# nativeImage

> Create tray, dock, and application icons using PNG or JPG files.

Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)

The `nativeImage` module provides a unified interface for manipulating
system images. These can be handy if you want to provide multiple scaled
versions of the same icon or take advantage of macOS [template images][template-image].

Electron APIs that take image files accept either file paths or
`NativeImage` instances. An empty and transparent image will be used when `null` is passed.

For example, when creating a [Tray](../api/tray.md) or setting a [BrowserWindow](../api/browser-window.md)'s
icon, you can either pass an image file path as a string:

```js title='Main Process'
const { BrowserWindow, Tray } = require('electron')

const tray = new Tray('/Users/somebody/images/icon.png')
const win = new BrowserWindow({ icon: '/Users/somebody/images/window.png' })
```

or generate a `NativeImage` instance from the same file:

```js title='Main Process'
const { BrowserWindow, nativeImage, Tray } = require('electron')

const trayIcon = nativeImage.createFromPath('/Users/somebody/images/icon.png')
const appIcon = nativeImage.createFromPath('/Users/somebody/images/window.png')
const tray = new Tray(trayIcon)
const win = new BrowserWindow({ icon: appIcon })
```

## Supported Formats

Currently, `PNG` and `JPEG` image formats are supported across all platforms.
`PNG` is recommended because of its support for transparency and lossless compression.

On Windows, you can also load `ICO` icons from file paths. For best visual
quality, we recommend including at least the following sizes:

* Small icon
  * 16x16 (100% DPI scale)
  * 20x20 (125% DPI scale)
  * 24x24 (150% DPI scale)
  * 32x32 (200% DPI scale)
* Large icon
  * 32x32 (100% DPI scale)
  * 40x40 (125% DPI scale)
  * 48x48 (150% DPI scale)
  * 64x64 (200% DPI scale)
  * 256x256

Check the _Icon Scaling_ section in the Windows [App Icon Construction][icons] reference.

[icons]: https://learn.microsoft.com/en-us/windows/apps/design/style/iconography/app-icon-construction#icon-scaling

:::note

EXIF metadata is currently not supported and will not be taken into account during
image encoding and decoding.

:::

## High Resolution Image

On platforms that support high pixel density displays (such as Apple Retina),
you can append `@2x` after image's base filename to mark it as a 2x scale
high resolution image.

For example, if `icon.png` is a normal image that has standard resolution, then
`icon@2x.png` will be treated as a high resolution image that has double
Dots per Inch (DPI) density.

If you want to support displays with different DPI densities at the same time,
you can put images with different sizes in the same folder and use the filename
without DPI suffixes within Electron. For example:

```plaintext
images/
├── icon.png
├── icon@2x.png
└── icon@3x.png
```

```js title='Main Process'
const { Tray } = require('electron')
const appTray = new Tray('/Users/somebody/images/icon.png')
```

The following suffixes for DPI are also supported:

* `@1x`
* `@1.25x`
* `@1.33x`
* `@1.4x`
* `@1.5x`
* `@1.8x`
* `@2x`
* `@2.5x`
* `@3x`
* `@4x`
* `@5x`

## Template Image _macOS_

On macOS, [template images][template-image] consist of black and an alpha channel.
Template images are not intended to be used as standalone images and are usually
mixed with other content to create the desired final appearance.

The most common case is to use template images for a menu bar (Tray) icon, so it can
adapt to both light and dark menu bars.

To mark an image as a template image, its base filename should end with the word
`Template` (e.g. `xxxTemplate.png`). You can also specify template images at
different DPI densities (e.g. `xxxTemplate@2x.png`).

## Methods

The `nativeImage` module has the following methods, all of which return
an instance of the [`NativeImage`](#class-nativeimage) class:

### `nativeImage.createEmpty()`

Returns `NativeImage`

Creates an empty `NativeImage` instance.

