--- /dev/null
+/**
+ * @license
+ * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
+
+/**
+ * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
+ * needs of dygraphs.
+ *
+ * In particular, support for:
+ * - grid overlays
+ * - error bars
+ * - dygraphs attribute system
+ */
+
+/**
+ * The DygraphCanvasRenderer class does the actual rendering of the chart onto
+ * a canvas. It's based on PlotKit.CanvasRenderer.
+ * @param {Object} element The canvas to attach to
+ * @param {Object} elementContext The 2d context of the canvas (injected so it
+ * can be mocked for testing.)
+ * @param {Layout} layout The DygraphLayout object for this graph.
+ * @constructor
+ */
+
+var DygraphCanvasRenderer = (function() {
+/*global Dygraph:false */
+"use strict";
+
+
+/**
+ * @constructor
+ *
+ * This gets called when there are "new points" to chart. This is generally the
+ * case when the underlying data being charted has changed. It is _not_ called
+ * in the common case that the user has zoomed or is panning the view.
+ *
+ * The chart canvas has already been created by the Dygraph object. The
+ * renderer simply gets a drawing context.
+ *
+ * @param {Dygraph} dygraph The chart to which this renderer belongs.
+ * @param {HTMLCanvasElement} element The <canvas> DOM element on which to draw.
+ * @param {CanvasRenderingContext2D} elementContext The drawing context.
+ * @param {DygraphLayout} layout The chart's DygraphLayout object.
+ *
+ * TODO(danvk): remove the elementContext property.
+ */
+var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
+ this.dygraph_ = dygraph;
+
+ this.layout = layout;
+ this.element = element;
+ this.elementContext = elementContext;
+
+ this.height = dygraph.height_;
+ this.width = dygraph.width_;
+
+ // --- check whether everything is ok before we return
+ if (!Dygraph.isCanvasSupported(this.element)) {
+ throw "Canvas is not supported.";
+ }
+
+ // internal state
+ this.area = layout.getPlotArea();
+
+ // Set up a clipping area for the canvas (and the interaction canvas).
+ // This ensures that we don't overdraw.
+ // on Android 3 and 4, setting a clipping area on a canvas prevents it from
+ // displaying anything.
+ if (!Dygraph.isAndroid()) {
+ var ctx = this.dygraph_.canvas_ctx_;
+ ctx.beginPath();
+ ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
+ ctx.clip();
+
+ ctx = this.dygraph_.hidden_ctx_;
+ ctx.beginPath();
+ ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
+ ctx.clip();
+ }
+};
+
+/**
+ * Clears out all chart content and DOM elements.
+ * This is called immediately before render() on every frame, including
+ * during zooms and pans.
+ * @private
+ */
+DygraphCanvasRenderer.prototype.clear = function() {
+ this.elementContext.clearRect(0, 0, this.width, this.height);
+};
+
+/**
+ * This method is responsible for drawing everything on the chart, including
+ * lines, error bars, fills and axes.
+ * It is called immediately after clear() on every frame, including during pans
+ * and zooms.
+ * @private
+ */
+DygraphCanvasRenderer.prototype.render = function() {
+ // attaches point.canvas{x,y}
+ this._updatePoints();
+
+ // actually draws the chart.
+ this._renderLineChart();
+};
+
+/**
+ * Returns a predicate to be used with an iterator, which will
+ * iterate over points appropriately, depending on whether
+ * connectSeparatedPoints is true. When it's false, the predicate will
+ * skip over points with missing yVals.
+ */
+DygraphCanvasRenderer._getIteratorPredicate = function(connectSeparatedPoints) {
+ return connectSeparatedPoints ?
+ DygraphCanvasRenderer._predicateThatSkipsEmptyPoints :
+ null;
+};
+
+DygraphCanvasRenderer._predicateThatSkipsEmptyPoints =
+ function(array, idx) {
+ return array[idx].yval !== null;
+};
+
+/**
+ * Draws a line with the styles passed in and calls all the drawPointCallbacks.
+ * @param {Object} e The dictionary passed to the plotter function.
+ * @private
+ */
+DygraphCanvasRenderer._drawStyledLine = function(e,
+ color, strokeWidth, strokePattern, drawPoints,
+ drawPointCallback, pointSize) {
+ var g = e.dygraph;
+ // TODO(konigsberg): Compute attributes outside this method call.
