/*
* Copyright 2013 Google Inc.
*
* 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.marshalchen.common.uimodule.superlistview;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.annotation.TargetApi;
import android.os.Build;
import android.view.*;
/**
* A {@link android.view.View.OnTouchListener} that makes any {@link android.view.View} dismissable when the
* user swipes (drags her finger) horizontally across the view.
*
* <p><em>For {@link android.widget.ListView} list items that don't manage their own touch events
* (i.e. you're using
* {@link android.widget.ListView#setOnItemClickListener(android.widget.AdapterView.OnItemClickListener)}
* or an equivalent listener on {@link android.app.ListActivity} or
* {@link android.app.ListFragment}, use {@link SwipeDismissListViewTouchListener} instead.</em></p>
*
* <p>Example usage:</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>This class Requires API level 12 or later due to use of {@link
* android.view.ViewPropertyAnimator}.</p>
*
* @see SwipeDismissListViewTouchListener
*/
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 DismissCallbacks mCallbacks;
private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero
// Transient properties
private float mDownX;
private float mDownY;
private boolean mSwiping;
private int mSwipingSlop;
private Object mToken;
private VelocityTracker mVelocityTracker;
private float mTranslationX;
/**
* The callback interface used by {@link com.marshalchen.common.uimodule.superlistview.SwipeDismissTouchListener} to inform its client
* about a successful dismissal of the view for which it was created.
*/
public interface DismissCallbacks {
/**
* Called to determine whether the view can be dismissed.
*/
boolean canDismiss(Object token);
/**
* Called when the user has indicated they she would like to dismiss the view.
*
* @param view The originating {@link android.view.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 callbacks The callback to trigger when the user has indicated that she would like to
* dismiss this view.
*/
@TargetApi(Build.VERSION_CODES.DONUT)
public SwipeDismissTouchListener(View view, Object token, DismissCallbacks callbacks) {
ViewConfiguration vc = ViewConfiguration.get(view.getContext());
mSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
mAnimationTime = view.getContext().getResources().getInteger(
android.R.integer.config_shortAnimTime);
mView = view;
mToken = token;
mCallbacks = callbacks;
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
@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();
mDownY = motionEvent.getRawY();
if (mCallbacks.canDismiss(mToken)) {
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement(motionEvent);
}
return false;
}
case MotionEvent.ACTION_UP: {
if (mVelocityTracker == null) {
break;
}
float deltaX = motionEvent.getRawX() - mDownX;
mVelocityTracker.addMovement(motionEvent);
mVelocityTracker.computeCurrentVelocity(1000);
float velocityX = mVelocityTracker.getXVelocity();
float absVelocityX = Math.abs(velocityX);
float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
boolean dismiss = false;
boolean dismissRight = false;
if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
dismiss = true;
dismissRight = deltaX > 0;
} else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity
&& absVelocityY < absVelocityX
&& absVelocityY < absVelocityX && mSwiping) {
// dismiss only if flinging in the same direction as dragging
dismiss = (velocityX < 0) == (deltaX < 0);
dismissRight = mVelocityTracker.getXVelocity() > 0;
}
if (dismiss) {
// dismiss
mView.animate()
.translationX(dismissRight ? mViewWidth : -mViewWidth)
.alpha(0)
.setDuration(mAnimationTime)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
performDismiss();
}
});
} else if (mSwiping) {
// cancel
mView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mTranslationX = 0;
mDownX = 0;
mDownY = 0;
mSwiping = false;
break;
}
case MotionEvent.ACTION_CANCEL: {
if (mVelocityTracker == null) {
break;
}
mView.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
mVelocityTracker.recycle();
mVelocityTracker = null;
mTranslationX = 0;
mDownX = 0;
mDownY = 0;
mSwiping = false;
break;
}
case MotionEvent.ACTION_MOVE: {
if (mVelocityTracker == null) {
break;
}
mVelocityTracker.addMovement(motionEvent);
float deltaX = motionEvent.getRawX() - mDownX;
float deltaY = motionEvent.getRawY() - mDownY;
if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
mSwiping = true;
mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop);
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);
cancelEvent.recycle();
}
if (mSwiping) {
mTranslationX = deltaX;
mView.setTranslationX(deltaX - mSwipingSlop);
// TODO: use an ease-out interpolator or such
mView.setAlpha(Math.max(0f, Math.min(1f,
1f - 2f * Math.abs(deltaX) / mViewWidth)));
return true;
}
break;
}
}
return false;
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
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) {
mCallbacks.onDismiss(mView, mToken);
// Reset view presentation
mView.setAlpha(1f);
mView.setTranslationX(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();
}
}