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Add experimental, entropy-based auto-crop

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Remove deprecated extract API
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Lovell Fuller
2016-03-05 12:29:16 +00:00
parent 38ddb3b866
commit 2034efcf55
11 changed files with 214 additions and 96 deletions
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25
docs/api.md
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@@ -125,23 +125,34 @@ Scale output to `width` x `height`. By default, the resized image is cropped to
`height` is the integral Number of pixels high the resultant image should be, between 1 and 16383. Use `null` or `undefined` to auto-scale the height to match the width.
#### crop([gravity])
#### crop([option])
Crop the resized image to the exact size specified, the default behaviour.
`gravity`, if present, is a String or an attribute of the `sharp.gravity` Object e.g. `sharp.gravity.north`.
`option`, if present, is an attribute of:
Possible values are `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` and `centre`.
The default gravity is `center`/`centre`.
* `sharp.gravity` e.g. `sharp.gravity.north`, to crop to an edge or corner, or
* `sharp.strategy` e.g. `sharp.strategy.entropy`, to crop dynamically.
Possible attributes of `sharp.gravity` are
`north`, `northeast`, `east`, `southeast`, `south`,
`southwest`, `west`, `northwest`, `center` and `centre`.
`sharp.strategy` currently contains only the experimental `entropy`,
which will retain the part of the image with the highest
[Shannon entropy](https://en.wikipedia.org/wiki/Entropy_%28information_theory%29) value.
The default option is a `center`/`centre` gravity.
```javascript
var transformer = sharp()
.resize(300, 200)
.crop(sharp.gravity.north)
.resize(200, 200)
.crop(sharp.strategy.entropy)
.on('error', function(err) {
console.log(err);
});
// Read image data from readableStream, resize and write image data to writableStream
// Read image data from readableStream
// Write 200px square auto-cropped image data to writableStream
readableStream.pipe(transformer).pipe(writableStream);
```

4
docs/changelog.md
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@@ -14,6 +14,10 @@
[#239](https://github.com/lovell/sharp/issues/239)
[@chrisriley](https://github.com/chrisriley)
* Add entropy-based strategy to determine crop region.
[#295](https://github.com/lovell/sharp/issues/295)
[@rightaway](https://github.com/rightaway)
* Expose density metadata; set density of images from vector input.
[#338](https://github.com/lovell/sharp/issues/338)
[@lookfirst](https://github.com/lookfirst)