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File extend, extract and trim ops under 'resize' #1135
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Should make them easier to find in the docs
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@lovell
lovell committed Sep 22, 2018
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110 changes: 14 additions & 96 deletions docs/api-operation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -38,54 +38,14 @@ readableStream.pipe(pipeline);

Returns **Sharp**

## extract

Extract a region of the image.

- Use `extract` before `resize` for pre-resize extraction.
- Use `extract` after `resize` for post-resize extraction.
- Use `extract` before and after for both.

### Parameters

- `options` **[Object][3]**
- `options.left` **[Number][1]** zero-indexed offset from left edge
- `options.top` **[Number][1]** zero-indexed offset from top edge
- `options.width` **[Number][1]** dimension of extracted image
- `options.height` **[Number][1]** dimension of extracted image

### Examples

```javascript
sharp(input)
.extract({ left: left, top: top, width: width, height: height })
.toFile(output, function(err) {
// Extract a region of the input image, saving in the same format.
});
```

```javascript
sharp(input)
.extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
.resize(width, height)
.extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
.toFile(output, function(err) {
// Extract a region, resize, then extract from the resized image
});
```

- Throws **[Error][2]** Invalid parameters

Returns **Sharp**

## flip

Flip the image about the vertical Y axis. This always occurs after rotation, if any.
The use of `flip` implies the removal of the EXIF `Orientation` tag, if any.

### Parameters

- `flip` **[Boolean][4]** (optional, default `true`)
- `flip` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand All @@ -96,7 +56,7 @@ The use of `flop` implies the removal of the EXIF `Orientation` tag, if any.

### Parameters

- `flop` **[Boolean][4]** (optional, default `true`)
- `flop` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand Down Expand Up @@ -143,35 +103,6 @@ When a `sigma` is provided, performs a slower, more accurate Gaussian blur.
- `sigma` **[Number][1]?** a value between 0.3 and 1000 representing the sigma of the Gaussian mask, where `sigma = 1 + radius / 2`.


- Throws **[Error][2]** Invalid parameters

Returns **Sharp**

## extend

Extends/pads the edges of the image with the colour provided to the `background` method.
This operation will always occur after resizing and extraction, if any.

### Parameters

- `extend` **([Number][1] \| [Object][3])** single pixel count to add to all edges or an Object with per-edge counts
- `extend.top` **[Number][1]?**
- `extend.left` **[Number][1]?**
- `extend.bottom` **[Number][1]?**
- `extend.right` **[Number][1]?**

### Examples

```javascript
// Resize to 140 pixels wide, then add 10 transparent pixels
// to the top, left and right edges and 20 to the bottom edge
sharp(input)
.resize(140)
.background({r: 0, g: 0, b: 0, alpha: 0})
.extend({top: 10, bottom: 20, left: 10, right: 10})
...
```

- Throws **[Error][2]** Invalid parameters

Returns **Sharp**
Expand All @@ -182,20 +113,7 @@ Merge alpha transparency channel, if any, with `background`.

### Parameters

- `flatten` **[Boolean][4]** (optional, default `true`)

Returns **Sharp**

## trim

Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel.

### Parameters

- `tolerance` **[Number][1]** value between 1 and 99 representing the percentage similarity. (optional, default `10`)


- Throws **[Error][2]** Invalid parameters
- `flatten` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand All @@ -222,7 +140,7 @@ Produce the "negative" of the image.

### Parameters

- `negate` **[Boolean][4]** (optional, default `true`)
- `negate` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand All @@ -232,7 +150,7 @@ Enhance output image contrast by stretching its luminance to cover the full dyna

### Parameters

- `normalise` **[Boolean][4]** (optional, default `true`)
- `normalise` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand All @@ -242,7 +160,7 @@ Alternative spelling of normalise.

### Parameters

- `normalize` **[Boolean][4]** (optional, default `true`)
- `normalize` **[Boolean][3]** (optional, default `true`)

Returns **Sharp**

Expand All @@ -252,7 +170,7 @@ Convolve the image with the specified kernel.