+ var stepPlot = g.getBooleanOption("stepPlot", e.setName);
+
+ if (!Dygraph.isArrayLike(strokePattern)) {
+ strokePattern = null;
+ }
+
+ var drawGapPoints = g.getBooleanOption('drawGapEdgePoints', e.setName);
+
+ var points = e.points;
+ var setName = e.setName;
+ var iter = Dygraph.createIterator(points, 0, points.length,
+ DygraphCanvasRenderer._getIteratorPredicate(
+ g.getBooleanOption("connectSeparatedPoints", setName)));
+
+ var stroking = strokePattern && (strokePattern.length >= 2);
+
+ var ctx = e.drawingContext;
+ ctx.save();
+ if (stroking) {
+ ctx.installPattern(strokePattern);
+ }
+
+ var pointsOnLine = DygraphCanvasRenderer._drawSeries(
+ e, iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, color);
+ DygraphCanvasRenderer._drawPointsOnLine(
+ e, pointsOnLine, drawPointCallback, color, pointSize);
+
+ if (stroking) {
+ ctx.uninstallPattern();
+ }
+
+ ctx.restore();
+};
+
+/**
+ * This does the actual drawing of lines on the canvas, for just one series.
+ * Returns a list of [canvasx, canvasy] pairs for points for which a
+ * drawPointCallback should be fired. These include isolated points, or all
+ * points if drawPoints=true.
+ * @param {Object} e The dictionary passed to the plotter function.
+ * @private
+ */
+DygraphCanvasRenderer._drawSeries = function(e,
+ iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, color) {
+
+ var prevCanvasX = null;
+ var prevCanvasY = null;
+ var nextCanvasY = null;
+ var isIsolated; // true if this point is isolated (no line segments)
+ var point; // the point being processed in the while loop
+ var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
+ var first = true; // the first cycle through the while loop
+
+ var ctx = e.drawingContext;
+ ctx.beginPath();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = strokeWidth;
+
+ // NOTE: we break the iterator's encapsulation here for about a 25% speedup.
+ var arr = iter.array_;
+ var limit = iter.end_;
+ var predicate = iter.predicate_;
+
+ for (var i = iter.start_; i < limit; i++) {
+ point = arr[i];
+ if (predicate) {
+ while (i < limit && !predicate(arr, i)) {
+ i++;
+ }
+ if (i == limit) break;
+ point = arr[i];
+ }
+
+ // FIXME: The 'canvasy != canvasy' test here catches NaN values but the test
+ // doesn't catch Infinity values. Could change this to
+ // !isFinite(point.canvasy), but I assume it avoids isNaN for performance?
+ if (point.canvasy === null || point.canvasy != point.canvasy) {
+ if (stepPlot && prevCanvasX !== null) {
+ // Draw a horizontal line to the start of the missing data
+ ctx.moveTo(prevCanvasX, prevCanvasY);
+ ctx.lineTo(point.canvasx, prevCanvasY);
+ }
+ prevCanvasX = prevCanvasY = null;
+ } else {
+ isIsolated = false;
+ if (drawGapPoints || !prevCanvasX) {
+ iter.nextIdx_ = i;
+ iter.next();
+ nextCanvasY = iter.hasNext ? iter.peek.canvasy : null;
+
+ var isNextCanvasYNullOrNaN = nextCanvasY === null ||
+ nextCanvasY != nextCanvasY;
+ isIsolated = (!prevCanvasX && isNextCanvasYNullOrNaN);
+ if (drawGapPoints) {
+ // Also consider a point to be "isolated" if it's adjacent to a
+ // null point, excluding the graph edges.
+ if ((!first && !prevCanvasX) ||
+ (iter.hasNext && isNextCanvasYNullOrNaN)) {
+ isIsolated = true;
+ }
+ }
+ }
+
+ if (prevCanvasX !== null) {
+ if (strokeWidth) {
+ if (stepPlot) {
+ ctx.moveTo(prevCanvasX, prevCanvasY);
+ ctx.lineTo(point.canvasx, prevCanvasY);
+ }
+
+ ctx.lineTo(point.canvasx, point.canvasy);
+ }
+ } else {
+ ctx.moveTo(point.canvasx, point.canvasy);
+ }
+ if (drawPoints || isIsolated) {
+ pointsOnLine.push([point.canvasx, point.canvasy, point.idx]);
+ }
+ prevCanvasX = point.canvasx;
+ prevCanvasY = point.canvasy;
+ }
+ first = false;
+ }
+ ctx.stroke();
+ return pointsOnLine;
+};
+
+/**
+ * This fires the drawPointCallback functions, which draw dots on the points by
+ * default. This gets used when the "drawPoints" option is set, or when there
+ * are isolated points.
