/*
* Copyright 2012 Roman Nurik
*
* 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.adamnickle.deck;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import com.nineoldandroids.animation.Animator;
import com.nineoldandroids.animation.AnimatorListenerAdapter;
import com.nineoldandroids.animation.ValueAnimator;
import com.nineoldandroids.view.ViewHelper;
import com.nineoldandroids.view.ViewPropertyAnimator;
/**
* A {@link android.view.View.OnTouchListener} that makes any {@link View} dismissable when the
* user swipes (drags her finger) horizontally across the view.
* <p/>
* <p>Example usage:</p>
* <p/>
* <pre>
* view.setOnTouchListener(new SwipeDismissTouchListener(
* view,
* null, // Optional token/cookie object
* new SwipeDismissTouchListener.OnDismissCallback() {
* public void onDismiss(View view, Object token) {
* parent.removeView(view);
* }
* }));
* </pre>
* <p/>
* <p>This class Requires API level 12 or later due to use of {@link
* android.view.ViewPropertyAnimator}.</p>
*/
public class SwipeDismissTouchListener implements View.OnTouchListener
{
// Cached ViewConfiguration and system-wide constant values
private int mSlop;
private int mMinFlingVelocity;
private int mMaxFlingVelocity;
private long mAnimationTime;
// Fixed properties
private View mView;
private OnDismissCallback mCallback;
private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero
// Transient properties
private float mDownX;
private boolean mSwiping;
private Object mToken;
private VelocityTracker mVelocityTracker;
private float mTranslationX;
/**
* The callback interface used by {@link SwipeDismissTouchListener} to inform its client
* about a successful dismissal of the view for which it was created.
*/
public interface OnDismissCallback
{
/**
* Called when the user has indicated they she would like to dismiss the view.
*
* @param view The originating {@link View} to be dismissed.
* @param token The optional token passed to this object's constructor.
*/
void onDismiss( View view, Object token );
}
/**
* Constructs a new swipe-to-dismiss touch listener for the given view.
*
* @param view The view to make dismissable.
* @param token An optional token/cookie object to be passed through to the callback.
* @param callback The callback to trigger when the user has indicated that she would like to
* dismiss this view.
*/
public SwipeDismissTouchListener( View view, Object token, OnDismissCallback callback )
{
ViewConfiguration vc = ViewConfiguration.get( view.getContext() );
mSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
mAnimationTime = view.getContext().getResources().getInteger(
android.R.integer.config_shortAnimTime );
mView = view;
mToken = token;
mCallback = callback;
}
@Override
public boolean onTouch( View view, MotionEvent motionEvent )
{
// offset because the view is translated during swipe
motionEvent.offsetLocation( mTranslationX, 0 );
if( mViewWidth < 2 )
{
mViewWidth = mView.getWidth();
}
switch( motionEvent.getActionMasked() )
{
case MotionEvent.ACTION_DOWN:
{
// TODO: ensure this is a finger, and set a flag
mDownX = motionEvent.getRawX();
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement( motionEvent );
view.onTouchEvent( motionEvent );
return false;
}
case MotionEvent.ACTION_UP:
{
if( mVelocityTracker == null )
{
break;
}
float deltaX = motionEvent.getRawX() - mDownX;
mVelocityTracker.addMovement( motionEvent );
mVelocityTracker.computeCurrentVelocity( 1000 );
float velocityX = Math.abs( mVelocityTracker.getXVelocity() );
float velocityY = Math.abs( mVelocityTracker.getYVelocity() );
boolean dismiss = false;
boolean dismissRight = false;
if( Math.abs( deltaX ) > mViewWidth / 2 )
{
dismiss = true;
dismissRight = deltaX > 0;
}else if( mMinFlingVelocity <= velocityX && velocityX <= mMaxFlingVelocity
&& velocityY < velocityX )
{
dismiss = true;
dismissRight = mVelocityTracker.getXVelocity() > 0;
}
if( dismiss )
{
// dismiss
ViewPropertyAnimator
.animate( mView )
.translationX( dismissRight ? mViewWidth : -mViewWidth )
.alpha( 0 )
.setDuration( mAnimationTime )
.setListener( new AnimatorListenerAdapter()
{
@Override
public void onAnimationEnd( Animator animation )
{
performDismiss();
}
} );
}else
{
// cancel
ViewPropertyAnimator
.animate( mView )
.translationX( 0 )
.alpha( 1 )
.setDuration( mAnimationTime )
.setListener( null );
}
mVelocityTracker = null;
mTranslationX = 0;
mDownX = 0;
mSwiping = false;
break;
}
case MotionEvent.ACTION_MOVE:
{
if( mVelocityTracker == null )
{
break;
}
mVelocityTracker.addMovement( motionEvent );
float deltaX = motionEvent.getRawX() - mDownX;
if( Math.abs( deltaX ) > mSlop )
{
mSwiping = true;
mView.getParent().requestDisallowInterceptTouchEvent( true );
// Cancel listview's touch
MotionEvent cancelEvent = MotionEvent.obtain( motionEvent );
cancelEvent.setAction( MotionEvent.ACTION_CANCEL |
( motionEvent.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT ) );
mView.onTouchEvent( cancelEvent );
}
if( mSwiping )
{
mTranslationX = deltaX;
ViewHelper.setTranslationX( mView, deltaX );
// TODO: use an ease-out interpolator or such
ViewHelper.setAlpha( mView, Math.max( 0f, Math.min( 1f,
1f - 2f * Math.abs( deltaX ) / mViewWidth ) ) );
return true;
}
break;
}
}
return false;
}
private void performDismiss()
{
// Animate the dismissed view to zero-height and then fire the dismiss callback.
// This triggers layout on each animation frame; in the future we may want to do something
// smarter and more performant.
final ViewGroup.LayoutParams lp = mView.getLayoutParams();
final int originalHeight = mView.getHeight();
ValueAnimator animator = ValueAnimator.ofInt( originalHeight, 1 ).setDuration( mAnimationTime );
animator.addListener( new AnimatorListenerAdapter()
{
@Override
public void onAnimationEnd( Animator animation )
{
mCallback.onDismiss( mView, mToken );
// Reset view presentation
ViewHelper.setAlpha( mView, 1f );
ViewHelper.setTranslationX( mView, 0 );
lp.height = originalHeight;
mView.setLayoutParams( lp );
}
} );
animator.addUpdateListener( new ValueAnimator.AnimatorUpdateListener()
{
@Override
public void onAnimationUpdate( ValueAnimator valueAnimator )
{
lp.height = (Integer) valueAnimator.getAnimatedValue();
mView.setLayoutParams( lp );
}
} );
animator.start();
}
}