307 lines
9.1 KiB
Markdown
307 lines
9.1 KiB
Markdown
# nativeImage
|
|
|
|
> Create tray, dock, and application icons using PNG or JPG files.
|
|
|
|
Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)
|
|
|
|
In Electron, for the APIs that take images, you can pass either file paths or
|
|
`NativeImage` instances. An empty image will be used when `null` is passed.
|
|
|
|
For example, when creating a tray or setting a window's icon, you can pass an
|
|
image file path as a `String`:
|
|
|
|
```javascript
|
|
const { BrowserWindow, Tray } = require('electron')
|
|
|
|
const appIcon = new Tray('/Users/somebody/images/icon.png')
|
|
let win = new BrowserWindow({ icon: '/Users/somebody/images/window.png' })
|
|
console.log(appIcon, win)
|
|
```
|
|
|
|
Or read the image from the clipboard which returns a `NativeImage`:
|
|
|
|
```javascript
|
|
const { clipboard, Tray } = require('electron')
|
|
const image = clipboard.readImage()
|
|
const appIcon = new Tray(image)
|
|
console.log(appIcon)
|
|
```
|
|
|
|
## Supported Formats
|
|
|
|
Currently `PNG` and `JPEG` image formats are supported. `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 it is recommended to include at least the following sizes in the:
|
|
|
|
* 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 *Size requirements* section in [this article][icons].
|
|
|
|
[icons]:https://msdn.microsoft.com/en-us/library/windows/desktop/dn742485(v=vs.85).aspx
|
|
|
|
## High Resolution Image
|
|
|
|
On platforms that have high-DPI support such as Apple Retina displays, you can
|
|
append `@2x` after image's base filename to mark it as a 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 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. For example:
|
|
|
|
```text
|
|
images/
|
|
├── icon.png
|
|
├── icon@2x.png
|
|
└── icon@3x.png
|
|
```
|
|
|
|
|
|
```javascript
|
|
const { Tray } = require('electron')
|
|
let appIcon = new Tray('/Users/somebody/images/icon.png')
|
|
console.log(appIcon)
|
|
```
|
|
|
|
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
|
|
|
|
Template images 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 icon so it can
|
|
adapt to both light and dark menu bars.
|
|
|
|
**Note:** Template image is only supported on macOS.
|
|
|
|
To mark an image as a template image, its filename should end with the word
|
|
`Template`. For example:
|
|
|
|
* `xxxTemplate.png`
|
|
* `xxxTemplate@2x.png`
|
|
|
|
## Methods
|
|
|
|
The `nativeImage` module has the following methods, all of which return
|
|
an instance of the `NativeImage` class:
|
|
|
|
### `nativeImage.createEmpty()`
|
|
|
|
Returns `NativeImage`
|
|
|
|
Creates an empty `NativeImage` instance.
|
|
|
|
### `nativeImage.createFromPath(path)`
|
|
|
|
* `path` String
|
|
|
|
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.
|
|
|
|
```javascript
|
|
const nativeImage = require('electron').nativeImage
|
|
|
|
let image = nativeImage.createFromPath('/Users/somebody/images/icon.png')
|
|
console.log(image)
|
|
```
|
|
|
|
### `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` Double (optional) - Defaults to 1.0.
|
|
|
|
Returns `NativeImage`
|
|
|
|
Creates a new `NativeImage` instance from `buffer`.
|
|
|
|
### `nativeImage.createFromDataURL(dataURL)`
|
|
|
|
* `dataURL` String
|
|
|
|
Returns `NativeImage`
|
|
|
|
Creates a new `NativeImage` instance from `dataURL`.
|
|
|
|
### `nativeImage.createFromNamedImage(imageName[, hslShift])` _macOS_
|
|
|
|
* `imageName` String
|
|
* `hslShift` Number[]
|
|
|
|
Returns `NativeImage`
|
|
|
|
Creates a new `NativeImage` instance from the NSImage that maps to the
|
|
given image name. See [`NSImageName`](https://developer.apple.com/documentation/appkit/nsimagename?language=objc)
|
|
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.
|
|
|
|
## Class: NativeImage
|
|
|
|
> Natively wrap images such as tray, dock, and application icons.
|
|
|
|
Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)
|
|
|
|
### Instance Methods
|
|
|
|
The following methods are available on instances of the `NativeImage` class:
|
|
|
|
#### `image.toPNG([options])`
|
|
|
|
* `options` Object (optional)
|
|
* `scaleFactor` Double (optional) - Defaults to 1.0.
|
|
|
|
Returns `Buffer` - A [Buffer][buffer] that contains the image's `PNG` encoded data.
|
|
|
|
#### `image.toJPEG(quality)`
|
|
|
|
* `quality` Integer (**required**) - Between 0 - 100.
|
|
|
|
Returns `Buffer` - A [Buffer][buffer] that contains the image's `JPEG` encoded data.
|
|
|
|
#### `image.toBitmap([options])`
|
|
|
|
* `options` Object (optional)
|
|
* `scaleFactor` Double (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` Double (optional) - Defaults to 1.0.
|
|
|
|
Returns `String` - The data URL of the image.
|
|
|
|
#### `image.getBitmap([options])`
|
|
|
|
* `options` Object (optional)
|
|
* `scaleFactor` Double (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, `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 would be 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()`
|
|
|
|
Returns [`Size`](structures/size.md)
|
|
|
|
#### `image.setTemplateImage(option)`
|
|
|
|
* `option` Boolean
|
|
|
|
Marks the image as a template image.
|
|
|
|
#### `image.isTemplateImage()`
|
|
|
|
Returns `Boolean` - Whether the image is a 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 are `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()`
|
|
|
|
Returns `Float` - The image's aspect ratio.
|
|
|
|
#### `image.addRepresentation(options)`
|
|
|
|
* `options` Object
|
|
* `scaleFactor` Double - 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 explicitly add different scale factor representations to an image. This
|
|
can be called on empty images.
|
|
|
|
[buffer]: https://nodejs.org/api/buffer.html#buffer_class_buffer
|