3 * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
4 * MIT-licensed (http://opensource.org/licenses/MIT)
8 * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
11 * In particular, support for:
14 * - dygraphs attribute system
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.
27 var DygraphCanvasRenderer
= (function() {
28 /*global Dygraph:false */
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.
39 * The chart canvas has already been created by the Dygraph object. The
40 * renderer simply gets a drawing context.
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.
47 * TODO(danvk): remove the elementContext property.
49 var DygraphCanvasRenderer
= function(dygraph
, element
, elementContext
, layout
) {
50 this.dygraph_
= dygraph
;
53 this.element
= element
;
54 this.elementContext
= elementContext
;
56 this.height
= dygraph
.height_
;
57 this.width
= dygraph
.width_
;
59 // --- check whether everything is ok before we return
60 if (!Dygraph
.isCanvasSupported(this.element
)) {
61 throw "Canvas is not supported.";
65 this.area
= layout
.getPlotArea();
67 // Set up a clipping area for the canvas (and the interaction canvas).
68 // This ensures that we don't overdraw.
69 // on Android 3 and 4, setting a clipping area on a canvas prevents it from
70 // displaying anything.
71 if (!Dygraph
.isAndroid()) {
72 var ctx
= this.dygraph_
.canvas_ctx_
;
74 ctx
.rect(this.area
.x
, this.area
.y
, this.area
.w
, this.area
.h
);
77 ctx
= this.dygraph_
.hidden_ctx_
;
79 ctx
.rect(this.area
.x
, this.area
.y
, this.area
.w
, this.area
.h
);
85 * Clears out all chart content and DOM elements.
86 * This is called immediately before render() on every frame, including
87 * during zooms and pans.
90 DygraphCanvasRenderer
.prototype.clear
= function() {
91 this.elementContext
.clearRect(0, 0, this.width
, this.height
);
95 * This method is responsible for drawing everything on the chart, including
96 * lines, error bars, fills and axes.
97 * It is called immediately after clear() on every frame, including during pans
101 DygraphCanvasRenderer
.prototype.render
= function() {
102 // attaches point.canvas{x,y}
103 this._updatePoints();
105 // actually draws the chart.
106 this._renderLineChart();
110 * Returns a predicate to be used with an iterator, which will
111 * iterate over points appropriately, depending on whether
112 * connectSeparatedPoints is true. When it's false, the predicate will
113 * skip over points with missing yVals.
115 DygraphCanvasRenderer
._getIteratorPredicate
= function(connectSeparatedPoints
) {
116 return connectSeparatedPoints
?
117 DygraphCanvasRenderer
._predicateThatSkipsEmptyPoints
:
121 DygraphCanvasRenderer
._predicateThatSkipsEmptyPoints
=
122 function(array
, idx
) {
123 return array
[idx
].yval
!== null;
127 * Draws a line with the styles passed in and calls all the drawPointCallbacks.
128 * @param {Object} e The dictionary passed to the plotter function.
131 DygraphCanvasRenderer
._drawStyledLine
= function(e
,
132 color
, strokeWidth
, strokePattern
, drawPoints
,
133 drawPointCallback
, pointSize
) {
135 // TODO(konigsberg): Compute attributes outside this method call.
136 var stepPlot
= g
.getBooleanOption("stepPlot", e
.setName
);
138 if (!Dygraph
.isArrayLike(strokePattern
)) {
139 strokePattern
= null;
142 var drawGapPoints
= g
.getBooleanOption('drawGapEdgePoints', e
.setName
);
144 var points
= e
.points
;
145 var setName
= e
.setName
;
146 var iter
= Dygraph
.createIterator(points
, 0, points
.length
,
147 DygraphCanvasRenderer
._getIteratorPredicate(
148 g
.getBooleanOption("connectSeparatedPoints", setName
)));
150 var stroking
= strokePattern
&& (strokePattern
.length
>= 2);
152 var ctx
= e
.drawingContext
;
155 ctx
.installPattern(strokePattern
);
158 var pointsOnLine
= DygraphCanvasRenderer
._drawSeries(
159 e
, iter
, strokeWidth
, pointSize
, drawPoints
, drawGapPoints
, stepPlot
, color
);
160 DygraphCanvasRenderer
._drawPointsOnLine(
161 e
, pointsOnLine
, drawPointCallback
, color
, pointSize
);
164 ctx
.uninstallPattern();
171 * This does the actual drawing of lines on the canvas, for just one series.
