Patch up NaN values in error bars
[dygraphs.git] / dygraph-canvas.js
1 /**
2 * @license
3 * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
4 * MIT-licensed (http://opensource.org/licenses/MIT)
5 */
6
7 /**
8 * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
9 * needs of dygraphs.
10 *
11 * In particular, support for:
12 * - grid overlays
13 * - error bars
14 * - dygraphs attribute system
15 */
16
17 /**
18 * The DygraphCanvasRenderer class does the actual rendering of the chart onto
19 * a canvas. It's based on PlotKit.CanvasRenderer.
20 * @param {Object} element The canvas to attach to
21 * @param {Object} elementContext The 2d context of the canvas (injected so it
22 * can be mocked for testing.)
23 * @param {Layout} layout The DygraphLayout object for this graph.
24 * @constructor
25 */
26
27 var DygraphCanvasRenderer = (function() {
28 /*global Dygraph:false */
29 "use strict";
30
31
32 /**
33 * @constructor
34 *
35 * This gets called when there are "new points" to chart. This is generally the
36 * case when the underlying data being charted has changed. It is _not_ called
37 * in the common case that the user has zoomed or is panning the view.
38 *
39 * The chart canvas has already been created by the Dygraph object. The
40 * renderer simply gets a drawing context.
41 *
42 * @param {Dygraph} dygraph The chart to which this renderer belongs.
43 * @param {HTMLCanvasElement} element The <canvas> DOM element on which to draw.
44 * @param {CanvasRenderingContext2D} elementContext The drawing context.
45 * @param {DygraphLayout} layout The chart's DygraphLayout object.
46 *
47 * TODO(danvk): remove the elementContext property.
48 */
49 var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
50 this.dygraph_ = dygraph;
51
52 this.layout = layout;
53 this.element = element;
54 this.elementContext = elementContext;
55
56 this.height = dygraph.height_;
57 this.width = dygraph.width_;
58
59 // --- check whether everything is ok before we return
60 // NOTE(konigsberg): isIE is never defined in this object. Bug of some sort.
61 if (!this.isIE && !(Dygraph.isCanvasSupported(this.element)))
62 throw "Canvas is not supported.";
63
64 // internal state
65 this.area = layout.getPlotArea();
66
67 // Set up a clipping area for the canvas (and the interaction canvas).
68 // This ensures that we don't overdraw.
69 if (this.dygraph_.isUsingExcanvas_) {
70 this._createIEClipArea();
71 } else {
72 // on Android 3 and 4, setting a clipping area on a canvas prevents it from
73 // displaying anything.
74 if (!Dygraph.isAndroid()) {
75 var ctx = this.dygraph_.canvas_ctx_;
76 ctx.beginPath();
77 ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
78 ctx.clip();
79
80 ctx = this.dygraph_.hidden_ctx_;
81 ctx.beginPath();
82 ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
83 ctx.clip();
84 }
85 }
86 };
87
88 /**
89 * Clears out all chart content and DOM elements.
90 * This is called immediately before render() on every frame, including
91 * during zooms and pans.
92 * @private
93 */
94 DygraphCanvasRenderer.prototype.clear = function() {
95 var context;
96 if (this.isIE) {
97 // VML takes a while to start up, so we just poll every this.IEDelay
98 try {
99 if (this.clearDelay) {
100 this.clearDelay.cancel();
101 this.clearDelay = null;
102 }
103 context = this.elementContext;
104 }
105 catch (e) {
106 // TODO(danvk): this is broken, since MochiKit.Async is gone.
107 // this.clearDelay = MochiKit.Async.wait(this.IEDelay);
108 // this.clearDelay.addCallback(bind(this.clear, this));
109 return;
110 }
111 }
112
113 context = this.elementContext;
114 context.clearRect(0, 0, this.width, this.height);
115 };
116
117 /**
118 * This method is responsible for drawing everything on the chart, including
119 * lines, error bars, fills and axes.
120 * It is called immediately after clear() on every frame, including during pans
121 * and zooms.
122 * @private
123 */
124 DygraphCanvasRenderer.prototype.render = function() {
125 // attaches point.canvas{x,y}
126 this._updatePoints();
127
128 // actually draws the chart.
