Android - Dim the system bars

Dim the system bars

This lesson describes how to dim the system bars (that is, the status and the navigation bars) on Android 4.0 (API level 14) and higher. Android does not provide a built-in way to dim the system bars on earlier versions.

When you use this approach, the content doesn’t resize, but the icons in the system bars visually recede. As soon as the user touches either the status bar or the navigation bar area of the screen, both bars become fully visible. The advantage of this approach is that the bars are still present but their details are obscured, thus creating an immersive experience without sacrificing easy access to the bars.

Dim the Status and Navigation Bars

You can dim the status and navigation bars using the SYSTEM_UI_FLAG_LOW_PROFILE flag, as follows:

// This example uses decor view, but you can use any visible view.
View decorView = getActivity().getWindow().getDecorView();
int uiOptions = View.SYSTEM_UI_FLAG_LOW_PROFILE;
decorView.setSystemUiVisibility(uiOptions);

As soon as the user touches the status or navigation bar, the flag is cleared, causing the bars to be undimmed. Once the flag has been cleared, your app needs to reset it if you want to dim the bars again.

Reveal the Status and Navigation Bars

If you want to programmatically clear flags set with setSystemUiVisibility(), you can do so as follows:

View decorView = getActivity().getWindow().getDecorView();
// Calling setSystemUiVisibility() with a value of 0 clears
// all flags.
decorView.setSystemUiVisibility(0);

准备

IDE：

Android Studio 4.1.1
Build #AI-201.8743.12.41.6953283, built on November 5, 2020
Runtime version: 1.8.0_242-release-1644-b01 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0

Android Virtual Devices：

Name: Pixel_2_API_28
CPU/ABI: Google Play Intel Atom (x86)
Path: C:\Users\86188\.android\avd\Pixel_2_API_28.avd
Target: google_apis_playstore [Google Play] (API level 28)
Skin: pixel_2
SD Card: 512M
fastboot.chosenSnapshotFile: 
runtime.network.speed: full
hw.accelerometer: yes
hw.device.name: pixel_2
hw.lcd.width: 1080
hw.initialOrientation: Portrait
image.androidVersion.api: 28
tag.id: google_apis_playstore
hw.mainKeys: no
hw.camera.front: emulated
avd.ini.displayname: Pixel 2 API 28
hw.gpu.mode: auto
hw.ramSize: 1536
PlayStore.enabled: true
fastboot.forceColdBoot: no
hw.cpu.ncore: 4
hw.keyboard: yes
hw.sensors.proximity: yes
hw.dPad: no
hw.lcd.height: 1920
vm.heapSize: 256
skin.dynamic: yes
hw.device.manufacturer: Google
hw.gps: yes
hw.audioInput: yes
image.sysdir.1: system-images\android-28\google_apis_playstore\x86\
showDeviceFrame: yes
hw.camera.back: virtualscene
AvdId: Pixel_2_API_28
hw.lcd.density: 420
hw.arc: false
hw.device.hash2: MD5:55acbc835978f326788ed66a5cd4c9a7
fastboot.forceChosenSnapshotBoot: no
fastboot.forceFastBoot: yes
hw.trackBall: no
hw.battery: yes
hw.sdCard: yes
tag.display: Google Play
runtime.network.latency: none
disk.dataPartition.size: 6442450944
hw.sensors.orientation: yes
avd.ini.encoding: UTF-8
hw.gpu.enabled: yes

注意：以下示例仅在安卓虚拟设备上运行测试，并没有在真实的设备上运行测试。

项目

效果：

新建项目，选择 Empty Activity，在配置项目时，Minimum SDK 选择 API 16: Android 4.1 (Jelly Bean)

编辑 src\main\res\layout\activity_main.xml，添加两个 Button 组件：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/buttonDim"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="Dim"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/buttonUndim"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginRight="16dp"
        android:text="Undim"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/buttonDim" />
</androidx.constraintlayout.widget.ConstraintLayout>

编辑 MainActivity（第 18、21 ~ 30 行）：

package com.mk;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button buttonDim = (Button) findViewById(R.id.buttonDim);
        buttonDim.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                View decorView = getWindow().getDecorView();
                decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);
            }
        });

        Button buttonUndimmed = (Button) findViewById(R.id.buttonUndim);
        buttonUndimmed.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                View decorView = getWindow().getDecorView();
                decorView.setSystemUiVisibility(0);
            }
        });
    }
}

参考

Dim the system bars