172 * Returns a list of [canvasx, canvasy] pairs for points for which a
173 * drawPointCallback should be fired. These include isolated points, or all
174 * points if drawPoints=true.
175 * @param {Object} e The dictionary passed to the plotter function.
178 DygraphCanvasRenderer
._drawSeries
= function(e
,
179 iter
, strokeWidth
, pointSize
, drawPoints
, drawGapPoints
, stepPlot
, color
) {
181 var prevCanvasX
= null;
182 var prevCanvasY
= null;
183 var nextCanvasY
= null;
184 var isIsolated
; // true if this point is isolated (no line segments)
185 var point
; // the point being processed in the while loop
186 var pointsOnLine
= []; // Array of [canvasx, canvasy] pairs.
187 var first
= true; // the first cycle through the while loop
189 var ctx
= e
.drawingContext
;
191 ctx
.strokeStyle
= color
;
192 ctx
.lineWidth
= strokeWidth
;
194 // NOTE: we break the iterator's encapsulation here for about a 25% speedup.
195 var arr
= iter
.array_
;
196 var limit
= iter
.end_
;
197 var predicate
= iter
.predicate_
;
199 for (var i
= iter
.start_
; i
< limit
; i
++) {
202 while (i
< limit
&& !predicate(arr
, i
)) {
205 if (i
== limit
) break;
209 // FIXME: The 'canvasy != canvasy' test here catches NaN values but the test
210 // doesn't catch Infinity values. Could change this to
211 // !isFinite(point.canvasy), but I assume it avoids isNaN for performance?
212 if (point
.canvasy
=== null || point
.canvasy
!= point
.canvasy
) {
213 if (stepPlot
&& prevCanvasX
!== null) {
214 // Draw a horizontal line to the start of the missing data
215 ctx
.moveTo(prevCanvasX
, prevCanvasY
);
216 ctx
.lineTo(point
.canvasx
, prevCanvasY
);
218 prevCanvasX
= prevCanvasY
= null;
221 if (drawGapPoints
|| !prevCanvasX
) {
224 nextCanvasY
= iter
.hasNext
? iter
.peek
.canvasy
: null;
226 var isNextCanvasYNullOrNaN
= nextCanvasY
=== null ||
227 nextCanvasY
!= nextCanvasY
;
228 isIsolated
= (!prevCanvasX
&& isNextCanvasYNullOrNaN
);
230 // Also consider a point to be "isolated" if it's adjacent to a
231 // null point, excluding the graph edges.
232 if ((!first
&& !prevCanvasX
) ||
233 (iter
.hasNext
&& isNextCanvasYNullOrNaN
)) {
239 if (prevCanvasX
!== null) {
242 ctx
.moveTo(prevCanvasX
, prevCanvasY
);
243 ctx
.lineTo(point
.canvasx
, prevCanvasY
);
246 ctx
.lineTo(point
.canvasx
, point
.canvasy
);
249 ctx
.moveTo(point
.canvasx
, point
.canvasy
);
251 if (drawPoints
|| isIsolated
) {
252 pointsOnLine
.push([point
.canvasx
, point
.canvasy
, point
.idx
]);
254 prevCanvasX
= point
.canvasx
;
255 prevCanvasY
= point
.canvasy
;
264 * This fires the drawPointCallback functions, which draw dots on the points by
265 * default. This gets used when the "drawPoints" option is set, or when there
266 * are isolated points.
267 * @param {Object} e The dictionary passed to the plotter function.
