DragScrollBar.java

/*
 *  Copyright © 2016, Turing Technologies, an unincorporated organisation of Wynne Plaga
 *
 *  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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  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.turingtechnologies.materialscrollbar;

import android.content.Context;
import android.content.res.TypedArray;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.RecyclerView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class DragScrollBar extends MaterialScrollBar<DragScrollBar>{

    Boolean draggableFromAnywhere = false;
    float handleOffset = 0;
    float indicatorOffset = 0;

    public DragScrollBar(Context context, AttributeSet attributeSet, int defStyle){
        super(context, attributeSet, defStyle);
    }

    public DragScrollBar(Context context, AttributeSet attributeSet){
        super(context, attributeSet);
    }

    public DragScrollBar(Context context, RecyclerView recyclerView, boolean lightOnTouch){
        super(context, recyclerView, lightOnTouch);
    }

    boolean held = false;

    public DragScrollBar setDraggableFromAnywhere(boolean draggableFromAnywhere){
        this.draggableFromAnywhere = draggableFromAnywhere;
        return this;
    }

    //Tests to ensure that the touch is on the handleThumb depending on the user preference
    private boolean validTouch(MotionEvent event){
        return draggableFromAnywhere || (event.getY() >= ViewCompat.getY(handleThumb) - Utils.getDP(20, recyclerView.getContext()) && event.getY() <= ViewCompat.getY(handleThumb) + handleThumb.getHeight());
    }

    @Override
    void setTouchIntercept() {
        final Handle handle = super.handleThumb;
        OnTouchListener otl = new OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
            if (!hiddenByUser) {
                if(event.getAction() == MotionEvent.ACTION_DOWN && validTouch(event)){
                    held = true;

                    indicatorOffset = event.getY() - handle.getY() - handle.getLayoutParams().height / 2;
                    float offset2 = event.getY() - handle.getY();
                    float balance = handle.getY() / scrollUtils.getAvailableScrollBarHeight();
                    handleOffset = (offset2 * balance) + (indicatorOffset * (1 - balance));
                }
                //On Down
                if ((event.getAction() == MotionEvent.ACTION_MOVE || event.getAction() == MotionEvent.ACTION_DOWN) && held) {
                    onDown(event);
                    fadeIn();
                //On Up
                } else {
                    onUp();

                    held = false;

                    fadeOut();
                }
                return true;
            }
            return false;
            }
        };
        setOnTouchListener(otl);
    }

    @Override
    int getMode() {
        return 0;
    }

    @Override
    float getHideRatio() {
        return .65F;
    }

    @Override
    void onScroll() {}

    @Override
    boolean getHide() {
        return true;
    }

    @Override
    void implementFlavourPreferences(TypedArray a) {}

    @Override
    float getHandleOffset(){
        return draggableFromAnywhere ? 0 : handleOffset;
    }

    @Override
    float getIndicatorOffset(){
        return draggableFromAnywhere ? 0 : indicatorOffset;
    }
}