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ex-00500-relative-time.ts
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ex-00500-relative-time.ts
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// ### Animated, relative time [(source)](https://github.com/wwwtyro/candygraph/blob/master/docs/examples/src/{{filename}})
// Click to toggle animation:
//
// <canvas id="ex-00500" style="box-shadow: 0px 0px 8px #ccc;" width=512 height=384></canvas>
// skip-doc-start
import CandyGraph, {
createDefaultFont,
Grid,
OrthoAxis,
LinearScale,
CartesianCoordinateSystem,
LineStrip,
} from "../../../src";
export default async function RelativeTime(cg: CandyGraph) {
const HISTORY = 1.0; // Seconds of history to keep
const TRACE_LENGTH = 5; // Number of seconds for each trace
const TRACE_RESOLUTION = 100; // Number of points per trace
// Keep track of the traces.
let traces: ReturnType<typeof createTrace>[] = [];
// Create a canvas and add it to the page.
const canvas = document.getElementById("ex-00500") as HTMLCanvasElement;
// Scale the canvas by the device pixel ratio.
const dpr = window.devicePixelRatio;
canvas.style.width = `${canvas.width}px`;
canvas.style.height = `${canvas.height}px`;
canvas.width *= dpr;
canvas.height *= dpr;
// The viewport for our plot. Units are pixels.
const viewport = { x: 0, y: 0, width: canvas.width, height: canvas.height };
// We'll make two coordinate systems; one for the x-axis, which is relative time,
// and one for the traces, which are in real time. We'll share the y scale between
// them.
const yScale = new LinearScale([0, 25], [32 * dpr, viewport.height - 16 * dpr]);
const axisCoords = new CartesianCoordinateSystem(
cg,
new LinearScale([-1, 5], [16 * dpr, viewport.width - 16 * dpr]),
yScale
);
const timeCoords = new CartesianCoordinateSystem(
cg,
new LinearScale([-1, 5], [16 * dpr, viewport.width - 16 * dpr]),
yScale
);
const font = await createDefaultFont(cg);
// Make our two axes.
const axes = [
new OrthoAxis(cg, axisCoords, "x", font, {
labelSide: 1,
tickOffset: -3 * dpr,
tickLength: 6 * dpr,
tickWidth: 1 * dpr,
axisWidth: 1 * dpr,
labelSize: 12 * dpr,
}),
new OrthoAxis(cg, axisCoords, "y", font, {
axisIntercept: 0,
labelAnchor: [1, 1.25],
tickOrigin: 0,
tickStep: 5,
tickLength: 0,
tickWidth: 1 * dpr,
axisWidth: 1 * dpr,
labelSize: 12 * dpr,
labelFormatter: (n: number) => (n === 0 ? "" : n.toString()),
}),
];
const grid = new Grid(
cg,
axes[0].computed.ticks,
axes[1].computed.ticks,
axisCoords.xscale.domain,
axisCoords.yscale.domain,
{ width: 1 * dpr }
);
function primenoise(t: number) {
const primes = [2, 3, 5, 7, 11, 13, 17, 19];
let sum = 0;
for (const p of primes) {
sum += Math.sin(t / p);
}
return sum / primes.length;
}
// Make a new trace. This is just a line strip with an associated
// timestamp. We'll make it change as a function of time to make
// the animation obvious.
function createTrace(time: number) {
const xs = [];
const ys = [];
const y0 = 12.5 + 12.5 * primenoise(32 * time);
for (let i = 0; i < TRACE_RESOLUTION; i++) {
const x = (TRACE_LENGTH * i) / (TRACE_RESOLUTION - 1);
const y = y0 + 12.5 * primenoise(4 * x + 32 * time);
xs.push(x + time);
ys.push(y);
}
return {
timestamp: time,
trace: new LineStrip(cg, xs, ys, {
colors: [1, 0, 1, 1],
widths: 3.0 * dpr,
}),
};
}
function render(time: number) {
time = time / 1000;
traces.push(createTrace(time));
// Remove old traces.
traces = traces.filter((trace) => {
if (time - trace.timestamp > HISTORY) {
trace.trace.dispose();
return false;
}
return true;
});
// Update the styling according to the age of the trace. Skip
// the most recently added trace.
for (let i = 0; i < traces.length - 1; i++) {
const trace = traces[i];
const age = time - trace.timestamp;
trace.trace.colors.update([0, 0, 0, 0.5 * (1 - age / HISTORY)])
trace.trace.widths.update(1 * dpr);
}
// Update the timeCoords.
timeCoords.xscale.domain = [time - 1, time + 5];
// Clear the canvas.
cg.clear([1, 1, 1, 1]);
// Render the grid with the relative time coordinate system.
cg.render(axisCoords, viewport, grid);
// Render the traces with the real time coordinate system.
cg.render(
timeCoords,
viewport,
traces.map((trace) => trace.trace)
);
// Render the axes with the relative time coordinate system.
cg.render(axisCoords, viewport, axes);
// Copy to our canvas.
cg.copyTo(viewport, canvas);
}
let animating = false;
function animate(time: number) {
requestAnimationFrame(animate);
if (!animating) {
return;
}
render(time);
}
document.getElementById("ex-00500")?.addEventListener("click", function () {
animating = !animating;
});
render(0);
animate(0);
}
// skip-doc-stop