使用 ConstraintLayout 折叠工具栏布局

Question

我正在尝试使用 ConstraintLayout 实现折叠工具栏。在尝试了很多之后，我无法满足 effects.I 在 youtube 中关注这个 link 的愿望（https://www.youtube.com/watch?v=8lAXJ5NFXTM 在第 21 分钟）。我的源代码是：-

activity.main.xml:-

    <android.support.design.widget.CoordinatorLayout 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=".activities.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="@dimen/app_bar_height"
        android:theme="@style/AppTheme.AppBarOverlay"
        android:fitsSystemWindows="false">

        <com.example.study.helpers.NoAnimCollapsibleConstraintLayout
            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:id="@+id/root"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            android:minHeight="40dp"
            app:layout_scrollFlags="scroll|enterAlways|snap|exitUntilCollapsed"/>

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/ic_border_color_white_24dp"/>

</android.support.design.widget.CoordinatorLayout>

content_main.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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".activities.MainActivity"
    tools:showIn="@layout/activity_main">


    <TextView
        android:id="@+id/textView3"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/some_long_text"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

NoAnimCollapsibleConstraintLayout.java:-

import android.content.Context;
import android.support.constraint.ConstraintLayout;
import android.support.constraint.ConstraintSet;
import android.support.design.widget.AppBarLayout;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.Toast;
import com.example.study.R;

public class NoAnimCollapsibleConstraintLayout extends ConstraintLayout implements AppBarLayout.OnOffsetChangedListener {

    private static final String TAG = NoAnimCollapsibleConstraintLayout.class.getSimpleName();
    private float mTransitionThreshold = 0.35f;
    private int mLastPosition = 0;
    private boolean mToolbarOpen = true;

    private ConstraintSet mOpenToolbarSet = new ConstraintSet();
    private ConstraintSet mCloseToolbarSet = new ConstraintSet();

    public NoAnimCollapsibleConstraintLayout(Context context) { super(context, null); }

    public NoAnimCollapsibleConstraintLayout(Context context, AttributeSet attrs) { super(context, attrs, 0); }

    public NoAnimCollapsibleConstraintLayout(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        if (getParent() instanceof AppBarLayout){
            Log.d(TAG, "Instance AppBarLayout");
            AppBarLayout appBarLayout = (AppBarLayout)getParent();
            appBarLayout.addOnOffsetChangedListener(this);
            mOpenToolbarSet.clone(getContext(), R.layout.open);
            mCloseToolbarSet.clone(getContext(), R.layout.close);

        }else {
            Log.d(TAG, "Instance if Not Parent");
        }
    }

    @Override
    public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
        Log.d(TAG, "onOffsetChanged");
        if (mLastPosition == verticalOffset){
            return;
        }

        mLastPosition = verticalOffset;
        Float progress =  ( Math.abs(verticalOffset / (float) (appBarLayout.getHeight()))) ;

        AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) getLayoutParams();
        params.topMargin = -verticalOffset;
        setLayoutParams(params);

        if ( mToolbarOpen && progress > mTransitionThreshold) {
            Log.d(TAG, "Apply close.xml");
            mCloseToolbarSet.applyTo(this);
            mToolbarOpen = false;
        }else if ( !mToolbarOpen && progress < mTransitionThreshold){
            Log.d(TAG, "Apply open.xml");
            mOpenToolbarSet.applyTo(this);
            mToolbarOpen = true;

        }
    }
}

open.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:id="@+id/open"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:contentDescription="@string/app_name"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@drawable/study" />

</android.support.constraint.ConstraintLayout>

close.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:id="@+id/close"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <TextView
        android:id="@+id/textView4"
        android:layout_width="0dp"
        android:layout_height="30dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="@string/app_name"
        android:textColor="@android:color/white"
        android:textSize="@dimen/text_size_16"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>

应用此代码后 open.xml 和 close.xml 设计在我尝试折叠工具栏时未显示。这是我在输出中得到的屏幕截图：-

没有折叠（open.xml 缺少设计）：- https://www.dropbox.com/s/c0rh126rinmopd4/Screen_Shot1.png?dl=0)

使用 Collpase（close.xml 缺少设计）：- https://www.dropbox.com/s/cdlbg84lmht3gv0/Screen_Shot2.png?dl=0

Answer 1

看完视频后，我一直在尝试做同样的事情。

将 id "constraint" 添加到两个根 ConstraintLayout

您确实在 NoAnimCollapsibleConstraintLayout 中膨胀了您的视图，所以膨胀然后找到约束视图

import android.content.Context;
import android.support.constraint.ConstraintLayout;
import android.support.constraint.ConstraintSet;
import android.support.design.widget.AppBarLayout;
import android.support.transition.TransitionManager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;

public class NoAnimCollapsibleConstraintLayout extends ConstraintLayout
    implements AppBarLayout.OnOffsetChangedListener {

  private static final String TAG = NoAnimCollapsibleConstraintLayout.class.getSimpleName();
  private float mTransitionThreshold = 0.35f;
  private int mLastPosition = 0;
  private boolean mToolbarOpen = true;

  private ConstraintSet mOpenToolbarSet = new ConstraintSet();
  private ConstraintSet mCloseToolbarSet = new ConstraintSet();
  private ConstraintLayout constraint;

  public NoAnimCollapsibleConstraintLayout(Context context) {
    this(context, null);
  }

  public NoAnimCollapsibleConstraintLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public NoAnimCollapsibleConstraintLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    LayoutInflater.from(getContext()).inflate(R.layout.open, this, true);
    constraint = findViewById(R.id.constraint);
  }

  @Override
  protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    if (getParent() instanceof AppBarLayout) {
      Log.d(TAG, "Instance AppBarLayout");
      AppBarLayout appBarLayout = (AppBarLayout) getParent();
      appBarLayout.addOnOffsetChangedListener(this);
      mOpenToolbarSet.clone(constraint);
      mCloseToolbarSet.clone(getContext(), R.layout.close);
    } else {
      Log.d(TAG, "Instance if Not Parent");
    }
  }

  @Override
  public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
    Log.d(TAG, "onOffsetChanged");
    if (mLastPosition == verticalOffset) {
      return;
    }

    mLastPosition = verticalOffset;
    Float progress = (Math.abs(verticalOffset / (float) (appBarLayout.getHeight())));

    AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) getLayoutParams();
    params.topMargin = -verticalOffset;
    setLayoutParams(params);
    TransitionManager.beginDelayedTransition(constraint);
    if (mToolbarOpen && progress > mTransitionThreshold) {
      Log.d(TAG, "Apply close.xml");
      mCloseToolbarSet.applyTo(constraint);
      mToolbarOpen = false;
    } else if (!mToolbarOpen && progress < mTransitionThreshold) {
      Log.d(TAG, "Apply open.xml");
      mOpenToolbarSet.applyTo(constraint);
      mToolbarOpen = true;
    }
  }
}

这里面有一个动画，它似乎对我有用。尝试并确保两者中存在相同的视图，即使只是移动它或可见性消失

编辑：https://github.com/BigFishStudios/ConstraintToolbar这里是这个工作的代码示例

希望对您有所帮助 :D

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