ForkView.java

package com.joker.rxweather.ui;

import android.content.Context;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.design.widget.AppBarLayout;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPropertyAnimatorListener;
import android.support.v4.view.animation.FastOutLinearInInterpolator;
import android.support.v4.view.animation.FastOutSlowInInterpolator;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.joker.rxweather.common.Constants;

/**
 * Created by Joker on 2015/11/5.
 */
@CoordinatorLayout.DefaultBehavior(ForkView.Behavior.class) public class ForkView extends TextView {

  private static final String TAG = ForkView.class.getSimpleName();

  public ForkView(Context context) {
    super(context);
  }

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

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

  @Override protected void onAttachedToWindow() {
    super.onAttachedToWindow();

    if (ForkView.this.getY() == 0 && ForkView.this.getVisibility() != GONE) {
      ViewCompat.setY(ForkView.this, ForkView.calculateTranslation(ForkView.this));
      ForkView.this.setVisibility(GONE);
    }
  }

  @Override public Parcelable onSaveInstanceState() {

    SavedState savedState = new SavedState(super.onSaveInstanceState());
    savedState.stateToSave = ForkView.this.getTranslationY();
    return savedState;
  }

  @Override public void onRestoreInstanceState(Parcelable state) {
    if (!(state instanceof SavedState)) {
      super.onRestoreInstanceState(state);
      return;
    }

    SavedState savedState = (SavedState) state;
    super.onRestoreInstanceState(savedState.getSuperState());
    ForkView.this.setTranslationY(savedState.stateToSave);
  }

  static class SavedState extends BaseSavedState {
    private float stateToSave;

    SavedState(Parcelable superState) {
      super(superState);
    }

    private SavedState(Parcel in) {
      super(in);
      this.stateToSave = in.readFloat();
    }

    @Override public void writeToParcel(Parcel out, int flags) {
      super.writeToParcel(out, flags);
      out.writeFloat(this.stateToSave);
    }

    public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {
      public SavedState createFromParcel(Parcel in) {
        return new SavedState(in);
      }

      public SavedState[] newArray(int size) {
        return new SavedState[size];
      }
    };
  }

  public static class Behavior extends android.support.design.widget.CoordinatorLayout.Behavior<ForkView> {

    private boolean isOuting;

    public Behavior() {

    }

    @Override public boolean layoutDependsOn(CoordinatorLayout parent, ForkView child, View dependency) {
      return dependency instanceof AppBarLayout;
    }

    @Override public boolean onDependentViewChanged(CoordinatorLayout parent, ForkView child, View dependency) {
      if (dependency instanceof AppBarLayout) {
        Behavior.this.updateVisibility(parent, (AppBarLayout) dependency, child);
      }
      return false;
    }

    private boolean updateVisibility(CoordinatorLayout parent, AppBarLayout appBarLayout, ForkView child) {

      CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) child.getLayoutParams();

      if (layoutParams.getAnchorId() != appBarLayout.getId()) {
        return false;
      }

      int distanceToScroll = ForkView.calculateTranslation(child);

      /*other animation......*/
      //ViewCompat.setTranslationY(child, Math.abs(y) - distanceToScroll);

      if (Math.abs(appBarLayout.getY()) >= getMinimumHeightForVisibleOverlappingContent(appBarLayout)) {

        if (child.getVisibility() != VISIBLE) {
          this.animateIn(child, distanceToScroll);
        }
      } else {

        if (!Behavior.this.isOuting && child.getVisibility() == View.VISIBLE) {
          this.animateOut(child, -distanceToScroll);
        }
      }
      return true;
    }

    final int getMinimumHeightForVisibleOverlappingContent(AppBarLayout appBarLayout) {
      int topInset = 0;
      int minHeight = ViewCompat.getMinimumHeight(appBarLayout);
      if (minHeight != 0) {
        return minHeight * 2 + topInset;
      } else {
        int childCount = appBarLayout.getChildCount();
        return childCount >= 1 ? ViewCompat.getMinimumHeight(appBarLayout.getChildAt(childCount - 1)) * 2 + topInset
                               : 0;
      }

     /* try {
        Method method =
            AppBarLayout.class.getDeclaredMethod("getMinimumHeightForVisibleOverlappingContent");
        method.setAccessible(true);
        method.invoke(appBarLayout);
      } catch (NoSuchMethodException e) {
        e.printStackTrace();
      } catch (InvocationTargetException e) {
        e.printStackTrace();
      } catch (IllegalAccessException e) {
        e.printStackTrace();
      }*/

    }

    private void animateIn(ForkView child, float distanceToScroll) {

      child.setVisibility(VISIBLE);
      ViewCompat
          .animate(child)
          .alpha(1.0f)
          .translationY(distanceToScroll)
          .setDuration(Constants.MILLISECONDS_400)
          .setInterpolator(new FastOutSlowInInterpolator())
          .withLayer()
          .setListener(null);
    }

    private void animateOut(final ForkView child, float distanceToScroll) {

      ViewCompat
          .animate(child)
          .alpha(0.4f)
          .translationY(distanceToScroll)
          .setDuration(Constants.MILLISECONDS_400)
          .setInterpolator(new FastOutLinearInInterpolator())
          .withLayer()
          .setListener(new ViewPropertyAnimatorListener() {
            public void onAnimationStart(View view) {
              Behavior.this.isOuting = true;
            }

            public void onAnimationCancel(View view) {
              Behavior.this.isOuting = false;
            }

            public void onAnimationEnd(View view) {
              Behavior.this.isOuting = false;
              view.setVisibility(View.GONE);
            }
          });
    }
  }

  private static int calculateTranslation(View view) {
    int height = view.getHeight();

    ViewGroup.MarginLayoutParams params = (ViewGroup.MarginLayoutParams) view.getLayoutParams();
    int margins = params.topMargin + params.bottomMargin;

    return height + margins;
  }
}