129 this._renderLineChart();
130 };
131
132 DygraphCanvasRenderer.prototype._createIEClipArea = function() {
133 var className = 'dygraph-clip-div';
134 var graphDiv = this.dygraph_.graphDiv;
135
136 // Remove old clip divs.
137 for (var i = graphDiv.childNodes.length-1; i >= 0; i--) {
138 if (graphDiv.childNodes[i].className == className) {
139 graphDiv.removeChild(graphDiv.childNodes[i]);
140 }
141 }
142
143 // Determine background color to give clip divs.
144 var backgroundColor = document.bgColor;
145 var element = this.dygraph_.graphDiv;
146 while (element != document) {
147 var bgcolor = element.currentStyle.backgroundColor;
148 if (bgcolor && bgcolor != 'transparent') {
149 backgroundColor = bgcolor;
150 break;
151 }
152 element = element.parentNode;
153 }
154
155 function createClipDiv(area) {
156 if (area.w === 0 || area.h === 0) {
157 return;
158 }
159 var elem = document.createElement('div');
160 elem.className = className;
161 elem.style.backgroundColor = backgroundColor;
162 elem.style.position = 'absolute';
163 elem.style.left = area.x + 'px';
164 elem.style.top = area.y + 'px';
165 elem.style.width = area.w + 'px';
166 elem.style.height = area.h + 'px';
167 graphDiv.appendChild(elem);
168 }
169
170 var plotArea = this.area;
171 // Left side
172 createClipDiv({
173 x:0, y:0,
174 w:plotArea.x,
175 h:this.height
176 });
177
178 // Top
179 createClipDiv({
180 x: plotArea.x, y: 0,
181 w: this.width - plotArea.x,
182 h: plotArea.y
183 });
184
185 // Right side
186 createClipDiv({
187 x: plotArea.x + plotArea.w, y: 0,
188 w: this.width - plotArea.x - plotArea.w,
189 h: this.height
190 });
191
192 // Bottom
193 createClipDiv({
194 x: plotArea.x,
195 y: plotArea.y + plotArea.h,
196 w: this.width - plotArea.x,
197 h: this.height - plotArea.h - plotArea.y
198 });
199 };
200
201
202 /**
203 * Returns a predicate to be used with an iterator, which will
204 * iterate over points appropriately, depending on whether
205 * connectSeparatedPoints is true. When it's false, the predicate will
206 * skip over points with missing yVals.
207 */
208 DygraphCanvasRenderer._getIteratorPredicate = function(connectSeparatedPoints) {
209 return connectSeparatedPoints ?
210 DygraphCanvasRenderer._predicateThatSkipsEmptyPoints :
211 null;
212 };
213
214 DygraphCanvasRenderer._predicateThatSkipsEmptyPoints =
215 function(array, idx) {
216 return array[idx].yval !== null;
217 };
218
219 /**
220 * Draws a line with the styles passed in and calls all the drawPointCallbacks.
221 * @param {Object} e The dictionary passed to the plotter function.
222 * @private
223 */
224 DygraphCanvasRenderer._drawStyledLine = function(e,
225 color, strokeWidth, strokePattern, drawPoints,
226 drawPointCallback, pointSize) {
227 var g = e.dygraph;
228 // TODO(konigsberg): Compute attributes outside this method call.
229 var stepPlot = g.getBooleanOption("stepPlot", e.setName);
230
231 if (!Dygraph.isArrayLike(strokePattern)) {
232 strokePattern = null;
233 }
234
235 var drawGapPoints = g.getBooleanOption('drawGapEdgePoints', e.setName);
236
237 var points = e.points;
238 var setName = e.setName;
239 var iter = Dygraph.createIterator(points, 0, points.length,
240 DygraphCanvasRenderer._getIteratorPredicate(
241 g.getBooleanOption("connectSeparatedPoints", setName)));
242
243 var stroking = strokePattern && (strokePattern.length >= 2);
244
245 var ctx = e.drawingContext;
246 ctx.save();
247 if (stroking) {
248 ctx.installPattern(strokePattern);
249 }
250
251 var pointsOnLine = DygraphCanvasRenderer._drawSeries(
252 e, iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, color);
253 DygraphCanvasRenderer._drawPointsOnLine(
254 e, pointsOnLine, drawPointCallback, color, pointSize);
255
256 if (stroking) {
257 ctx.uninstallPattern();
258 }
259
260 ctx.restore();
261 };
262
263 /**
264 * This does the actual drawing of lines on the canvas, for just one series.
