ngoctdn.vng.gesture.CupcakeGestureDetector.java Source code

Introduction

Here is the source code for ngoctdn.vng.gesture.CupcakeGestureDetector.java

Source

/*******************************************************************************
 * Copyright 2011, 2012 Chris Banes.
 *
 * 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 ngoctdn.vng.gesture;

import android.content.Context;
import android.support.v4.view.MotionEventCompat;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.ViewConfiguration;

import ngoctdn.vng.utils.Log;

public class CupcakeGestureDetector {

    protected OnGestureListener mListener;
    private static final String LOG_TAG = "CupcakeGestureDetector";
    float mLastTouchX;
    float mLastTouchY;
    final float mTouchSlop;
    final float mMinimumVelocity;

    private float mFirstRawTouchY;
    private float mLastRawTouchY;
    private int mActivePointerId;

    public void setOnGestureListener(OnGestureListener listener) {
        this.mListener = listener;
    }

    public CupcakeGestureDetector(Context context) {
        final ViewConfiguration configuration = ViewConfiguration.get(context);
        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
        mTouchSlop = configuration.getScaledTouchSlop();
    }

    private VelocityTracker mVelocityTracker;
    private boolean mIsDragging;

    float getActiveX(MotionEvent ev) {
        return ev.getX();
    }

    float getActiveY(MotionEvent ev) {
        return ev.getY();
    }

    public boolean isScaling() {
        return false;
    }

    public boolean onTouchEvent(MotionEvent ev) {
        switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            mVelocityTracker = VelocityTracker.obtain();
            if (null != mVelocityTracker) {
                mVelocityTracker.addMovement(ev);
            } else {
                Log.i(LOG_TAG, "Velocity tracker is null");
            }

            mLastTouchX = getActiveX(ev);
            mLastTouchY = getActiveY(ev);
            mFirstRawTouchY = ev.getRawY();
            mLastRawTouchY = ev.getRawY();
            mIsDragging = false;
            mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
            break;
        }

        case MotionEvent.ACTION_POINTER_DOWN:
            mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
            break;

        case MotionEvent.ACTION_MOVE: {
            final float x = getActiveX(ev);
            final float y = getActiveY(ev);
            final float dx = x - mLastTouchX, dy = y - mLastTouchY;

            if (!mIsDragging) {
                // Use Pythagoras to see if drag length is larger than
                // touch slop
                mIsDragging = Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop;
            }

            if (mIsDragging) {
                if (ev.getPointerCount() == 1)
                    mListener.onDrag(mLastRawTouchY, ev.getRawY(), dx, dy);
                mLastTouchX = x;
                mLastTouchY = y;
                mLastRawTouchY = ev.getRawY();
                // if (mListener != null) {
                // mListener.onScrolling(mLastRawTouchY, ev.getRawY());
                // mLastRawTouchY = ev.getRawY();
                // }

                if (null != mVelocityTracker) {
                    mVelocityTracker.addMovement(ev);
                }
            }
            if (mActivePointerId == -1 && mListener != null) {
                mListener.onRelease(mFirstRawTouchY, ev.getRawY(), 0);
            }
            break;
        }

        case MotionEvent.ACTION_POINTER_UP:
        case MotionEvent.ACTION_CANCEL:
        case MotionEvent.ACTION_UP: {

            if (mIsDragging) {
                if (null != mVelocityTracker) {

                    mLastTouchX = getActiveX(ev);
                    mLastTouchY = getActiveY(ev);

                    // if (mListener != null) {
                    // mListener.onScrolling(mFirstTouchY, mLastTouchY);
                    // }

                    // Compute velocity within the last 1000ms
                    mVelocityTracker.addMovement(ev);
                    mVelocityTracker.computeCurrentVelocity(1000);

                    final float vX = mVelocityTracker.getXVelocity(), vY = mVelocityTracker.getYVelocity();

                    // If the velocity is greater than minVelocity, call
                    // listener
                    if (Math.max(Math.abs(vX), Math.abs(vY)) >= mMinimumVelocity) {
                        mListener.onFling(mLastTouchX, mLastTouchY, -vX, -vY);
                    }
                }
            }

            if (mListener != null) {
                mLastRawTouchY = ev.getRawY();
                if (mVelocityTracker != null)
                    mListener.onRelease(mFirstRawTouchY, ev.getRawY(), mVelocityTracker.getYVelocity());
                else
                    mListener.onRelease(mFirstRawTouchY, ev.getRawY(), 0);
            }

            // Recycle Velocity Tracker
            if (null != mVelocityTracker) {
                mVelocityTracker.recycle();
                mVelocityTracker = null;
            }
            break;
        }
        }

        return true;
    }
}