1.android佈局-ConstraintLayout-約束佈局

摘要： ConstraintLayout 是什麼？ ConstraintLayout ConstraintLayout 怎麼用？ 基本用法 layout_constraint[當前控制元件位置]_[目標控制元件位置]="[目標控制元件ID]" 1.上下排列 ...

ConstraintLayout 是什麼？

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ConstraintLayout 怎麼用？

基本用法

layout_constraint[當前控制元件位置]_[目標控制元件位置]="[目標控制元件ID]"

1.上下排列

a
b

b:
app:layout_constraintTop_toBottomOf="a"

例項：

<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/a"
style="@style/text"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
android:text="@string/b"
app:layout_constraintTop_toBottomOf="@id/a" />
</android.support.constraint.ConstraintLayout>

2.左右排列

a b
a:
app:layout_constraintRight_toLeftOf="b"
b:
app:layout_constraintLeft_toRightOf="a"

例項：

<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/a"
style="@style/text"
app:layout_constraintRight_toLeftOf="@id/b"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
android:text="@string/b"
app:layout_constraintLeft_toRightOf="@id/a" />
</android.support.constraint.ConstraintLayout>

左右排列更嚴謹的寫法

a b
b:
app:layout_constraintStart_toEndOf="a"
app:layout_constraintTop_toTopOf="a"
app:layout_constraintBottom_toBottomOf="a"

例項：

<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/a"
style="@style/text"
app:layout_constraintRight_toLeftOf="@id/b"
app:layout_constraintEnd_toStartOf="@id/b"
app:layout_constraintTop_toTopOf="@id/b"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
android:text="@string/b"
app:layout_constraintStart_toEndOf="@id/a"
app:layout_constraintTop_toTopOf="@id/a"
app:layout_constraintLeft_toRightOf="@id/a" />
</android.support.constraint.ConstraintLayout>

3.靠最右邊

a 靠介面最右邊
a：
app:layout_constraiontEnd_toEndOf="parent"

例項：

<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/a"
style="@style/text"
app:layout_constraintEnd_toEndOf="parent"
android:text="@string/a" />
</android.support.constraint.ConstraintLayout>

constraiontEnd 是自己本身的
toEnd 底部停靠的
parent 是父佈局

4.三等分然後停靠最底部

a b c
a:
app:layout_constraiontBottom_toBottomOf="parent"
app:layout_constraiontLeft_toLeftOf="parent"
app:layout_constraiontRight_toLeftOf="b"

b:
app:layout_constraiontBottom_toBottomOf="parent"
app:layout_constraiontLeft_toRightOf="a"
app:layout_constraiontRight_toLeftOf="c"

c:
app:layout_constraiontBottom_toBottomOf="parent"
app:layout_constraiontLeft_toRightOf="b"
app:layout_constraiontRight_toRightOf="parent"

上面就是構成官網所說的鏈(chain)

例項：

<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/a"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@id/b"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toRightOf="@id/a"
app:layout_constraintRight_toLeftOf="@id/c"
android:text="@string/b"/>
<TextView
android:id="@+id/c"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toRightOf="@id/b"
android:text="@string/c"/>
</android.support.constraint.ConstraintLayout>

延伸兩個屬性

app:layout_constraiontHorizontal_weight="1" //等分屬性

app:layout_constraiontHorizontal_chainstyle="spread_inside" //spread_inside 兩端對齊 packed 聚中spread(預設)控制元件之間留空

例項：

聚中：

<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/a"
style="@style/text"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@id/b"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toRightOf="@id/a"
app:layout_constraintRight_toLeftOf="@id/c"
android:text="@string/b"/>
<TextView
android:id="@+id/c"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toRightOf="@id/b"
android:text="@string/c"/>
</android.support.constraint.ConstraintLayout>

左右分散：

<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/a"
style="@style/text"
app:layout_constraintHorizontal_chainStyle="spread_inside"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@id/b"
android:text="@string/a" />

<TextView
android:id="@+id/b"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toRightOf="@id/a"
app:layout_constraintRight_toLeftOf="@id/c"
android:text="@string/b"/>
<TextView
android:id="@+id/c"
style="@style/text"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toRightOf="@id/b"
android:text="@string/c"/>
</android.support.constraint.ConstraintLayout>

Guideline （約束線）

例項：

<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">

<android.support.constraint.Guideline
android:id="@+id/guideline"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.5" />

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/guideline"
app:layout_constraintWidth_default="spread" />

<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintBottom_toBottomOf="@+id/button"
app:layout_constraintStart_toStartOf="@+id/guideline"
app:layout_constraintTop_toTopOf="@+id/button" />
</android.support.constraint.ConstraintLayout>



Guideline 是一個約束線（不會畫出來）
app:layout_constraintGuide_percent="0.5" 0.5是50%
上面程式碼是 在檢視50%位置 左右兩邊有兩個butthon

例項：

<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">

<android.support.constraint.Guideline
android:id="@+id/guideline"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
app:layout_constraintGuide_begin="40dp"/>

<TextView
android:id="@+id/a"
style="@style/text"
app:layout_constraintTop_toTopOf="@id/guideline"
android:text="@string/a"/>
<TextView
android:id="@+id/b"
style="@style/text"
app:layout_constraintTop_toTopOf="@id/guideline"
app:layout_constraintLeft_toRightOf="@id/a"
android:text="@string/b"/>
<TextView
android:id="@+id/c"
style="@style/text"
app:layout_constraintTop_toTopOf="@id/guideline"
app:layout_constraintLeft_toRightOf="@id/b"
android:text="@string/c"/>
</android.support.constraint.ConstraintLayout>

在40dp上畫一條約束線 
textview以此排列

原始碼

原始碼