{selection} sets the initial position of the brush

Author: Fil

src/marks/brush.js

@@ -11,6 +11,7 @@ export class Brush extends Mark {
     {
       x = first,
       y = second,
+      selection,
       transform,
       ...style
     } = {}
@@ -25,6 +26,7 @@ export class Brush extends Mark {
       transform
     );
     Style(this, style);
+    this.initialSelection = selection;
   }
   render(
     I,
@@ -78,7 +80,20 @@ export class Brush extends Mark {
       svg = g.node().ownerSVGElement;
       if (!svg.__brushes) svg.__brushes = [];
       svg.__brushes.push({b: brush, g});
-      g.call(brush.clear);
+      if (this.initialSelection) {
+        const s = this.initialSelection;
+        if (x && y) {
+          const [x0, x1] = extent([x(s[0][0]), x(s[1][0])]);
+          const [y0, y1] = extent([y(s[0][1]), y(s[1][1])]);
+          g.call(brush.move, [[x0, y0], [x1, y1]]);
+        } else if (x) {
+          g.call(brush.move, extent(s.map(x)));
+        } else if (y) {
+          g.call(brush.move, extent(s.map(y)));
+        }
+      } else {
+        g.call(brush.clear);
+      }
     }, 1);
 
     return g.node();