+ * @param {Object} e The dictionary passed to the plotter function.
+ * @private
+ */
+DygraphCanvasRenderer._drawPointsOnLine = function(
+ e, pointsOnLine, drawPointCallback, color, pointSize) {
+ var ctx = e.drawingContext;
+ for (var idx = 0; idx < pointsOnLine.length; idx++) {
+ var cb = pointsOnLine[idx];
+ ctx.save();
+ drawPointCallback.call(e.dygraph,
+ e.dygraph, e.setName, ctx, cb[0], cb[1], color, pointSize, cb[2]);
+ ctx.restore();
+ }
+};
+
+/**
+ * Attaches canvas coordinates to the points array.
+ * @private
+ */
+DygraphCanvasRenderer.prototype._updatePoints = function() {
+ // Update Points
+ // TODO(danvk): here
+ //
+ // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
+ // transformations can be pushed into the canvas via linear transformation
+ // matrices.
+ // NOTE(danvk): this is trickier than it sounds at first. The transformation
+ // needs to be done before the .moveTo() and .lineTo() calls, but must be
+ // undone before the .stroke() call to ensure that the stroke width is
+ // unaffected. An alternative is to reduce the stroke width in the
+ // transformed coordinate space, but you can't specify different values for
+ // each dimension (as you can with .scale()). The speedup here is ~12%.
+ var sets = this.layout.points;
+ for (var i = sets.length; i--;) {
+ var points = sets[i];
+ for (var j = points.length; j--;) {
+ var point = points[j];
+ point.canvasx = this.area.w * point.x + this.area.x;
+ point.canvasy = this.area.h * point.y + this.area.y;
+ }
+ }
+};
+
+/**
+ * Add canvas Actually draw the lines chart, including error bars.
+ *
+ * This function can only be called if DygraphLayout's points array has been
+ * updated with canvas{x,y} attributes, i.e. by
+ * DygraphCanvasRenderer._updatePoints.
+ *
+ * @param {string=} opt_seriesName when specified, only that series will
+ * be drawn. (This is used for expedited redrawing with highlightSeriesOpts)
+ * @param {CanvasRenderingContext2D} opt_ctx when specified, the drawing
+ * context. However, lines are typically drawn on the object's
+ * elementContext.
+ * @private
+ */
+DygraphCanvasRenderer.prototype._renderLineChart = function(opt_seriesName, opt_ctx) {
+ var ctx = opt_ctx || this.elementContext;
+ var i;
+
+ var sets = this.layout.points;
+ var setNames = this.layout.setNames;
+ var setName;
+
+ this.colors = this.dygraph_.colorsMap_;
+
+ // Determine which series have specialized plotters.
+ var plotter_attr = this.dygraph_.getOption("plotter");
+ var plotters = plotter_attr;
+ if (!Dygraph.isArrayLike(plotters)) {
+ plotters = [plotters];
+ }
+
+ var setPlotters = {}; // series name -> plotter fn.
+ for (i = 0; i < setNames.length; i++) {
+ setName = setNames[i];
+ var setPlotter = this.dygraph_.getOption("plotter", setName);
+ if (setPlotter == plotter_attr) continue; // not specialized.
+
+ setPlotters[setName] = setPlotter;
+ }
+
+ for (i = 0; i < plotters.length; i++) {
+ var plotter = plotters[i];
+ var is_last = (i == plotters.length - 1);
+
+ for (var j = 0; j < sets.length; j++) {
+ setName = setNames[j];
+ if (opt_seriesName && setName != opt_seriesName) continue;
+
+ var points = sets[j];
+
+ // Only throw in the specialized plotters on the last iteration.
+ var p = plotter;
+ if (setName in setPlotters) {
+ if (is_last) {
+ p = setPlotters[setName];
+ } else {
+ // Don't use the standard plotters in this case.
