don't drop empty arcs in evaluate + use relative lines in unarc, clos…

…ing #20

lib/svgpath.js

@@ -77,17 +77,25 @@ SvgPath.prototype.__matrix = function (m) {
         // ARC is: ['A', rx, ry, x-axis-rotation, large-arc-flag, sweep-flag, x, y]
 
         // Drop segment if arc is empty (end point === start point)
-        if ((s[0] === 'A' && s[6] === x && s[7] === y) ||
+        /*if ((s[0] === 'A' && s[6] === x && s[7] === y) ||
             (s[0] === 'a' && s[6] === 0 && s[7] === 0)) {
           return [];
-        }
+        }*/
 
         // Transform rx, ry and the x-axis-rotation
         var e = ellipse(s[1], s[2], s[3]).transform(m.toArray());
 
         // Transform end point as usual (without translation for relative notation)
         p = m.calc(s[6], s[7], s[0] === 'a');
 
+        // Empty arcs can be ignored by renderer, but should not be dropped
+        // to avoid collisions with `S A S` and so on. Replace with empty line.
+        if ((s[0] === 'A' && s[6] === x && s[7] === y) ||
+            (s[0] === 'a' && s[6] === 0 && s[7] === 0)) {
+          result = [ s[0] === 'a' ? 'l' : 'L', p[0], p[1] ];
+          break;
+        }
+
         // if the resulting ellipse is (almost) a segment ...
         if (e.isDegenerate()) {
           // replace the arc by a line
@@ -499,9 +507,9 @@ SvgPath.prototype.unarc = function () {
     new_segments = a2c(x, y, nextX, nextY, s[4], s[5], s[1], s[2], s[3]);
 
     // Degenerated arcs can be ignored by renderer, but should not be dropped
-    // to avoid collisions wish `S A S` and so on. Replace with empty line.
+    // to avoid collisions with `S A S` and so on. Replace with empty line.
     if (new_segments.length === 0) {
-      return [ [ 'L', nextX, nextY ] ];
+      return [ [ s[0] === 'a' ? 'l' : 'L', s[6], s[7] ] ];
     }
 
     new_segments.forEach(function (s) {

test/api.js

@@ -492,6 +492,11 @@ describe('API', function () {
         svgpath('M100 100A123 456 90 0 1 100 100').unarc().round(0).toString(),
         'M100 100L100 100'
       );
+
+      assert.equal(
+        svgpath('M100 100a123 456 90 0 1 0 0').unarc().round(0).toString(),
+        'M100 100l0 0'
+      );
     });
 
     it('radii are zero', function () {
@@ -521,12 +526,12 @@ describe('API', function () {
     it('drop arcs with end point === start point', function () {
       assert.equal(
         svgpath('M40 30a20 40 -45 0 1 0 0').scale(2, 2).toString(),
-        'M80 60'
+        'M80 60l0 0'
       );
 
       assert.equal(
         svgpath('M40 30A20 40 -45 0 1 40 30').scale(2, 2).toString(),
-        'M80 60'
+        'M80 60L80 60'
       );
     });