主要介紹app:layout_constraintWidth_max、app:layout_constrainedWidth、app:layout_constraintDimensionRatio和Guideline的使用
一、app:layout_constraintWidth_max、app:layout_constrainedWidth、app:layout_constraintDimensionRatio的使用
<?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">
<!--
app:layout_constrainedWidth="true",此屬性默認爲false
android:layout_width,值爲“wrap_content”與“0dp”時,約束才能生效
app:layout_constraintWidth_max="100dp",此屬性必須與兩個屬性同時使用
-->
<TextView
android:id="@+id/tv_first"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#00ff00"
android:textSize="20sp"
app:layout_constrainedWidth="true"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_max="100dp"
tools:text="壯士一去不復還" />
<TextView
android:id="@+id/tv_second"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#ff0000"
android:textSize="20sp"
app:layout_constrainedWidth="false"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/tv_first"
app:layout_constraintWidth_max="100dp"
tools:text="風蕭蕭兮易水寒" />
<!--
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintDimensionRatio="1:2",此時代表寬高比=1:2
這種情況是本來是寬隨高走的,但是經過測試發現是高隨寬走,寬的最大值是跟屏幕寬相匹配,高是寬的兩倍。
很費解。
-->
<TextView
android:id="@+id/tv_third"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#0000ff"
android:textSize="20sp"
app:layout_constraintDimensionRatio="1:2"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/tv_second"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
<!--
android:layout_width="wrap_content"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="1:2"
這種情況是高隨寬走,寬包裹內容,寬的最大值是跟屏幕寬相匹配。
高是寬的兩倍
-->
<TextView
android:id="@+id/tv_forth"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:background="#00fafa"
android:textSize="20sp"
app:layout_constraintDimensionRatio="1:2"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/tv_third"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
</androidx.constraintlayout.widget.ConstraintLayout>
二、app:layout_constraintDimensionRatio的使用
<?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">
<!--
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="H,2:1"
高將按照2:1的比例展示(實質是高是寬的1/2),但是寬將會按照所給約束進行
-->
<TextView
android:id="@+id/tv_fifth"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#ff4b4d"
android:textSize="20sp"
app:layout_constraintDimensionRatio="H,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?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">
<!--
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="W,2:1"
寬將按照2:1的比例展示(實質是寬是寬的1/2),但是寬將會按照所給約束進行展示
-->
<TextView
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#00ff00"
android:textSize="20sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintDimensionRatio="W,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
<?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">
<!--
android:layout_width="100dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="H,2:1"
寬將會按照100dp展示,高是寬的1/2
-->
<TextView
android:id="@+id/tv_fifth"
android:layout_width="100dp"
android:layout_height="0dp"
android:background="#ff4b4d"
android:textSize="20sp"
app:layout_constraintDimensionRatio="H,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
<!--
android:layout_width="0dp"
android:layout_height="100dp"
app:layout_constraintDimensionRatio="H,2:1"
寬將會按照自己的約束展示,高是給定的100dp
-->
<TextView
android:layout_width="0dp"
android:layout_height="100dp"
android:background="#00ff00"
android:textSize="20sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintDimensionRatio="H,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?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">
<!--
android:layout_width="100dp"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="W,2:1"
寬將按照100dp展示,但是高將會是寬的2倍
-->
<TextView
android:layout_width="100dp"
android:layout_height="0dp"
android:background="#00ff00"
android:textSize="20sp"
app:layout_constraintDimensionRatio="W,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
<!--
android:layout_width="0dp"
android:layout_height="100dp"
app:layout_constraintDimensionRatio="W,2:1"
高將按照100dp展示,但是寬將會是高的2倍
-->
<TextView
android:layout_width="0dp"
android:layout_height="100dp"
android:background="#ff0000"
android:textSize="20sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintDimensionRatio="W,2:1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintWidth_default="percent"
tools:text="風蕭蕭兮易水寒" />
</androidx.constraintlayout.widget.ConstraintLayout>
三、Guideline的使用
<?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">
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_begin="100dp" />
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideline1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_begin="100dp" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintLeft_toLeftOf="@+id/guideline"
app:layout_constraintTop_toTopOf="@id/guideline1" />
</androidx.constraintlayout.widget.ConstraintLayout>