Android SwipeToDismiss：左滑/右滑删除ListView条目Item

ゞ浴缸里的玫瑰 2023-10-16 21:54 1阅读 0赞

《Android SwipeToDismiss：左右滑动删除ListView条目Item》

Android的SwipeToDismiss是github上一个第三方开源框架（github上的项目链接地址：[https://github.com/romannurik/Android-SwipeToDismiss][https_github.com_romannurik_Android-SwipeToDismiss] ）。该开源项目旨在：使得一个ListView的item在用户的手指在屏幕上左滑或者右滑时候，删除当前的这个ListView Item。  
此种特效在新版的Android中应用不少，比如在Android 5.0及以上版本中，通知栏下拉菜单中的条目，就是这种操作效果，用户把通知栏下拉出来，手指轻触某一项，左滑或者右滑，删除（清除）此项。  
在 [https://github.com/romannurik/Android-SwipeToDismiss][https_github.com_romannurik_Android-SwipeToDismiss] 上下载到到库文件有两个（此说是基于截止2015年7月27日的版本，后续版本也许会有所不同）：SwipeDismissListViewTouchListener.java 和 SwipeDismissTouchListener.java 。如果只是打算简单的只是支持一个ListView列表中item左滑/右滑删除，那么仅仅只导入SwipeDismissListViewTouchListener.java这一个库文件即可。  
现在就给出一个简单例子，说明如何改造一个标准ListView，使其支持左右滑动某个item然后删除之。

测试用的MainActivity.java :

package zhangphil.listview;
 
 import java.util.ArrayList;
 
 import android.app.ListActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.widget.ArrayAdapter;
 import android.widget.ListView;
 
 public class MainActivity extends ListActivity {
 
 	private ArrayAdapter<String> adapter = null;
 	private ArrayList<String> items = null;
 
 	@Override
 	protected void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
 		ListView listView = this.getListView();
 
 		// 测试数据集。
 		items = new ArrayList<String>();
 		for (int i = 0; i < 50; i++) {
 			items.add("数据:" + i);
 		}
 
 		adapter = new ArrayAdapter<String>(this,
 				android.R.layout.simple_list_item_1, items);
 		listView.setAdapter(adapter);
 
 		// 将ListView传递过来。
 		SwipeDismissListViewTouchListener touchListener = new SwipeDismissListViewTouchListener(
 				listView,
 				new SwipeDismissListViewTouchListener.DismissCallbacks() {
 
 					@Override
 					public boolean canDismiss(int position) {
 						return true;
 					}
 
 					// 此处将执行删除，记得要notifyDataSetChanged()。
 					@Override
 					public void onDismiss(ListView listView,
 							int[] reverseSortedPositions) {
 						for (int pos : reverseSortedPositions) {
 							items.remove(pos);
 							Log.i(this.getClass().getName(), "删除:" + pos);
 						}
 
 						adapter.notifyDataSetChanged();
 					}
 				});
 