270 DygraphCanvasRenderer
._drawPointsOnLine
= function(
271 e
, pointsOnLine
, drawPointCallback
, color
, pointSize
) {
272 var ctx
= e
.drawingContext
;
273 for (var idx
= 0; idx
< pointsOnLine
.length
; idx
++) {
274 var cb
= pointsOnLine
[idx
];
276 drawPointCallback
.call(e
.dygraph
,
277 e
.dygraph
, e
.setName
, ctx
, cb
[0], cb
[1], color
, pointSize
, cb
[2]);
283 * Attaches canvas coordinates to the points array.
286 DygraphCanvasRenderer
.prototype._updatePoints
= function() {
290 // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
291 // transformations can be pushed into the canvas via linear transformation
293 // NOTE(danvk): this is trickier than it sounds at first. The transformation
294 // needs to be done before the .moveTo() and .lineTo() calls, but must be
295 // undone before the .stroke() call to ensure that the stroke width is
296 // unaffected. An alternative is to reduce the stroke width in the
297 // transformed coordinate space, but you can't specify different values for
298 // each dimension (as you can with .scale()). The speedup here is ~12%.
299 var sets
= this.layout
.points
;
300 for (var i
= sets
.length
; i
--;) {
301 var points
= sets
[i
];
302 for (var j
= points
.length
; j
--;) {
303 var point
= points
[j
];
304 point
.canvasx
= this.area
.w
* point
.x
+ this.area
.x
;
305 point
.canvasy
= this.area
.h
* point
.y
+ this.area
.y
;
311 * Add canvas Actually draw the lines chart, including error bars.
313 * This function can only be called if DygraphLayout's points array has been
314 * updated with canvas{x,y} attributes, i.e. by
315 * DygraphCanvasRenderer._updatePoints.
317 * @param {string=} opt_seriesName when specified, only that series will
318 * be drawn. (This is used for expedited redrawing with highlightSeriesOpts)
319 * @param {CanvasRenderingContext2D} opt_ctx when specified, the drawing
320 * context. However, lines are typically drawn on the object's
324 DygraphCanvasRenderer
.prototype._renderLineChart
= function(opt_seriesName
, opt_ctx
) {
325 var ctx
= opt_ctx
|| this.elementContext
;
328 var sets
= this.layout
.points
;
329 var setNames
= this.layout
.setNames
;
332 this.colors
= this.dygraph_
.colorsMap_
;
334 // Determine which series have specialized plotters.
335 var plotter_attr
= this.dygraph_
.getOption("plotter");
336 var plotters
= plotter_attr
;
337 if (!Dygraph
.isArrayLike(plotters
)) {
338 plotters
= [plotters
];
341 var setPlotters
= {}; // series name -> plotter fn.
342 for (i
= 0; i
< setNames
.length
; i
++) {
343 setName
= setNames
[i
];
344 var setPlotter
= this.dygraph_
.getOption("plotter", setName
);
345 if (setPlotter
== plotter_attr
) continue; // not specialized.
347 setPlotters
[setName
] = setPlotter
;
350 for (i
= 0; i
< plotters
.length
; i
++) {
351 var plotter
= plotters
[i
];
352 var is_last
= (i
== plotters
.length
- 1);
354 for (var j
= 0; j
< sets
.length
; j
++) {
355 setName
= setNames
[j
];
356 if (opt_seriesName
&& setName
!= opt_seriesName
) continue;
358 var points
= sets
[j
];
360 // Only throw in the specialized plotters on the last iteration.
362 if (setName
in setPlotters
) {
364 p
= setPlotters
[setName
];
366 // Don't use the standard plotters in this case.
371 var color
= this.colors
[setName
];
372 var strokeWidth
= this.dygraph_
.getOption("strokeWidth", setName
);
375 ctx
.strokeStyle
= color
;
376 ctx
.lineWidth
= strokeWidth
;
382 strokeWidth
: strokeWidth
,
383 dygraph
: this.dygraph_
,
384 axis
: this.dygraph_
.axisPropertiesForSeries(setName
),
387 seriesCount
: sets
.length
,
388 singleSeriesName
: opt_seriesName
,
389 allSeriesPoints
: sets
397 * Standard plotters. These may be used by clients via Dygraph.Plotters.
