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/*
* Copyright (C) 2013 The Android Open Source Project
*
* 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.example.android.listviewremovalanimation;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewTreeObserver;
import android.widget.ListView;
/**
* This example shows how to use a swipe effect to remove items from a ListView,
* and how to use animations to complete the swipe as well as to animate the other
* items in the list into their final places.
*
* Watch the associated video for this demo on the DevBytes channel of developer.android.com
* or on YouTube at https://www.youtube.com/watch?v=NewCSg2JKLk.
*/
public class ListViewRemovalAnimation extends Activity {
StableArrayAdapter mAdapter;
ListView mListView;
BackgroundContainer mBackgroundContainer;
boolean mSwiping = false;
boolean mItemPressed = false;
HashMap<Long, Integer> mItemIdTopMap = new HashMap<Long, Integer>();
private static final int SWIPE_DURATION = 250;
private static final int MOVE_DURATION = 150;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_view_deletion);
mBackgroundContainer = (BackgroundContainer) findViewById(R.id.listViewBackground);
mListView = (ListView) findViewById(R.id.listview);
android.util.Log.d("Debug", "d=" + mListView.getDivider());
final ArrayList<String> cheeseList = new ArrayList<String>();
for (int i = 0; i < Cheeses.sCheeseStrings.length; ++i) {
cheeseList.add(Cheeses.sCheeseStrings[i]);
}
mAdapter = new StableArrayAdapter(this,R.layout.opaque_text_view, cheeseList,
mTouchListener);
mListView.setAdapter(mAdapter);
}
/**
* Handle touch events to fade/move dragged items as they are swiped out
*/
private View.OnTouchListener mTouchListener = new View.OnTouchListener() {
float mDownX;
private int mSwipeSlop = -1;
@Override
public boolean onTouch(final View v, MotionEvent event) {
if (mSwipeSlop < 0) {
mSwipeSlop = ViewConfiguration.get(ListViewRemovalAnimation.this).
getScaledTouchSlop();
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (mItemPressed) {
// Multi-item swipes not handled
return false;
}
mItemPressed = true;
mDownX = event.getX();
break;
case MotionEvent.ACTION_CANCEL:
v.setAlpha(1);
v.setTranslationX(0);
mItemPressed = false;
break;
case MotionEvent.ACTION_MOVE:
{
float x = event.getX() + v.getTranslationX();
float deltaX = x - mDownX;
float deltaXAbs = Math.abs(deltaX);
if (!mSwiping) {
if (deltaXAbs > mSwipeSlop) {
mSwiping = true;
mListView.requestDisallowInterceptTouchEvent(true);
mBackgroundContainer.showBackground(v.getTop(), v.getHeight());
}
}
if (mSwiping) {
v.setTranslationX((x - mDownX));
v.setAlpha(1 - deltaXAbs / v.getWidth());
}
}
break;
case MotionEvent.ACTION_UP:
{
// User let go - figure out whether to animate the view out, or back into place
if (mSwiping) {
float x = event.getX() + v.getTranslationX();
float deltaX = x - mDownX;
float deltaXAbs = Math.abs(deltaX);
float fractionCovered;
float endX;
float endAlpha;
final boolean remove;
if (deltaXAbs > v.getWidth() / 4) {
// Greater than a quarter of the width - animate it out
fractionCovered = deltaXAbs / v.getWidth();
endX = deltaX < 0 ? -v.getWidth() : v.getWidth();
endAlpha = 0;
remove = true;
} else {
// Not far enough - animate it back
fractionCovered = 1 - (deltaXAbs / v.getWidth());
endX = 0;
endAlpha = 1;
remove = false;
}
// Animate position and alpha of swiped item
// NOTE: This is a simplified version of swipe behavior, for the
// purposes of this demo about animation. A real version should use
// velocity (via the VelocityTracker class) to send the item off or
// back at an appropriate speed.
long duration = (int) ((1 - fractionCovered) * SWIPE_DURATION);
mListView.setEnabled(false);
v.animate().setDuration(duration).
alpha(endAlpha).translationX(endX).
withEndAction(new Runnable() {
@Override
public void run() {
// Restore animated values
v.setAlpha(1);
v.setTranslationX(0);
if (remove) {
animateRemoval(mListView, v);
} else {
mBackgroundContainer.hideBackground();
mSwiping = false;
mListView.setEnabled(true);
}
}
});
}
}
mItemPressed = false;
break;
default:
return false;
}
return true;
}
};
/**
* This method animates all other views in the ListView container (not including ignoreView)
* into their final positions. It is called after ignoreView has been removed from the
* adapter, but before layout has been run. The approach here is to figure out where
* everything is now, then allow layout to run, then figure out where everything is after
* layout, and then to run animations between all of those start/end positions.
*/
private void animateRemoval(final ListView listview, View viewToRemove) {
int firstVisiblePosition = listview.getFirstVisiblePosition();
for (int i = 0; i < listview.getChildCount(); ++i) {
View child = listview.getChildAt(i);
if (child != viewToRemove) {
int position = firstVisiblePosition + i;
long itemId = mAdapter.getItemId(position);
mItemIdTopMap.put(itemId, child.getTop());
}
}
// Delete the item from the adapter
int position = mListView.getPositionForView(viewToRemove);
mAdapter.remove(mAdapter.getItem(position));
final ViewTreeObserver observer = listview.getViewTreeObserver();
observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
public boolean onPreDraw() {
observer.removeOnPreDrawListener(this);
boolean firstAnimation = true;
int firstVisiblePosition = listview.getFirstVisiblePosition();
for (int i = 0; i < listview.getChildCount(); ++i) {
final View child = listview.getChildAt(i);
int position = firstVisiblePosition + i;
long itemId = mAdapter.getItemId(position);
Integer startTop = mItemIdTopMap.get(itemId);
int top = child.getTop();
if (startTop != null) {
if (startTop != top) {
int delta = startTop - top;
child.setTranslationY(delta);
child.animate().setDuration(MOVE_DURATION).translationY(0);
if (firstAnimation) {
child.animate().withEndAction(new Runnable() {
public void run() {
mBackgroundContainer.hideBackground();
mSwiping = false;
mListView.setEnabled(true);
}
});
firstAnimation = false;
}
}
} else {
// Animate new views along with the others. The catch is that they did not
// exist in the start state, so we must calculate their starting position
// based on neighboring views.
int childHeight = child.getHeight() + listview.getDividerHeight();
startTop = top + (i > 0 ? childHeight : -childHeight);
int delta = startTop - top;
child.setTranslationY(delta);
child.animate().setDuration(MOVE_DURATION).translationY(0);
if (firstAnimation) {
child.animate().withEndAction(new Runnable() {
public void run() {
mBackgroundContainer.hideBackground();
mSwiping = false;
mListView.setEnabled(true);
}
});
firstAnimation = false;
}
}
}
mItemIdTopMap.clear();
return true;
}
});
}
}
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