android使用ViewPager实现图片自动切换的方法
1、activity_main.xml布局
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因为我的ViewPager是继承RelativeLayout
2、layout_recommend_item.xml中的布局
<?xml version="1.0" encoding="utf-8"?>
ImageView是显示图片 TextView用来显示每一个pager的标题
3、MyViewPager类，因为图个方便，把能够实现这个功能否合成一个类、这样用起来比较方便
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.DisplayMetrics;
import android.util.Log;
import android.util.TypedValue;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class MyViewPager extends RelativeLayout {
private static final int START_SCROLL = 1;
private static final int SCROLL_NEXT = 2;
private static final int SHOW_TIME = 5000;//显示时间
private List mDatas = new ArrayList<>();//viewpager每一页对应的标题
private ViewPager mPager;
private Context mContext;
private int mWidth, mHeight; //viewpager的宽高
private int mTitleHeight; //标题高度
private TipView mTipView; //标题对应的view
//在主ui中更新viewpager，也就是切换图片
private static Handler sHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
int w = msg.what;
ViewPager pager = (ViewPager) msg.obj;
switch (w) {
case START_SCROLL:
pager.setCurrentItem(msg.arg1, true);
break;
case SCROLL_NEXT:
pager.setCurrentItem(msg.arg1, true);
break;
}
}
};
/**
* 构造函数
* @param context content
* @param w 要显示的viewpager的宽
* @param h 要显示的viewpager的高
*/
public MyViewPager(Context context, int w, int h) {
super(context);
mContext = context;
mWidth = w;
mHeight = h;
initView(); //取得数据 左边随便取的 只是为了看起来有效果
// 对viewpager滑动进行监听
mPager.setOnPageChangeListener(new MOnPagerChangeListener());
init();
DisplayMetrics dm = mContext.getResources().getDisplayMetrics();
mTitleHeight = cm_DptoPx(48, dm);
}
/**
* 对viewpager控件进行绘制宽高
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
ViewGroup.LayoutParams vp = getLayoutParams();
if (vp != null) {
vp.width = mWidth;
vp.height = mHeight;
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
/**
* 把dp转化成px
*/
public static int cm_DptoPx(int dp,DisplayMetrics dis){
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, dis);
}
private void init() {
getData();
}
private void initView() {
mPager = new ViewPager(mContext);
RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
addView(mPager, rp);
}
public void getData() {
for (int i = 0; i < 4 ; i++){
mDatas.add(i,"viewpager"+i);
}
sHandler.postDelayed(new Runnable() {
@Override
public void run() {
stopAnimation();
initTipView();
mPager.setAdapter(new RecommendAdapter());
mPager.setCurrentItem(10000 * mDatas.size());
}
}, 2000);
}
/**
* 删除队列中的消息
*/
public void stopAnimation() {
sHandler.removeMessages(START_SCROLL);
sHandler.removeMessages(SCROLL_NEXT);
}
public void startAnimation() {
if (mDatas.size() == 0) {
return;
}
Message msg = sHandler.obtainMessage(START_SCROLL);
msg.obj = mPager;
msg.arg1 = (mPager.getCurrentItem() + 1);//取得后一张图片
sHandler.sendMessageDelayed(msg, SHOW_TIME);//5秒后发送给ui线程
}
/**
* 对标题view移动的光标初始化
*/
private void initTipView() {
if (mTipView == null) {
RelativeLayout.LayoutParams rp = new RelativeLayout.LayoutParams(10, 10);
rp.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
rp.bottomMargin = mTitleHeight;
mTipView = new TipView(mContext, mDatas.size());
addView(mTipView, rp);
} else {
mTipView.setCount(mDatas.size());
}
}
private class MOnPagerChangeListener implements ViewPager.OnPageChangeListener {
private int curState;
@Override
public void onPageScrolled(int i, float v, int i1) {
}
@Override
public void onPageSelected(int i) { //滑动结束
sHandler.removeMessages(SCROLL_NEXT);
sHandler.removeMessages(START_SCROLL);
if(curState == ViewPager.SCROLL_STATE_DRAGGING){
return;
}
Message msg = sHandler.obtainMessage(SCROLL_NEXT);
msg.arg1 = i + 1;
msg.obj = mPager;
sHandler.sendMessageDelayed(msg, SHOW_TIME);
mTipView.setCurPostion(i % mDatas.size());
}
@Override
public void onPageScrollStateChanged(int i) { //正在滑动时
curState = i;
if(i == ViewPager.SCROLL_STATE_DRAGGING){ //SCROLL_STATE_DRAGGING正在滑动 SCROLL_STATE_IDLE什么都没有做
//SCROLL_STATE_SETTLING 滑动完毕
stopAnimation();
}else {
if(!(sHandler.hasMessages(START_SCROLL)&&sHandler.hasMessages(SCROLL_NEXT))){
startAnimation();
}
}
}
}
private class RecommendAdapter extends PagerAdapter {
@Override
public Object instantiateItem(ViewGroup container, int position) {
Log.i("MyViewPager","instantiateItem ");
int curPos = position % mDatas.size();
View view = View.inflate(mContext, R.layout.layout_recommend_item, null);
ViewGroup.LayoutParams vp = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
ImageView iv = (ImageView) view.findViewById(R.id.iv_pic);
TextView tv = (TextView) view.findViewById(R.id.tv_desc);
tv.setText(mDatas.get(curPos));
container.addView(view, vp);
view.setTag(curPos);
view.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
return view;
}
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
}
private class TipView extends View {
private int mPadding;
private int mCount;
private int mCurPos;
private Paint mNorPaint;
private Paint mSelPaint;
private int mHeight;
public TipView(Context context, int count) {
super(context);
mNorPaint = new Paint();
mNorPaint.setAntiAlias(true);
DisplayMetrics dm = context.getResources().getDisplayMetrics();
int selHeight = cm_DptoPx(2, dm);
int norHeight = cm_DptoPx(1, dm);
mHeight = cm_DptoPx(2, dm);
mNorPaint.setStrokeWidth(norHeight);
mNorPaint.setColor(Color.argb(80, 255, 255, 255));
mSelPaint = new Paint();
mSelPaint.setAntiAlias(true);
mSelPaint.setStrokeWidth(selHeight);
mSelPaint.setColor(Color.WHITE);
mCount = count;
mPadding = cm_DptoPx(0, dm);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int ow = (getWidth()-2*mPadding)/ mCount;
int y = getHeight() / 2;
canvas.drawLine(mPadding, y, mCurPos * ow + mPadding, y, mNorPaint);
canvas.drawLine(mCurPos * ow + mPadding, y, (mCurPos + 1) * ow + mPadding, y, mSelPaint);
canvas.drawLine((mCurPos + 1) * ow + mPadding, y, getWidth() - mPadding, y, mNorPaint);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
ViewGroup.LayoutParams vp = getLayoutParams();
vp.width = ViewGroup.LayoutParams.MATCH_PARENT;
vp.height = mHeight;
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void setCurPostion(int pos) {
mCurPos = pos;
invalidate();
}
public void setCount(int count) {
mCount = count;
}
}
} 4、还有MainActivity中的实现
import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.widget.RelativeLayout;
public class MainActivity extends Activity {
private RelativeLayout mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DisplayMetrics dm = getResources().getDisplayMetrics();
mViewPager = (RelativeLayout) findViewById(R.id.my_viewpager);
mViewPager.addView(new MyViewPager(getApplicationContext(),dm.widthPixels ,(dm.widthPixels)/2));
}
}新闻名称：android使用ViewPager实现图片自动切换的方法
标题来源：http://6mz.cn/article/jjhhse.html