96 lines
4.1 KiB
Markdown
96 lines
4.1 KiB
Markdown
# image-pixels [](https://travis-ci.org/dy/image-pixels) [](http://github.com/badges/stability-badges)
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Get pixel data for a given URL, path, buffer, canvas, image or any other source. Intented for image based tests, first of all.
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## Usage
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[](http://npmjs.org/package/image-pixels)
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```javascript
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var pixels = require('image-pixels')
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// load single source
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var {data, width, height} = await pixels('lena.png')
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// load multiple sources in parallel
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var [a, b, c] = await pixels.all([
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'./a.jpg',
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{ source: './b.png', cache: false },
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canvas
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])
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```
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## API
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### `let {data, width, height} = await pixels(source, options?, cb?)`
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Loads pixel data from a `source` based on options. Possibly provide a callback for old-style async calls. Function returns a promise that gets resolved once the source is ready, so that is handy for await call.
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In browser the result is `ImageData` object to easily output to context:
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```js
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document.body.appendChild(document.createElement('canvas'))
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.getContext('2d')
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.putImageData(await pixels('lena.png'))
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```
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#### `source`
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Type | Meaning
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---|---
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`url`, `path` | Relative/absolute path.
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`data-uri`, `base64` | String with encoded or raw pixel data. Raw data requires `options.shape`. Encoded data may require `options.type` to skip mime type detection.
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`HTMLImageElement`, `SVGImageElement`, `HTMLVideoElement`, `CSSImageValue` | DOM/SVG image elements.
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`Image`, `ImageData`, `ImageBitmap` | Browser image data containers.
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`File`, `Blob` | Encoded image data.
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`Canvas`, `Context2D` | 2D drawing context, browser-only.
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`WebGLContext` | GL context, node/browser.
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`Buffer`, `ArrayBuffer`, `Uint8Array`, `Uint8ClampedArray` | Raw or encoded pixel data. Raw data requires `options.shape`. For encoded data `options.type`skips mime type detection. Supported formats: `png`, `bmp`, `gif`, `jpg`.
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`Float32Array`, `Float64Array`, `Array`, `Array` of arrays | Float pixel data with values from `0..1` range.
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`Promise` | Promise expecting resolution to an image source.
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`ndarray` | [Ndarray](https://ghub.io/ndarray) container with pixel data, compatible with [get-pixels](https://ghub.io/get-pixels).
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options object | If `source` argument is omitted, it is taken from `options.source`, useful for `pixels.all`.
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#### `options`
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Option | Meaning
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---|---
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`source` | Source data, one from the list above. Applicable for multiple sources.
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`shape` or `width`/`height` | Input raw data shape `[width, height]`.
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`type`/`mime` | Mime type, optional for raw data to skip detection.
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`clip` | Clipping rectangle, `[left, top, right, bottom]` or `{x?, y?, width?, height?}`.
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`cache` | Cache loaded data for the source/url for faster subsequent fetch.
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### `let list|dict = await pixels.all(list|dict, options?)`
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Load multiple sources or dict of sources in parallel. `options` can provide common for every source options.
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```js
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// load font atlas sprite dict
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var atlas = require('font-atlas')({chars: 'abc', step: [10, 10], shape: [20, 20]})
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var dict = await pixels({
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a: {clip: [0,0,10,10]},
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b: {clip: [10,0,10,10]},
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c: {clip: [0,10,10,10]}
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}, {cache: true, source: atlas})
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```
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## Related packages
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* [image-save](https://ghub.io/image-save) − save image/pixel data to a file, canvas or array.
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* [image-equal](https://ghub.io/image-equal) − assert image with baseline.
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## Similar packages
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* [get-pixels](https://ghub.io/get-pixels) − get ndarray with pixel data, limited set of sources.
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* [ndarray-from-image](https://github.com/thibauts/ndarray-from-image) − get-pixels with dtype.
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* [get-image-pixels](https://ghub.io/get-image-pixels) − get pixel data for Canvas/Image/Video elements, browser-only.
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* [get-image-data](https://ghub.io/get-image-data) − get image data for Canvas/Image/Video elements, browser-only.
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* [readimage](https://ghub.io/readimage) − read pixels data into an array in sync fashion in node.
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## License
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© 2018 Dmitry Yv. MIT License.
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