X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=dygraph-canvas.js;h=c0d142f34aa0f9c1e32e4f8234adf67732c63c8b;hb=79253bd07d1fd37d53e0793c08030df4aaf871be;hp=e1c24b9ef04b57226468a9ed15ea2bbc15970fbd;hpb=971870e5232350812bf91dc7b555332a8993efda;p=dygraphs.git diff --git a/dygraph-canvas.js b/dygraph-canvas.js index e1c24b9..c0d142f 100644 --- a/dygraph-canvas.js +++ b/dygraph-canvas.js @@ -24,8 +24,11 @@ * @constructor */ +/*jshint globalstrict: true */ +/*global Dygraph:false,RGBColor:false */ "use strict"; + var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) { this.dygraph_ = dygraph; @@ -42,9 +45,9 @@ var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) { throw "Canvas is not supported."; // internal state - this.xlabels = new Array(); - this.ylabels = new Array(); - this.annotations = new Array(); + this.xlabels = []; + this.ylabels = []; + this.annotations = []; this.chartLabels = {}; this.area = layout.getPlotArea(); @@ -77,6 +80,7 @@ DygraphCanvasRenderer.prototype.attr_ = function(x) { }; DygraphCanvasRenderer.prototype.clear = function() { + var context; if (this.isIE) { // VML takes a while to start up, so we just poll every this.IEDelay try { @@ -84,39 +88,38 @@ DygraphCanvasRenderer.prototype.clear = function() { this.clearDelay.cancel(); this.clearDelay = null; } - var context = this.elementContext; + context = this.elementContext; } catch (e) { // TODO(danvk): this is broken, since MochiKit.Async is gone. - this.clearDelay = MochiKit.Async.wait(this.IEDelay); - this.clearDelay.addCallback(bind(this.clear, this)); + // this.clearDelay = MochiKit.Async.wait(this.IEDelay); + // this.clearDelay.addCallback(bind(this.clear, this)); return; } } - var context = this.elementContext; + context = this.elementContext; context.clearRect(0, 0, this.width, this.height); - for (var i = 0; i < this.xlabels.length; i++) { - var el = this.xlabels[i]; - if (el.parentNode) el.parentNode.removeChild(el); - } - for (var i = 0; i < this.ylabels.length; i++) { - var el = this.ylabels[i]; - if (el.parentNode) el.parentNode.removeChild(el); - } - for (var i = 0; i < this.annotations.length; i++) { - var el = this.annotations[i]; - if (el.parentNode) el.parentNode.removeChild(el); + function removeArray(ary) { + for (var i = 0; i < ary.length; i++) { + var el = ary[i]; + if (el.parentNode) el.parentNode.removeChild(el); + } } + + removeArray(this.xlabels); + removeArray(this.ylabels); + removeArray(this.annotations); + for (var k in this.chartLabels) { if (!this.chartLabels.hasOwnProperty(k)) continue; var el = this.chartLabels[k]; if (el.parentNode) el.parentNode.removeChild(el); } - this.xlabels = new Array(); - this.ylabels = new Array(); - this.annotations = new Array(); + this.xlabels = []; + this.ylabels = []; + this.annotations = []; this.chartLabels = {}; }; @@ -124,11 +127,12 @@ DygraphCanvasRenderer.prototype.clear = function() { DygraphCanvasRenderer.isSupported = function(canvasName) { var canvas = null; try { - if (typeof(canvasName) == 'undefined' || canvasName == null) + if (typeof(canvasName) == 'undefined' || canvasName === null) { canvas = document.createElement("canvas"); - else + } else { canvas = canvasName; - var context = canvas.getContext("2d"); + } + canvas.getContext("2d"); } catch (e) { var ie = navigator.appVersion.match(/MSIE (\d\.