265 * Returns a list of [canvasx, canvasy] pairs for points for which a
266 * drawPointCallback should be fired. These include isolated points, or all
267 * points if drawPoints=true.
268 * @param {Object} e The dictionary passed to the plotter function.
269 * @private
270 */
271 DygraphCanvasRenderer._drawSeries = function(e,
272 iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, color) {
273
274 var prevCanvasX = null;
275 var prevCanvasY = null;
276 var nextCanvasY = null;
277 var isIsolated; // true if this point is isolated (no line segments)
278 var point; // the point being processed in the while loop
279 var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
280 var first = true; // the first cycle through the while loop
281
282 var ctx = e.drawingContext;
283 ctx.beginPath();
284 ctx.strokeStyle = color;
285 ctx.lineWidth = strokeWidth;
286
287 // NOTE: we break the iterator's encapsulation here for about a 25% speedup.
288 var arr = iter.array_;
289 var limit = iter.end_;
290 var predicate = iter.predicate_;
291
292 for (var i = iter.start_; i < limit; i++) {
293 point = arr[i];
294 if (predicate) {
295 while (i < limit && !predicate(arr, i)) {
296 i++;
297 }
298 if (i == limit) break;
299 point = arr[i];
300 }
301
302 // FIXME: The 'canvasy != canvasy' test here catches NaN values but the test
303 // doesn't catch Infinity values. Could change this to
304 // !isFinite(point.canvasy), but I assume it avoids isNaN for performance?
305 if (point.canvasy === null || point.canvasy != point.canvasy) {
306 if (stepPlot && prevCanvasX !== null) {
307 // Draw a horizontal line to the start of the missing data
308 ctx.moveTo(prevCanvasX, prevCanvasY);
309 ctx.lineTo(point.canvasx, prevCanvasY);
310 }
311 prevCanvasX = prevCanvasY = null;
312 } else {
313 isIsolated = false;
314 if (drawGapPoints || !prevCanvasX) {
315 iter.nextIdx_ = i;
316 iter.next();
317 nextCanvasY = iter.hasNext ? iter.peek.canvasy : null;
318
319 var isNextCanvasYNullOrNaN = nextCanvasY === null ||
320 nextCanvasY != nextCanvasY;
321 isIsolated = (!prevCanvasX && isNextCanvasYNullOrNaN);
322 if (drawGapPoints) {
323 // Also consider a point to be "isolated" if it's adjacent to a
324 // null point, excluding the graph edges.
325 if ((!first && !prevCanvasX) ||
326 (iter.hasNext && isNextCanvasYNullOrNaN)) {
327 isIsolated = true;
328 }
329 }
330 }
331
332 if (prevCanvasX !== null) {
333 if (strokeWidth) {
334 if (stepPlot) {
335 ctx.moveTo(prevCanvasX, prevCanvasY);
336 ctx.lineTo(point.canvasx, prevCanvasY);
337 }
338
339 ctx.lineTo(point.canvasx, point.canvasy);
340 }
341 } else {
342 ctx.moveTo(point.canvasx, point.canvasy);
343 }
344 if (drawPoints || isIsolated) {
345 pointsOnLine.push([point.canvasx, point.canvasy, point.idx]);
346 }
347 prevCanvasX = point.canvasx;
348 prevCanvasY = point.canvasy;
349 }
350 first = false;
351 }
352 ctx.stroke();
353 return pointsOnLine;
354 };
355
356 /**
357 * This fires the drawPointCallback functions, which draw dots on the points by
358 * default. This gets used when the "drawPoints" option is set, or when there
359 * are isolated points.
360 * @param {Object} e The dictionary passed to the plotter function.
361 * @private
362 */
363 DygraphCanvasRenderer._drawPointsOnLine = function(
364 e, pointsOnLine, drawPointCallback, color, pointSize) {
365 var ctx = e.drawingContext;
366 for (var idx = 0; idx < pointsOnLine.length; idx++) {
367 var cb = pointsOnLine[idx];
368 ctx.save();
369 drawPointCallback.call(e.dygraph,
370 e.dygraph, e.setName, ctx, cb[0], cb[1], color, pointSize, cb[2]);
371 ctx.restore();
372 }
373 };
374
375 /**
376 * Attaches canvas coordinates to the points array.
