DC School BudgetsHot spotsZIP codesMy U.S. Map (Canvas)Planes IIPIREPMy U.S. Map (SVG)Earthquakes on Mapbox GLMapzen DEMMapbox + ThreeChoropleth with OpenLayersHello, LeafletMy Zoom to Bounding BoxD3 + LeafletProject to Bounding BoxZoom to CountyBrushable earthquakesStinkyMapLibre quakesHello, MapLibre!MapLibre earthquake slider
devicePixelRatio
demo(2) // high resolution
demo(1) // low resolution (relatively fuzzy on a retina display)
function demo(scale = 1) {
const canvas = html`<canvas>`
var ctx = canvas.getContext('2d');
// Set display size (css pixels).
var size = 200;
canvas.style.width = size + "px";
canvas.style.height = size + "px";
// Set actual size in memory (scaled to account for extra pixel density).
//var scale = window.devicePixelRatio; // Change to 1 on retina screens to see blurry canvas.
canvas.width = Math.floor(size * scale);
canvas.height = Math.floor(size * scale);
// Normalize coordinate system to use css pixels.
ctx.scale(scale, scale);
ctx.fillStyle = "#bada55";
ctx.fillRect(10, 10, 300, 300);
ctx.fillStyle = "#ffffff";
ctx.font = '18px Arial';
ctx.textAlign = 'center';
ctx.textBaseline = 'middle';
var x = size / 2;
var y = size / 2;
var textString = "I love MDN";
ctx.fillText(textString, x, y);
return canvas
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.