Android自定义ViewPager实例

本文实例讲述了Android自定义ViewPager的方法。分享给大家供大家参考，具体如下：

package com.rong.activity;
import android.content.Context;
import android.graphics.Color;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.Scroller;
public class CustomViewPager extends ViewGroup {
 private Context mContext;
 private int screenWidth;
 private int screenHight;
 private int lastMoveX = 0;
 private VelocityTracker velocityTracker;
 private int MAX_VELOCITY=600;
 private int curScreen=0;
 private Scroller scroller;
 public CustomViewPager(Context context) {
   super(context);
   mContext = context;
   initView();
 }
 public CustomViewPager(Context context, AttributeSet attrs) {
   super(context, attrs);
   mContext = context;
   initView();
 }
 public CustomViewPager(Context context, AttributeSet attrs, int defStyle) {
   super(context, attrs, defStyle);
   mContext = context;
   initView();
 }
 @Override
 public boolean onTouchEvent(MotionEvent event) {
   if (velocityTracker == null) {
     velocityTracker = VelocityTracker.obtain();
   }
   velocityTracker.addMovement(event);
   int x = (int) event.getX();
   switch (event.getAction()) {
   case MotionEvent.ACTION_DOWN:
     lastMoveX = x;
     break;
   case MotionEvent.ACTION_MOVE:
     int dis = lastMoveX - x;
     scrollBy(dis, 0);
     lastMoveX = x;
     break;
   case MotionEvent.ACTION_UP:
     velocityTracker.computeCurrentVelocity(1000);
     int velocityX=(int)velocityTracker.getXVelocity();
     if(velocityX>MAX_VELOCITY&&curScreen>0){
       jump2Screen(curScreen-1);
     }else if(velocityX<-MAX_VELOCITY&&curScreen<getChildCount()-1){
       jump2Screen(curScreen+1);
     }else{
       int screen=(getScrollX()+screenWidth/2)/screenWidth;
       jump2Screen(screen);
     }
     if (velocityTracker != null) {
       velocityTracker.recycle();
       velocityTracker = null;
     }
     break;
   }
   return true;
 }
 /**
  * 跳转到指定Screen
  * @param screen
  */
 public void jump2Screen(int screen){
   curScreen=screen;
   if(curScreen>getChildCount()-1){
     curScreen=getChildCount()-1;
   }
   int dis=curScreen*screenWidth-getScrollX();
   scroller.startScroll(getScrollX(), 0, dis, 0);
   invalidate();
 }
 @Override
 public void computeScroll() {
   if(scroller.computeScrollOffset()){
     scrollTo(scroller.getCurrX(), 0);
     postInvalidate();
   }
 }
 public void initView() {
   scroller=new Scroller(mContext);
   LinearLayout layout1 = new LinearLayout(getContext());
   layout1.setBackgroundColor(Color.RED);
   addView(layout1);
   LinearLayout layout2 = new LinearLayout(getContext());
   layout2.setBackgroundColor(Color.GREEN);
   addView(layout2);
   LinearLayout layout3 = new LinearLayout(getContext());
   layout3.setBackgroundColor(Color.BLUE);
   addView(layout3);
 }
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   super.onMeasure(widthMeasureSpec, heightMeasureSpec);
   screenWidth = MeasureSpec.getSize(widthMeasureSpec);
   screenHight = MeasureSpec.getSize(heightMeasureSpec);
   setMeasuredDimension(screenWidth, screenHight);
   for (int i = 0; i < getChildCount(); i++) {
     View view = getChildAt(i);
     view.measure(screenWidth, screenHight);
   }
 }
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
   int leftWidth = 0;
   for (int i = 0; i < getChildCount(); i++) {
     View view = getChildAt(i);
     view.layout(leftWidth, 0, leftWidth + screenWidth, screenHight);
     leftWidth = leftWidth + screenWidth;
   }
 }
}

希望本文所述对大家Android程序设计有所帮助。