 		listView.setOnTouchListener(touchListener);
 	}
 }

需要的库文件 SwipeDismissListViewTouchListener.java ：

/*
 * 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 zhangphil.listview;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ValueAnimator;
 import android.graphics.Rect;
 import android.os.SystemClock;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.view.ViewPropertyAnimator;
 import android.widget.AbsListView;
 import android.widget.ListView;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
 /**
 * A {@link View.OnTouchListener} that makes the list items in a
 * {@link ListView} dismissable. {@link ListView} is given special treatment
 * because by default it handles touches for its list items... i.e. it's in
 * charge of drawing the pressed state (the list selector), handling list item
 * clicks, etc.
 *
 * 
 * After creating the listener, the caller should also call
 * {@link ListView#setOnScrollListener(AbsListView.OnScrollListener)}, passing
 * in the scroll listener returned by {@link #makeScrollListener()}. If a scroll
 * listener is already assigned, the caller should still pass scroll changes
 * through to this listener. This will ensure that this
 * {@link SwipeDismissListViewTouchListener} is paused during list view
 * scrolling.
 * 
 *
 * 
 * Example usage:
 * 
 *
 * <pre>
 * SwipeDismissListViewTouchListener touchListener = new SwipeDismissListViewTouchListener(
 * 		listView, new SwipeDismissListViewTouchListener.OnDismissCallback() {
 * 			public void onDismiss(ListView listView,
 * 					int[] reverseSortedPositions) {
 * 				for (int position : reverseSortedPositions) {
 * 					adapter.remove(adapter.getItem(position));
 * 				}
 * 				adapter.notifyDataSetChanged();
 * 			}
 * 		});
 * listView.setOnTouchListener(touchListener);
 * listView.setOnScrollListener(touchListener.makeScrollListener());
 * </pre>
 *
 * 
 * This class Requires API level 12 or later due to use of
 * {@link ViewPropertyAnimator}.
 * 
 *
 * 
 * For a generalized {@link View.OnTouchListener} that makes any view
 * dismissable, see {@link SwipeDismissTouchListener}.
 * 
 *
 * @see SwipeDismissTouchListener
 */
 public class SwipeDismissListViewTouchListener 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 ListView mListView;
 	private DismissCallbacks mCallbacks;
 	private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero
 
 	// Transient properties
 	private List<PendingDismissData> mPendingDismisses = new ArrayList<PendingDismissData>();
 	private int mDismissAnimationRefCount = 0;
 	private float mDownX;
 	private float mDownY;
 	private boolean mSwiping;
 	private int mSwipingSlop;
 	private VelocityTracker mVelocityTracker;
 	private int mDownPosition;
 	private View mDownView;
 	private boolean mPaused;
 
 	/**
 	 * The callback interface used by {@link SwipeDismissListViewTouchListener}
 	 * to inform its client about a successful dismissal of one or more list
 	 * item positions.
 	 */
 	public interface DismissCallbacks {
 		/**
 		 * Called to determine whether the given position can be dismissed.
 		 */
 		boolean canDismiss(int position);
 
 		/**
 		 * Called when the user has indicated they she would like to dismiss one
 		 * or more list item positions.
 		 *
 		 * @param listView
 		 * The originating {@link ListView}.
 		 * @param reverseSortedPositions
 		 * An array of positions to dismiss, sorted in descending
 		 * order for convenience.
 		 */
 		void onDismiss(ListView listView, int[] reverseSortedPositions);
 	}
 
 	/**
 	 * Constructs a new swipe-to-dismiss touch listener for the given list view.
 	 *
 	 * @param listView
 	 * The list view whose items should be dismissable.
 	 * @param callbacks
 	 * The callback to trigger when the user has indicated that she
 	 * would like to dismiss one or more list items.
 	 */
 	public SwipeDismissListViewTouchListener(ListView listView,
 			DismissCallbacks callbacks) {
 		ViewConfiguration vc = ViewConfiguration.get(listView.getContext());
 		mSlop = vc.getScaledTouchSlop();
 		mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
 		mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
 		mAnimationTime = listView.getContext().getResources()
 				.getInteger(android.R.integer.config_shortAnimTime);
 		mListView = listView;
 		mCallbacks = callbacks;
 	}
 
 	/**
 	 * Enables or disables (pauses or resumes) watching for swipe-to-dismiss
 	 * gestures.
 	 *
 	 * @param enabled
 	 * Whether or not to watch for gestures.
 	 */
 	public void setEnabled(boolean enabled) {
 		mPaused = !enabled;
 	}
 
 	/**
 	 * Returns an {@link AbsListView.OnScrollListener} to be added to the
 	 * {@link ListView} using
 	 * {@link ListView#setOnScrollListener(AbsListView.OnScrollListener)}. If a
 	 * scroll listener is already assigned, the caller should still pass scroll
 	 * changes through to this listener. This will ensure that this
 	 * {@link SwipeDismissListViewTouchListener} is paused during list view
 	 * scrolling.
 	 *
 	 * @see SwipeDismissListViewTouchListener
 	 */
 	public AbsListView.OnScrollListener makeScrollListener() {
 		return new AbsListView.OnScrollListener() {
 			@Override
 			public void onScrollStateChanged(AbsListView absListView,
 					int scrollState) {
 				setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
 			}
 
