Android 类似launcher左右滑动(实例二)

ゞ浴缸里的玫瑰 2022-06-17 01:43 142阅读 0赞

原文地址：[http://iaiai.iteye.com/blog/1193466][http_iaiai.iteye.com_blog_1193466]

运行效果:   
![0_1322295466RXUF.gif][]

main.xml

<?xml version="1.0" encoding="utf-8"?>
 <com.cn.ScrollLayout xmlns:android="http://schemas.android.com/apk/res/android"
 	android:id="@+id/ScrollLayoutTest" android:layout_width="fill_parent"
 	android:layout_height="fill_parent">
 	<LinearLayout android:background="#FF00"
 		android:layout_width="fill_parent" android:layout_height="fill_parent"></LinearLayout>
 
 	<FrameLayout android:background="#F00F"
 		android:layout_width="fill_parent" android:layout_height="fill_parent">
 	</FrameLayout>
 
 	<LinearLayout android:layout_width="wrap_content"
 		android:layout_height="wrap_content">
 		<Button android:layout_width="wrap_content"
 			android:layout_height="wrap_content" android:text="Button2" />
 	</LinearLayout>
 </com.cn.ScrollLayout>

MainActivity.java

package com.cn;
 
 import android.app.Activity;
 import android.os.Bundle;
 
 /**
 * 
 * 
 * Title: MainActivity.java
 * 
 * 
 * E-Mail: 176291935@qq.com
 * 
 * 
 * QQ: 176291935
 * 
 * 
 * Http: iaiai.iteye.com
 * 
 * 
 * Create time: 2011-10-13
 * 
 * 
 * @author 丸子
 * @version 0.0.1
 */
 public class MainActivity extends Activity {
 	/** Called when the activity is first created. */
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 		setContentView(R.layout.main);
 	}
 }

ScrollLayout.java

package com.cn;
 
 import android.content.Context;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.widget.Scroller;
 
 /**
 * 
 * 
 * Title: ScrollLayout.java
 * 
 * 
 * E-Mail: 176291935@qq.com
 * 
 * 
 * QQ: 176291935
 * 
 * 
 * Http: iaiai.iteye.com
 * 
 * 
 * Create time: 2011-10-13
 * 
 * 
 * @author 丸子
 * @version 0.0.1
 */
 public class ScrollLayout extends ViewGroup {
 
 	private static final String TAG = "ScrollLayout";
 
 	private Scroller mScroller;
 
 	private VelocityTracker mVelocityTracker;
 
 	private int mCurScreen;
 
 	private int mDefaultScreen = 0;
 
 	private static final int TOUCH_STATE_REST = 0;
 
 	private static final int TOUCH_STATE_SCROLLING = 1;
 
 	private static final int SNAP_VELOCITY = 600;
 
 	private int mTouchState = TOUCH_STATE_REST;
 
 	private int mTouchSlop;
 
 	private float mLastMotionX;
 
 	private float mLastMotionY;
 
 	public ScrollLayout(Context context, AttributeSet attrs) {
 		this(context, attrs, 0);
 	}
 
 	public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
 		super(context, attrs, defStyle);
 
 		mScroller = new Scroller(context);
 		mCurScreen = mDefaultScreen;
 		mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
 	}
 
 	@Override
 	protected void onLayout(boolean changed, int l, int t, int r, int b) {
 		if (changed) {
 			int childLeft = 0;
 			final int childCount = getChildCount();
 
 			for (int i = 0; i < childCount; i++) {
 				final View childView = getChildAt(i);
 
 				if (childView.getVisibility() != View.GONE) {
 					final int childWidth = childView.getMeasuredWidth();
 					childView.layout(childLeft, 0, childLeft + childWidth,
 							childView.getMeasuredHeight());
 					childLeft += childWidth;
 				}
 			}
 		}
 	}
 
 	@Override
 	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 		Log.e(TAG, "onMeasure");
 		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 
 		final int width = MeasureSpec.getSize(widthMeasureSpec);
 		final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
 
 		if (widthMode != MeasureSpec.EXACTLY) {
 			throw new IllegalStateException(
 					"ScrollLayout only canmCurScreen run at EXACTLY mode!");
 		}
 
 		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
 
 		if (heightMode != MeasureSpec.EXACTLY) {
 			throw new IllegalStateException(
 					"ScrollLayout only can run at EXACTLY mode!");
 		}
 
 		// The children are given the same width and height as the scrollLayout
 		final int count = getChildCount();
 		for (int i = 0; i < count; i++) {
 			getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
 		}
 
 		// Log.e(TAG, "moving to screen "+mCurScreen);
 		scrollTo(mCurScreen * width, 0);
 	}
 
 	/**
 	 * 
 	 * According to the position of current layout
 	 * 
 	 * scroll to the destination page.
 	 */
 	public void snapToDestination() {
 		final int screenWidth = getWidth();
 		final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
 		snapToScreen(destScreen);
 	}
 
 	public void snapToScreen(int whichScreen) {
 		// get the valid layout page
 		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
 
 		if (getScrollX() != (whichScreen * getWidth())) {
 			final int delta = whichScreen * getWidth() - getScrollX();
 			mScroller.startScroll(getScrollX(), 0, delta, 0,
 					Math.abs(delta) * 2);
 			mCurScreen = whichScreen;
 			invalidate(); // Redraw the layout
 		}
 	}
 
 	public void setToScreen(int whichScreen) {
 		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
 		mCurScreen = whichScreen;
 		scrollTo(whichScreen * getWidth(), 0);
 	}
 
 	public int getCurScreen() {
 		return mCurScreen;
 	}
 
 	@Override
 	public void computeScroll() {
 		if (mScroller.computeScrollOffset()) {
 			scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
 			postInvalidate();
 		}
 	}
 
