strokeWidth as a channel

closes #311

Author: Fil

src/marks/link.js

@@ -16,11 +16,13 @@ export class Link extends Mark {
       title,
       stroke,
       strokeOpacity,
+      strokeWidth,
       ...options
     } = {}
   ) {
     const [vstroke, cstroke] = maybeColor(stroke, "currentColor");
     const [vstrokeOpacity, cstrokeOpacity] = maybeNumber(strokeOpacity);
+    const [vstrokeWidth, cstrokeWidth] = maybeNumber(strokeWidth, 1);
     super(
       data,
       [
@@ -31,20 +33,22 @@ export class Link extends Mark {
         {name: "z", value: z, optional: true},
         {name: "title", value: title, optional: true},
         {name: "stroke", value: vstroke, scale: "color", optional: true},
-        {name: "strokeOpacity", value: vstrokeOpacity, scale: "opacity", optional: true}
+        {name: "strokeOpacity", value: vstrokeOpacity, scale: "opacity", optional: true},
+        {name: "strokeWidth", value: vstrokeWidth, optional: true},
       ],
       options
     );
     Style(this, {
       stroke: cstroke,
       strokeOpacity: cstrokeOpacity,
+      strokeWidth: cstrokeWidth,
       ...options
     });
   }
   render(
     I,
     {x, y},
-    {x1: X1, y1: Y1, x2: X2, y2: Y2, z: Z, title: L, stroke: S, strokeOpacity: SO}
+    {x1: X1, y1: Y1, x2: X2, y2: Y2, z: Z, title: L, stroke: S, strokeOpacity: SO, strokeWidth: SW}
   ) {
     const index = filter(I, X1, Y1, X2, Y2, S, SO);
     if (Z) index.sort((i, j) => ascending(Z[i], Z[j]));
@@ -61,6 +65,7 @@ export class Link extends Mark {
             .attr("y2", i => Y2[i])
             .call(applyAttr, "stroke", S && (i => S[i]))
             .call(applyAttr, "stroke-opacity", SO && (i => SO[i]))
+            .call(applyAttr, "stroke-width", SW && (i => SW[i]))
             .call(title(L)))
       .node();
   }