+ continue;
+ }
+ }
+
+ var color = this.colors[setName];
+ var strokeWidth = this.dygraph_.getOption("strokeWidth", setName);
+
+ ctx.save();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = strokeWidth;
+ p({
+ points: points,
+ setName: setName,
+ drawingContext: ctx,
+ color: color,
+ strokeWidth: strokeWidth,
+ dygraph: this.dygraph_,
+ axis: this.dygraph_.axisPropertiesForSeries(setName),
+ plotArea: this.area,
+ seriesIndex: j,
+ seriesCount: sets.length,
+ singleSeriesName: opt_seriesName,
+ allSeriesPoints: sets
+ });
+ ctx.restore();
+ }
+ }
+};
+
+/**
+ * Standard plotters. These may be used by clients via Dygraph.Plotters.
+ * See comments there for more details.
+ */
+DygraphCanvasRenderer._Plotters = {
+ linePlotter: function(e) {
+ DygraphCanvasRenderer._linePlotter(e);
+ },
+
+ fillPlotter: function(e) {
+ DygraphCanvasRenderer._fillPlotter(e);
+ },
+
+ errorPlotter: function(e) {
+ DygraphCanvasRenderer._errorPlotter(e);
+ }
+};
+
+/**
+ * Plotter which draws the central lines for a series.
+ * @private
+ */
+DygraphCanvasRenderer._linePlotter = function(e) {
+ var g = e.dygraph;
+ var setName = e.setName;
+ var strokeWidth = e.strokeWidth;
+
+ // TODO(danvk): Check if there's any performance impact of just calling
+ // getOption() inside of _drawStyledLine. Passing in so many parameters makes
+ // this code a bit nasty.
+ var borderWidth = g.getNumericOption("strokeBorderWidth", setName);
+ var drawPointCallback = g.getOption("drawPointCallback", setName) ||
+ Dygraph.Circles.DEFAULT;
+ var strokePattern = g.getOption("strokePattern", setName);
+ var drawPoints = g.getBooleanOption("drawPoints", setName);
+ var pointSize = g.getNumericOption("pointSize", setName);
+
+ if (borderWidth && strokeWidth) {
+ DygraphCanvasRenderer._drawStyledLine(e,
+ g.getOption("strokeBorderColor", setName),
+ strokeWidth + 2 * borderWidth,
+ strokePattern,
+ drawPoints,
+ drawPointCallback,
+ pointSize
+ );
+ }
+
+ DygraphCanvasRenderer._drawStyledLine(e,
+ e.color,
+ strokeWidth,
+ strokePattern,
+ drawPoints,
+ drawPointCallback,
+ pointSize
+ );
+};
+
+/**
+ * Draws the shaded error bars/confidence intervals for each series.
+ * This happens before the center lines are drawn, since the center lines
+ * need to be drawn on top of the error bars for all series.
+ * @private
+ */
+DygraphCanvasRenderer._errorPlotter = function(e) {
+ var g = e.dygraph;
+ var setName = e.setName;
+ var errorBars = g.getBooleanOption("errorBars") ||
+ g.getBooleanOption("customBars");
+ if (!errorBars) return;
+
+ var fillGraph = g.getBooleanOption("fillGraph", setName);
+ if (fillGraph) {
+ console.warn("Can't use fillGraph option with error bars");
+ }
+
+ var ctx = e.drawingContext;
+ var color = e.color;
+ var fillAlpha = g.getNumericOption('fillAlpha', setName);
+ var stepPlot = g.getBooleanOption("stepPlot", setName);
+ var points = e.points;
+
+ var iter = Dygraph.createIterator(points, 0, points.length,
+ DygraphCanvasRenderer._getIteratorPredicate(
+ g.getBooleanOption("connectSeparatedPoints", setName)));
+
+ var newYs;
+
+ // setup graphics context
+ var prevX = NaN;
+ var prevY = NaN;
+ var prevYs = [-1, -1];
+ // should be same color as the lines but only 15% opaque.
+ var rgb = Dygraph.toRGB_(color);
+ var err_color =
+ 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
+ ctx.fillStyle = err_color;
+ ctx.beginPath();
+
+ var isNullUndefinedOrNaN = function(x) {
+ return (x === null ||
+ x === undefined ||
+ isNaN(x));
+ };
+
+ while (iter.hasNext) {
+ var point = iter.next();
+ if ((!stepPlot && isNullUndefinedOrNaN(point.y)) ||
+ (stepPlot && !isNaN(prevY) && isNullUndefinedOrNaN(prevY))) {
+ prevX = NaN;
+ continue;
+ }
+
+ newYs = [ point.y_bottom, point.y_top ];
+ if (stepPlot) {
+ prevY = point.y;
+ }
+
+ // The documentation specifically disallows nulls inside the point arrays,
+ // but in case it happens we should do something sensible.
