Android 类似launcher左右滑动(实例二)
运行效果:
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>
package com.cn;import android.app.Activity;import android.os.Bundle;/** * * <p> * Title: MainActivity.java * </p> * <p> * E-Mail: 176291935@qq.com * </p> * <p> * QQ: 176291935 * </p> * <p> * Http: iaiai.iteye.com * </p> * <p> * Create time: 2011-10-13 * </p> * * @author 丸子 * @version 0.0.1 */public class MainActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);}}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;/** * * <p> * Title: ScrollLayout.java * </p> * <p> * E-Mail: 176291935@qq.com * </p> * <p> * QQ: 176291935 * </p> * <p> * Http: iaiai.iteye.com * </p> * <p> * Create time: 2011-10-13 * </p> * * @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();}@Overrideprotected 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;}}}}@Overrideprotected 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 scrollLayoutfinal 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 pagewhichScreen = 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;}@Overridepublic void computeScroll() {if (mScroller.computeScrollOffset()) {scrollTo(mScroller.getCurrX(), mScroller.getCurrY());postInvalidate();}}@Overridepublic 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 leftLog.e(TAG, "snap left");snapToScreen(mCurScreen - 1);} else if (velocityX < -SNAP_VELOCITY&& mCurScreen < getChildCount() - 1) {// Fling enough to move rightLog.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;}@Overridepublic 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;}}