### Parameters

- `kernel` **[Object][3]**
- `kernel` **[Object][4]**
- `kernel.width` **[Number][1]** width of the kernel in pixels.
- `kernel.height` **[Number][1]** width of the kernel in pixels.
- `kernel.kernel` **[Array][5]<[Number][1]>** Array of length `width*height` containing the kernel values.
Expand Down Expand Up @@ -286,9 +204,9 @@ Any pixel value greather than or equal to the threshold value will be set to 255
### Parameters

- `threshold` **[Number][1]** a value in the range 0-255 representing the level at which the threshold will be applied. (optional, default `128`)
- `options` **[Object][3]?**
- `options.greyscale` **[Boolean][4]** convert to single channel greyscale. (optional, default `true`)
- `options.grayscale` **[Boolean][4]** alternative spelling for greyscale. (optional, default `true`)
- `options` **[Object][4]?**
- `options.greyscale` **[Boolean][3]** convert to single channel greyscale. (optional, default `true`)
- `options.grayscale` **[Boolean][3]** alternative spelling for greyscale. (optional, default `true`)


- Throws **[Error][2]** Invalid parameters
Expand All @@ -306,8 +224,8 @@ the selected bitwise boolean `operation` between the corresponding pixels of the

- `operand` **([Buffer][6] \| [String][7])** Buffer containing image data or String containing the path to an image file.
- `operator` **[String][7]** one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
- `options` **[Object][3]?**
- `options.raw` **[Object][3]?** describes operand when using raw pixel data.
- `options` **[Object][4]?**
- `options.raw` **[Object][4]?** describes operand when using raw pixel data.
- `options.raw.width` **[Number][1]?**
- `options.raw.height` **[Number][1]?**
- `options.raw.channels` **[Number][1]?**
Expand Down Expand Up @@ -335,9 +253,9 @@ Returns **Sharp**

[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
[4]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object

[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

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82 changes: 82 additions & 0 deletions docs/api-resize.md
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Expand Up @@ -163,6 +163,88 @@ The default behaviour _before_ function call is `false`, meaning the image will

Returns **Sharp**

## extend

Extends/pads the edges of the image with the colour provided to the `background` method.
This operation will always occur after resizing and extraction, if any.

### Parameters

- `extend` **([Number][4] \| [Object][5])** single pixel count to add to all edges or an Object with per-edge counts
- `extend.top` **[Number][4]?**
- `extend.left` **[Number][4]?**
- `extend.bottom` **[Number][4]?**
- `extend.right` **[Number][4]?**

### Examples

```javascript
// Resize to 140 pixels wide, then add 10 transparent pixels
// to the top, left and right edges and 20 to the bottom edge
sharp(input)
.resize(140)
.background({r: 0, g: 0, b: 0, alpha: 0})
.extend({top: 10, bottom: 20, left: 10, right: 10})
...
```

- Throws **[Error][8]** Invalid parameters

Returns **Sharp**

## extract

Extract a region of the image.

- Use `extract` before `resize` for pre-resize extraction.
- Use `extract` after `resize` for post-resize extraction.
- Use `extract` before and after for both.

### Parameters

- `options` **[Object][5]**
- `options.left` **[Number][4]** zero-indexed offset from left edge
- `options.top` **[Number][4]** zero-indexed offset from top edge
- `options.width` **[Number][4]** dimension of extracted image
- `options.height` **[Number][4]** dimension of extracted image

### Examples

```javascript
sharp(input)
.extract({ left: left, top: top, width: width, height: height })
.toFile(output, function(err) {
// Extract a region of the input image, saving in the same format.
});
```

```javascript
sharp(input)
.extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
.resize(width, height)
.extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
.toFile(output, function(err) {
// Extract a region, resize, then extract from the resized image
});
```

- Throws **[Error][8]** Invalid parameters

Returns **Sharp**

## trim

Trim "boring" pixels from all edges that contain values within a percentage similarity of the top-left pixel.

### Parameters

- `tolerance` **[Number][4]** value between 1 and 99 representing the percentage similarity. (optional, default `10`)


- Throws **[Error][8]** Invalid parameters

Returns **Sharp**

[1]: http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation

[2]: https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
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