+ if (isNaN(newYs[0])) newYs[0] = point.y;
+ if (isNaN(newYs[1])) newYs[1] = point.y;
+
+ newYs[0] = e.plotArea.h * newYs[0] + e.plotArea.y;
+ newYs[1] = e.plotArea.h * newYs[1] + e.plotArea.y;
+ if (!isNaN(prevX)) {
+ if (stepPlot) {
+ ctx.moveTo(prevX, prevYs[0]);
+ ctx.lineTo(point.canvasx, prevYs[0]);
+ ctx.lineTo(point.canvasx, prevYs[1]);
+ } else {
+ ctx.moveTo(prevX, prevYs[0]);
+ ctx.lineTo(point.canvasx, newYs[0]);
+ ctx.lineTo(point.canvasx, newYs[1]);
+ }
+ ctx.lineTo(prevX, prevYs[1]);
+ ctx.closePath();
+ }
+ prevYs = newYs;
+ prevX = point.canvasx;
+ }
+ ctx.fill();
+};
+
+
+/**
+ * Proxy for CanvasRenderingContext2D which drops moveTo/lineTo calls which are
+ * superfluous. It accumulates all movements which haven't changed the x-value
+ * and only applies the two with the most extreme y-values.
+ *
+ * Calls to lineTo/moveTo must have non-decreasing x-values.
+ */
+DygraphCanvasRenderer._fastCanvasProxy = function(context) {
+ var pendingActions = []; // array of [type, x, y] tuples
+ var lastRoundedX = null;
+
+ var LINE_TO = 1,
+ MOVE_TO = 2;
+
+ var actionCount = 0; // number of moveTos and lineTos passed to context.
+
+ // Drop superfluous motions
+ // Assumes all pendingActions have the same (rounded) x-value.
+ var compressActions = function(opt_losslessOnly) {
+ if (pendingActions.length <= 1) return;
+
+ // Lossless compression: drop inconsequential moveTos.
+ for (var i = pendingActions.length - 1; i > 0; i--) {
+ var action = pendingActions[i];
+ if (action[0] == MOVE_TO) {
+ var prevAction = pendingActions[i - 1];
+ if (prevAction[1] == action[1] && prevAction[2] == action[2]) {
+ pendingActions.splice(i, 1);
+ }
+ }
+ }
+
+ // Lossless compression: ... drop consecutive moveTos ...
+ for (var i = 0; i < pendingActions.length - 1; /* incremented internally */) {
+ var action = pendingActions[i];
+ if (action[0] == MOVE_TO && pendingActions[i + 1][0] == MOVE_TO) {
+ pendingActions.splice(i, 1);
+ } else {
+ i++;
+ }
+ }
+
+ // Lossy compression: ... drop all but the extreme y-values ...
+ if (pendingActions.length > 2 && !opt_losslessOnly) {
+ // keep an initial moveTo, but drop all others.
