace.width * Math.max(0, numColumns));
@@ -223,7 +224,46 @@ export class GridLayout<T, O extends GridLayoutOptions = GridLayoutOptions> exte
     x += this.virtualizer!.visibleRect.x;
     y += this.virtualizer!.visibleRect.y;
 
-    let key = this.virtualizer!.keyAtPoint(new Point(x, y));
+    // Find the closest item within on either side of the point using the gap width.
+    let key: Key | null = null;
+    if (this.numColumns === 1) {
+      let searchRect = new Rect(x, Math.max(0, y - this.gap.height), 1, this.gap.height * 2);
+      let candidates = this.getVisibleLayoutInfos(searchRect);
+      let minDistance = Infinity;
+      for (let candidate of candidates) {
+        // Ignore items outside the search rect, e.g. persisted keys.
+        if (!candidate.rect.intersects(searchRect)) {
+          continue;
+        }
+
+        let yDist = Math.abs(candidate.rect.y - x);
+        let maxYDist = Math.abs(candidate.rect.maxY - x);
+        let dist = Math.min(yDist, maxYDist);
+        if (dist < minDistance) {
+          minDistance = dist;
+          key = candidate.key;
+        }
+      }
+    } else {
+      let searchRect = new Rect(Math.max(0, x - this.gap.width), y, this.gap.width * 2, 1);
+      let candidates = this.getVisibleLayoutInfos(searchRect);
+      let minDistance = Infinity;
+      for (let candidate of candidates) {
+        // Ignore items outside the search rect, e.g. persisted keys.
+        if (!candidate.rect.intersects(searchRect)) {
+          continue;
+        }
+
+        let xDist = Math.abs(candidate.rect.x - x);
+        let maxXDist = Math.abs(candidate.rect.maxX - x);
+        let dist = Math.min(xDist, maxXDist);
+        if (dist < minDistance) {
+          minDistance = dist;
+          key = candidate.key;
+        }
+      }
+    }
+
     let layoutInfo = key != null ? this.getLayoutInfo(key) : null;
     if (!layoutInfo) {
       return {type: 'root'};

packages/@react-stately/layout/src/ListLayout.ts

@@ -505,7 +505,26 @@ export class ListLayout<T, O extends ListLayoutOptions = ListLayoutOptions> exte
     x += this.virtualizer!.visibleRect.x;
     y += this.virtualizer!.visibleRect.y;
 
-    let key = this.virtualizer!.keyAtPoint(new Point(x, y));
+    // Find the closest item within on either side of the point using the gap width.
+    let searchRect = new Rect(x, Math.max(0, y - this.gap), 1, this.gap * 2);
+    let candidates = this.getVisibleLayoutInfos(searchRect);
+    let key: Key | null = null;
+    let minDistance = Infinity;
+    for (let candidate of candidates) {
+      // Ignore items outside the search rect, e.g. persisted keys.
+      if (!candidate.rect.intersects(searchRect)) {
+        continue;
+      }
+
+      let yDist = Math.abs(candidate.rect.y - x);
+      let maxYDist = Math.abs(candidate.rect.maxY - x);
+      let dist = Math.min(yDist, maxYDist);
+      if (dist < minDistance) {
+        minDistance = dist;
+        key = candidate.key;
+      }
+    }
+
     if (key == null || this.virtualizer!.collection.size === 0) {
       return {type: 'root'};
     }

packages/@react-stately/layout/src/TableLayout.ts

@@ -542,17 +542,23 @@ export class TableLayout<T, O extends TableLayoutProps = TableLayoutProps> exten
     x += this.virtualizer!.visibleRect.x;
     y += this.virtualizer!.visibleRect.y;
 
-    // Custom variation of this.virtualizer.keyAtPoint that ignores body
+    // Find the closest item within on either side of the point using the gap width.
+    let searchRect = new Rect(x, Math.max(0, y - this.gap), 1, this.gap * 2);
+    let candidates = this.getVisibleLayoutInfos(searchRect);
     let key: Key | null = null;
-    let point = new Point(x, y);
-    let rectAtPoint = new Rect(point.x, point.y, 1, 1);
-    let layoutInfos = this.virtualizer!.layout.getVisibleLayoutInfos(rectAtPoint).filter(info => info.type === 'row');
-
-    // Layout may return multiple layout infos in the case of
-    // persisted keys, so find the first one that actually intersects.
-    for (let layoutInfo of layoutInfos) {
-      if (layoutInfo.rect.intersects(rectAtPoint)) {
-        key = layoutInfo.key;
+    let minDistance = Infinity;
+    for (let candidate of candidates) {
+      // Ignore items outside the search rect, e.g. persisted keys.
+      if (candidate.type !== 'row' || !candidate.rect.intersects(searchRect)) {
+        continue;
+      }
+
+      let yDist = Math.abs(candidate.rect.y - x);
+      let maxYDist = Math.abs(candidate.rect.maxY - x);
+      let dist = Math.min(yDist, maxYDist);
+      if (dist < minDistance) {
+        minDistance = dist;
+        key = candidate.key;
       }
     }
 

packages/react-aria-components/stories/ListBox.stories.tsx

@@ -317,7 +317,8 @@ export function VirtualizedListBoxDnd() {
       <Virtualizer
         layout={ListLayout}
         layoutOptions={{
-          rowHeight: 25
+          rowHeight: 25,
+          gap: 8
         }}>
         <ListBox
           className={styles.menu}