377 * @private
378 */
379 DygraphCanvasRenderer.prototype._updatePoints = function() {
380 // Update Points
381 // TODO(danvk): here
382 //
383 // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
384 // transformations can be pushed into the canvas via linear transformation
385 // matrices.
386 // NOTE(danvk): this is trickier than it sounds at first. The transformation
387 // needs to be done before the .moveTo() and .lineTo() calls, but must be
388 // undone before the .stroke() call to ensure that the stroke width is
389 // unaffected. An alternative is to reduce the stroke width in the
390 // transformed coordinate space, but you can't specify different values for
391 // each dimension (as you can with .scale()). The speedup here is ~12%.
392 var sets = this.layout.points;
393 for (var i = sets.length; i--;) {
394 var points = sets[i];
395 for (var j = points.length; j--;) {
396 var point = points[j];
397 point.canvasx = this.area.w * point.x + this.area.x;
398 point.canvasy = this.area.h * point.y + this.area.y;
399 }
400 }
401 };
402
403 /**
404 * Add canvas Actually draw the lines chart, including error bars.
405 *
406 * This function can only be called if DygraphLayout's points array has been
407 * updated with canvas{x,y} attributes, i.e. by
408 * DygraphCanvasRenderer._updatePoints.
409 *
410 * @param {string=} opt_seriesName when specified, only that series will
411 * be drawn. (This is used for expedited redrawing with highlightSeriesOpts)
412 * @param {CanvasRenderingContext2D} opt_ctx when specified, the drawing
413 * context. However, lines are typically drawn on the object's
414 * elementContext.
415 * @private
416 */
417 DygraphCanvasRenderer.prototype._renderLineChart = function(opt_seriesName, opt_ctx) {
418 var ctx = opt_ctx || this.elementContext;
419 var i;
420
421 var sets = this.layout.points;
422 var setNames = this.layout.setNames;
423 var setName;
424
425 this.colors = this.dygraph_.colorsMap_;
426
427 // Determine which series have specialized plotters.
428 var plotter_attr = this.dygraph_.getOption("plotter");
429 var plotters = plotter_attr;
430 if (!Dygraph.isArrayLike(plotters)) {
431 plotters = [plotters];
432 }
433
434 var setPlotters = {}; // series name -> plotter fn.
435 for (i = 0; i < setNames.length; i++) {
436 setName = setNames[i];
437 var setPlotter = this.dygraph_.getOption("plotter", setName);
438 if (setPlotter == plotter_attr) continue; // not specialized.
439
440 setPlotters[setName] = setPlotter;
441 }
442
443 for (i = 0; i < plotters.length; i++) {
444 var plotter = plotters[i];
445 var is_last = (i == plotters.length - 1);
446
447 for (var j = 0; j < sets.length; j++) {
448 setName = setNames[j];
449 if (opt_seriesName && setName != opt_seriesName) continue;
450
451 var points = sets[j];
452
453 // Only throw in the specialized plotters on the last iteration.
454 var p = plotter;
455 if (setName in setPlotters) {
456 if (is_last) {
457 p = setPlotters[setName];
458 } else {
459 // Don't use the standard plotters in this case.
460 continue;
461 }
462 }
463
464 var color = this.colors[setName];
465 var strokeWidth = this.dygraph_.getOption("strokeWidth", setName);
466
467 ctx.save();
468 ctx.strokeStyle = color;
469 ctx.lineWidth = strokeWidth;
470 p({
471 points: points,
472 setName: setName,
473 drawingContext: ctx,
474 color: color,
475 strokeWidth: strokeWidth,
476 dygraph: this.dygraph_,
477 axis: this.dygraph_.axisPropertiesForSeries(setName),
478 plotArea: this.area,
479 seriesIndex: j,
480 seriesCount: sets.length,
481 singleSeriesName: opt_seriesName,
482 allSeriesPoints: sets
483 });
484 ctx.restore();
485 }
486 }
487 };
488
489 /**
490 * Standard plotters. These may be used by clients via Dygraph.Plotters.
