+};
+
+Util.getLegend = function(parent) {
+ parent = parent || document;
+ var legend = parent.getElementsByClassName("dygraph-legend")[0];
+ var re = new RegExp(String.fromCharCode(160), 'g');
+ return legend.textContent.replace(re, ' ');
+};
+
+/**
+ * Assert that all elements have a certain style property.
+ */
+Util.assertStyleOfChildren = function(selector, property, expectedValue) {
+ assertTrue(selector.length > 0);
+ $.each(selector, function(idx, child) {
+ assertEquals(expectedValue, $(child).css(property));
+ });
+};
+
+
+/**
+ * Takes in an array of strings and returns an array of floats.
+ */
+Util.makeNumbers = function(ary) {
+ var ret = [];
+ for (var i = 0; i < ary.length; i++) {
+ ret.push(parseFloat(ary[i]));
+ }
+ return ret;
+};
+
+
+/**
+ * Sample a pixel from the canvas.
+ * Returns an [r, g, b, a] tuple where each values is in [0, 255].
+ */
+Util.samplePixel = function(canvas, x, y) {
+ var ctx = canvas.getContext("2d"); // bypasses Proxy if applied.
+
+ // TODO(danvk): Any performance issues with this?
+ var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+
+ var scale = Dygraph.getContextPixelRatio(ctx);
+
+ var i = 4 * (x * scale + imageData.width * y * scale);
+ var d = imageData.data;
+ return [d[i], d[i+1], d[i+2], d[i+3]];
+};
+
+/**
+ * Overrides the browser's built-in XMLHttpRequest with a mock.
+ * Usage:
+ *
+ * var mockXhr = Util.overrideXMLHttpRequest(your_data);
+ * ... call code that does an XHR ...
+ * mockXhr.respond(); // restores default behavior.
+ * ... do your assertions ...
+ */
+Util.overrideXMLHttpRequest = function(data) {
+ var originalXMLHttpRequest = XMLHttpRequest;
+
+ var requests = [];
+ var FakeXMLHttpRequest = function () {
+ requests.push(this);
+ };
+ FakeXMLHttpRequest.prototype.open = function () {};
+ FakeXMLHttpRequest.prototype.send = function () {
+ this.readyState = 4;
+ this.status = 200;
+ this.responseText = data;
+ };
+ FakeXMLHttpRequest.restore = function() {
+ XMLHttpRequest = originalXMLHttpRequest;
+ };
+ FakeXMLHttpRequest.respond = function() {
+ for (var i = 0; i < requests.length; i++) {
+ requests[i].onreadystatechange();
+ }
+ FakeXMLHttpRequest.restore();
+ };
+ XMLHttpRequest = FakeXMLHttpRequest;
+ return FakeXMLHttpRequest;
+};
+
+/**
+ * Format a date as 2000/01/23
+ * @param {number} dateMillis Millis since epoch.
+ * @return {string} The date formatted as YYYY-MM-DD.
+ */
+Util.formatDate = function(dateMillis) {
+ return Dygraph.dateString_(dateMillis).slice(0, 10); // 10 == "YYYY/MM/DD".length
+};