\d)/); @@ -155,8 +159,8 @@ DygraphCanvasRenderer.prototype.render = function() { // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to // half-integers. This prevents them from drawing in two rows/cols. var ctx = this.elementContext; - function halfUp(x){return Math.round(x)+0.5}; - function halfDown(y){return Math.round(y)-0.5}; + function halfUp(x) { return Math.round(x) + 0.5; } + function halfDown(y){ return Math.round(y) - 0.5; } if (this.attr_('underlayCallback')) { // NOTE: we pass the dygraph object to this callback twice to avoid breaking @@ -164,17 +168,18 @@ DygraphCanvasRenderer.prototype.render = function() { this.attr_('underlayCallback')(ctx, this.area, this.dygraph_, this.dygraph_); } + var x, y, i, ticks; if (this.attr_('drawYGrid')) { - var ticks = this.layout.yticks; + ticks = this.layout.yticks; // TODO(konigsberg): I don't think these calls to save() have a corresponding restore(). ctx.save(); ctx.strokeStyle = this.attr_('gridLineColor'); ctx.lineWidth = this.attr_('gridLineWidth'); - for (var i = 0; i < ticks.length; i++) { + for (i = 0; i < ticks.length; i++) { // TODO(danvk): allow secondary axes to draw a grid, too. - if (ticks[i][0] != 0) continue; - var x = halfUp(this.area.x); - var y = halfDown(this.area.y + ticks[i][1] * this.area.h); + if (ticks[i][0] !== 0) continue; + x = halfUp(this.area.x); + y = halfDown(this.area.y + ticks[i][1] * this.area.h); ctx.beginPath(); ctx.moveTo(x, y); ctx.lineTo(x + this.area.w, y); @@ -184,13 +189,13 @@ DygraphCanvasRenderer.prototype.render = function() { } if (this.attr_('drawXGrid')) { - var ticks = this.layout.xticks; + ticks = this.layout.xticks; ctx.save(); ctx.strokeStyle = this.attr_('gridLineColor'); ctx.lineWidth = this.attr_('gridLineWidth'); - for (var i=0; i 0) { var num_axes = this.dygraph_.numAxes(); - for (var i = 0; i < this.layout.yticks.length; i++) { - var tick = this.layout.yticks[i]; + for (i = 0; i < this.layout.yticks.length; i++) { + tick = this.layout.yticks[i]; if (typeof(tick) == "function") return; - var x = this.area.x; + x = this.area.x; var sgn = 1; var prec_axis = 'y1'; if (tick[0] == 1) { // right-side y-axis @@ -309,7 +336,7 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { sgn = -1; prec_axis = 'y2'; } - var y = this.area.y + tick[1] * this.area.h; + y = this.area.y + tick[1] * this.area.h; /* Tick marks are currently clipped, so don't bother drawing them. context.beginPath(); @@ -319,7 +346,7 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { context.stroke(); */ - var label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null); + label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null); var top = (y - this.attr_('axisLabelFontSize') / 2); if (top < 0) top = 0; @@ -328,7 +355,7 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { } else { label.style.top = top + "px"; } - if (tick[0] == 0) { + if (tick[0] === 0) { label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px"; label.style.textAlign = "right"; } else if (tick[0] == 1) { @@ -346,9 +373,9 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { // compensate if necessary. var bottomTick = this.ylabels[0]; var fontSize = this.attr_('axisLabelFontSize'); - var bottom = parseInt(bottomTick.style.top) + fontSize; + var bottom = parseInt(bottomTick.style.top, 10) + fontSize; if (bottom > this.height - fontSize) { - bottomTick.style.top = (parseInt(bottomTick.style.top) - + bottomTick.style.top = (parseInt(bottomTick.style.top, 10) - fontSize / 2) + "px"; } } @@ -372,12 +399,10 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { if (this.attr_('drawXAxis')) { if (this.layout.xticks) { - for (var i = 0; i < this.layout.xticks.length; i++) { - var tick = this.layout.xticks[i]; - if (typeof(dataset) == "function") return; - - var x = this.area.x + tick[0] * this.area.w; - var y = this.area.y + this.area.h; + for (i = 0; i < this.layout.xticks.length; i++) { + tick = this.layout.xticks[i]; + x = this.area.x + tick[0] * this.area.w; + y = this.area.y + this.area.h; /* Tick marks are currently clipped, so don't bother drawing them. context.beginPath(); @@ -387,7 +412,7 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { context.stroke(); */ - var label = makeDiv(tick[1], 