108 lines
3.2 KiB
Markdown
108 lines
3.2 KiB
Markdown
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# path2d-polyfill
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[](https://github.com/nilzona/path2d-polyfill/actions/workflows/validate.yaml)
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Polyfills `Path2D` api and `roundRect` for CanvasRenderingContext2D
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## Usage
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Add this script tag to your page to enable the feature.
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```html
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<script lang="javascript" src="https://cdn.jsdelivr.net/npm/path2d-polyfill/dist/path2d-polyfill.min.js"></script>
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```
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or install from npm
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```shell
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npm install --save path2d-polyfill
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```
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and import with module bundler e.g. webpack _before_ using the feature
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```javascript
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import "path2d-polyfill";
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```
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This will polyfill the browser's window object with Path2D features and it will also polyfill roundRect if they are missing in both CanvasRenderingContexst and Path2D.
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Example of usage
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```javascript
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ctx.fill(new Path2D("M 80 80 A 45 45 0 0 0 125 125 L 125 80 Z"));
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ctx.stroke(new Path2D("M 80 80 A 45 45 0 0 0 125 125 L 125 80 Z"));
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```
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## Usage in a node environment
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It is possible to use this library in a node environment as well. The package exports a few functions that can be used:
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- `Path2D` - class to create Path2D objects used by the polyfill methods
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- `polyfillPath2D` - function that adds Path2D to a "window like" object and polyfills CanvasRenderingContext2D to use Path2D
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- `polyfillRoundRect` - polyfills roundRect function on Path2D and CanvasRenderingContext2D (missing in firefox)
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- `parsePath` - function for parsing an SVG path string into canvas commands
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use any of these functions like:
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```js
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const { polyfillRoundRect } = require "path2d-polyfill";
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const windowlike = { CanvasRenderingContext2D, Path2D };
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polyfillRoundRect(windowLike);
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// roundRect functions has now been added if they were missing
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```
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### usage with node-canvas
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To get Path2D features with the [node-canvas library](https://github.com/Automattic/node-canvas) use the following pattern:
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```js
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const { createCanvas, CanvasRenderingContext2D } = require("canvas");
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const { polyfillPath2D } = require("path2d-polyfill/path2d");
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global.CanvasRenderingContext2D = CanvasRenderingContext2D;
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polyfillPath2D(global);
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// Path2D has now been added to global object
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const canvas = createCanvas(200, 200);
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const ctx = canvas.getContext("2d");
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const p = new Path2D("M10 10 l 20 0 l 0 20 Z");
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ctx.fillStyle = "green";
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ctx.fill(p);
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```
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A working example of a node express server that serves an image drawn with canvas can be seen [here](https://gist.github.com/nilzona/e611c99336d8ea1f645bd391a459c24f)
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## Support table
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| Method | Supported |
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| -------------------- | :-------: |
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| constructor(SVGPath) | Yes |
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| addPath() | Yes |
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| closePath() | Yes |
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| moveTo() | Yes |
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| lineTo() | Yes |
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| bezierCurveTo() | Yes |
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| quadraticCurveTo() | Yes |
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| arc() | Yes |
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| ellipse() | Yes |
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| rect() | Yes |
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| roundRect() | Yes |
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## See it in action
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Clone this repo and run the following
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```shell
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yarn
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yarn start
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```
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open <http://localhost:10001> to see the example page.
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## Contributing
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Recommended to use vscode with the prettier extension to keep formatting intact.
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