README.md

CandyGraph

A flexible and fast-by-default 2D plotting library tuned for rendering huge datasets on the GPU at interactive speeds.

Tutorial | Examples | API Docs

• Adopts D3's elegant concept of scales, but implements them on the GPU to maximize data throughput and handle scale changes with no additional cost.
• Performs all rendering on the GPU, even axes and text. This keeps rendering and compositing fast and simple - no need to overlay a canvas or svg over your plot.
• Provides a small but growing set of highly optimized primitives that are tuned for handling huge datasets.
• Provides a set of higher-level composite objects composed of primitives to simplify common rendering tasks.

CandyGraph is still in major version zero; the API should be considered unstable.

Example

import CandyGraph, {
  createDefaultFont,
  LinearScale,
  OpaqueLineStrip,
  OrthoAxis,
  CartesianCoordinateSystem,
} from "candygraph";

async function main() {
  const cg = new CandyGraph();
  cg.canvas.width = cg.canvas.height = 384;

  // Generate some x & y data.
  const xs = [];
  const ys = [];
  for (let x = 0; x <= 1; x += 0.001) {
    xs.push(x);
    ys.push(0.5 + 0.25 * Math.sin(x * 2 * Math.PI));
  }

  // Create a viewport. Units are in pixels.
  const viewport = {
    x: 0,
    y: 0,
    width: cg.canvas.width,
    height: cg.canvas.height,
  };

  // Create a coordinate system from two linear scales. Note
  // that we add 32 pixels of padding to the left and bottom
  // of the viewport, and 16 pixels to the top and right.
  const coords = new CartesianCoordinateSystem(
    cg,
    new LinearScale([0, 1], [32, viewport.width - 16]),
    new LinearScale([0, 1], [32, viewport.height - 16])
  );

  // Load the default Lato font
  const font = await createDefaultFont(cg);

  // Clear the viewport.
  cg.clear([1, 1, 1, 1]);

  // Render the a line strip representing the x & y data, and axes.
  cg.render(coords, viewport, [
    new OpaqueLineStrip(cg, xs, ys, {
      colors: [1, 0.5, 0.0],
      widths: 3,
    }),
    new OrthoAxis(cg, coords, "x", font, {
      labelSide: 1,
      tickOffset: -2.5,
      tickLength: 6,
      tickStep: 0.2,
      labelFormatter: (n) => n.toFixed(1),
    }),
    new OrthoAxis(cg, coords, "y", font, {
      tickOffset: 2.5,
      tickLength: 6,
      tickStep: 0.2,
      labelFormatter: (n) => n.toFixed(1),
    }),
  ]);

  // Copy the plot to a new canvas and add it to the document.
  document.body.appendChild(cg.copyTo(viewport));
}

main();