Android 控件保持宽高比得几种方式

adjustViewBounds

仅适用于 ImageView，保持横竖比。

<ImageViewandroid:layout_width="match_parent"android:layout_height="wrap_content"android:layout_gravity="center"android:adjustViewBounds="true"android:scaleType="fitXY"android:src="@drawable/bg" />

百分比布局

宽高比为 16:9

<androidx.percentlayout.widget.PercentFrameLayout 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=".ratio.PercentFragment"><ImageViewandroid:layout_width="0dp"android:layout_height="0dp"android:scaleType="fitXY"android:src="@drawable/bg"app:layout_aspectRatio="178%"app:layout_widthPercent="100%" /></androidx.percentlayout.widget.PercentFrameLayout>

ConstraintLayout

宽高比为 16:9

<?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=".ratio.ConstraintLayoutFragment"><ImageViewandroid:layout_width="0dp"android:layout_height="0dp"android:scaleType="fitXY"android:src="@drawable/bg"app:layout_constraintDimensionRatio="16:9"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent" /></androidx.constraintlayout.widget.ConstraintLayout>

自定义View

自定义View：

<declare-styleable name="MyRatioFrameLayout"><attr name="whRatio" format="string" />
</declare-styleable>

class MyRatioFrameLayout @JvmOverloads constructor(context: Context,attrs: AttributeSet? = null,defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr) {private var widthRatio: Float = 0Fprivate var heightRatio: Float = 0Finit {val a = context.obtainStyledAttributes(attrs, R.styleable.MyRatioFrameLayout)val whRatio = a.getString(R.styleable.MyRatioFrameLayout_whRatio)a.recycle()whRatio?.let {val strs = it.split(":");when (strs.size) {1 -> {widthRatio = strs[0].toFloat()heightRatio = 1F}2 -> {widthRatio = strs[0].toFloat()heightRatio = strs[1].toFloat()}}}}override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {var wMeasureSpec = widthMeasureSpecvar hMeasureSpec = heightMeasureSpecif (widthRatio != 0F && heightRatio != 0F) {val ratio = getRatio()val lp: ViewGroup.LayoutParams = layoutParamsval widthMode = MeasureSpec.getMode(widthMeasureSpec)val widthSize = MeasureSpec.getSize(widthMeasureSpec)val heightMode = MeasureSpec.getMode(heightMeasureSpec)val heightSize = MeasureSpec.getSize(heightMeasureSpec)if (lp.width != ViewGroup.LayoutParams.WRAP_CONTENT && widthMode == MeasureSpec.EXACTLY &&lp.height != ViewGroup.LayoutParams.WRAP_CONTENT && heightMode == MeasureSpec.EXACTLY) {// 宽度和高度都是固定值if (widthSize / ratio < heightSize) {// 如果计算后高度小于原有高度hMeasureSpec = MeasureSpec.makeMeasureSpec((widthSize / ratio).toInt(),MeasureSpec.EXACTLY)} else if (heightSize * ratio <= widthSize) {// 如果计算后的宽度小于原有宽度wMeasureSpec = MeasureSpec.makeMeasureSpec((heightSize * ratio).toInt(),MeasureSpec.EXACTLY)}} else if (lp.width != ViewGroup.LayoutParams.WRAP_CONTENT && widthMode == MeasureSpec.EXACTLY && heightMode != MeasureSpec.EXACTLY) {// 宽度固定值hMeasureSpec =MeasureSpec.makeMeasureSpec((widthSize / ratio).toInt(), MeasureSpec.EXACTLY)} else if (lp.height != ViewGroup.LayoutParams.WRAP_CONTENT && heightMode == MeasureSpec.EXACTLY && widthMode != MeasureSpec.EXACTLY) {// 高度固定值wMeasureSpec =MeasureSpec.makeMeasureSpec((heightSize * ratio).toInt(), MeasureSpec.EXACTLY)}}super.onMeasure(wMeasureSpec, hMeasureSpec)}fun setRatio(widthRatio: Float, heightRatio: Float) {this.widthRatio = widthRatiothis.heightRatio = heightRatio}fun getRatio(): Float {return widthRatio / heightRatio}
}

使用：

<?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:orientation="vertical"tools:context=".ratio.RatioViewFragment"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical"><com.example.tools.ratio.MyRatioFrameLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:background="#ff0000"app:whRatio="16:9"><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitXY"android:src="@drawable/bg" /></com.example.tools.ratio.MyRatioFrameLayout><com.example.tools.ratio.MyRatioFrameLayoutandroid:layout_width="200dp"android:layout_height="300dp"android:layout_marginTop="10dp"android:background="#00ff00"app:whRatio="16:9"><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitXY"android:src="@drawable/bg" /></com.example.tools.ratio.MyRatioFrameLayout><com.example.tools.ratio.MyRatioFrameLayoutandroid:layout_width="300dp"android:layout_height="200dp"android:layout_marginTop="10dp"android:background="#0000ff"app:whRatio="16:9"><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitXY"android:src="@drawable/bg" /></com.example.tools.ratio.MyRatioFrameLayout></LinearLayout>
</ScrollView>