398 * See comments there for more details.
400 DygraphCanvasRenderer
._Plotters
= {
401 linePlotter
: function(e
) {
402 DygraphCanvasRenderer
._linePlotter(e
);
405 fillPlotter
: function(e
) {
406 DygraphCanvasRenderer
._fillPlotter(e
);
409 errorPlotter
: function(e
) {
410 DygraphCanvasRenderer
._errorPlotter(e
);
415 * Plotter which draws the central lines for a series.
418 DygraphCanvasRenderer
._linePlotter
= function(e
) {
420 var setName
= e
.setName
;
421 var strokeWidth
= e
.strokeWidth
;
423 // TODO(danvk): Check if there's any performance impact of just calling
424 // getOption() inside of _drawStyledLine. Passing in so many parameters makes
425 // this code a bit nasty.
426 var borderWidth
= g
.getNumericOption("strokeBorderWidth", setName
);
427 var drawPointCallback
= g
.getOption("drawPointCallback", setName
) ||
428 Dygraph
.Circles
.DEFAULT
;
429 var strokePattern
= g
.getOption("strokePattern", setName
);
430 var drawPoints
= g
.getBooleanOption("drawPoints", setName
);
431 var pointSize
= g
.getNumericOption("pointSize", setName
);
433 if (borderWidth
&& strokeWidth
) {
434 DygraphCanvasRenderer
._drawStyledLine(e
,
435 g
.getOption("strokeBorderColor", setName
),
436 strokeWidth
+ 2 * borderWidth
,
444 DygraphCanvasRenderer
._drawStyledLine(e
,
455 * Draws the shaded error bars/confidence intervals for each series.
456 * This happens before the center lines are drawn, since the center lines
457 * need to be drawn on top of the error bars for all series.
460 DygraphCanvasRenderer
._errorPlotter
= function(e
) {
462 var setName
= e
.setName
;
463 var errorBars
= g
.getBooleanOption("errorBars") ||
464 g
.getBooleanOption("customBars");
465 if (!errorBars
) return;
467 var fillGraph
= g
.getBooleanOption("fillGraph", setName
);
469 console
.warn("Can't use fillGraph option with error bars");
472 var ctx
= e
.drawingContext
;
474 var fillAlpha
= g
.getNumericOption('fillAlpha', setName
);
475 var stepPlot
= g
.getBooleanOption("stepPlot", setName
);
476 var points
= e
.points
;
478 var iter
= Dygraph
.createIterator(points
, 0, points
.length
,
479 DygraphCanvasRenderer
._getIteratorPredicate(
480 g
.getBooleanOption("connectSeparatedPoints", setName
)));
484 // setup graphics context
487 var prevYs
= [-1, -1];
488 // should be same color as the lines but only 15% opaque.
489 var rgb
= Dygraph
.toRGB_(color
);
491 'rgba(' + rgb
.r
+ ',' + rgb
.g
+ ',' + rgb
.b
+ ',' + fillAlpha
+ ')';
492 ctx
.fillStyle
= err_color
;
495 var isNullUndefinedOrNaN
= function(x
) {
496 return (x
=== null ||
501 while (iter
.hasNext
) {
502 var point
= iter
.next();
503 if ((!stepPlot
&& isNullUndefinedOrNaN(point
.y
)) ||
504 (stepPlot
&& !isNaN(prevY
) && isNullUndefinedOrNaN(prevY
))) {
509 newYs
= [ point
.y_bottom
, point
.y_top
];
514 // The documentation specifically disallows nulls inside the point arrays,
515 // but in case it happens we should do something sensible.