### `nativeImage.createThumbnailFromPath(path, size)` _macOS_ _Windows_

* `path` string - path to a file that we intend to construct a thumbnail out of.
* `size` [Size](structures/size.md) - the desired width and height (positive numbers) of the thumbnail.

Returns `Promise<NativeImage>` - fulfilled with the file's thumbnail preview image, which is a [NativeImage](native-image.md).

Note: The Windows implementation will ignore `size.height` and scale the height according to `size.width`.

### `nativeImage.createFromPath(path)`

* `path` string - path to a file that we intend to construct an image out of.

Returns `NativeImage`

Creates a new `NativeImage` instance from a file located at `path`. This method
returns an empty image if the `path` does not exist, cannot be read, or is not
a valid image.

```js
const { nativeImage } = require('electron')

const image = nativeImage.createFromPath('/Users/somebody/images/icon.png')
console.log(image)
```

### `nativeImage.createFromBitmap(buffer, options)`

* `buffer` [Buffer][buffer]
* `options` Object
  * `width` Integer
  * `height` Integer
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `NativeImage`

Creates a new `NativeImage` instance from `buffer` that contains the raw bitmap
pixel data returned by `toBitmap()`. The specific format is platform-dependent.

### `nativeImage.createFromBuffer(buffer[, options])`

* `buffer` [Buffer][buffer]
* `options` Object (optional)
  * `width` Integer (optional) - Required for bitmap buffers.
  * `height` Integer (optional) - Required for bitmap buffers.
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `NativeImage`

Creates a new `NativeImage` instance from `buffer`. Tries to decode as PNG or JPEG first.

### `nativeImage.createFromDataURL(dataURL)`

* `dataURL` string

Returns `NativeImage`

Creates a new `NativeImage` instance from `dataUrl`, a base 64 encoded [Data URL][data-url] string.

### `nativeImage.createFromNamedImage(imageName[, hslShift])` _macOS_

* `imageName` string
* `hslShift` number[] (optional)

Returns `NativeImage`

Creates a new `NativeImage` instance from the `NSImage` that maps to the
given image name. See Apple's [`NSImageName`](https://developer.apple.com/documentation/appkit/nsimagename#2901388)
documentation for a list of possible values.

The `hslShift` is applied to the image with the following rules:

* `hsl_shift[0]` (hue): The absolute hue value for the image - 0 and 1 map
    to 0 and 360 on the hue color wheel (red).
* `hsl_shift[1]` (saturation): A saturation shift for the image, with the
    following key values:
    0 = remove all color.
    0.5 = leave unchanged.
    1 = fully saturate the image.
* `hsl_shift[2]` (lightness): A lightness shift for the image, with the
    following key values:
    0 = remove all lightness (make all pixels black).
    0.5 = leave unchanged.
    1 = full lightness (make all pixels white).

This means that `[-1, 0, 1]` will make the image completely white and
`[-1, 1, 0]` will make the image completely black.

In some cases, the `NSImageName` doesn't match its string representation; one example of this is `NSFolderImageName`, whose string representation would actually be `NSFolder`. Therefore, you'll need to determine the correct string representation for your image before passing it in. This can be done with the following:

```sh
echo -e '#import <Cocoa/Cocoa.h>\nint main() { NSLog(@"%@", SYSTEM_IMAGE_NAME); }' | clang -otest -x objective-c -framework Cocoa - && ./test
```

where `SYSTEM_IMAGE_NAME` should be replaced with any value from [this list](https://developer.apple.com/documentation/appkit/nsimagename?language=objc).

## Class: NativeImage

> Natively wrap images such as tray, dock, and application icons.

Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)<br />
_This class is not exported from the `'electron'` module. It is only available as a return value of other methods in the Electron API._

### Instance Methods

The following methods are available on instances of the `NativeImage` class:

#### `image.toPNG([options])`

* `options` Object (optional)
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `Buffer` - A [Buffer][buffer] that contains the image's `PNG` encoded data.

#### `image.toJPEG(quality)`

* `quality` Integer - Between 0 - 100.

