com.anandmuralidhar.assimpandroid.GestureClass.java Source code

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Here is the source code for com.anandmuralidhar.assimpandroid.GestureClass.java

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/*
 *    Copyright 2016 Anand Muralidhar
 *
 *    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.anandmuralidhar.assimpandroid;

import android.app.Activity;
import android.support.v4.view.GestureDetectorCompat;
import android.support.v4.view.MotionEventCompat;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;

public class GestureClass {

    private GestureDetectorCompat mTapScrollDetector;
    private ScaleGestureDetector mScaleDetector;

    private native void DoubleTapNative();

    private native void ScrollNative(float distanceX, float distanceY, float positionX, float positionY);

    private native void ScaleNative(float scaleFactor);

    private native void MoveNative(float distanceX, float distanceY);

    public GestureClass(Activity activity) {

        // instantiate two listeners for detecting double-tap/drag and pinch-zoom
        mTapScrollDetector = new GestureDetectorCompat(activity, new MyTapScrollListener());
        mScaleDetector = new ScaleGestureDetector(activity.getApplicationContext(), new ScaleListener());

    }

    static int INVALID_POINTER_ID = -100;
    private int mTwoFingerPointerId = INVALID_POINTER_ID;

    // this listener detects gesture of dragging with two fingers
    public View.OnTouchListener TwoFingerGestureListener = new View.OnTouchListener() {
        private float mLastTouchX, mLastTouchY;

        @Override
        public boolean onTouch(View v, MotionEvent event) {

            // let the other detectors also consume the event
            mTapScrollDetector.onTouchEvent(event);
            mScaleDetector.onTouchEvent(event);

            final int action = MotionEventCompat.getActionMasked(event);

            switch (action) {
            case MotionEvent.ACTION_DOWN: {
                break;
            }

            case MotionEvent.ACTION_MOVE: {
                // track the drag only if two fingers are placed on screen
                if (mTwoFingerPointerId != INVALID_POINTER_ID) {

                    final float x = MotionEventCompat.getX(event, mTwoFingerPointerId);
                    final float y = MotionEventCompat.getY(event, mTwoFingerPointerId);

                    // Calculate the distance moved
                    final float dx = x - mLastTouchX;
                    final float dy = y - mLastTouchY;

                    // Remember this touch position for the next move event
                    mLastTouchX = x;
                    mLastTouchY = y;
                    MoveNative(dx, dy);
                }
                break;
            }

            case MotionEvent.ACTION_UP: {
                mTwoFingerPointerId = INVALID_POINTER_ID;
                break;
            }

            case MotionEvent.ACTION_CANCEL: {
                mTwoFingerPointerId = INVALID_POINTER_ID;
                break;
            }

            case MotionEvent.ACTION_POINTER_DOWN: {
                // detected two fingers, start the drag
                mTwoFingerPointerId = MotionEventCompat.getActionIndex(event);
                final float x = MotionEventCompat.getX(event, mTwoFingerPointerId);
                final float y = MotionEventCompat.getY(event, mTwoFingerPointerId);

                // Remember where we started (for dragging)
                mLastTouchX = x;
                mLastTouchY = y;
                break;
            }

            case MotionEvent.ACTION_POINTER_UP: {
                // two fingers are not placed on screen anymore
                mTwoFingerPointerId = INVALID_POINTER_ID;
                break;
            }
            }
            return true;
        }
    };

    // this class detects double-tap gesture and tracks the drag gesture by single finger
    class MyTapScrollListener extends GestureDetector.SimpleOnGestureListener {

        public boolean onDoubleTap(MotionEvent event) {
            DoubleTapNative();
            return true;
        }

        // function is called if user scrolls with one/two fingers
        // we ignore the call if two fingers are placed on screen
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {

            if (mTwoFingerPointerId == INVALID_POINTER_ID) {
                ScrollNative(distanceX, distanceY, e2.getX(), e2.getY());
            }
            return true;
        }
    }

    // this class detects pinch and zoom gestures
    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            ScaleNative(detector.getScaleFactor());
            return true;
        }
    }

}