android控件实现多张图片渐变切换

本来项目是用的viewpager实现的轮播滚动，但是客户觉得轮播的效果太大众化了，于是就要我们改成渐变切换的效果。听到这需求，我最先想到是给viewpager设置切换动画，但是无论怎么设置动画，都要手动切换的时候才有效果。于是我就自定义了一个控件，利用淡入淡出动画实现了这效果，还是先上效果图，没效果图说再多也没用。

public class Gradient extends RelativeLayout {

  private List<ImageView> imageViews;
  private List<Animation> outAnim;//淡出动画
  private List<Animation> inAnim;//淡入动画
  private Context mContext;
  private Handler handler = new Handler(Looper.getMainLooper());
  private int couot;
  private int currentIndex;//当前的页面
  private LinearLayout linearLayout;
  private onClickListner listner;
  private long time=3000;//动画间隔时间

  public Gradient(Context context) {
    this(context, null);
  }

  public Gradient(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.mContext = context;
  }

  /**
   * 画点
   */
  public void cratePoint() {
    if (null != imageViews && imageViews.size() > 0) {
      int size = imageViews.size();

      linearLayout = new LinearLayout(mContext);
      linearLayout.setOrientation(LinearLayout.HORIZONTAL);
      linearLayout.setGravity(Gravity.CENTER);
      // 添加图片
      for (int i = 0; i < size; i++) {
        // 设置圆点
        View viewPoint = new View(mContext);
        viewPoint.setBackgroundResource(R.drawable.point_background);
        int weight = dip2px(mContext, 5);
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(weight, weight);
        lp.leftMargin = weight;
        viewPoint.setLayoutParams(lp);
        viewPoint.setEnabled(false);
        linearLayout.addView(viewPoint);
      }
      View childAt = linearLayout.getChildAt(0);
      if (null != childAt) {
        childAt.setEnabled(true);
      }
      //添加到图片的下边
      RelativeLayout.LayoutParams rlp = new RelativeLayout.LayoutParams(-1,-2);
      rlp.bottomMargin = dip2px(mContext, 5);
      rlp.addRule(ALIGN_PARENT_BOTTOM);
      this.addView(linearLayout, rlp);

    }

  }

  /**
   * 根据手机的分辨率从 dip 的单位 转成为 px(像素)
   */
  public static int dip2px(Context context, float dpValue) {
    final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (dpValue * scale + 0.5f);
  }

  /**
   * 设置图片
   * @param imageViews
   */
  public void setImageViews(List<ImageView> imageViews) {
    this.imageViews = imageViews;
    for (int i = 0; i < imageViews.size(); i++) {
      RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(-1,-1);
      addView(imageViews.get(i),layoutParams);
    }
    setonClick();
    cratePoint();
    createAnim();
    start();

  }

  /**
   * 开启动画
   */
  private void start() {
    final int size = imageViews.size();
    handler.post(new Runnable() {
      @Override
      public void run() {
        final int i = couot % size;
        //解决点击事件的冲突
        for (int j = 0; j < size; j++) {

          if (j == i) {
            imageViews.get(i).setClickable(true);

          } else {
            imageViews.get(i).setClickable(false);
          }
        }
        if (couot < size) {
          if (i == size - 1) {

            ImageView imageView = imageViews.get(0);
            imageView.startAnimation(outAnim.get(0));

            ImageView imageView2 = imageViews.get(size - 1);
            imageView2.startAnimation(inAnim.get(size - 1));

          } else {
            //当前的淡出,下一张淡入
            ImageView imageView = imageViews.get(size - 1 - i);
            imageView.startAnimation(outAnim.get(size - 1 - i));

          }
        } else {
          if (i == size - 1) {
            //当显示到最后一张的时候,要跳到第一张
            ImageView imageView = imageViews.get(0);
            imageView.startAnimation(outAnim.get(0));

            ImageView imageView2 = imageViews.get(size - 1);
            imageView2.startAnimation(inAnim.get(size - 1));

          } else {
            //当前的淡出,下一张淡入
            ImageView imageView = imageViews.get(size - 1 - i);
            imageView.startAnimation(outAnim.get(size - 1 - i));

            ImageView imageView2 = imageViews.get(size - 2 - i);
            imageView2.startAnimation(inAnim.get(size - 2 - i));

          }
        }

        currentIndex = i;
        linearLayout.getChildAt(currentIndex % size).setEnabled(false);
        currentIndex++;
        linearLayout.getChildAt(currentIndex % size).setEnabled(true);
        couot++;
        handler.postDelayed(this, time);
      }
    });
  }

  /**
   * 创建动画
   */
  private void createAnim() {
    outAnim = new ArrayList<>();
    inAnim = new ArrayList<>();
    for (int i = 0; i < imageViews.size(); i++) {
      Animation zoomOutAwayAnim = createZoomOutAwayAnim();
      zoomOutAwayAnim.setFillAfter(true);
      outAnim.add(zoomOutAwayAnim);

      Animation zoomOutNearAnim = createZoomOutNearAnim();
      zoomOutNearAnim.setFillAfter(true);
      inAnim.add(zoomOutNearAnim);

    }
  }

  /**
   * 设置点击事件
   */
  public void setonClick() {
    for (int i = 0; i < imageViews.size(); i++) {
      imageViews.get(i).setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
          if (listner != null) {
            listner.setonClick((currentIndex) % imageViews.size());
          }

        }
      });
    }
  }

  public interface onClickListner{

    void setonClick(int position);
  }

  /**
   * 设置动画播放和handler延迟时间
   * @param time
   */
  public void setTime(long time) {
    this.time = time;
  }

  public void setListner(onClickListner listner) {
    this.listner = listner;
  }

  /** 创建一个淡出缩小的动画 */
  public Animation createZoomOutAwayAnim() {
    AnimationSet ret;
    Animation anim;
    ret = new AnimationSet(false);
    // 创建一个淡出的动画
    anim = new AlphaAnimation(1f, 0f);
    anim.setDuration(time);
    anim.setInterpolator(new DecelerateInterpolator());
    ret.addAnimation(anim);
    // 创建一个缩小的动画
    /*anim = new ScaleAnimation(1, 0, 1, 0, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
    anim.setDuration(MEDIUM);
    anim.setInterpolator(new DecelerateInterpolator());
    ret.addAnimation(anim);*/
    return ret;
  }
  /** 创建一个淡入缩小的动画 */
  public Animation createZoomOutNearAnim() {
    AnimationSet ret;
    Animation anim;
    ret = new AnimationSet(false);
    // 创建一个淡入的动画
    anim = new AlphaAnimation(0f, 1f);
    anim.setDuration(time);
    anim.setInterpolator(new LinearInterpolator());
    ret.addAnimation(anim);
    // 创建一个缩小的动画
    /*anim = new ScaleAnimation(3, 1, 3, 1, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
    anim.setDuration(MEDIUM);
    anim.setInterpolator(new DecelerateInterpolator());
    ret.addAnimation(anim);*/
    return ret;
  }
}

这个控件的使用非常简单只要在布局文件中使用我们自定义的控件，然后调用setTime设置动画切换的时间，setListener设置图片的点击事件，setImagevies设置图片就可以实现效果.考虑到内存泄漏的问题，只要在ondestry方法里面调用stop方法即可，点击下载Demo

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