Android ConstraintLayout按比例缩放View

Android ConstraintLayout按比例缩放View

关键点有两个，第一，使用Android ConstraintLayout的layout_constraintDimensionRatio属性，设置宽高比缩放比例，宽:高。第二，恒定宽和高，另外一个方向就会按照比例缩放。

    <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="match_parent">

        <TextView
            android:id="@+id/text0"
            android:layout_width="0dp"
            android:layout_height="100dp"
            android:background="@android:color/holo_orange_light"
            android:gravity="center"
            android:text="w=0,h=100\n5:2"
            android:textColor="@android:color/white"
            android:textSize="10dp"
            app:layout_constraintDimensionRatio="5:2"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <TextView
            android:id="@+id/text1"
            android:layout_width="100dp"
            android:layout_height="0dp"
            android:background="@android:color/holo_red_light"
            android:gravity="center"
            android:text="w=100,h=0\n5:2"
            android:textColor="@android:color/white"
            android:textSize="10dp"
            app:layout_constraintDimensionRatio="5:2"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintTop_toBottomOf="@id/text0" />
    </android.support.constraint.ConstraintLayout>

运行结果如图：