516 if (isNaN(newYs
[0])) newYs
[0] = point
.y
;
517 if (isNaN(newYs
[1])) newYs
[1] = point
.y
;
519 newYs
[0] = e
.plotArea
.h
* newYs
[0] + e
.plotArea
.y
;
520 newYs
[1] = e
.plotArea
.h
* newYs
[1] + e
.plotArea
.y
;
523 ctx
.moveTo(prevX
, prevYs
[0]);
524 ctx
.lineTo(point
.canvasx
, prevYs
[0]);
525 ctx
.lineTo(point
.canvasx
, prevYs
[1]);
527 ctx
.moveTo(prevX
, prevYs
[0]);
528 ctx
.lineTo(point
.canvasx
, newYs
[0]);
529 ctx
.lineTo(point
.canvasx
, newYs
[1]);
531 ctx
.lineTo(prevX
, prevYs
[1]);
535 prevX
= point
.canvasx
;
542 * Proxy for CanvasRenderingContext2D which drops moveTo/lineTo calls which are
543 * superfluous. It accumulates all movements which haven't changed the x-value
544 * and only applies the two with the most extreme y-values.
546 * Calls to lineTo/moveTo must have non-decreasing x-values.
548 DygraphCanvasRenderer
._fastCanvasProxy
= function(context
) {
549 var pendingActions
= []; // array of [type, x, y] tuples
550 var lastRoundedX
= null;
551 var lastFlushedX
= null;
556 var actionCount
= 0; // number of moveTos and lineTos passed to context.
558 // Drop superfluous motions
559 // Assumes all pendingActions have the same (rounded) x-value.
560 var compressActions
= function(opt_losslessOnly
) {
561 if (pendingActions
.length
<= 1) return;
563 // Lossless compression: drop inconsequential moveTos.
564 for (var i
= pendingActions
.length
- 1; i
> 0; i
--) {
565 var action
= pendingActions
[i
];
566 if (action
[0] == MOVE_TO
) {
567 var prevAction
= pendingActions
[i
- 1];
568 if (prevAction
[1] == action
[1] && prevAction
[2] == action
[2]) {
569 pendingActions
.splice(i
, 1);
574 // Lossless compression: ... drop consecutive moveTos ...
575 for (var i
= 0; i
< pendingActions
.length
- 1; /* incremented internally */) {
576 var action
= pendingActions
[i
];
577 if (action
[0] == MOVE_TO
&& pendingActions
[i
+ 1][0] == MOVE_TO
) {
578 pendingActions
.splice(i
, 1);
584 // Lossy compression: ... drop all but the extreme y-values ...
585 if (pendingActions
.length
> 2 && !opt_losslessOnly
) {
586 // keep an initial moveTo, but drop all others.
588 if (pendingActions
[0][0] == MOVE_TO
) startIdx
++;
589 var minIdx
= null, maxIdx
= null;
590 for (var i
= startIdx
; i
< pendingActions
.length
; i
++) {
591 var action
= pendingActions
[i
];
592 if (action
[0] != LINE_TO
) continue;
593 if (minIdx
=== null && maxIdx
=== null) {
598 if (y
< pendingActions
[minIdx
][2]) {
600 } else if (y
> pendingActions
[maxIdx
][2]) {
605 var minAction
= pendingActions
[minIdx
],
606 maxAction
= pendingActions
[maxIdx
];
607 pendingActions
.splice(startIdx
, pendingActions
.length
- startIdx
);
608 if (minIdx
< maxIdx
) {
609 pendingActions
.push(minAction
);
610 pendingActions
.push(maxAction
);
611 } else if (minIdx
> maxIdx
) {
612 pendingActions
.push(maxAction
);
613 pendingActions
.push(minAction
);
615 pendingActions
.push(minAction
);
620 var flushActions
= function(opt_noLossyCompression
) {
621 compressActions(opt_noLossyCompression
);
622 for (var i
= 0, len
= pendingActions
.length
; i
< len
; i
++) {
623 var action
= pendingActions
[i
];
624 if (action
[0] == LINE_TO
) {
625 context
.lineTo(action
[1], action
[2]);
626 } else if (action
[0] == MOVE_TO
) {
627 context
.moveTo(action
[1], action
[2]);
630 if (pendingActions
.length
) {
631 lastFlushedX
= pendingActions
[pendingActions
.length
- 1][1];
633 actionCount
+= pendingActions
.length
;
637 var addAction
= function(action
, x
, y
) {
638 var rx
= Math
.round(x
);
639 if (lastRoundedX
=== null || rx
!= lastRoundedX
) {
640 // if there are large gaps on the x-axis, it's essential to keep the
641 // first and last point as well.
