Android开发笔记（一百四十九）约束布局ConstraintLayout

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/cl_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/tv_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="40dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginLeft="200dp"
        android:background="@color/blue"
        android:text="我是山大王"
        android:textSize="17sp"
        android:textColor="@color/black" />

    <TextView
        android:id="@+id/tv_second"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        app:layout_constraintTop_toBottomOf="@+id/tv_first"
        android:layout_marginLeft="20dp"
        app:layout_constraintLeft_toLeftOf="@+id/tv_first"
        android:background="@color/blue"
        android:text="我是巡山的小喽啰"
        android:textSize="17sp"
        android:textColor="@color/black" />
</android.support.constraint.ConstraintLayout>

private void addNewView() {
    TextView tv = new TextView(this);
    tv.setText("长按删除该文本");
    tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 17);
    tv.setGravity(Gravity.CENTER);
    tv.setBackgroundColor(Color.YELLOW);
    ConstraintLayout.LayoutParams container = new ConstraintLayout.LayoutParams(
            ConstraintLayout.LayoutParams.WRAP_CONTENT,
            ConstraintLayout.LayoutParams.WRAP_CONTENT
    );
    //设置控件左侧与另一个控件的左侧对齐
    //水平方向上只能使用start和end，因为left和right可能无法奏效
    container.startToStart = mLastViewId;
    //设置控件顶部与另一个控件的底部对齐
    container.topToBottom = mLastViewId;
    container.setMargins(0, Utils.dip2px(this, 30), 0, 0);
    //左侧间距要使用Start，不能用Left，因为set.applyTo方法会清空Left的间距
    container.setMarginStart(Utils.dip2px(this, 10));
    tv.setLayoutParams(container);
    tv.setOnLongClickListener(new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View vv) {
            cl_content.removeView(vv);
            return true;
        }
    });
    mLastViewId += 1000;
    tv.setId(mLastViewId);
    cl_content.addView(tv);
}

private void moveView() {
    //使用动画展示新旧约束关系的切换过程。如果删掉这行则不展示切换动画
    TransitionManager.beginDelayedTransition(cl_content);
    int margin = Utils.dip2px(this, isMoved?200:20);
    //需要下载最新的constraint-layout，才能使用ConstraintSet
    ConstraintSet set = new ConstraintSet();
    //复制原有的约束关系
    set.clone(cl_content);
    //清空该控件的约束关系
    //set.clear(tv_first.getId());
    //设置该控件的约束宽度
    //set.constrainWidth(tv_first.getId(), ConstraintLayout.LayoutParams.WRAP_CONTENT);
    //设置该控件的约束高度
    //set.constrainHeight(tv_first.getId(),ConstraintLayout.LayoutParams.WRAP_CONTENT);
    //设置该控件的顶部约束关系与间距
    //set.connect(tv_first.getId(), ConstraintSet.TOP, cl_content.getId(), ConstraintSet.BOTTOM, margin);
    //设置该控件的底部约束关系与间距
    //set.connect(tv_first.getId(), ConstraintSet.BOTTOM, cl_content.getId(), ConstraintSet.BOTTOM, margin);
    //设置该控件的左侧约束关系与间距
    set.connect(tv_first.getId(), ConstraintSet.START, cl_content.getId(), ConstraintSet.START, margin);
    //设置该控件的右侧约束关系与间距
    //set.connect(tv_first.getId(), ConstraintSet.END, cl_content.getId(), ConstraintSet.END, margin);
    //LEFT和RIGHT的margin不管用，只有START和END的margin才管用
    //set.setMargin(tv_init.getId(), ConstraintSet.START, 200);
    //启用新的约束关系
    set.applyTo(cl_content);
    isMoved = !isMoved;
}