ConstraintLayout学习笔记

ConstraintLayout: 约束性布局， 类似于相对性布局(RelativeLayout), 但是代码更简洁。

参考了大神的介绍，学习了基本属性，自己动手写了下代码，增加记忆，Mark 一下

(大神链接:https://www.baidu.com/link?url=S0vGu-ixKTCrSmXh9AwhZE8GW0drUi85-T-qfUf9zznuaGEcJbn8zTBdqnFszpqnVNfmJx6h7wra6oj1xpPVdq&wd=&eqid=d0d108d500714758000000065e51e43b)

效果图:

XML 布局文件:

<?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_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity"
    tools:showIn="@layout/activity_main">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/item_text_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@mipmap/ic_launcher"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <TextView
        android:id="@+id/item_text_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="10dp"
        app:layout_constraintStart_toEndOf="@+id/item_text_image"
        app:layout_constraintTop_toTopOf="@+id/item_text_image"
        android:text="I am title"/>

    <TextView
        android:id="@+id/item_text_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        app:layout_constraintTop_toBottomOf="@+id/item_text_title"
        app:layout_constraintStart_toStartOf="@+id/item_text_title"
        android:text="I am content"/>

    <Button
        android:id="@+id/first_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="First button"
        app:layout_constraintTop_toBottomOf="@+id/item_text_image"
        app:layout_constraintStart_toStartOf="@+id/item_text_image"/>

    <Button
        android:id="@+id/second_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Second button"
        android:visibility="visible"
        app:layout_constraintStart_toEndOf="@+id/first_button"
        app:layout_constraintTop_toBottomOf="@+id/first_button"/>

    <Button
        android:id="@+id/third_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Third Button"
        app:layout_constraintStart_toEndOf="@+id/second_button"
        app:layout_constraintTop_toBottomOf="@+id/second_button"/>

    <Button
        android:id="@+id/fourth_botton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="fourth_button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintVertical_bias="0.4"
        app:layout_constraintHorizontal_bias="0.6"/>

    <Button
        android:id="@+id/fifth_button"
        android:layout_width="0dp"
        android:layout_height="35dp"
        android:text="fifth button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/fourth_botton"
        app:layout_constraintDimensionRatio="4"/>

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/text_guidle_line"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.6"/>
    <Button
        android:id="@+id/six_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="six button"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/text_guidle_line" />

    <androidx.constraintlayout.widget.Group
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="visible"
        app:constraint_referenced_ids="seven_button,eight_button"/>
    <Button
        android:id="@+id/seven_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="seventh"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/six_button"/>
    <Button
        android:id="@+id/eight_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="eighth"
        app:layout_constraintStart_toEndOf="@+id/seven_button"
        app:layout_constraintBottom_toBottomOf="@id/seven_button"/>


</androidx.constraintlayout.widget.ConstraintLayout>