642 var hasGapOnLeft
= (lastRoundedX
- lastFlushedX
> 1),
643 hasGapOnRight
= (rx
- lastRoundedX
> 1),
644 hasGap
= hasGapOnLeft
|| hasGapOnRight
;
645 flushActions(hasGap
);
648 pendingActions
.push([action
, x
, y
]);
652 moveTo
: function(x
, y
) {
653 addAction(MOVE_TO
, x
, y
);
655 lineTo
: function(x
, y
) {
656 addAction(LINE_TO
, x
, y
);
659 // for major operations like stroke/fill
, we skip compression to ensure
660 // that there are no artifacts at the right edge.
661 stroke
: function() { flushActions(true); context
.stroke(); },
662 fill
: function() { flushActions(true); context
.fill(); },
663 beginPath
: function() { flushActions(true); context
.beginPath(); },
664 closePath
: function() { flushActions(true); context
.closePath(); },
666 _count
: function() { return actionCount
; }
671 * Draws the shaded regions when "fillGraph" is set. Not to be confused with
674 * For stacked charts, it's more convenient to handle all the series
675 * simultaneously. So this plotter plots all the points on the first series
676 * it's asked to draw, then ignores all the other series.
680 DygraphCanvasRenderer
._fillPlotter
= function(e
) {
681 // Skip if we're drawing a single series for interactive highlight overlay.
682 if (e
.singleSeriesName
) return;
684 // We'll handle all the series at once, not one-by-one.
685 if (e
.seriesIndex
!== 0) return;
688 var setNames
= g
.getLabels().slice(1); // remove x-axis
690 // getLabels() includes names for invisible series, which are not included in
691 // allSeriesPoints. We remove those to make the two match.
692 // TODO(danvk): provide a simpler way to get this information.
693 for (var i
= setNames
.length
; i
>= 0; i
--) {
694 if (!g
.visibility()[i
]) setNames
.splice(i
, 1);
697 var anySeriesFilled
= (function() {
698 for (var i
= 0; i
< setNames
.length
; i
++) {
699 if (g
.getBooleanOption("fillGraph", setNames
[i
])) return true;
704 if (!anySeriesFilled
) return;
706 var area
= e
.plotArea
;
707 var sets
= e
.allSeriesPoints
;
708 var setCount
= sets
.length
;
710 var fillAlpha
= g
.getNumericOption('fillAlpha');
711 var stackedGraph
= g
.getBooleanOption("stackedGraph");
712 var colors
= g
.getColors();
714 // For stacked graphs, track the baseline for filling.
716 // The filled areas below graph lines are trapezoids with two
717 // vertical edges. The top edge is the line segment being drawn, and
718 // the baseline is the bottom edge. Each baseline corresponds to the
719 // top line segment from the previous stacked line. In the case of
720 // step plots, the trapezoids are rectangles.
723 var prevStepPlot
; // for different line drawing modes (line/step) per series
725 // Helper function to trace a line back along the baseline.
726 var traceBackPath
= function(ctx
, baselineX
, baselineY
, pathBack
) {
727 ctx
.lineTo(baselineX
, baselineY
);
729 for (var i
= pathBack
.length
- 1; i
>= 0; i
--) {
730 var pt
= pathBack
[i
];
731 ctx
.lineTo(pt
[0], pt
[1]);
736 // process sets in reverse order (needed for stacked graphs)
737 for (var setIdx
= setCount
- 1; setIdx
>= 0; setIdx
--) {
738 var ctx
= e
.drawingContext
;
739 var setName
= setNames
[setIdx
];
740 if (!g
.getBooleanOption('fillGraph', setName
)) continue;
742 var stepPlot
= g
.getBooleanOption('stepPlot', setName
);
743 var color
= colors
[setIdx
];
744 var axis
= g
.axisPropertiesForSeries(setName
);
745 var axisY
= 1.0 + axis
.minyval
* axis
.yscale
;
746 if (axisY
< 0.0) axisY
= 0.0;
747 else if (axisY
> 1.0) axisY
= 1.0;
748 axisY
= area
.h
* axisY
+ area
.y
;
750 var points
= sets
[setIdx
];
751 var iter
= Dygraph
.createIterator(points
, 0, points
.length
,
752 DygraphCanvasRenderer
._getIteratorPredicate(
753 g
.getBooleanOption("connectSeparatedPoints", setName
)));
755 // setup graphics context
757 var prevYs
= [-1, -1];
759 // should be same color as the lines but only 15% opaque.
