esri-symbol-renderer
v1.0.1
Published
Render Esri REST API symbol and renderer objects to canvas for use in legends
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Readme
Renders Esri Renderer and Symbol objects from the REST API to html canvas elements. These can then be used to render custom legends. The goal is to fully support the range of rendering options without relying directly on the Esri JS API. Fully custom legends and table of contents components can be developed without the constraints of the dojo widgets, or even used in conjunction with another mapping API.
Usage
const renderSymbols = require('esri-symbol-renderer');
let options = {
scale: 2,
blackFillPatterns: false
};
renderSymbols({ "type" : "classBreaks", ... }, options, (err, items) => {
for (var legendItem of items) {
console.log(legendItem);
}
});
>> { label: "10.0 - 1000.000000", canvas: <Canvas>}
>> { label: "1000.000001 - 5000.000000", canvas: <Canvas>}
>> { label: "8000.000001 - 10000.000000", canvas: <Canvas>}
Environment
Works in the browser using native apis, and in node via node-canvas
. For use
in node, you'll need to provide the canvas renderer as an option.
const Canvas = require('canvas-prebuilt');
renderSymbols(json, {canvas: Canvas}, callback);
Options
scale
can be used to increase the size of the output canvas. Defaults to1.0
. Base scale is 30px to match ArcGIS.com legends.includeDefaultValues
will include default symbols for uniqueValue and classBreaks renderers. Defaults tofalse
.blackFillPatterns
defaults totrue
. Fill patterns such as esriSFSForwardDiagonal will not display "correctly" in the Esri JS API. Assuming you are using the Esri API you will want to keep this set to true to match map output. If using anothe rendering method you may want to set to false to get appropriate fill colors.canvas
can be set to thenode-canvas
Canvas constructor for use in node.
Examples
Checkout the playground for renderings of test cases as well as a tool to render services by url.