electron/docs/api/screen.md
2020-07-09 10:18:49 -07:00

156 lines
4.1 KiB
Markdown

# screen
> Retrieve information about screen size, displays, cursor position, etc.
Process: [Main](../glossary.md#main-process)
This module cannot be used until the `ready` event of the `app`
module is emitted.
`screen` is an [EventEmitter][event-emitter].
**Note:** In the renderer / DevTools, `window.screen` is a reserved DOM
property, so writing `let { screen } = require('electron')` will not work.
An example of creating a window that fills the whole screen:
```javascript fiddle='docs/fiddles/screen/fit-screen'
const { app, BrowserWindow, screen } = require('electron')
let win
app.whenReady().then(() => {
const { width, height } = screen.getPrimaryDisplay().workAreaSize
win = new BrowserWindow({ width, height })
win.loadURL('https://github.com')
})
```
Another example of creating a window in the external display:
```javascript
const { app, BrowserWindow, screen } = require('electron')
let win
app.whenReady().then(() => {
const displays = screen.getAllDisplays()
const externalDisplay = displays.find((display) => {
return display.bounds.x !== 0 || display.bounds.y !== 0
})
if (externalDisplay) {
win = new BrowserWindow({
x: externalDisplay.bounds.x + 50,
y: externalDisplay.bounds.y + 50
})
win.loadURL('https://github.com')
}
})
```
## Events
The `screen` module emits the following events:
### Event: 'display-added'
Returns:
* `event` Event
* `newDisplay` [Display](structures/display.md)
Emitted when `newDisplay` has been added.
### Event: 'display-removed'
Returns:
* `event` Event
* `oldDisplay` [Display](structures/display.md)
Emitted when `oldDisplay` has been removed.
### Event: 'display-metrics-changed'
Returns:
* `event` Event
* `display` [Display](structures/display.md)
* `changedMetrics` String[]
Emitted when one or more metrics change in a `display`. The `changedMetrics` is
an array of strings that describe the changes. Possible changes are `bounds`,
`workArea`, `scaleFactor` and `rotation`.
## Methods
The `screen` module has the following methods:
### `screen.getCursorScreenPoint()`
Returns [`Point`](structures/point.md)
The current absolute position of the mouse pointer.
### `screen.getPrimaryDisplay()`
Returns [`Display`](structures/display.md) - The primary display.
### `screen.getAllDisplays()`
Returns [`Display[]`](structures/display.md) - An array of displays that are currently available.
### `screen.getDisplayNearestPoint(point)`
* `point` [Point](structures/point.md)
Returns [`Display`](structures/display.md) - The display nearest the specified point.
### `screen.getDisplayMatching(rect)`
* `rect` [Rectangle](structures/rectangle.md)
Returns [`Display`](structures/display.md) - The display that most closely
intersects the provided bounds.
### `screen.screenToDipPoint(point)` _Windows_
* `point` [Point](structures/point.md)
Returns [`Point`](structures/point.md)
Converts a screen physical point to a screen DIP point.
The DPI scale is performed relative to the display containing the physical point.
### `screen.dipToScreenPoint(point)` _Windows_
* `point` [Point](structures/point.md)
Returns [`Point`](structures/point.md)
Converts a screen DIP point to a screen physical point.
The DPI scale is performed relative to the display containing the DIP point.
### `screen.screenToDipRect(window, rect)` _Windows_
* `window` [BrowserWindow](browser-window.md) | null
* `rect` [Rectangle](structures/rectangle.md)
Returns [`Rectangle`](structures/rectangle.md)
Converts a screen physical rect to a screen DIP rect.
The DPI scale is performed relative to the display nearest to `window`.
If `window` is null, scaling will be performed to the display nearest to `rect`.
### `screen.dipToScreenRect(window, rect)` _Windows_
* `window` [BrowserWindow](browser-window.md) | null
* `rect` [Rectangle](structures/rectangle.md)
Returns [`Rectangle`](structures/rectangle.md)
Converts a screen DIP rect to a screen physical rect.
The DPI scale is performed relative to the display nearest to `window`.
If `window` is null, scaling will be performed to the display nearest to `rect`.
[event-emitter]: https://nodejs.org/api/events.html#events_class_eventemitter