new plugin: decrease accuracy of floating-point numbers (close #8)

.svgo.yml

@@ -36,6 +36,13 @@ plugins:
     active: true
     type: perItem
 
+  - name: roundNumericValues
+    active: true
+    type: perItem
+    params:
+      floatPrecision: 3
+      leadingZero: true
+
   - name: removeUnknownsAndDefaults
     active: true
     type: perItem

lib/svgo/tools.js

@@ -75,13 +75,7 @@ exports.cleanupOutData = function(data, params) {
         // 0.5 → .5
         // -0.5 → -.5
         if (params.leadingZero) {
-            if (item > 0 && item < 1) {
-                item = ('' + item).slice(1);
-            }
-
-            if (item < 0 && item > -1) {
-                item = '-' + ('' + item).slice(2);
-            }
+            item = removeLeadingZero(item);
         }
 
         str += delimiter + item;
@@ -91,3 +85,28 @@ exports.cleanupOutData = function(data, params) {
     return str;
 
 };
+
+/**
+ * Remove floating-point numbers leading zero.
+ *
+ * @example
+ * 0.5 → .5
+ *
+ * @example
+ * -0.5 → -.5
+ *
+ * @param {Float} num input number
+ *
+ * @return {String} output number as string
+ */
+var removeLeadingZero = exports.removeLeadingZero = function(num) {
+
+    if (num > 0 && num < 1) {
+        num = ('' + num).slice(1);
+    } else if (num < 0 && num > -1) {
+        num = '-' + ('' + num).slice(2);
+    }
+
+    return num;
+
+};

plugins/removeDefaultPx.js

@@ -1,6 +1,6 @@
 'use strict';
 
-var regValPx = /^(-?(?:[0-9]+|[0-9]*\.[0-9]+))px$/;
+var regValPx = /^([\-+]?\d*\.?\d+)px$/;
 
 /**
  * Remove default "px" unit from attributes values.

plugins/roundNumericValues.js

@@ -0,0 +1,40 @@
+'use strict';
+
+var regNumericValues = /^([\-+]?\d*\.?\d+)(px|pt|pc|mm|cm|m|in|ft|em|ex|%)?$/,
+    removeLeadingZero = require('../lib/svgo/tools').removeLeadingZero;
+
+/**
+ * Round numeric values to the fixed precision.
+ *
+ * @param {Object} item current iteration item
+ * @param {Object} params plugin params
+ * @return {Boolean} if false, item will be filtered out
+ *
+ * @author Kir Belevich
+ */
+exports.roundNumericValues = function(item, params) {
+
+    if (item.isElem()) {
+
+        var match;
+
+        item.eachAttr(function(attr) {
+            match = attr.value.match(regNumericValues);
+
+            // if attribute value matches regNumericValues
+            if (match) {
+                // then round it to the fixed precision
+                var num = +(+match[1]).toFixed(params.floatPrecision) + (match[2] || '');
+
+                // and remove leading zero
+                if (params.leadingZero) {
+                    num = removeLeadingZero(num);
+                }
+
+                attr.value = num;
+            }
+        });
+
+    }
+
+};