android - 如何在自定义 "square"TextView 中居中文本

Question

我已经创建了一个自定义 TextView，因为我想要:

• 它的高度匹配某些约束(另一个 TextView 的顶部到顶部和底部到底部)
• 它的宽度与该高度匹配，因此设置为 TextView 背景的椭圆形 xml 显示一个圆。

这是自定义 View 的代码:

public class SquareTextView extends AppCompatTextView {
    public static final String TAG = "SquareTextView";
    int squareDim = 0;

    public SquareTextView(Context context) {
        super(context);
    }

    public SquareTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SquareTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        int h = this.getMeasuredHeight();
        int w = this.getMeasuredWidth();
        squareDim = Math.max(w, h);

        setMeasuredDimension(squareDim, squareDim);
    }
}

布局 xml:

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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">

    <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/tv_registration"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="24dp"
            android:layout_marginTop="16dp"
            android:text="WW-WWW"
            android:textAppearance="@style/TextAppearance.AppCompat.Large"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/tv_aircraft_type"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="MMMMMMMMM"
            android:textAppearance="@style/TextAppearance.AppCompat.Medium"
            app:layout_constraintStart_toStartOf="@+id/tv_registration"
            app:layout_constraintTop_toBottomOf="@+id/tv_registration" />

        <com.mydomain.SquareTextView
            android:id="@+id/tv_counter"
            android:layout_width="wrap_content"
            android:layout_height="0dp"
            android:layout_marginEnd="24dp"
            android:background="@drawable/shape_circle"
            android:gravity="center"
            android:text="0"
            android:textAlignment="center"
            android:textAppearance="@style/TextAppearance.AppCompat.Large"
            android:textStyle="bold"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="@+id/tv_registration"
            app:layout_constraintBottom_toTopOf="@+id/cv_ops_restrictions"/>

    </android.support.constraint.ConstraintLayout>

</ScrollView>

shape_circle.xml:

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval" >
    <size android:width="50dp"
        android:height="50dp"/>
    <solid android:color="@android:color/white"/>
</shape>

问题是我希望文本在圆圈中居中。有关如何实现此目标或我做错了什么的任何指示？目前它看起来像这样:

Answer 1

我建议您不要使用自定义 TextView子类在这里。你已经在里面工作了 ConstraintLayout ，它支持其子项的纵横比。这意味着您可以替换 <com.mydomain.SquareTextView>与 <TextView>并添加此属性以获得完美的方形 View :

app:layout_constraintDimensionRatio="1:1"