491 * See comments there for more details.
492 */
493 DygraphCanvasRenderer._Plotters = {
494 linePlotter: function(e) {
495 DygraphCanvasRenderer._linePlotter(e);
496 },
497
498 fillPlotter: function(e) {
499 DygraphCanvasRenderer._fillPlotter(e);
500 },
501
502 errorPlotter: function(e) {
503 DygraphCanvasRenderer._errorPlotter(e);
504 }
505 };
506
507 /**
508 * Plotter which draws the central lines for a series.
509 * @private
510 */
511 DygraphCanvasRenderer._linePlotter = function(e) {
512 var g = e.dygraph;
513 var setName = e.setName;
514 var strokeWidth = e.strokeWidth;
515
516 // TODO(danvk): Check if there's any performance impact of just calling
517 // getOption() inside of _drawStyledLine. Passing in so many parameters makes
518 // this code a bit nasty.
519 var borderWidth = g.getNumericOption("strokeBorderWidth", setName);
520 var drawPointCallback = g.getOption("drawPointCallback", setName) ||
521 Dygraph.Circles.DEFAULT;
522 var strokePattern = g.getOption("strokePattern", setName);
523 var drawPoints = g.getBooleanOption("drawPoints", setName);
524 var pointSize = g.getNumericOption("pointSize", setName);
525
526 if (borderWidth && strokeWidth) {
527 DygraphCanvasRenderer._drawStyledLine(e,
528 g.getOption("strokeBorderColor", setName),
529 strokeWidth + 2 * borderWidth,
530 strokePattern,
531 drawPoints,
532 drawPointCallback,
533 pointSize
534 );
535 }
536
537 DygraphCanvasRenderer._drawStyledLine(e,
538 e.color,
539 strokeWidth,
540 strokePattern,
541 drawPoints,
542 drawPointCallback,
543 pointSize
544 );
545 };
546
547 /**
548 * Draws the shaded error bars/confidence intervals for each series.
549 * This happens before the center lines are drawn, since the center lines
550 * need to be drawn on top of the error bars for all series.
551 * @private
552 */
553 DygraphCanvasRenderer._errorPlotter = function(e) {
554 var g = e.dygraph;
555 var setName = e.setName;
556 var errorBars = g.getBooleanOption("errorBars") ||
557 g.getBooleanOption("customBars");
558 if (!errorBars) return;
559
560 var fillGraph = g.getBooleanOption("fillGraph", setName);
561 if (fillGraph) {
562 console.warn("Can't use fillGraph option with error bars");
563 }
564
565 var ctx = e.drawingContext;
566 var color = e.color;
567 var fillAlpha = g.getNumericOption('fillAlpha', setName);
568 var stepPlot = g.getBooleanOption("stepPlot", setName);
569 var points = e.points;
570
571 var iter = Dygraph.createIterator(points, 0, points.length,
572 DygraphCanvasRenderer._getIteratorPredicate(
573 g.getBooleanOption("connectSeparatedPoints", setName)));
574
575 var newYs;
576
577 // setup graphics context
578 var prevX = NaN;
579 var prevY = NaN;
580 var prevYs = [-1, -1];
581 // should be same color as the lines but only 15% opaque.
582 var rgb = Dygraph.toRGB_(color);
583 var err_color =
584 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
585 ctx.fillStyle = err_color;
586 ctx.beginPath();
587
588 var isNullUndefinedOrNaN = function(x) {
589 return (x === null ||
590 x === undefined ||
591 isNaN(x));
592 };
593
594 while (iter.hasNext) {
595 var point = iter.next();
596 if ((!stepPlot && isNullUndefinedOrNaN(point.y)) ||
597 (stepPlot && !isNaN(prevY) && isNullUndefinedOrNaN(prevY))) {
598 prevX = NaN;
599 continue;
600 }
601
602 newYs = [ point.y_bottom, point.y_top ];
603 if (stepPlot) {
604 prevY = point.y;
605 }
606
607 // The documentation specifically disallows nulls inside the point arrays,
608 // but in case it happens we should do something sensible.