+ var startIdx = 0;
+ if (pendingActions[0][0] == MOVE_TO) startIdx++;
+ var minIdx = null, maxIdx = null;
+ for (var i = startIdx; i < pendingActions.length; i++) {
+ var action = pendingActions[i];
+ if (action[0] != LINE_TO) continue;
+ if (minIdx === null && maxIdx === null) {
+ minIdx = i;
+ maxIdx = i;
+ } else {
+ var y = action[2];
+ if (y < pendingActions[minIdx][2]) {
+ minIdx = i;
+ } else if (y > pendingActions[maxIdx][2]) {
+ maxIdx = i;
+ }
+ }
+ }
+ var minAction = pendingActions[minIdx],
+ maxAction = pendingActions[maxIdx];
+ pendingActions.splice(startIdx, pendingActions.length - startIdx);
+ if (minIdx < maxIdx) {
+ pendingActions.push(minAction);
+ pendingActions.push(maxAction);
+ } else if (minIdx > maxIdx) {
+ pendingActions.push(maxAction);
+ pendingActions.push(minAction);
+ } else {
+ pendingActions.push(minAction);
+ }
+ }
+ };
+
+ var flushActions = function(opt_noLossyCompression) {
+ compressActions(opt_noLossyCompression);
+ for (var i = 0, len = pendingActions.length; i < len; i++) {
+ var action = pendingActions[i];
+ if (action[0] == LINE_TO) {
+ context.lineTo(action[1], action[2]);
+ } else if (action[0] == MOVE_TO) {
+ context.moveTo(action[1], action[2]);
+ }
+ }
+ actionCount += pendingActions.length;
+ pendingActions = [];
+ };
+
+ var addAction = function(action, x, y) {
+ var rx = Math.round(x);
+ if (lastRoundedX === null || rx != lastRoundedX) {
+ flushActions();
+ lastRoundedX = rx;
+ }
+ pendingActions.push([action, x, y]);
+ };
+
+ return {
+ moveTo: function(x, y) {
+ addAction(MOVE_TO, x, y);
+ },
+ lineTo: function(x, y) {
+ addAction(LINE_TO, x, y);
+ },
+
+ // for major operations like stroke/fill, we skip compression to ensure
+ // that there are no artifacts at the right edge.
+ stroke: function() { flushActions(true); context.stroke(); },
+ fill: function() { flushActions(true); context.fill(); },
+ beginPath: function() { flushActions(true); context.beginPath(); },
+ closePath: function() { flushActions(true); context.closePath(); },
+
+ _count: function() { return actionCount; }
+ };
+};
+
+/**
+ * Draws the shaded regions when "fillGraph" is set. Not to be confused with
+ * error bars.
+ *
+ * For stacked charts, it's more convenient to handle all the series
+ * simultaneously. So this plotter plots all the points on the first series
+ * it's asked to draw, then ignores all the other series.
+ *
+ * @private
+ */
+DygraphCanvasRenderer._fillPlotter = function(e) {
+ // Skip if we're drawing a single series for interactive highlight overlay.
+ if (e.singleSeriesName) return;
+
+ // We'll handle all the series at once, not one-by-one.
+ if (e.seriesIndex !== 0) return;
+
+ var g = e.dygraph;
+ var setNames = g.getLabels().slice(1); // remove x-axis
+
+ // getLabels() includes names for invisible series, which are not included in
+ // allSeriesPoints. We remove those to make the two match.
+ // TODO(danvk): provide a simpler way to get this information.
+ for (var i = setNames.length; i >= 0; i--) {
+ if (!g.visibility()[i]) setNames.splice(i, 1);
+ }
+
+ var anySeriesFilled = (function() {
+ for (var i = 0; i < setNames.length; i++) {
+ if (g.getBooleanOption("fillGraph", setNames[i])) return true;
+ }
+ return false;
+ })();
+
+ if (!anySeriesFilled) return;
+
+ var area = e.plotArea;
+ var sets = e.allSeriesPoints;
+ var setCount = sets.length;
+
+ var fillAlpha = g.getNumericOption('fillAlpha');
+ var stackedGraph = g.getBooleanOption("stackedGraph");
+ var colors = g.getColors();
+
+ // For stacked graphs, track the baseline for filling.
+ //
+ // The filled areas below graph lines are trapezoids with two
+ // vertical edges. The top edge is the line segment being drawn, and
+ // the baseline is the bottom edge. Each baseline corresponds to the
+ // top line segment from the previous stacked line. In the case of
+ // step plots, the trapezoids are rectangles.
+ var baseline = {};
+ var currBaseline;
+ var prevStepPlot; // for different line drawing modes (line/step) per series
+
+ // Helper function to trace a line back along the baseline.
+ var traceBackPath = function(ctx, baselineX, baselineY, pathBack) {
+ ctx.lineTo(baselineX, baselineY);
+ if (stackedGraph) {
+ for (var i = pathBack.length - 1; i >= 0; i--) {
+ var pt = pathBack[i];
+ ctx.lineTo(pt[0], pt[1]);
+ }
+ }
+ };
+
+ // process sets in reverse order (needed for stacked graphs)
+ for (var setIdx = setCount - 1; setIdx >= 0; setIdx--) {
+ var ctx = e.drawingContext;
+ var setName = setNames[setIdx];
+ if (!g.getBooleanOption('fillGraph', setName)) continue;
+
+ var stepPlot = g.getBooleanOption('stepPlot', setName);
+ var color = colors[setIdx];
+ var axis = g.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;
+ axisY = area.h * axisY + area.y;
+
+ var points = sets[setIdx];
+ var iter = Dygraph.createIterator(points, 0, points.length,
+ DygraphCanvasRenderer._getIteratorPredicate(
+ g.getBooleanOption("connectSeparatedPoints", setName)));
+
+ // setup graphics context
+ var prevX = NaN;
+ var prevYs = [-1, -1];
+ var newYs;
+ // should be same color as the lines but only 15% opaque.
