new plugin: remove useless 'stroke' and 'fill' attrs (close svg#75)

.svgo.yml

@@ -40,6 +40,14 @@ plugins:
       leadingZero: true
       defaultPx: true
 
+  - name: convertColors
+    active: true
+    type: perItem
+    params:
+      names2hex: true
+      rgb2hex: true
+      shorthex: true
+
   - name: removeUnknownsAndDefaults
     active: true
     type: perItem
@@ -49,6 +57,13 @@ plugins:
       unknownAttrs: true
       defaultAttrs: true
 
+  - name: removeUselessStrokeAndFill
+    active: true
+    type: perItem
+    params:
+      stroke: true
+      fill: true
+
   - name: removeViewBox
     active: true
     type: perItem
@@ -88,14 +103,6 @@ plugins:
       tspan: true
       tref: true
 
-  - name: convertColors
-    active: true
-    type: perItem
-    params:
-      names2hex: true
-      rgb2hex: true
-      shorthex: true
-
   - name: convertPathData
     active: true
     type: perItem

plugins/removeUselessStrokeAndFill.js

@@ -0,0 +1,56 @@
+'use strict';
+
+var regStrokeProps = /^stroke/,
+    regFillProps = /^fill/;
+
+/**
+ * Remove useless stroke and fill attrs.
+ *
+ * @param {Object} item current iteration item
+ * @param {Object} params plugin params
+ * @return {Boolean} if false, item will be filtered out
+ *
+ * @author Kir Belevich
+ */
+exports.removeUselessStrokeAndFill = function(item, params) {
+
+    if (item.isElem()) {
+
+        // remove stroke*
+        if (
+            params.stroke &&
+            (!item.hasAttr('stroke') ||
+             item.hasAttr('stroke-opacity', '0') ||
+             item.hasAttr('stroke-width', '0')
+            )
+        ) {
+            item.eachAttr(function(attr) {
+                if (regStrokeProps.test(attr.name)) {
+                    item.removeAttr(attr.name);
+                }
+            });
+        }
+
+        // remove fill*
+        if (
+            params.fill &&
+            item.hasAttr('fill', 'none') ||
+            item.hasAttr('fill-opacity', '0')
+        ) {
+            item.eachAttr(function(attr) {
+                if (regFillProps.test(attr.name)) {
+                    item.removeAttr(attr.name);
+                }
+            });
+
+            item.addAttr({
+                name: 'fill',
+                value: 'none',
+                prefix: '',
+                local: 'fill'
+            });
+        }
+
+    }
+
+};