'x'); + label = makeDiv(tick[1], 'x'); label.style.textAlign = "center"; label.style.top = (y + this.attr_('axisTickSize')) + 'px'; @@ -420,11 +445,13 @@ DygraphCanvasRenderer.prototype._renderAxis = function() { DygraphCanvasRenderer.prototype._renderChartLabels = function() { + var div, class_div; + // Generate divs for the chart title, xlabel and ylabel. // Space for these divs has already been taken away from the charting area in // the DygraphCanvasRenderer constructor. if (this.attr_('title')) { - var div = document.createElement("div"); + div = document.createElement("div"); div.style.position = 'absolute'; div.style.top = '0px'; div.style.left = this.area.x + 'px'; @@ -433,7 +460,7 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { div.style.textAlign = 'center'; div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px'; div.style.fontWeight = 'bold'; - var class_div = document.createElement("div"); + class_div = document.createElement("div"); class_div.className = 'dygraph-label dygraph-title'; class_div.innerHTML = this.attr_('title'); div.appendChild(class_div); @@ -442,7 +469,7 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { } if (this.attr_('xlabel')) { - var div = document.createElement("div"); + div = document.createElement("div"); div.style.position = 'absolute'; div.style.bottom = 0; // TODO(danvk): this is lazy. Calculate style.top. div.style.left = this.area.x + 'px'; @@ -451,7 +478,7 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { div.style.textAlign = 'center'; div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px'; - var class_div = document.createElement("div"); + class_div = document.createElement("div"); class_div.className = 'dygraph-label dygraph-xlabel'; class_div.innerHTML = this.attr_('xlabel'); div.appendChild(class_div); @@ -459,21 +486,26 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { this.chartLabels.xlabel = div; } - if (this.attr_('ylabel')) { + var that = this; + function createRotatedDiv(axis, classes, html) { var box = { left: 0, - top: this.area.y, - width: this.attr_('yLabelWidth'), - height: this.area.h + top: that.area.y, + width: that.attr_('yLabelWidth'), + height: that.area.h }; // TODO(danvk): is this outer div actually necessary? - var div = document.createElement("div"); + div = document.createElement("div"); div.style.position = 'absolute'; - div.style.left = box.left; + if (axis == 1) { + div.style.left = box.left; + } else { + div.style.right = box.left; + } div.style.top = box.top + 'px'; div.style.width = box.width + 'px'; div.style.height = box.height + 'px'; - div.style.fontSize = (this.attr_('yLabelWidth') - 2) + 'px'; + div.style.fontSize = (that.attr_('yLabelWidth') - 2) + 'px'; var inner_div = document.createElement("div"); inner_div.style.position = 'absolute'; @@ -485,11 +517,12 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { // CSS rotation is an HTML5 feature which is not standardized. Hence every // browser has its own name for the CSS style. - inner_div.style.transform = 'rotate(-90deg)'; // HTML5 - inner_div.style.WebkitTransform = 'rotate(-90deg)'; // Safari/Chrome - inner_div.style.MozTransform = 'rotate(-90deg)'; // Firefox - inner_div.style.OTransform = 'rotate(-90deg)'; // Opera - inner_div.style.msTransform = 'rotate(-90deg)'; // IE9 + var val = 'rotate(' + (axis == 1 ? '-' : '') + '90deg)'; + inner_div.style.transform = val; // HTML5 + inner_div.style.WebkitTransform = val; // Safari/Chrome + inner_div.style.MozTransform = val; // Firefox + inner_div.style.OTransform = val; // Opera + inner_div.style.msTransform = val; // IE9 if (typeof(document.documentMode) !