TouchDelegateGroup.java

/*
 * Copyright 2013 Gleb Godonoga.
 *
 * 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.andrada.sitracker.ui.widget;

import android.graphics.Rect;
import android.view.MotionEvent;
import android.view.TouchDelegate;
import android.view.View;

import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.ArrayList;

public class TouchDelegateGroup extends TouchDelegate {

    private static final Rect USELESS_HACKY_RECT = new Rect();

    @Nullable
    private ArrayList<TouchDelegate> mTouchDelegates;
    @Nullable
    private TouchDelegate mCurrentTouchDelegate;

    public TouchDelegateGroup(@NotNull View uselessHackyView) {
        // I know this is pretty hacky. Unfortunately there is no other way to
        // create a TouchDelegate containing TouchDelegates since TouchDelegate
        // is not an interface ...
        super(USELESS_HACKY_RECT, uselessHackyView);
    }

    public void addTouchDelegate(TouchDelegate touchDelegate) {
        if (mTouchDelegates == null) {
            mTouchDelegates = new ArrayList<TouchDelegate>();
        }
        mTouchDelegates.add(touchDelegate);
    }

    public void removeTouchDelegate(TouchDelegate touchDelegate) {
        if (mTouchDelegates != null) {
            mTouchDelegates.remove(touchDelegate);
            if (mTouchDelegates.isEmpty()) {
                mTouchDelegates = null;
            }
        }
    }

    public void clearTouchDelegates() {
        if (mTouchDelegates != null) {
            mTouchDelegates.clear();
        }
        mCurrentTouchDelegate = null;
    }

    @Override
    public boolean onTouchEvent(@NotNull MotionEvent event) {

        TouchDelegate delegate = null;

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (mTouchDelegates != null) {
                    for (TouchDelegate touchDelegate : mTouchDelegates) {
                        if (touchDelegate != null) {
                            if (touchDelegate.onTouchEvent(event)) {
                                mCurrentTouchDelegate = touchDelegate;
                                return true;
                            }
                        }
                    }
                }
                break;

            case MotionEvent.ACTION_MOVE:
                delegate = mCurrentTouchDelegate;
                break;

            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
                delegate = mCurrentTouchDelegate;
                mCurrentTouchDelegate = null;
                break;
        }

        return delegate != null && delegate.onTouchEvent(event);
    }

}