我刚开始学习约束布局，它很酷，我来到了主题约束集，陷入了困境。
我在开发人员文档中看到了constraintset的一个例子，但是我不能理解这个想法，我已经实现了它的原样，它正在工作，但是我真的不清楚这个概念。
我只想知道约束如何在不同的约束集中工作。
以下是我所做的：
活动\主.xml
<?xml version="1.0" encoding="utf-8"?>
<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/act_main"
tools:context="com.reversebits.constraintanimdemo.MainActivity">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:text="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum"
app:layout_constraintEnd_toStartOf="@+id/guideline2"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="8dp" />
<ImageView
android:id="@+id/imageView"
android:layout_width="0dp"
android:layout_height="160dp"
app:srcCompat="@mipmap/ic_launcher"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="@+id/guideline2"
android:layout_marginStart="8dp" />
<android.support.constraint.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/guideline"
android:orientation="vertical"
app:layout_constraintGuide_end="364dp" />
<android.support.constraint.Guideline
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/guideline2"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.5" />
<Button
android:onClick="foo"
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"/>
</android.support.constraint.ConstraintLayout>
克隆语言
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="com.reversebits.constraintanimdemo.MainActivity">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginStart="8dp"
android:id="@+id/textView"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="8dp" />
<ImageView
android:id="@+id/imageView"
android:layout_width="0dp"
android:layout_height="160dp"
app:srcCompat="@mipmap/ic_launcher"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="@+id/textView" />
<Button
android:onClick="foo"
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"/>
</android.support.constraint.ConstraintLayout>
主要活动如下：
import android.content.Context;
import android.os.Build;
import android.support.constraint.ConstraintLayout;
import android.support.constraint.ConstraintSet;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.transition.TransitionManager;
import android.view.View;
public class MainActivity extends AppCompatActivity {
ConstraintSet mConstraintSet1 = new ConstraintSet(); // create a Constraint Set
ConstraintSet mConstraintSet2 = new ConstraintSet(); // create a Constraint Set
ConstraintLayout mConstraintLayout; // cache the ConstraintLayout
boolean mOld = true;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Context context = this;
mConstraintSet2.clone(context, R.layout.clone); // get constraints from layout
setContentView(R.layout.activity_main);
mConstraintLayout = (ConstraintLayout) findViewById(R.id.act_main);
mConstraintSet1.clone(mConstraintLayout); // get constraints from ConstraintSet
}
public void foo(View view) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
TransitionManager.beginDelayedTransition(mConstraintLayout);
}
if (mOld = !mOld) {
mConstraintSet1.applyTo(mConstraintLayout); // set new constraints
} else {
mConstraintSet2.applyTo(mConstraintLayout); // set new constraints
}
}
}
最佳答案
假设您想在单击按钮后移动一些视图。例如，您可以在activity_main.xml中定义一个布局，其中包含按钮。要获取主布局的ConstraintSet，调用mConstraintSet1.clone(mConstraintLayout)。辅助布局（单击按钮后要显示的布局）是从辅助布局文件clone.xml克隆的。该布局包含具有相同ID的相同视图，但应用了其他约束。
用户单击按钮后，将执行foo()。foo()启动动画Transition，然后将所需的ConstraintSet应用于ConstraintLayout，从而使视图四处移动。由于调用了TransitionManager，移动被设置为动画。