*变换图片 TransitionDrawable
<?xml version="1.0" encoding="UTF-8"?>
<transition xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:drawable="@drawable/sample_0"/>
    <item android:drawable="@drawable/sample_1"/>
</transition>

Resources res=getResources();
TransitionDrawable transition=  (TransitionDrawable)res.getDrawable(R.drawable.transition);
ImageView view=new ImageView(this);
view.setImageDrawable(transition);
transition.startTransition(1000);

*绘制形状 ShapeDrawable
public class MyView:View{
  private ShapeDrawable shape;
  public MyView(Context c){
     super(c);
     shape=new ShapeDrawable(new OvalShape);
     shape.getPaint().setColor(0xffffffff);
     shape.setBounds(0,0,100,199);
  }
  
  @Override
  public void onDraw(Canvas canvas){
    shape.draw(canvas);
  }
}

*操作assets中的文件
  ImageView img=new ImageView(this);
    setContentView(img);
   
    AssetManager manager=this.getAssets();
    String[] files;
    try {
    files=manager.list("");
    InputStream file= manager.open(files[1]);
    img.setImageBitmap(BitmapFactory.decodeStream(file));
    } catch (IOException e) {
  // TODO Auto-generated catch block
    e.printStackTrace();
    }