未检测到键盘。 MediaQuery.of(context).viewInsets.bottom 总是返回 0.0

Question

I have a scaffold with a TextField inside. The keyboard always covers this field when it previously would move the field above the keyboard. This is happening on all the pages in my project.

I've added MediaQuery.of(context).viewInsets.bottom to my build method and it always returns 0.0. When the keyboard comes up there is no rebuild. I've tried settings resizeToAvoidBottomInset to true and false with no change. I've tried wrapping it in a Scrollable widget, no change.

Everything works fine in IOS, this only affects android build.

Doctor summary (to see all details, run flutter doctor -v):  
[✓] Flutter (Channel unknown, v1.10.15, on Mac OS X 10.15.1 19B88, locale en-US)  

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)  
[✓] Xcode - develop for iOS and macOS (Xcode 11.2.1)  
[✓] Android Studio  
[✓] Android Studio (version 3.5)  
[✓] VS Code (version 1.40.2)  
[✓] Connected device (1 available)

Answer 1

I've had this issue recently. Do you have fullscreen set to true? If fullscreen is enabled, MediaQuery.viewInsets.bottom will return 0.0. Since you mentioned the problem only occurs in android, It's possible you set the fullscreen property in the native android files. Check styles.xml

    <item name="android:windowFullscreen">false</item>

Other way to remove fullscreen from the app is SystemChrome.setEnabledSystemUIOverlays([]) in flutter page.

One more thing you might want to check is resizeToAvoidBottomPadding: to false in Scaffold.

The issue has been raised in Flutter issues as well: https://github.com/flutter/flutter/issues/25050

Answer 2

I found the reason for this problem, but I don't know why. When the control is in Scaffold, the appearance and disappearance of the keyboard will not rebuild the body in Scaffold. You can try to replace Scaffold with Material to observe. If you don't want to replace Scaffold, one way I can find is:

final bottom= EdgeInsets.fromWindowPadding(
    WidgetsBinding.instance.window.viewInsets,
    WidgetsBinding.instance.window.devicePixelRatio).bottom;

Answer 3

In case of complicated widget tree MediaQuery.of(context).viewInsets.bottom gives null even if the keyboard is open. So, we have to mutate values down the tree.

This package gives simple in use provider for getting info down the tree https://pub.dev/packages/flutter_keyboard_size

Or, you can mutate info about keyboard size down the tree by yourselves (you can look the code in the package).

Answer 4

When the keyboard opens, MediaQuery.of(context).viewInsets.bottom changes to reflect the new bottom (which is now at the top of the keyboard).

However, the Android app may be in fullscreen:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
        <!-- Show a splash screen on the activity. Automatically removed when
             Flutter draws its first frame -->
        <item name="android:windowBackground">@drawable/launch_background</item>
        <item name="android:windowFullscreen">true</item>
    </style>
    <color name="xxx">#FFFF00</color>
</resources>

When this is the case, viewInsets.bottom will always be 0.0 , even when the keyboard is open,

Answer 5

in AndroidManifest.xml为托管 Flutter 屏幕的 Activity 设置android:windowSoftInputMode="adjustResize"将解决此问题。

Answer 6

I need to mix flutter and Android, the situation may be more complicated, <item name="android:windowFullscreen">false</item> and SystemChrome.setEnabledSystemUIOverlays([]) do not work for me.

Finally the setting android:windowSoftInputMode="adjustResize" in AndroidManifest.xml worked for me.

Answer 7

try MediaQuery.of(context).viewInsets.bottom with scaffold context not child widgets one.

It works for me.

Answer 8

See if you have useInheritedMediaQuery set to true in MaterialApp . Set it to false if so. This is caused because that property forces widgets to use an inherited context. So if you, for example, pop the keyboard immediately when the app starts, the value of MediaQuery.of(context).viewInsets.bottom is the same as the size of the keyboard, but since that context now works for children, it never changes, even when the keyboard collapses. So, my simple solution when I faced the issue was to set useInheritedMediaQuery to false , which is the default in flutter apps these days.