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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2018-11-07 12:19:29 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2018-11-07 12:20:17 +0000 |
commit | a64a253794ac64cb40befee54db53bde17dd0d49 (patch) | |
tree | c1024acc5f6e508814b944d99f112259bb28b1be /web/gui/lib/dygraph-smooth-plotter-c91c859.js | |
parent | New upstream version 1.10.0+dfsg (diff) | |
download | netdata-2dec20452b290c484d509f7ac9a29b38cf690223.tar.xz netdata-2dec20452b290c484d509f7ac9a29b38cf690223.zip |
New upstream version 1.11.0+dfsgupstream/1.11.0+dfsg
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'web/gui/lib/dygraph-smooth-plotter-c91c859.js')
-rw-r--r-- | web/gui/lib/dygraph-smooth-plotter-c91c859.js | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/web/gui/lib/dygraph-smooth-plotter-c91c859.js b/web/gui/lib/dygraph-smooth-plotter-c91c859.js new file mode 100644 index 000000000..c0b76fb0a --- /dev/null +++ b/web/gui/lib/dygraph-smooth-plotter-c91c859.js @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: MIT +(function() { +"use strict"; + +var Dygraph; +if (window.Dygraph) { + Dygraph = window.Dygraph; +} else if (typeof(module) !== 'undefined') { + Dygraph = require('../dygraph'); +} + +/** + * Given three sequential points, p0, p1 and p2, find the left and right + * control points for p1. + * + * The three points are expected to have x and y properties. + * + * The alpha parameter controls the amount of smoothing. + * If α=0, then both control points will be the same as p1 (i.e. no smoothing). + * + * Returns [l1x, l1y, r1x, r1y] + * + * It's guaranteed that the line from (l1x, l1y)-(r1x, r1y) passes through p1. + * Unless allowFalseExtrema is set, then it's also guaranteed that: + * l1y ∈ [p0.y, p1.y] + * r1y ∈ [p1.y, p2.y] + * + * The basic algorithm is: + * 1. Put the control points l1 and r1 α of the way down (p0, p1) and (p1, p2). + * 2. Shift l1 and r2 so that the line l1–r1 passes through p1 + * 3. Adjust to prevent false extrema while keeping p1 on the l1–r1 line. + * + * This is loosely based on the HighCharts algorithm. + */ +function getControlPoints(p0, p1, p2, opt_alpha, opt_allowFalseExtrema) { + var alpha = (opt_alpha !== undefined) ? opt_alpha : 1/3; // 0=no smoothing, 1=crazy smoothing + var allowFalseExtrema = opt_allowFalseExtrema || false; + + if (!p2) { + return [p1.x, p1.y, null, null]; + } + + // Step 1: Position the control points along each line segment. + var l1x = (1 - alpha) * p1.x + alpha * p0.x, + l1y = (1 - alpha) * p1.y + alpha * p0.y, + r1x = (1 - alpha) * p1.x + alpha * p2.x, + r1y = (1 - alpha) * p1.y + alpha * p2.y; + + // Step 2: shift the points up so that p1 is on the l1–r1 line. + if (l1x != r1x) { + // This can be derived w/ some basic algebra. + var deltaY = p1.y - r1y - (p1.x - r1x) * (l1y - r1y) / (l1x - r1x); + l1y += deltaY; + r1y += deltaY; + } + + // Step 3: correct to avoid false extrema. + if (!allowFalseExtrema) { + if (l1y > p0.y && l1y > p1.y) { + l1y = Math.max(p0.y, p1.y); + r1y = 2 * p1.y - l1y; + } else if (l1y < p0.y && l1y < p1.y) { + l1y = Math.min(p0.y, p1.y); + r1y = 2 * p1.y - l1y; + } + + if (r1y > p1.y && r1y > p2.y) { + r1y = Math.max(p1.y, p2.y); + l1y = 2 * p1.y - r1y; + } else if (r1y < p1.y && r1y < p2.y) { + r1y = Math.min(p1.y, p2.y); + l1y = 2 * p1.y - r1y; + } + } + + return [l1x, l1y, r1x, r1y]; +} + +// i.e. is none of (null, undefined, NaN) +function isOK(x) { + return !!x && !isNaN(x); +}; + +// A plotter which uses splines to create a smooth curve. +// See tests/plotters.html for a demo. +// Can be controlled via smoothPlotter.smoothing +function smoothPlotter(e) { + var ctx = e.drawingContext, + points = e.points; + + ctx.beginPath(); + ctx.moveTo(points[0].canvasx, points[0].canvasy); + + // right control point for previous point + var lastRightX = points[0].canvasx, lastRightY = points[0].canvasy; + + for (var i = 1; i < points.length; i++) { + var p0 = points[i - 1], + p1 = points[i], + p2 = points[i + 1]; + p0 = p0 && isOK(p0.canvasy) ? p0 : null; + p1 = p1 && isOK(p1.canvasy) ? p1 : null; + p2 = p2 && isOK(p2.canvasy) ? p2 : null; + if (p0 && p1) { + var controls = getControlPoints({x: p0.canvasx, y: p0.canvasy}, + {x: p1.canvasx, y: p1.canvasy}, + p2 && {x: p2.canvasx, y: p2.canvasy}, + smoothPlotter.smoothing); + // Uncomment to show the control points: + // ctx.lineTo(lastRightX, lastRightY); + // ctx.lineTo(controls[0], controls[1]); + // ctx.lineTo(p1.canvasx, p1.canvasy); + lastRightX = (lastRightX !== null) ? lastRightX : p0.canvasx; + lastRightY = (lastRightY !== null) ? lastRightY : p0.canvasy; + ctx.bezierCurveTo(lastRightX, lastRightY, + controls[0], controls[1], + p1.canvasx, p1.canvasy); + lastRightX = controls[2]; + lastRightY = controls[3]; + } else if (p1) { + // We're starting again after a missing point. + ctx.moveTo(p1.canvasx, p1.canvasy); + lastRightX = p1.canvasx; + lastRightY = p1.canvasy; + } else { + lastRightX = lastRightY = null; + } + } + + ctx.stroke(); +} +smoothPlotter.smoothing = 1/3; +smoothPlotter._getControlPoints = getControlPoints; // for testing + +// older versions exported a global. +// This will be removed in the future. +// The preferred way to access smoothPlotter is via Dygraph.smoothPlotter. +window.smoothPlotter = smoothPlotter; +Dygraph.smoothPlotter = smoothPlotter; + +})(); |