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  • Android SwipeToDismiss:左滑/右滑删除ListView条目Item

    

    《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 )。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。比方在Android 5.0及以上版本号中,通知栏下拉菜单中的条目。就是这样的操作效果,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 上下载到到库文件有两个(此说是基于截止2015年7月27日的版本号,兴许版本号或许会有所不同):SwipeDismissListViewTouchListener.java 和 SwipeDismissTouchListener.java 。假设仅仅是打算简单的仅仅是支持一个ListView列表中item左滑/右滑删除,那么仅仅仅仅导入SwipeDismissListViewTouchListener.java这一个库文件就可以。
    如今就给出一个简单样例,说明怎样改造一个标准ListView。使其支持左右滑动某个item然后删除之。


    測试用的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();
    
    		// 測试数据集。

    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; } // 此处将运行删除。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); } }



    须要的库文件 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.
     *
     * <p>
     * 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.
     * </p>
     *
     * <p>
     * Example usage:
     * </p>
     *
     * <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>
     *
     * <p>
     * This class Requires API level 12 or later due to use of
     * {@link ViewPropertyAnimator}.
     * </p>
     *
     * <p>
     * For a generalized {@link View.OnTouchListener} that makes any view
     * dismissable, see {@link SwipeDismissTouchListener}.
     * </p>
     *
     * @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.</p>
    	 *
    	 * @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(); } }



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  • 原文地址:https://www.cnblogs.com/cxchanpin/p/6901956.html
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