+/**
+ * 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; }
+
+DygraphCanvasRenderer.prototype._drawStyledLine = function(
+ ctx, i, setName, color, strokeWidth, strokePattern, drawPoints,
+ drawPointCallback, pointSize) {
+ // TODO(konigsberg): Compute attributes outside this method call.
+ var stepPlot = this.attr_("stepPlot");
+ var firstIndexInSet = this.layout.setPointsOffsets[i];
+ var setLength = this.layout.setPointsLengths[i];
+ var points = this.layout.points;
+ if (!Dygraph.isArrayLike(strokePattern)) {
+ strokePattern = null;
+ }
+ var drawGapPoints = this.dygraph_.attr_('drawGapEdgePoints', setName);
+
+ ctx.save();
+
+ var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
+ DygraphCanvasRenderer._getIteratorPredicate(this.attr_("connectSeparatedPoints")));
+
+ var pointsOnLine;
+ var strategy;
+ if (!strokePattern || strokePattern.length <= 1) {
+ strategy = trivialStrategy(ctx, color, strokeWidth);
+ } else {
+ strategy = nonTrivialStrategy(this, ctx, color, strokeWidth, strokePattern);
+ }
+ pointsOnLine = this._drawSeries(ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, strategy);
+ this._drawPointsOnLine(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize);
+
+ ctx.restore();
+};
+
+var nonTrivialStrategy = function(renderer, ctx, color, strokeWidth, strokePattern) {
+ return new function() {
+ this.init = function() { };
+ this.finish = function() { };
+ this.startSegment = function() {
+ ctx.beginPath();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = strokeWidth;
+ };
+ this.endSegment = function() {
+ ctx.stroke(); // should this include closePath?
+ };
+ this.drawLine = function(x1, y1, x2, y2) {
+ renderer._dashedLine(ctx, x1, y1, x2, y2, strokePattern);
+ };
+ this.skipPixel = function(prevX, prevY, curX, curY) {
+ // TODO(konigsberg): optimize with http://jsperf.com/math-round-vs-hack/6 ?
+ return (Math.round(prevX) == Math.round(curX) &&
+ Math.round(prevY) == Math.round(curY));
+ };
+ };
+};
+
+var trivialStrategy = function(ctx, color, strokeWidth) {
+ return new function() {
+ this.init = function() {
+ ctx.beginPath();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = strokeWidth;
+ };
+ this.finish = function() {
+ ctx.stroke(); // should this include closePath?
+ };
+ this.startSegment = function() { };
+ this.endSegment = function() { };
+ this.drawLine = function(x1, y1, x2, y2) {
+ ctx.moveTo(x1, y1);
+ ctx.lineTo(x2, y2);
+ };
+ // don't skip pixels.
+ this.skipPixel = function() {
+ return false;
+ };
+ };
+};
+
+DygraphCanvasRenderer.prototype._drawPointsOnLine = function(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize) {
+ for (var idx = 0; idx < pointsOnLine.length; idx++) {
+ var cb = pointsOnLine[idx];
+ ctx.save();
+ drawPointCallback(
+ this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
+ ctx.restore();
+ }
+}
+
+DygraphCanvasRenderer.prototype._drawSeries = function(
+ ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints,
+ stepPlot, strategy) {
+
+ var isNullOrNaN = function(x) {
+ return (x === null || isNaN(x));
+ };
+
+ 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
+
+ strategy.init();
+
+ while(iter.hasNext()) {
+ point = iter.next();
+ if (isNullOrNaN(point.canvasy)) {
+ if (stepPlot && prevCanvasX !== null) {
+ // Draw a horizontal line to the start of the missing data
+ strategy.startSegment();
+ strategy.drawLine(prevX, prevY, point.canvasx, prevY);
+ strategy.endSegment();
+ }
+ prevCanvasX = prevCanvasY = null;
+ } else {
+ nextCanvasY = iter.hasNext() ? iter.peek().canvasy : null;
+ isIsolated = (!prevCanvasX && isNullOrNaN(nextCanvasY));
+ 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() && isNullOrNaN(nextCanvasY))) {
+ isIsolated = true;
+ }
+ }
+ if (prevCanvasX !== null) {
+ if (strategy.skipPixel(prevCanvasX, prevCanvasY, point.canvasx, point.canvasy)) {
+ continue;
+ }
+ if (strokeWidth) {
+ strategy.startSegment();
+ if (stepPlot) {
+ strategy.drawLine(prevCanvasX, prevCanvasY, point.canvasx, prevCanvasY);
+ prevCanvasX = point.canvasx;
+ }
+ strategy.drawLine(prevCanvasX, prevCanvasY, point.canvasx, point.canvasy);
+ strategy.endSegment();
+ }
+ }
+ if (drawPoints || isIsolated) {
+ pointsOnLine.push([point.canvasx, point.canvasy]);
+ }
+ prevCanvasX = point.canvasx;
+ prevCanvasY = point.canvasy;
+ }
+ first = false;
+ }
+ strategy.finish();
+ return pointsOnLine;
+};
+
+DygraphCanvasRenderer.prototype._drawLine = function(ctx, i) {
+ var setNames = this.layout.setNames;
+ var setName = setNames[i];
+
+ var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
+ var borderWidth = this.dygraph_.attr_("strokeBorderWidth", setName);
+ var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName) ||
+ Dygraph.Circles.DEFAULT;
+
+ if (borderWidth && strokeWidth) {
+ this._drawStyledLine(ctx, i, setName,
+ this.dygraph_.attr_("strokeBorderColor", setName),
+ strokeWidth + 2 * borderWidth,
+ this.dygraph_.attr_("strokePattern", setName),
+ this.dygraph_.attr_("drawPoints", setName),
+ drawPointCallback,
+ this.dygraph_.attr_("pointSize", setName));
+ }
+
+ this._drawStyledLine(ctx, i, setName,
+ this.colors[setName],
+ strokeWidth,
+ this.dygraph_.attr_("strokePattern", setName),
+ this.dygraph_.attr_("drawPoints", setName),
+ drawPointCallback,
+ this.dygraph_.attr_("pointSize", setName));
+};