c83f836faf* docs: add references to app.whenReady() in isReady
* refactor: prefer app.whenReady()
In the docs, specs, and lib, replace instances of `app.once('ready')`
(seen occasionally) and `app.on('ready')` (extremely common) with
`app.whenReady()`.
It's better to encourage users to use whenReady():
1. it handles the edge case of registering for 'ready' after it's fired
2. it avoids the minor wart of leaving an active listener alive for
an event that wll never fire again
156 lines
4.1 KiB
Markdown
156 lines
4.1 KiB
Markdown
# screen
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> Retrieve information about screen size, displays, cursor position, etc.
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Process: [Main](../glossary.md#main-process)
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This module cannot be used until the `ready` event of the `app`
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module is emitted.
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`screen` is an [EventEmitter][event-emitter].
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**Note:** In the renderer / DevTools, `window.screen` is a reserved DOM
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property, so writing `let { screen } = require('electron')` will not work.
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An example of creating a window that fills the whole screen:
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```javascript fiddle='docs/fiddles/screen/fit-screen'
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const { app, BrowserWindow, screen } = require('electron')
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let win
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app.whenReady().then(() => {
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const { width, height } = screen.getPrimaryDisplay().workAreaSize
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win = new BrowserWindow({ width, height })
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win.loadURL('https://github.com')
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})
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```
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Another example of creating a window in the external display:
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```javascript
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const { app, BrowserWindow, screen } = require('electron')
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let win
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app.whenReady().then(() => {
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let displays = screen.getAllDisplays()
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let externalDisplay = displays.find((display) => {
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return display.bounds.x !== 0 || display.bounds.y !== 0
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})
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if (externalDisplay) {
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win = new BrowserWindow({
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x: externalDisplay.bounds.x + 50,
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y: externalDisplay.bounds.y + 50
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})
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win.loadURL('https://github.com')
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}
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})
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```
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## Events
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The `screen` module emits the following events:
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### Event: 'display-added'
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Returns:
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* `event` Event
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* `newDisplay` [Display](structures/display.md)
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Emitted when `newDisplay` has been added.
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### Event: 'display-removed'
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Returns:
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* `event` Event
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* `oldDisplay` [Display](structures/display.md)
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Emitted when `oldDisplay` has been removed.
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### Event: 'display-metrics-changed'
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Returns:
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* `event` Event
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* `display` [Display](structures/display.md)
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* `changedMetrics` String[]
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Emitted when one or more metrics change in a `display`. The `changedMetrics` is
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an array of strings that describe the changes. Possible changes are `bounds`,
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`workArea`, `scaleFactor` and `rotation`.
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## Methods
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The `screen` module has the following methods:
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### `screen.getCursorScreenPoint()`
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Returns [`Point`](structures/point.md)
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The current absolute position of the mouse pointer.
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### `screen.getPrimaryDisplay()`
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Returns [`Display`](structures/display.md) - The primary display.
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### `screen.getAllDisplays()`
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Returns [`Display[]`](structures/display.md) - An array of displays that are currently available.
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### `screen.getDisplayNearestPoint(point)`
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* `point` [Point](structures/point.md)
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Returns [`Display`](structures/display.md) - The display nearest the specified point.
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### `screen.getDisplayMatching(rect)`
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* `rect` [Rectangle](structures/rectangle.md)
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Returns [`Display`](structures/display.md) - The display that most closely
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intersects the provided bounds.
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### `screen.screenToDipPoint(point)` _Windows_
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* `point` [Point](structures/point.md)
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Returns [`Point`](structures/point.md)
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Converts a screen physical point to a screen DIP point.
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The DPI scale is performed relative to the display containing the physical point.
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### `screen.dipToScreenPoint(point)` _Windows_
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* `point` [Point](structures/point.md)
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Returns [`Point`](structures/point.md)
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Converts a screen DIP point to a screen physical point.
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The DPI scale is performed relative to the display containing the DIP point.
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### `screen.screenToDipRect(window, rect)` _Windows_
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* `window` [BrowserWindow](browser-window.md) | null
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* `rect` [Rectangle](structures/rectangle.md)
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Returns [`Rectangle`](structures/rectangle.md)
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Converts a screen physical rect to a screen DIP rect.
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The DPI scale is performed relative to the display nearest to `window`.
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If `window` is null, scaling will be performed to the display nearest to `rect`.
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### `screen.dipToScreenRect(window, rect)` _Windows_
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* `window` [BrowserWindow](browser-window.md) | null
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* `rect` [Rectangle](structures/rectangle.md)
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Returns [`Rectangle`](structures/rectangle.md)
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Converts a screen DIP rect to a screen physical rect.
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The DPI scale is performed relative to the display nearest to `window`.
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If `window` is null, scaling will be performed to the display nearest to `rect`.
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[event-emitter]: https://nodejs.org/api/events.html#events_class_eventemitter
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