mirror of https://github.com/electron/electron
117 lines
3.5 KiB
Markdown
117 lines
3.5 KiB
Markdown
---
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title: Progress Bars
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description: Provide progress information to users outside of a BrowserWindow.
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slug: progress-bar
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hide_title: true
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---
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# Progress Bars
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## Overview
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A progress bar enables a window to provide progress information to the user
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without the need of switching to the window itself.
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On Windows, you can use a taskbar button to display a progress bar.
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On macOS, the progress bar will be displayed as a part of the dock icon.
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On Linux, the Unity graphical interface also has a similar feature that allows
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you to specify the progress bar in the launcher.
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> NOTE: on Windows, each window can have its own progress bar, whereas on macOS
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and Linux (Unity) there can be only one progress bar for the application.
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----
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All three cases are covered by the same API - the
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[`setProgressBar()`][setprogressbar] method available on an instance of
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`BrowserWindow`. To indicate your progress, call this method with a number
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between `0` and `1`. For example, if you have a long-running task that is
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currently at 63% towards completion, you would call it as
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`setProgressBar(0.63)`.
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Setting the parameter to negative values (e.g. `-1`) will remove the progress
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bar. Setting it to a value greater than `1` will indicate an indeterminate progress bar
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in Windows or clamp to 100% in other operating systems. An indeterminate progress bar
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remains active but does not show an actual percentage, and is used for situations when
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you do not know how long an operation will take to complete.
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See the [API documentation for more options and modes][setprogressbar].
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## Example
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In this example, we add a progress bar to the main window that increments over time
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using Node.js timers.
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```fiddle docs/fiddles/features/progress-bar
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const { app, BrowserWindow } = require('electron/main')
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let progressInterval
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function createWindow () {
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const win = new BrowserWindow({
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width: 800,
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height: 600
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})
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win.loadFile('index.html')
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const INCREMENT = 0.03
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const INTERVAL_DELAY = 100 // ms
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let c = 0
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progressInterval = setInterval(() => {
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// update progress bar to next value
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// values between 0 and 1 will show progress, >1 will show indeterminate or stick at 100%
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win.setProgressBar(c)
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// increment or reset progress bar
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if (c < 2) {
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c += INCREMENT
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} else {
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c = (-INCREMENT * 5) // reset to a bit less than 0 to show reset state
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}
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}, INTERVAL_DELAY)
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}
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app.whenReady().then(createWindow)
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// before the app is terminated, clear both timers
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app.on('before-quit', () => {
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clearInterval(progressInterval)
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})
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app.on('window-all-closed', () => {
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if (process.platform !== 'darwin') {
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app.quit()
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}
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})
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app.on('activate', () => {
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if (BrowserWindow.getAllWindows().length === 0) {
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createWindow()
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}
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})
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```
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After launching the Electron application, the dock (macOS) or taskbar (Windows, Unity)
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should show a progress bar that starts at zero and progresses through 100% to completion.
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It should then show indeterminate (Windows) or pin to 100% (other operating systems)
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briefly and then loop.
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For macOS, the progress bar will also be indicated for your application
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when using [Mission Control](https://support.apple.com/en-us/HT204100):
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[setprogressbar]: ../api/browser-window.md#winsetprogressbarprogress-options
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