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 extremeYs = null; // [minY, maxY] for lastRoundedX
+
+ 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.
if (!anySeriesFilled) return;
- var ctx = e.drawingContext;
var area = e.plotArea;
var sets = e.allSeriesPoints;
var setCount = sets.length;
// 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);
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 = [];
+
+ var traceBackPath = function(baselineX, baselineY) {
+ 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]);
+ }
+ }
+ 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.
while (iter.hasNext) {
var point = iter.next();
if (!Dygraph.isOK(point.y) && !stepPlot) {
+ traceBackPath(prevX, prevYs[1]);
prevX = NaN;
if (point.y_stacked !== null && !isNaN(point.y_stacked)) {
baseline[point.canvasx] = area.h * point.y_stacked + area.y;
}
newYs = [ point.canvasy, lastY ];
- if(stepPlot) {
+ if (stepPlot) {
// Step plots must keep track of the top and bottom of
// the baseline at each point.
- if(prevYs[0] === -1) {
+ if (prevYs[0] === -1) {
baseline[point.canvasx] = [ point.canvasy, axisY ];
} else {
baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
}
}
if (!isNaN(prevX)) {
- ctx.moveTo(prevX, prevYs[0]);
-
// Move to top fill point
if (stepPlot) {
ctx.lineTo(point.canvasx, prevYs[0]);
- } else {
ctx.lineTo(point.canvasx, newYs[0]);
- }
- // Move to bottom fill point
- if (prevStepPlot && currBaseline) {
- // Draw to the bottom of the baseline
- ctx.lineTo(point.canvasx, currBaseline[1]);
} else {
- ctx.lineTo(point.canvasx, newYs[1]);
+ ctx.lineTo(point.canvasx, newYs[0]);
}
- ctx.lineTo(prevX, prevYs[1]);
- ctx.closePath();
+ // 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) {
+ traceBackPath(point.canvasx, newYs[1]);
+ }
ctx.fill();
}
};
projects / dygraphs.git / blobdiff