 	@Override
 	public boolean onTouchEvent(MotionEvent event) {
 		if (mVelocityTracker == null) {
 			mVelocityTracker = VelocityTracker.obtain();
 		}
 
 		mVelocityTracker.addMovement(event);
 
 		final int action = event.getAction();
 		final float x = event.getX();
 		final float y = event.getY();
 
 		switch (action) {
 		case MotionEvent.ACTION_DOWN:
 			Log.e(TAG, "event down!");
 			if (!mScroller.isFinished()) {
 				mScroller.abortAnimation();
 			}
 			mLastMotionX = x;
 			break;
 		case MotionEvent.ACTION_MOVE:
 			int deltaX = (int) (mLastMotionX - x);
 			mLastMotionX = x;
 			scrollBy(deltaX, 0);
 			break;
 		case MotionEvent.ACTION_UP:
 			Log.e(TAG, "event : up");
 			// if (mTouchState == TOUCH_STATE_SCROLLING) {
 			final VelocityTracker velocityTracker = mVelocityTracker;
 			velocityTracker.computeCurrentVelocity(1000);
 			int velocityX = (int) velocityTracker.getXVelocity();
 			Log.e(TAG, "velocityX:" + velocityX);
 
 			if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
 				// Fling enough to move left
 				Log.e(TAG, "snap left");
 				snapToScreen(mCurScreen - 1);
 			} else if (velocityX < -SNAP_VELOCITY
 					&& mCurScreen < getChildCount() - 1) {
 				// Fling enough to move right
 				Log.e(TAG, "snap right");
 				snapToScreen(mCurScreen + 1);
 			} else {
 				snapToDestination();
 			}
 			// if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
 			//
 			// // Fling enough to move left
 			//
 			// Log.e(TAG, "snap left");
 			// if (mCurScreen > getChildCount() - 1) {
 			// View v1 = getChildAt(0);
 			// View v2 = getChildAt(1);
 			// View v3 = getChildAt(2);
 			//
 			// }
 			// snapToScreen(mCurScreen - 1);
 			//
 			// } else if (velocityX < -SNAP_VELOCITY
 			//
 			// && mCurScreen < getChildCount() - 1) {
 			//
 			// // Fling enough to move right
 			//
 			// Log.e(TAG, "snap right");
 			//
 			// snapToScreen(mCurScreen + 1);
 			//
 			// } else {
 			//
 			// snapToDestination();
 			//
 			// }
 			//
 			// if (mVelocityTracker != null) {
 			//
 			// mVelocityTracker.recycle();
 			//
 			// mVelocityTracker = null;
 			//
 			// }
 			// }
 			mTouchState = TOUCH_STATE_REST;
 			break;
 		case MotionEvent.ACTION_CANCEL:
 			mTouchState = TOUCH_STATE_REST;
 			break;
 		}
 		return true;
 	}
 
 	@Override
 	public boolean onInterceptTouchEvent(MotionEvent ev) {
 		Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop + "; action = "
 				+ ev.getAction());
 		final int action = ev.getAction();
 
 		if ((action == MotionEvent.ACTION_MOVE)
 				&& (mTouchState != TOUCH_STATE_REST)) {
 			Log.e(TAG, "onInterceptTouchEvent-action:" + action);
 			return true;
 		}
 
 		final float x = ev.getX();
 		final float y = ev.getY();
 
 		switch (action) {
 		case MotionEvent.ACTION_MOVE:
 			final int xDiff = (int) Math.abs(mLastMotionX - x);
 			Log.e(TAG, "onInterceptTouchEvent-move: xDiff = " + xDiff
 					+ "; mLastMotionX = " + mLastMotionX);
 			if (xDiff > mTouchSlop) {
 				mTouchState = TOUCH_STATE_SCROLLING;
 			}
 			break;
 		case MotionEvent.ACTION_DOWN:
 			mLastMotionX = x;
 			mLastMotionY = y;
 			Log.e(TAG, "onInterceptTouchEvent-down: x = " + x + "; y = " + y);
 			mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
 					: TOUCH_STATE_SCROLLING;
 			break;
 		case MotionEvent.ACTION_CANCEL:
 		case MotionEvent.ACTION_UP:
 			Log.e(TAG, "onInterceptTouchEvent-up: mLastMotionX = "
 					+ mLastMotionX);
 			mTouchState = TOUCH_STATE_REST;
 			break;
 		}
 		return mTouchState != TOUCH_STATE_REST;
 	}
 
 }

[http_iaiai.iteye.com_blog_1193466]: http://iaiai.iteye.com/blog/1193466
[0_1322295466RXUF.gif]: /images/20220617/8d945bec29af40a7b81d32bb30c185ac.png