 			@Override
 			public void onScroll(AbsListView absListView, int i, int i1, int i2) {
 			}
 		};
 	}
 
 	@Override
 	public boolean onTouch(View view, MotionEvent motionEvent) {
 		if (mViewWidth < 2) {
 			mViewWidth = mListView.getWidth();
 		}
 
 		switch (motionEvent.getActionMasked()) {
 		case MotionEvent.ACTION_DOWN: {
 			if (mPaused) {
 				return false;
 			}
 
 			// TODO: ensure this is a finger, and set a flag
 
 			// Find the child view that was touched (perform a hit test)
 			Rect rect = new Rect();
 			int childCount = mListView.getChildCount();
 			int[] listViewCoords = new int[2];
 			mListView.getLocationOnScreen(listViewCoords);
 			int x = (int) motionEvent.getRawX() - listViewCoords[0];
 			int y = (int) motionEvent.getRawY() - listViewCoords[1];
 			View child;
 			for (int i = 0; i < childCount; i++) {
 				child = mListView.getChildAt(i);
 				child.getHitRect(rect);
 				if (rect.contains(x, y)) {
 					mDownView = child;
 					break;
 				}
 			}
 
 			if (mDownView != null) {
 				mDownX = motionEvent.getRawX();
 				mDownY = motionEvent.getRawY();
 				mDownPosition = mListView.getPositionForView(mDownView);
 				if (mCallbacks.canDismiss(mDownPosition)) {
 					mVelocityTracker = VelocityTracker.obtain();
 					mVelocityTracker.addMovement(motionEvent);
 				} else {
 					mDownView = null;
 				}
 			}
 			return false;
 		}
 
 		case MotionEvent.ACTION_CANCEL: {
 			if (mVelocityTracker == null) {
 				break;
 			}
 
 			if (mDownView != null && mSwiping) {
 				// cancel
 				mDownView.animate().translationX(0).alpha(1)
 						.setDuration(mAnimationTime).setListener(null);
 			}
 			mVelocityTracker.recycle();
 			mVelocityTracker = null;
 			mDownX = 0;
 			mDownY = 0;
 			mDownView = null;
 			mDownPosition = ListView.INVALID_POSITION;
 			mSwiping = false;
 			break;
 		}
 
 		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 && mSwiping) {
 				// dismiss only if flinging in the same direction as dragging
 				dismiss = (velocityX < 0) == (deltaX < 0);
 				dismissRight = mVelocityTracker.getXVelocity() > 0;
 			}
 			if (dismiss && mDownPosition != ListView.INVALID_POSITION) {
 				// dismiss
 				final View downView = mDownView; // mDownView gets null'd before
 													// animation ends
 				final int downPosition = mDownPosition;
 				++mDismissAnimationRefCount;
 				mDownView.animate()
 						.translationX(dismissRight ? mViewWidth : -mViewWidth)
 						.alpha(0).setDuration(mAnimationTime)
 						.setListener(new AnimatorListenerAdapter() {
 							@Override
 							public void onAnimationEnd(Animator animation) {
 								performDismiss(downView, downPosition);
 							}
 						});
 			} else {
 				// cancel
 				mDownView.animate().translationX(0).alpha(1)
 						.setDuration(mAnimationTime).setListener(null);
 			}
 			mVelocityTracker.recycle();
 			mVelocityTracker = null;
 			mDownX = 0;
 			mDownY = 0;
 			mDownView = null;
 			mDownPosition = ListView.INVALID_POSITION;
 			mSwiping = false;
 			break;
 		}
 
 		case MotionEvent.ACTION_MOVE: {
 			if (mVelocityTracker == null || mPaused) {
 				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);
 				mListView.requestDisallowInterceptTouchEvent(true);
 