609 if (isNaN(newYs[0])) newYs[0] = point.y;
610 if (isNaN(newYs[1])) newYs[1] = point.y;
611
612 newYs[0] = e.plotArea.h * newYs[0] + e.plotArea.y;
613 newYs[1] = e.plotArea.h * newYs[1] + e.plotArea.y;
614 if (!isNaN(prevX)) {
615 if (stepPlot) {
616 ctx.moveTo(prevX, prevYs[0]);
617 ctx.lineTo(point.canvasx, prevYs[0]);
618 ctx.lineTo(point.canvasx, prevYs[1]);
619 } else {
620 ctx.moveTo(prevX, prevYs[0]);
621 ctx.lineTo(point.canvasx, newYs[0]);
622 ctx.lineTo(point.canvasx, newYs[1]);
623 }
624 ctx.lineTo(prevX, prevYs[1]);
625 ctx.closePath();
626 }
627 prevYs = newYs;
628 prevX = point.canvasx;
629 }
630 ctx.fill();
631 };
632
633
634 /**
635 * Proxy for CanvasRenderingContext2D which drops moveTo/lineTo calls which are
636 * superfluous. It accumulates all movements which haven't changed the x-value
637 * and only applies the two with the most extreme y-values.
638 *
639 * Calls to lineTo/moveTo must have non-decreasing x-values.
640 */
641 DygraphCanvasRenderer._fastCanvasProxy = function(context) {
642 var pendingActions = []; // array of [type, x, y] tuples
643 var lastRoundedX = null;
644
645 var LINE_TO = 1,
646 MOVE_TO = 2;
647
648 var actionCount = 0; // number of moveTos and lineTos passed to context.
649
650 // Drop superfluous motions
651 // Assumes all pendingActions have the same (rounded) x-value.
652 var compressActions = function(opt_losslessOnly) {
653 if (pendingActions.length <= 1) return;
654
655 // Lossless compression: drop inconsequential moveTos.
656 for (var i = pendingActions.length - 1; i > 0; i--) {
657 var action = pendingActions[i];
658 if (action[0] == MOVE_TO) {
659 var prevAction = pendingActions[i - 1];
660 if (prevAction[1] == action[1] && prevAction[2] == action[2]) {
661 pendingActions.splice(i, 1);
662 }
663 }
664 }
665
666 // Lossless compression: ... drop consecutive moveTos ...
667 for (var i = 0; i < pendingActions.length - 1; /* incremented internally */) {
668 var action = pendingActions[i];
669 if (action[0] == MOVE_TO && pendingActions[i + 1][0] == MOVE_TO) {
670 pendingActions.splice(i, 1);
671 } else {
672 i++;
673 }
674 }
675
676 // Lossy compression: ... drop all but the extreme y-values ...
677 if (pendingActions.length > 2 && !opt_losslessOnly) {
678 // keep an initial moveTo, but drop all others.
679 var startIdx = 0;
680 if (pendingActions[0][0] == MOVE_TO) startIdx++;
681 var minIdx = null, maxIdx = null;
682 for (var i = startIdx; i < pendingActions.length; i++) {
683 var action = pendingActions[i];
684 if (action[0] != LINE_TO) continue;
685 if (minIdx === null && maxIdx === null) {
686 minIdx = i;
687 maxIdx = i;
688 } else {
689 var y = action[2];
690 if (y < pendingActions[minIdx][2]) {
691 minIdx = i;
692 } else if (y > pendingActions[maxIdx][2]) {
693 maxIdx = i;
694 }
695 }
696 }
697 var minAction = pendingActions[minIdx],
698 maxAction = pendingActions[maxIdx];
699 pendingActions.splice(startIdx, pendingActions.length - startIdx);
700 if (minIdx < maxIdx) {
701 pendingActions.push(minAction);
702 pendingActions.push(maxAction);
703 } else if (minIdx > maxIdx) {
704 pendingActions.push(maxAction);
705 pendingActions.push(minAction);
706 } else {
707 pendingActions.push(minAction);
708 }
709 }
710 };
711
712 var flushActions = function(opt_noLossyCompression) {
713 compressActions(opt_noLossyCompression);
714 for (var i = 0, len = pendingActions.length; i < len; i++) {
715 var action = pendingActions[i];
716 if (action[0] == LINE_TO) {
717 context.lineTo(action[1], action[2]);
718 } else if (action[0] == MOVE_TO) {
719 context.moveTo(action[1], action[2]);
720 }
721 }
722 actionCount += pendingActions.length;
723 pendingActions = [];
724 };
725
726 var addAction = function(action, x, y) {
727 var rx = Math.round(x);
728 if (lastRoundedX === null || rx != lastRoundedX) {
729 flushActions();
730 lastRoundedX = rx;
731 }
732 pendingActions.push([action, x, y]);
733 };
734
735 return {
736 moveTo: function(x, y) {
737 addAction(MOVE_TO, x, y);
738 },
739 lineTo: function(x, y) {
740 addAction(LINE_TO, x, y);
741 },
742
743 // for major operations like stroke/fill, we skip compression to ensure
744 // that there are no artifacts at the right edge.
