我需要帮助ConstraintSet。我的目标是在代码中改变视图的约束,但我不知道如何做到这一点。

我有4个textview和一个ImageView。我需要将ImageView约束设置为textview之一。

check_answer4 = (TextView) findViewById(R.id.check_answer4);
check_answer1 = (TextView) findViewById(R.id.check_answer1);
check_answer2 = (TextView) findViewById(R.id.check_answer2);
check_answer3 = (TextView) findViewById(R.id.check_answer3);

correct_answer_icon = (ImageView) findViewById(R.id.correct_answer_icon);

如果第一个答案是正确的,我需要设置ImageView的约束为

app:layout_constraintRight_toRightOf="@+id/check_answer1"
app:layout_constraintTop_toTopOf="@+id/check_answer1"

如果第二个答案是正确的,我需要设置ImageView的约束为

app:layout_constraintRight_toRightOf="@+id/check_answer2"
app:layout_constraintTop_toTopOf="@+id/check_answer2"

等等。


当前回答

除了azizbekian的回答,让我指出两件事:

如果左/右都不行,试着这样开始/结束:

参数个数。startToEnd = button2.id

如果你想移除一个约束,使用UNSET标志,像这样:

参数个数。startToEnd = ConstraintLayout.LayoutParams.UNSET

其他回答

To set constraints of image view to: app:layout_constraintRight_toRightOf="@+id/check_answer1" app:layout_constraintTop_toTopOf="@+id/check_answer1" use: ConstraintLayout constraintLayout = findViewById(R.id.parent_layout); ConstraintSet constraintSet = new ConstraintSet(); constraintSet.clone(constraintLayout); constraintSet.connect(R.id.imageView,ConstraintSet.RIGHT,R.id.check_answer1,ConstraintSet.RIGHT,0); constraintSet.connect(R.id.imageView,ConstraintSet.TOP,R.id.check_answer1,ConstraintSet.TOP,0); constraintSet.applyTo(constraintLayout); To set constraints of image view to: app:layout_constraintRight_toRightOf="@+id/check_answer2" app:layout_constraintTop_toTopOf="@+id/check_answer2" use: ConstraintLayout constraintLayout = findViewById(R.id.parent_layout); ConstraintSet constraintSet = new ConstraintSet(); constraintSet.clone(constraintLayout); constraintSet.connect(R.id.imageView,ConstraintSet.RIGHT,R.id.check_answer2,ConstraintSet.RIGHT,0); constraintSet.connect(R.id.imageView,ConstraintSet.TOP,R.id.check_answer2,ConstraintSet.TOP,0); constraintSet.applyTo(constraintLayout);

假设我们想要在运行时改变约束,使button1在点击时与button2对齐:

然后,有这样的布局:

<android.support.constraint.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:id="@+id/root"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">


    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button 1"
        app:layout_constraintTop_toTopOf="@+id/button3"
        app:layout_constraintBottom_toBottomOf="@+id/button3"
        app:layout_constraintStart_toEndOf="@+id/button3"
        android:layout_marginStart="0dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="0dp" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:text="Button 2"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        android:layout_marginStart="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        android:layout_marginBottom="8dp"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="8dp"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintVertical_bias="0.5" />

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:text="Button 3"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        android:layout_marginStart="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="8dp"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        android:layout_marginBottom="8dp"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintVertical_bias="0.223" />
</android.support.constraint.ConstraintLayout>

我们可以做以下几点:


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        button1.setOnClickListener {
            val params = button1.layoutParams as ConstraintLayout.LayoutParams
            params.leftToRight = button2.id
            params.topToTop = button2.id
            params.bottomToBottom = button2.id
            button1.requestLayout()
        }
    }

