Android自動播放Banner圖片輪播效果

先看一下效果圖

支持本地圖片以及網絡圖片or本地網絡混合。

使用方式：

<com.jalen.autobanner.BannerView
 android:id="@+id/banner"
 android:layout_width="match_parent"
 android:layout_height="230dip">
</com.jalen.autobanner.BannerView>

核心代碼：

 int length = mList.size();
 View view = LayoutInflater.from(mContext).inflate(R.layout.banner_view,this,true);
 LinearLayout ll = (LinearLayout) view.findViewById(R.id.ll_points);
 vp= (ViewPager) view.findViewById(R.id.vp);
 ll.removeAllViews();
 LinearLayout.LayoutParams ll_parmas = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
 ll_parmas.leftMargin=5;
 ll_parmas.rightMargin=5;
 for(int i=0;i<length;i++){
  ImageView img = new ImageView(mContext);
  img.setLayoutParams(ll_parmas);
  if(i==0){
  img.setImageResource(R.mipmap.dot_focus);
  }else{
  img.setImageResource(R.mipmap.dot_blur);
  }
  ll.addView(img);
  mImgs.add(img);

  final ImageView imgforview = new ImageView(mContext);
  imgforview.setOnClickListener(this);
  imgforview.setScaleType(ImageView.ScaleType.FIT_XY);
  if(mList.get(i).getType()==0){//本地圖片
  imgforview.setImageResource(mList.get(i).getDrawableforint());

  }else{//網絡
  Glide.with(mContext).load(mList.get(i).getDrawableforurl()).diskCacheStrategy(DiskCacheStrategy.ALL).into(imgforview);
//  Glide.with(mContext).load(mList.get(i).getDrawableforurl()).listener(new RequestListener<String, GlideDrawable>() {
//   @Override
//   public boolean onException(Exception e, String model, Target<GlideDrawable> target, boolean isFirstResource) {
//   Log.d("yu","Faile:"+e.toString());
//   return false;
//   }
//
//   @Override
//   public boolean onResourceReady(GlideDrawable resource, String model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
//    imgforview.setImageDrawable(resource);
//   return false;
//   }
//  }).into(imgforview);
//  Log.d("yu","url: "+mList.get(i).getDrawableforurl());
  }
  mViews.add(imgforview);
 }

 vp.setAdapter(new MyAdapter());
 vp.addOnPageChangeListener(onPageChange);

自動輪播利用的是handler的postdelay方法。

private Runnable task = new Runnable() {
 @Override
 public void run() {
  if(isAuto){
  currentItem = currentItem%(mViews.size());
//  Log.d("yu","runalbe "+currentItem);
  if(currentItem==0){
   vp.setCurrentItem(currentItem,false);
  }else{
   vp.setCurrentItem(currentItem);
  }
  currentItem++;
  mHandle.postDelayed(task,delaytime);
  }else{
  mHandle.postDelayed(task,delaytime);
  }
 }
 };

利用isAuto判斷是否正在自動輪播 如果為false 不自動切換item。isAuto賦值操作位於OnPageChangeListener的onPageScrollStateChanged方法中：

 public void onPageScrollStateChanged(int state) {

  switch (state){
  case ViewPager.SCROLL_STATE_IDLE://用戶什麼都沒有操作
   isAuto=true;
   currentItem = vp.getCurrentItem();
//   Log.d("yu","IDLE"+currentItem);
//   if(vp.getCurrentItem()==mViews.size()){
//   vp.setCurrentItem(0,false);
//   }
   break;
  case ViewPager.SCROLL_STATE_DRAGGING://正在滑動
   isAuto =false;
   break;
  case ViewPager.SCROLL_STATE_SETTLING://滑動結束
   isAuto=true;
   break;

  }
 }

當狀態為SCROLL_STATE_DRAGGING時 說明用戶正在操作 ，看下源碼中的解釋：

 /**
 * Indicates that the pager is in an idle, settled state. The current page
 * is fully in view and no animation is in progress.
 */
 public static final int SCROLL_STATE_IDLE = 0;

 /**
 * Indicates that the pager is currently being dragged by the user.
 */
 public static final int SCROLL_STATE_DRAGGING = 1;

 /**
 * Indicates that the pager is in the process of settling to a final position.
 */
 public static final int SCROLL_STATE_SETTLING = 2;

大致意思呢就是 0代碼沒有任何操作。1頁面正在被用戶拖動。2代表成功切換至下一頁面。

源碼地址：https://github.com/yudehai0204/autoBanner

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