745 stroke: function() { flushActions(true); context.stroke(); },
746 fill: function() { flushActions(true); context.fill(); },
747 beginPath: function() { flushActions(true); context.beginPath(); },
748 closePath: function() { flushActions(true); context.closePath(); },
749
750 _count: function() { return actionCount; }
751 };
752 };
753
754 /**
755 * Draws the shaded regions when "fillGraph" is set. Not to be confused with
756 * error bars.
757 *
758 * For stacked charts, it's more convenient to handle all the series
759 * simultaneously. So this plotter plots all the points on the first series
760 * it's asked to draw, then ignores all the other series.
761 *
762 * @private
763 */
764 DygraphCanvasRenderer._fillPlotter = function(e) {
765 // Skip if we're drawing a single series for interactive highlight overlay.
766 if (e.singleSeriesName) return;
767
768 // We'll handle all the series at once, not one-by-one.
769 if (e.seriesIndex !== 0) return;
770
771 var g = e.dygraph;
772 var setNames = g.getLabels().slice(1); // remove x-axis
773
774 // getLabels() includes names for invisible series, which are not included in
775 // allSeriesPoints. We remove those to make the two match.
776 // TODO(danvk): provide a simpler way to get this information.
777 for (var i = setNames.length; i >= 0; i--) {
778 if (!g.visibility()[i]) setNames.splice(i, 1);
779 }
780
781 var anySeriesFilled = (function() {
782 for (var i = 0; i < setNames.length; i++) {
783 if (g.getBooleanOption("fillGraph", setNames[i])) return true;
784 }
785 return false;
786 })();
787
788 if (!anySeriesFilled) return;
789
790 var area = e.plotArea;
791 var sets = e.allSeriesPoints;
792 var setCount = sets.length;
793
794 var fillAlpha = g.getNumericOption('fillAlpha');
795 var stackedGraph = g.getBooleanOption("stackedGraph");
796 var colors = g.getColors();
797
798 // For stacked graphs, track the baseline for filling.
799 //
800 // The filled areas below graph lines are trapezoids with two
801 // vertical edges. The top edge is the line segment being drawn, and
802 // the baseline is the bottom edge. Each baseline corresponds to the
803 // top line segment from the previous stacked line. In the case of
804 // step plots, the trapezoids are rectangles.
805 var baseline = {};
806 var currBaseline;
807 var prevStepPlot; // for different line drawing modes (line/step) per series
808
809 // Helper function to trace a line back along the baseline.
810 var traceBackPath = function(ctx, baselineX, baselineY, pathBack) {
811 ctx.lineTo(baselineX, baselineY);
812 if (stackedGraph) {
813 for (var i = pathBack.length - 1; i >= 0; i--) {
814 var pt = pathBack[i];
815 ctx.lineTo(pt[0], pt[1]);
816 }
817 }
818 };
819
820 // process sets in reverse order (needed for stacked graphs)
821 for (var setIdx = setCount - 1; setIdx >= 0; setIdx--) {
822 var ctx = e.drawingContext;
823 var setName = setNames[setIdx];
824 if (!g.getBooleanOption('fillGraph', setName)) continue;
825
826 var stepPlot = g.getBooleanOption('stepPlot', setName);
827 var color = colors[setIdx];
828 var axis = g.axisPropertiesForSeries(setName);
829 var axisY = 1.0 + axis.minyval * axis.yscale;
830 if (axisY < 0.0) axisY = 0.0;
831 else if (axisY > 1.0) axisY = 1.0;
832 axisY = area.h * axisY + area.y;
833
834 var points = sets[setIdx];
835 var iter = Dygraph.createIterator(points, 0, points.length,
836 DygraphCanvasRenderer._getIteratorPredicate(
837 g.getBooleanOption("connectSeparatedPoints", setName)));
838
839 // setup graphics context
840 var prevX = NaN;
841 var prevYs = [-1, -1];
842 var newYs;
843 // should be same color as the lines but only 15% opaque.
