Merge pull request #522 from yueyuzhao/issue/504-dots-to-sharp-corner

add precise guess first when adding points to paths

src/painteditor/Path.js

@@ -851,7 +851,9 @@ export default class Path {
     }
 
     static getHitIndex (ctx, commands, pt) {
+        var drawWithLineMask = function (lineWidth) {
             ctx.save();
+            ctx.lineWidth = lineWidth;
             ctx.beginPath();
             for (var i = 0; i < commands.length; i++) {
                 SVG2Canvas.drawCommand(ctx, commands[i]);
@@ -864,7 +866,15 @@ export default class Path {
             }
             ctx.stroke();
             ctx.restore();
-        return -1;
+        };
+        // When using a mouse to add dragging points to paths,
+        // we need to try a precise guess first.
+        // For more detail see #504
+        var index = drawWithLineMask(2);
+        if (index > -1) {
+            return index;
+        }
+        return drawWithLineMask(Ghost.linemask);
     }
 
     static getHitPointIndex (list, pt) {