== 'undefined' && document.documentMode < 9) { @@ -497,20 +530,34 @@ DygraphCanvasRenderer.prototype._renderChartLabels = function() { // using a BasicImage transform. This uses a different origin of rotation // than HTML5 rotation (top left of div vs. its center). inner_div.style.filter = - 'progid:DXImageTransform.Microsoft.BasicImage(rotation=3)'; + 'progid:DXImageTransform.Microsoft.BasicImage(rotation=' + + (axis == 1 ? '3' : '1') + ')'; inner_div.style.left = '0px'; inner_div.style.top = '0px'; } - var class_div = document.createElement("div"); - class_div.className = 'dygraph-label dygraph-ylabel'; - class_div.innerHTML = this.attr_('ylabel'); + class_div = document.createElement("div"); + class_div.className = classes; + class_div.innerHTML = html; inner_div.appendChild(class_div); div.appendChild(inner_div); + return div; + } + + var div; + if (this.attr_('ylabel')) { + div = createRotatedDiv(1, 'dygraph-label dygraph-ylabel', + this.attr_('ylabel')); this.container.appendChild(div); this.chartLabels.ylabel = div; } + if (this.attr_('y2label') && this.dygraph_.numAxes() == 2) { + div = createRotatedDiv(2, 'dygraph-label dygraph-y2label', + this.attr_('y2label')); + this.container.appendChild(div); + this.chartLabels.y2label = div; + } }; @@ -531,7 +578,7 @@ DygraphCanvasRenderer.prototype._renderAnnotations = function() { self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e ); } }; - } + }; // Get a list of point with annotations. var points = this.layout.annotated_points; @@ -613,7 +660,9 @@ DygraphCanvasRenderer.prototype._renderAnnotations = function() { /** - * Overrides the CanvasRenderer method to draw error bars + * Actually draw the lines chart, including error bars. + * TODO(danvk): split this into several smaller functions. + * @private */ DygraphCanvasRenderer.prototype._renderLineChart = function() { var isNullOrNaN = function(x) { @@ -629,6 +678,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { var stepPlot = this.attr_("stepPlot"); var points = this.layout.points; var pointsLength = points.length; + var point, i, j, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis; var setNames = []; for (var name in this.layout.datasets) { @@ -639,15 +689,15 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { var setCount = setNames.length; // TODO(danvk): Move this mapping into Dygraph and get it out of here. - this.colors = {} - for (var i = 0; i < setCount; i++) { + this.colors = {}; + for (i = 0; i < setCount; i++) { this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length]; } // Update Points // TODO(danvk): here - for (var i = pointsLength; i--;) { - var point = points[i]; + for (i = pointsLength; i--;) { + point = points[i]; point.canvasx = this.area.w * point.x + this.area.x; point.canvasy = this.area.h * point.y + this.area.y; } @@ -659,25 +709,25 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { this.dygraph_.warn("Can't use fillGraph option with error bars"); } - for (var i = 0; i < setCount; i++) { - var setName = setNames[i]; - var axis = this.dygraph_.axisPropertiesForSeries(setName); - var color = this.colors[setName]; + for (i = 0; i < setCount; i++) { + setName = setNames[i]; + axis = this.dygraph_.axisPropertiesForSeries(setName); + color = this.colors[setName]; // setup graphics context ctx.save(); - var prevX = NaN; - var prevY = NaN; - var prevYs = [-1, -1]; - var yscale = axis.yscale; + prevX = NaN; + prevY = NaN; + prevYs = [-1, -1]; + yscale = axis.yscale; // should be same color as the lines but only 15% opaque. - var rgb = new RGBColor(color); - var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + + rgb = new RGBColor(color); + err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')'; ctx.fillStyle = err_color; ctx.beginPath(); - for (var j = 0; j < pointsLength; j++) { - var point = points[j]; + for (j = 0; j < pointsLength; j++) { + point = points[j]; if (point.name == setName) { if (!Dygraph.isOK(point.y)) { prevX = NaN; @@ -686,10 +736,10 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { // TODO(danvk): here if (stepPlot) { - var newYs = [ point.y_bottom, point.y_top ]; + newYs = [ point.y_bottom, point.y_top ]; prevY = point.y; } else { - var newYs = [ point.y_bottom, point.y_top ]; + newYs = [ point.y_bottom, point.y_top ]; } newYs[0] = this.area.h * newYs[0] + this.area.y; newYs[1] = this.area.h * newYs[1] + this.area.y; @@ -715,13 +765,13 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { ctx.fill(); } } else if (fillGraph) { - var baseline = [] // for stacked graphs: baseline for filling + var baseline = []; // for stacked graphs: baseline for filling // process sets in reverse order (needed for stacked graphs) - for (var i = setCount - 1; i >= 0; i--) { - var setName = setNames[i]; - var color = this.colors[setName]; - var axis = this.dygraph_.axisPropertiesForSeries(setName); + for (i = setCount - 1; i >= 0; i--) { + setName = setNames[i]; + color = this.colors[setName]; + axis = this.dygraph_.axisPropertiesForSeries(setName); var axisY = 1.0 + axis.minyval * axis.yscale; if (axisY < 0.0) axisY = 0.0; else if (axisY > 1.0) axisY = 1.0; @@ -729,23 +779,22 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { // setup graphics context ctx.save(); - var prevX = NaN; - var prevYs = [-1, -1]; - var yscale = axis.yscale; + prevX = NaN; + prevYs = [-1, -1]; + yscale = axis.yscale; // should be same color as the lines but only 15% opaque. - var rgb = new RGBColor(color); - var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + + rgb = new RGBColor(color); + err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')'; ctx.fillStyle = err_color; ctx.beginPath(); - for (var j = 0; j < pointsLength; j++) { - var point = points[j]; + for (j = 0; j < pointsLength; j++) { + point = points[j]; if (point.name == setName) { if (!Dygraph.isOK(point.y)) { prevX = NaN; continue; } - var newYs; if (stackedGraph) { var lastY = baseline[point.canvasx]; if (lastY === undefined) lastY = axisY; @@ -777,28 +826,32 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { var firstIndexInSet = 0; var afterLastIndexInSet = 0; var setLength = 0; - for (var i = 0; i < setCount; i += 1) { + for (i = 0; i < setCount; i += 1) { setLength = this.layout.setPointsLengths[i]; afterLastIndexInSet += setLength; - var setName = setNames[i]; - var color = this.colors[setName]; + setName = setNames[i]; + color = this.colors[setName]; var strokeWidth = this.dygraph_.attr_("strokeWidth", setName); // setup graphics context context.save(); var pointSize = this.dygraph_.attr_("pointSize", setName); - var prevX = null, prevY = null; + prevX = null; + prevY = null; var drawPoints = this.dygraph_.attr_("drawPoints", setName); - for (var j = firstIndexInSet; j < afterLastIndexInSet; j++) { - var point = points[j]; + var strokePattern = this.dygraph_.attr_("strokePattern", setName); + if (!Dygraph.isArrayLike(strokePattern)) { + strokePattern = null; + } + for (j = firstIndexInSet; j < afterLastIndexInSet; j++) { + point = points[j]; if (isNullOrNaN(point.canvasy)) { - if (stepPlot && prevX != null) { + if (stepPlot && prevX !== null) { // Draw a horizontal line to the start of the missing data ctx.beginPath(); ctx.strokeStyle = color; ctx.lineWidth = this.attr_('strokeWidth'); - ctx.moveTo(prevX, prevY); - ctx.lineTo(point.canvasx, prevY); + this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern); ctx.stroke(); } // this will make us move to the next point, not draw a line to it. @@ -824,13 +877,12 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { ctx.beginPath(); ctx.strokeStyle = color; ctx.lineWidth = strokeWidth; - ctx.moveTo(prevX, prevY); if (stepPlot) { - ctx.lineTo(point.canvasx, prevY); + this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern); } + this._dashedLine(ctx, prevX, prevY, point.canvasx, point.canvasy, strokePattern); prevX = point.canvasx; prevY = point.canvasy; - ctx.lineTo(prevX, prevY); ctx.stroke(); } } @@ -849,3 +901,94 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() { context.restore(); }; + +/** + * This does dashed lines onto a canvas for a given pattern. You must call + * ctx.stroke() after to actually draw it, much line ctx.lineTo(). It remembers + * the state of the line in regards to where we left off on drawing the pattern. + * You can draw a dashed line in several function calls and the pattern will be + * continous as long as you didn't call this function with a different pattern + * in between. + * @param ctx The canvas 2d context to draw on. + * @param x The start of the line's x coordinate. + * @param y The start of the line's y coordinate. + * @param x2 The end of the line's x coordinate. + * @param y2 The end of the line's y coordinate. + * @param pattern The dash pattern to draw, an array of integers where even + * index is drawn and odd index is not drawn (Ex. [10, 2, 5, 2], 10 is drawn 5 + * is drawn, 2 is the space between.). A null pattern, array of length one, or + * empty array will do just a solid line. + * @private + */ +DygraphCanvasRenderer.prototype._dashedLine = function(ctx, x, y, x2, y2, pattern) { + // Original version http://stackoverflow.com/questions/4576724/dotted-stroke-in-canvas + // Modified by Russell Valentine to keep line history and continue the pattern + // where it left off. + var dx, dy, len, rot, patternIndex, segment; + + // If we don't have a pattern or it is an empty array or of size one just + // do a solid line. + if (!pattern || pattern.length <= 1) { + ctx.moveTo(x, y); + ctx.lineTo(x2, y2); + return; + } + + // If we have a different dash pattern than the last time this was called we + // reset our dash history and start the pattern from the begging + // regardless of state of the last pattern. + if (!Dygraph.compareArrays(pattern, this._dashedLineToHistoryPattern)) { + this._dashedLineToHistoryPattern = pattern; + this._dashedLineToHistory = [0, 0]; + } + ctx.save(); + + // Calculate transformation parameters + dx = (x2-x); + dy = (y2-y); + len = Math.sqrt(dx*dx + dy*dy); + rot = Math.atan2(dy, dx); + + // Set transformation + ctx.translate(x, y); + ctx.moveTo(0, 0); + ctx.rotate(rot); + + // Set last pattern index we used for this pattern. + patternIndex = this._dashedLineToHistory[0]; + x = 0; + while (len > x) { + // Get the length of the pattern segment we are dealing with. + segment = pattern[patternIndex]; + // If our last draw didn't complete the pattern segment all the way we + // will try to finish it. Otherwise we will try to do the whole segment. + if (this._dashedLineToHistory[1]) { + x += this._dashedLineToHistory[1]; + } else { + x += segment; + } + if (x > len) { + // We were unable to complete this pattern index all the way, keep + // where we are the history so our next draw continues where we left off + // in the pattern. + this._dashedLineToHistory = [patternIndex, x-len]; + x = len; + } else { + // We completed this patternIndex, we put in the history that we are on + // the beginning of the next segment. + this._dashedLineToHistory = [(patternIndex+1)%pattern.length, 0]; + } + + // We do a line on a even pattern index and just move on a odd pattern index. + // The move is the empty space in the dash. + if(patternIndex % 2 === 0) { + ctx.lineTo(x, 0); + } else { + ctx.moveTo(x, 0); + } + // If we are not done, next loop process the next pattern segment, or the + // first segment again if we are at the end of the pattern. + patternIndex = (patternIndex+1) % pattern.length; + } + ctx.restore(); +};