844 var rgb = Dygraph.toRGB_(color);
845 var err_color =
846 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
847 ctx.fillStyle = err_color;
848 ctx.beginPath();
849 var last_x, is_first = true;
850
851 // If the point density is high enough, dropping segments on their way to
852 // the canvas justifies the overhead of doing so.
853 if (points.length > 2 * g.width_) {
854 ctx = DygraphCanvasRenderer._fastCanvasProxy(ctx);
855 }
856
857 // For filled charts, we draw points from left to right, then back along
858 // the x-axis to complete a shape for filling.
859 // For stacked plots, this "back path" is a more complex shape. This array
860 // stores the [x, y] values needed to trace that shape.
861 var pathBack = [];
862
863 // TODO(danvk): there are a lot of options at play in this loop.
864 // The logic would be much clearer if some (e.g. stackGraph and
865 // stepPlot) were split off into separate sub-plotters.
866 var point;
867 while (iter.hasNext) {
868 point = iter.next();
869 if (!Dygraph.isOK(point.y) && !stepPlot) {
870 traceBackPath(ctx, prevX, prevYs[1], pathBack);
871 pathBack = [];
872 prevX = NaN;
873 if (point.y_stacked !== null && !isNaN(point.y_stacked)) {
874 baseline[point.canvasx] = area.h * point.y_stacked + area.y;
875 }
876 continue;
877 }
878 if (stackedGraph) {
879 if (!is_first && last_x == point.xval) {
880 continue;
881 } else {
882 is_first = false;
883 last_x = point.xval;
884 }
885
886 currBaseline = baseline[point.canvasx];
887 var lastY;
888 if (currBaseline === undefined) {
889 lastY = axisY;
890 } else {
891 if(prevStepPlot) {
892 lastY = currBaseline[0];
893 } else {
894 lastY = currBaseline;
895 }
896 }
897 newYs = [ point.canvasy, lastY ];
898
899 if (stepPlot) {
900 // Step plots must keep track of the top and bottom of
901 // the baseline at each point.
902 if (prevYs[0] === -1) {
903 baseline[point.canvasx] = [ point.canvasy, axisY ];
904 } else {
905 baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
906 }
907 } else {
908 baseline[point.canvasx] = point.canvasy;
909 }
910
911 } else {
912 if (isNaN(point.canvasy) && stepPlot) {
913 newYs = [ area.y + area.h, axisY ];
914 } else {
915 newYs = [ point.canvasy, axisY ];
916 }
917 }
918 if (!isNaN(prevX)) {
919 // Move to top fill point
920 if (stepPlot) {
921 ctx.lineTo(point.canvasx, prevYs[0]);
922 ctx.lineTo(point.canvasx, newYs[0]);
923 } else {
924 ctx.lineTo(point.canvasx, newYs[0]);
925 }
926
927 // Record the baseline for the reverse path.
928 if (stackedGraph) {
929 pathBack.push([prevX, prevYs[1]]);
930 if (prevStepPlot && currBaseline) {
931 // Draw to the bottom of the baseline
932 pathBack.push([point.canvasx, currBaseline[1]]);
933 } else {
934 pathBack.push([point.canvasx, newYs[1]]);
935 }
936 }
937 } else {
938 ctx.moveTo(point.canvasx, newYs[1]);
939 ctx.lineTo(point.canvasx, newYs[0]);
940 }
941 prevYs = newYs;
942 prevX = point.canvasx;
943 }
944 prevStepPlot = stepPlot;
945 if (newYs && point) {
946 traceBackPath(ctx, point.canvasx, newYs[1], pathBack);
947 pathBack = [];
948 }
949 ctx.fill();
950 }
951 };
952
953 return DygraphCanvasRenderer;
954
955 })();