我知道我的回答很晚了,但我相信它会帮助到其他经常来这里的人。 这篇文章不是我写的,但我做了一些修改,也就是说,你应该努力在这里查看完整的文章

约束集

在Java代码中使用约束集的关键是ConstraintSet类。这个类包含一系列的方法,这些方法允许执行诸如创建、配置和将约束应用到ConstraintLayout实例等任务。此外,ConstraintLayout实例的当前约束可以被复制到ConstraintSet对象中,并用于将相同的约束应用到其他布局(修改或不修改)。

ConstraintSet实例的创建就像其他Java对象一样:

ConstraintSet set = new ConstraintSet();

一旦创建了约束集,就可以在实例上调用方法来执行广泛的任务。 下面的代码配置了一个约束集,其中Button视图的左侧连接到EditText视图的右侧,边界为70dp:

set.connect(button1.getId(), ConstraintSet.LEFT, 
        editText1.getId(), ConstraintSet.RIGHT, 70);

将约束应用到布局中 一旦配置了约束集,它必须在ConstraintLayout实例生效之前应用到它。约束集是通过调用applyTo()方法来应用的,传递一个对要应用设置的布局对象的引用:

set.applyTo(myLayout);

还有很多东西你可以用ConstraintSet API,设置水平和垂直偏差,水平和垂直中心,操作链和更多。

读得真不错。

再说一次,这只是一种适应。

另一种方法是像这样更新视图的布局参数(不请求layout):

yourView.updateLayoutParams<ConstraintLayout.LayoutParams> {
        startToEnd = targetView.id
        topToTop = targetView.id
        bottomToBottom = targetView.id
        //add other constraints if needed
      }

你可以用ConstraintSet或ConstraintLayout在ConstraintLayout中创建约束。LayoutParams属性。

为了方便使用,我创建了一个ConstraintSet kotlin扩展。 这是简单而健壮的。

使用

 applyConstraint {
            centerHorizontallyParent(imageView)
            centerHorizontallyParent(textView)
            topToParent(imageView, px(12))
            topToBottom(textView, imageView, px(4))
        }

Code

fun ConstraintLayout.applyConstraint(block: ConstraintSet.() -> Unit) {
    ConstraintSet().apply {
        clone(this@applyConstraint)
        block(this)
    }.applyTo(this)
}

fun ConstraintSet.centerParent(v1: View) {
    centerHorizontallyParent(v1)
    centerVerticallyParent(v1)
}

fun ConstraintSet.centerHorizontallyParent(v1: View) {
    centerHorizontally(v1.id, PARENT_ID)
}

fun ConstraintSet.centerVerticallyParent(v1: View) {
    centerVertically(v1.id, PARENT_ID)
}

fun ConstraintSet.topToTop(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, TOP, v2.id, TOP, margin)
}

fun ConstraintSet.topToParent(v1: View, @Px margin: Int = 0) {
    connect(v1.id, TOP, PARENT_ID, TOP, margin)
}

fun ConstraintSet.bottomToBottom(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, BOTTOM, v2.id, BOTTOM, margin)
}

fun ConstraintSet.bottomToParent(v1: View, @Px margin: Int = 0) {
    connect(v1.id, BOTTOM, PARENT_ID, BOTTOM, margin)
}

fun ConstraintSet.topToBottom(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, TOP, v2.id, BOTTOM, margin)
}

fun ConstraintSet.bottomToTop(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, BOTTOM, v2.id, TOP, margin)
}

fun ConstraintSet.startToStart(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, START, v2.id, START, margin)
}

fun ConstraintSet.startToParent(v1: View, @Px margin: Int = 0) {
    connect(v1.id, START, PARENT_ID, START, margin)
}

fun ConstraintSet.endToEnd(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, END, v2.id, END, margin)
}

fun ConstraintSet.endToParent(v1: View, @Px margin: Int = 0) {
    connect(v1.id, END, PARENT_ID, END, margin)
}

fun ConstraintSet.startToEnd(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, START, v2.id, END, margin)
}

fun ConstraintSet.endToStart(v1: View, v2: View, @Px margin: Int = 0) {
    connect(v1.id, END, v2.id, START, margin)
}