Returns `Buffer` - A [Buffer][buffer] that contains the image's `JPEG` encoded data.

#### `image.toBitmap([options])`

* `options` Object (optional)
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `Buffer` - A [Buffer][buffer] that contains a copy of the image's raw bitmap pixel
data.

#### `image.toDataURL([options])`

* `options` Object (optional)
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `string` - The [Data URL][data-url] of the image.

#### `image.getBitmap([options])`

* `options` Object (optional)
  * `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `Buffer` - A [Buffer][buffer] that contains the image's raw bitmap pixel data.

The difference between `getBitmap()` and `toBitmap()` is that `getBitmap()` does not
copy the bitmap data, so you have to use the returned Buffer immediately in
current event loop tick; otherwise the data might be changed or destroyed.

#### `image.getNativeHandle()` _macOS_

Returns `Buffer` - A [Buffer][buffer] that stores C pointer to underlying native handle of
the image. On macOS, a pointer to `NSImage` instance is returned.

Notice that the returned pointer is a weak pointer to the underlying native
image instead of a copy, so you _must_ ensure that the associated
`nativeImage` instance is kept around.

#### `image.isEmpty()`

Returns `boolean` - Whether the image is empty.

#### `image.getSize([scaleFactor])`

* `scaleFactor` Number (optional) - Defaults to 1.0.

Returns [`Size`](structures/size.md).

If `scaleFactor` is passed, this will return the size corresponding to the image representation most closely matching the passed value.

#### `image.setTemplateImage(option)`

* `option` boolean

Marks the image as a macOS [template image][template-image].

#### `image.isTemplateImage()`

Returns `boolean` - Whether the image is a macOS [template image][template-image].

#### `image.crop(rect)`

* `rect` [Rectangle](structures/rectangle.md) - The area of the image to crop.

Returns `NativeImage` - The cropped image.

#### `image.resize(options)`

* `options` Object
  * `width` Integer (optional) - Defaults to the image's width.
  * `height` Integer (optional) - Defaults to the image's height.
  * `quality` string (optional) - The desired quality of the resize image.
    Possible values include `good`, `better`, or `best`. The default is `best`.
    These values express a desired quality/speed tradeoff. They are translated
    into an algorithm-specific method that depends on the capabilities
    (CPU, GPU) of the underlying platform. It is possible for all three methods
    to be mapped to the same algorithm on a given platform.

Returns `NativeImage` - The resized image.

If only the `height` or the `width` are specified then the current aspect ratio
will be preserved in the resized image.

#### `image.getAspectRatio([scaleFactor])`

* `scaleFactor` Number (optional) - Defaults to 1.0.

Returns `Number` - The image's aspect ratio (width divided by height).

If `scaleFactor` is passed, this will return the aspect ratio corresponding to the image representation most closely matching the passed value.

#### `image.getScaleFactors()`

Returns `Number[]` - An array of all scale factors corresponding to representations for a given `NativeImage`.

#### `image.addRepresentation(options)`

* `options` Object
  * `scaleFactor` Number (optional) - The scale factor to add the image representation for.
  * `width` Integer (optional) - Defaults to 0. Required if a bitmap buffer
    is specified as `buffer`.
  * `height` Integer (optional) - Defaults to 0. Required if a bitmap buffer
    is specified as `buffer`.
  * `buffer` Buffer (optional) - The buffer containing the raw image data.
  * `dataURL` string (optional) - The data URL containing either a base 64
    encoded PNG or JPEG image.

Add an image representation for a specific scale factor. This can be used
to programmatically add different scale factor representations to an image. This
can be called on empty images.

### Instance Properties

#### `nativeImage.isMacTemplateImage` _macOS_

A `boolean` property that determines whether the image is considered a [template image][template-image].

Please note that this property only has an effect on macOS.

[buffer]: https://nodejs.org/api/buffer.html#buffer_class_buffer
[data-url]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs
[template-image]: https://developer.apple.com/documentation/appkit/nsimage/1520017-template
