com.dbychkov.words.behavior.ScrollOffBottomBehavior.java Source code

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Here is the source code for com.dbychkov.words.behavior.ScrollOffBottomBehavior.java

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/**
 * Copyright (C) dbychkov.
 * <p/>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.dbychkov.words.behavior;

import android.animation.ObjectAnimator;
import android.content.Context;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;

/**
 * Fab behavior
 */
public class ScrollOffBottomBehavior extends CoordinatorLayout.Behavior<FloatingActionButton> {

    public static final int TRANSLATION_MULTIPLIER = 2;

    private int viewHeight;
    private ObjectAnimator animator;

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

    @Override
    public boolean onLayoutChild(CoordinatorLayout parent, FloatingActionButton child, int layoutDirection) {
        viewHeight = child.getHeight();
        return super.onLayoutChild(parent, child, layoutDirection);
    }

    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child, View target,
            int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
        if (animator == null || !animator.isRunning()) {
            int totalScroll = (dyConsumed + dyUnconsumed);
            int targetTranslation = totalScroll > 0 ? viewHeight : 0;
            animator = ObjectAnimator.ofFloat(child, "translationY", targetTranslation * TRANSLATION_MULTIPLIER);
            animator.start();
        }
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child,
            View directTargetChild, View target, int nestedScrollAxes) {
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton child, View dependency) {
        return dependency instanceof Snackbar.SnackbarLayout;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, FloatingActionButton child, View dependency) {
        float translationY = Math.min(0, dependency.getTranslationY() - dependency.getHeight());
        child.setTranslationY(translationY);
        return true;
    }

}