 				// Cancel ListView's touch (un-highlighting the item)
 				MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
 				cancelEvent
 						.setAction(MotionEvent.ACTION_CANCEL
 								| (motionEvent.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
 				mListView.onTouchEvent(cancelEvent);
 				cancelEvent.recycle();
 			}
 
 			if (mSwiping) {
 				mDownView.setTranslationX(deltaX - mSwipingSlop);
 				mDownView.setAlpha(Math.max(0f,
 						Math.min(1f, 1f - 2f * Math.abs(deltaX) / mViewWidth)));
 				return true;
 			}
 			break;
 		}
 		}
 		return false;
 	}
 
 	class PendingDismissData implements Comparable<PendingDismissData> {
 		public int position;
 		public View view;
 
 		public PendingDismissData(int position, View view) {
 			this.position = position;
 			this.view = view;
 		}
 
 		@Override
 		public int compareTo(PendingDismissData other) {
 			// Sort by descending position
 			return other.position - position;
 		}
 	}
 
 	private void performDismiss(final View dismissView,
 			final int dismissPosition) {
 		// Animate the dismissed list item to zero-height and fire the dismiss
 		// callback when
 		// all dismissed list item animations have completed. This triggers
 		// layout on each animation
 		// frame; in the future we may want to do something smarter and more
 		// performant.
 
 		final ViewGroup.LayoutParams lp = dismissView.getLayoutParams();
 		final int originalHeight = dismissView.getHeight();
 
 		ValueAnimator animator = ValueAnimator.ofInt(originalHeight, 1)
 				.setDuration(mAnimationTime);
 
 		animator.addListener(new AnimatorListenerAdapter() {
 			@Override
 			public void onAnimationEnd(Animator animation) {
 				--mDismissAnimationRefCount;
 				if (mDismissAnimationRefCount == 0) {
 					// No active animations, process all pending dismisses.
 					// Sort by descending position
 					Collections.sort(mPendingDismisses);
 
 					int[] dismissPositions = new int[mPendingDismisses.size()];
 					for (int i = mPendingDismisses.size() - 1; i >= 0; i--) {
 						dismissPositions[i] = mPendingDismisses.get(i).position;
 					}
 					mCallbacks.onDismiss(mListView, dismissPositions);
 
 					// Reset mDownPosition to avoid MotionEvent.ACTION_UP trying
 					// to start a dismiss
 					// animation with a stale position
 					mDownPosition = ListView.INVALID_POSITION;
 
 					ViewGroup.LayoutParams lp;
 					for (PendingDismissData pendingDismiss : mPendingDismisses) {
 						// Reset view presentation
 						pendingDismiss.view.setAlpha(1f);
 						pendingDismiss.view.setTranslationX(0);
 						lp = pendingDismiss.view.getLayoutParams();
 						lp.height = originalHeight;
 						pendingDismiss.view.setLayoutParams(lp);
 					}
 
 					// Send a cancel event
 					long time = SystemClock.uptimeMillis();
 					MotionEvent cancelEvent = MotionEvent.obtain(time, time,
 							MotionEvent.ACTION_CANCEL, 0, 0, 0);
 					mListView.dispatchTouchEvent(cancelEvent);
 
 					mPendingDismisses.clear();
 				}
 			}
 		});
 
 		animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
 			@Override
 			public void onAnimationUpdate(ValueAnimator valueAnimator) {
 				lp.height = (Integer) valueAnimator.getAnimatedValue();
 				dismissView.setLayoutParams(lp);
 			}
 		});
 
 		mPendingDismisses.add(new PendingDismissData(dismissPosition,
 				dismissView));
 		animator.start();
 	}
 }

目录结构：

![Center][]

[https_github.com_romannurik_Android-SwipeToDismiss]: https://github.com/romannurik/Android-SwipeToDismiss
[Center]: https://img-blog.csdn.net/20150727105816138?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center