+ var rgb = Dygraph.toRGB_(color);
+ var err_color =
+ 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
+ ctx.fillStyle = err_color;
+ ctx.beginPath();
+ var last_x, is_first = true;
+
+ // If the point density is high enough, dropping segments on their way to
+ // the canvas justifies the overhead of doing so.
+ if (points.length > 2 * g.width_) {
+ ctx = DygraphCanvasRenderer._fastCanvasProxy(ctx);
+ }
+
+ // For filled charts, we draw points from left to right, then back along
+ // the x-axis to complete a shape for filling.
+ // For stacked plots, this "back path" is a more complex shape. This array
+ // stores the [x, y] values needed to trace that shape.
+ var pathBack = [];
+
+ // TODO(danvk): there are a lot of options at play in this loop.
+ // The logic would be much clearer if some (e.g. stackGraph and
+ // stepPlot) were split off into separate sub-plotters.
+ var point;
+ while (iter.hasNext) {
+ point = iter.next();
+ if (!Dygraph.isOK(point.y) && !stepPlot) {
+ traceBackPath(ctx, prevX, prevYs[1], pathBack);
+ pathBack = [];
+ prevX = NaN;
+ if (point.y_stacked !== null && !isNaN(point.y_stacked)) {
+ baseline[point.canvasx] = area.h * point.y_stacked + area.y;
+ }
+ continue;
+ }
+ if (stackedGraph) {
+ if (!is_first && last_x == point.xval) {
+ continue;
+ } else {
+ is_first = false;
+ last_x = point.xval;
+ }
+
+ currBaseline = baseline[point.canvasx];
+ var lastY;
+ if (currBaseline === undefined) {
+ lastY = axisY;
+ } else {
+ if(prevStepPlot) {
+ lastY = currBaseline[0];
+ } else {
+ lastY = currBaseline;
+ }
+ }
+ newYs = [ point.canvasy, lastY ];
+
+ if (stepPlot) {
+ // Step plots must keep track of the top and bottom of
+ // the baseline at each point.
+ if (prevYs[0] === -1) {
+ baseline[point.canvasx] = [ point.canvasy, axisY ];
+ } else {
+ baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
+ }
+ } else {
+ baseline[point.canvasx] = point.canvasy;
+ }
+
+ } else {
+ if (isNaN(point.canvasy) && stepPlot) {
+ newYs = [ area.y + area.h, axisY ];
+ } else {
+ newYs = [ point.canvasy, axisY ];
+ }
+ }
+ if (!isNaN(prevX)) {
+ // Move to top fill point
+ if (stepPlot) {
+ ctx.lineTo(point.canvasx, prevYs[0]);
+ ctx.lineTo(point.canvasx, newYs[0]);
+ } else {
+ ctx.lineTo(point.canvasx, newYs[0]);
+ }
+
+ // Record the baseline for the reverse path.
+ if (stackedGraph) {
+ pathBack.push([prevX, prevYs[1]]);
+ if (prevStepPlot && currBaseline) {
+ // Draw to the bottom of the baseline
+ pathBack.push([point.canvasx, currBaseline[1]]);
+ } else {
+ pathBack.push([point.canvasx, newYs[1]]);
+ }
+ }
+ } else {
+ ctx.moveTo(point.canvasx, newYs[1]);
+ ctx.lineTo(point.canvasx, newYs[0]);
+ }
+ prevYs = newYs;
+ prevX = point.canvasx;
+ }
+ prevStepPlot = stepPlot;
+ if (newYs && point) {
+ traceBackPath(ctx, point.canvasx, newYs[1], pathBack);
+ pathBack = [];
+ }
+ ctx.fill();
+ }
+};
+
+return DygraphCanvasRenderer;
+
+})();
projects / dygraphs.git / blobdiff