add removeOffCanvasPaths plugin (#979)

plugins/removeOffCanvasPaths.js

@@ -0,0 +1,133 @@
+'use strict';
+
+exports.type = 'perItem';
+
+exports.active = false;
+
+exports.description = 'removes elements that are drawn outside of the viewbox (disabled by default)';
+
+var SVGO       = require('../lib/svgo.js'),
+	_path      = require('./_path.js'),
+	intersects = _path.intersects,
+	path2js    = _path.path2js,
+	viewBox,
+	viewBoxJS;
+
+/**
+ * Remove elements that are drawn outside of the viewbox.
+ *
+ * @param {Object} item current iteration item
+ * @return {Boolean} if false, item will be filtered out
+ *
+ * @author JoshyPHP
+ */
+exports.fn = function(item) {
+
+	if (item.isElem('path') && item.hasAttr('d') && typeof viewBox !== 'undefined')
+	{
+		// Consider that any item with a transform attribute or a M instruction
+		// within the viewBox is visible
+		if (hasTransform(item) || pathMovesWithinViewBox(item.attr('d').value))
+		{
+			return true;
+		}
+
+		var pathJS = path2js(item);
+		if (pathJS.length === 2)
+		{
+			// Use a closed clone of the path if it's too short for intersects()
+			pathJS = JSON.parse(JSON.stringify(pathJS));
+			pathJS.push({ instruction: 'z' });
+		}
+
+		return intersects(viewBoxJS, pathJS);
+	}
+	if (item.isElem('svg'))
+	{
+		parseViewBox(item);
+	}
+
+	return true;
+};
+
+/**
+ * Test whether given item or any of its ancestors has a transform attribute.
+ *
+ * @param {String} path
+ * @return {Boolean}
+ */
+function hasTransform(item)
+{
+	return item.hasAttr('transform') || (item.parentNode && hasTransform(item.parentNode));
+}
+
+/**
+ * Parse the viewBox coordinates and compute the JS representation of its path.
+ *
+ * @param {Object} svg svg element item
+ */
+function parseViewBox(svg)
+{
+	var viewBoxData = '';
+	if (svg.hasAttr('viewBox'))
+	{
+		// Remove commas and plus signs, normalize and trim whitespace
+		viewBoxData = svg.attr('viewBox').value;
+	}
+	else if (svg.hasAttr('height') && svg.hasAttr('width'))
+	{
+		viewBoxData = '0 0 ' + svg.attr('width').value + ' ' + svg.attr('height').value;
+	}
+
+	// Remove commas and plus signs, normalize and trim whitespace
+	viewBoxData = viewBoxData.replace(/[,+]|px/g, ' ').replace(/\s+/g, ' ').replace(/^\s*|\s*$/g, '');
+
+	// Ensure that the dimensions are 4 values separated by space
+	var m = /^(-?\d*\.?\d+) (-?\d*\.?\d+) (\d*\.?\d+) (\d*\.?\d+)$/.exec(viewBoxData);
+	if (!m)
+	{
+		return;
+	}
+
+	// Store the viewBox boundaries
+	viewBox = {
+		left:   parseFloat(m[1]),
+		top:    parseFloat(m[2]),
+		right:  parseFloat(m[1]) + parseFloat(m[3]),
+		bottom: parseFloat(m[2]) + parseFloat(m[4])
+	};
+
+	var path = new SVGO().createContentItem({
+		elem:   'path',
+		prefix: '',
+		local:  'path'
+	});
+	path.addAttr({
+		name:   'd',
+		prefix: '',
+		local:  'd',
+		value:  'M' + m[1] + ' ' + m[2] + 'h' + m[3] + 'v' + m[4] + 'H' + m[1] + 'z'
+	});
+
+	viewBoxJS = path2js(path);
+}
+
+/**
+ * Test whether given path has a M instruction with coordinates within the viewBox.
+ *
+ * @param {String} path
+ * @return {Boolean}
+ */
+function pathMovesWithinViewBox(path)
+{
+	var regexp = /M\s*(-?\d*\.?\d+)(?!\d)\s*(-?\d*\.?\d+)/g, m;
+	while (null !== (m = regexp.exec(path)))
+	{
+		if (m[1] >= viewBox.left && m[1] <= viewBox.right && m[2] >= viewBox.top && m[2] <= viewBox.bottom)
+		{
+			return true;
+		}
+	}
+
+	return false;
+}