android - Constraint layout button text center alignment

Question

I'm using the new Constraint layout to build my layout. I need to have Button that occupies almost the entire screen width and that was easy using constraints.

As you can see in the image I am setting the width to 0dp (Any size), but the text don't stick at the center what's usually the normal for a button text.

I've tried: - set gravity to center - set textAlignment to center

Looks like this properties can't work with 0dp width (Any size).

So I've tried to set the width to match_parent using gravity center.

It's a little bit to the right.

Does any one know how to fix that behavior ?

Note that i'm using alpha4

compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha4'

XML code

<android.support.constraint.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:id="@+id/content_login"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:context="br.com.marmotex.ui.LoginActivityFragment"
    tools:showIn="@layout/activity_login">

    <Button
        android:text="Log in"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:id="@+id/btLogin"
        android:layout_marginTop="48dp"
        app:layout_constraintTop_toBottomOf="@+id/textView6"
        android:layout_marginEnd="16dp"
        app:layout_constraintRight_toRightOf="@+id/content_login"
        android:layout_marginRight="16dp"
        android:layout_marginStart="16dp"
        app:layout_constraintLeft_toLeftOf="@+id/content_login"
        android:layout_marginLeft="16dp"
        android:textColor="@android:color/white"
        android:background="@color/BackgroundColor" />

</android.support.constraint.ConstraintLayout>

EDIT It was a bug in ConstraintLayout alpha4.

UPDATE Google has released alpha5, the above code now Works. Release note

Answer 1

它有点向右。

我认为保证金是造成这些的。根据我的经验，它不仅影响按钮。Margin 也在搞砸 TextInputEditText。

下面是一个工作代码，但请注意android:layout_width="match_parent"按钮。每当我在编辑器中单击时，它都会变为android:layout_width="0dp"，并破坏按钮对齐。

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <Button
        android:id="@+id/button_survey"
        android:layout_width="match_parent" 
        android:layout_height="52dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="@+id/activity_main"
        app:layout_constraintLeft_toLeftOf="@+id/activity_main"
        app:layout_constraintRight_toRightOf="@+id/activity_main"
        app:layout_constraintTop_toTopOf="@+id/activity_main"
        tools:text="@string/main_activity_btn_survey"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp" />


</android.support.constraint.ConstraintLayout>

受 Hobo joe 解决方案的启发，以下是我喜欢的方式。他的解决方案有效，但仍需要使用填充来创建间距。如果改为使用边距，按钮文本的对齐方式将略微向右。所以我在LinearLayout（或ConstraintLayout）上使用填充而不是按钮上的边距。

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="@+id/activity_main"
        app:layout_constraintTop_toTopOf="@+id/activity_main"
        app:layout_constraintRight_toRightOf="@+id/activity_main"
        app:layout_constraintBottom_toBottomOf="@+id/activity_main"
        android:padding="16dp">
        <Button
            android:text="Button"
            android:layout_width="match_parent"
            android:layout_height="52dp"
            android:id="@+id/button_survey"
            android:layout_weight="1"
            tools:text="@string/main_activity_btn_survey"
            />
    </LinearLayout>
</android.support.constraint.ConstraintLayout>

Answer 2

你有没有尝试过 ？

android:textAlignment="center"

这对我有用。

Answer 3

好吧，我认为这是因为这些限制 app:layout_constraintRight_toRightOf app:layout_constraintLeft_toLeftOf

用这个替换你当前的按钮：

    <Button
    android:text="Log in"
    android:layout_width="match_parent"
    android:layout_height="48dp"
    android:id="@+id/btLogin"
    android:textColor="@android:color/white"
    android:background="@color/BackgroundColor"
    android:gravity="center"
    android:textAlignment="center"
    android:layout_marginTop="100dp"
    tools:layout_editor_absoluteX="-1dp"
    app:layout_constraintTop_toBottomOf="@+id/textView6" />

希望这会有所帮助。

Answer 4

似乎问题出android:layout_width="match_parent"在使用 inside 时ConstraintLayout。只需设置android:layout_width="0dp"并添加约束app:layout_constraintStart_toStartOf="parent"& app:layout_constraintEnd_toEndOf="parent"，它就可以正常工作。

<Button
     android:layout_width="0dp"
     android:layout_height="wrap_content"
     android:text="Continue"
     app:layout_constraintEnd_toEndOf="parent"
     app:layout_constraintStart_toStartOf="parent" />

Answer 5

这是一个错误。但是，您可以通过将按钮放置在 LinearLayout（或其他标准 ViewGroup）中来解决它。将父视图和按钮宽度设置为match_parent，并将按钮上的任何约束移动到父布局。

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:layout_constraintLeft_toLeftOf="@+id/parent_left"
    app:layout_constraintTop_toTopOf="@+id/parent_top"
    app:layout_constraintRight_toRightOf="@+id/parent_right">

    <Button
        android:id="@+id/test"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Centered Text"/>

</LinearLayout>