760 var rgb
= Dygraph
.toRGB_(color
);
762 'rgba(' + rgb
.r
+ ',' + rgb
.g
+ ',' + rgb
.b
+ ',' + fillAlpha
+ ')';
763 ctx
.fillStyle
= err_color
;
765 var last_x
, is_first
= true;
767 // If the point density is high enough, dropping segments on their way to
768 // the canvas justifies the overhead of doing so.
769 if (points
.length
> 2 * g
.width_
|| Dygraph
.FORCE_FAST_PROXY
) {
770 ctx
= DygraphCanvasRenderer
._fastCanvasProxy(ctx
);
773 // For filled charts, we draw points from left to right, then back along
774 // the x-axis to complete a shape for filling.
775 // For stacked plots, this "back path" is a more complex shape. This array
776 // stores the [x, y] values needed to trace that shape.
779 // TODO(danvk): there are a lot of options at play in this loop.
780 // The logic would be much clearer if some (e.g. stackGraph and
781 // stepPlot) were split off into separate sub-plotters.
783 while (iter
.hasNext
) {
785 if (!Dygraph
.isOK(point
.y
) && !stepPlot
) {
786 traceBackPath(ctx
, prevX
, prevYs
[1], pathBack
);
789 if (point
.y_stacked
!== null && !isNaN(point
.y_stacked
)) {
790 baseline
[point
.canvasx
] = area
.h
* point
.y_stacked
+ area
.y
;
795 if (!is_first
&& last_x
== point
.xval
) {
802 currBaseline
= baseline
[point
.canvasx
];
804 if (currBaseline
=== undefined
) {
808 lastY
= currBaseline
[0];
810 lastY
= currBaseline
;
813 newYs
= [ point
.canvasy
, lastY
];
816 // Step plots must keep track of the top and bottom of
817 // the baseline at each point.
818 if (prevYs
[0] === -1) {
819 baseline
[point
.canvasx
] = [ point
.canvasy
, axisY
];
821 baseline
[point
.canvasx
] = [ point
.canvasy
, prevYs
[0] ];
824 baseline
[point
.canvasx
] = point
.canvasy
;
828 if (isNaN(point
.canvasy
) && stepPlot
) {
829 newYs
= [ area
.y
+ area
.h
, axisY
];
831 newYs
= [ point
.canvasy
, axisY
];
835 // Move to top fill point
837 ctx
.lineTo(point
.canvasx
, prevYs
[0]);
838 ctx
.lineTo(point
.canvasx
, newYs
[0]);
840 ctx
.lineTo(point
.canvasx
, newYs
[0]);
843 // Record the baseline for the reverse path.
845 pathBack
.push([prevX
, prevYs
[1]]);
846 if (prevStepPlot
&& currBaseline
) {
847 // Draw to the bottom of the baseline
848 pathBack
.push([point
.canvasx
, currBaseline
[1]]);
850 pathBack
.push([point
.canvasx
, newYs
[1]]);
854 ctx
.moveTo(point
.canvasx
, newYs
[1]);
855 ctx
.lineTo(point
.canvasx
, newYs
[0]);
858 prevX
= point
.canvasx
;
860 prevStepPlot
= stepPlot
;
861 if (newYs
&& point
) {
862 traceBackPath(ctx
, point
.canvasx
, newYs
[1], pathBack
);
869 return DygraphCanvasRenderer
;