public Shader setShader(Shader shader)

public BitmapShader(Bitmap bitmap,TileMode tileX,TileMode tileY)

public class BitmapShaderView extends View {
 private Paint paint;//畫(huà)筆工具
 private Bitmap bgBitmap,bitmap;//隱藏圖像以及原圖像
 private int mX=-1,mY=-1;//捕獲手指的位置坐標(biāo)
 public BitmapShaderView(Context context) {
  super(context);
 }
 
 public BitmapShaderView(Context context, @Nullable AttributeSet attrs) {
  super(context, attrs);
  this.paint=new Paint();//初始化畫(huà)筆工具
  this.bitmap= BitmapFactory.decodeResource(getResources(),R.drawable.background);//獲取原圖像
 }
 
 public BitmapShaderView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
 }
}

public boolean onTouchEvent(MotionEvent event) {
 switch (event.getAction()){
  case MotionEvent.ACTION_DOWN://手指按下事件
   this.mX=(int)event.getX();
   this.mY=(int)event.getY();
   postInvalidate();//重繪
   return true;
  case MotionEvent.ACTION_MOVE://手指移動(dòng)事件
   this.mX=(int)event.getX();
   this.mY=(int)event.getY();
   break;
  case MotionEvent.ACTION_UP://手指抬起
  case MotionEvent.ACTION_CANCEL://手指離開(kāi)事件
   this.mX=-1;
   this.mY=-1;
   break;
 
 }
 postInvalidate();//重繪
 return super.onTouchEvent(event);
}

protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 if(this.bgBitmap==null){
   this.bgBitmap=Bitmap.createBitmap(getWidth(),getHeight(),Bitmap.Config.ARGB_8888);//創(chuàng)建一個(gè)新空白位圖
  Canvas canvasBg=new Canvas(this.bgBitmap);
  //然后對(duì)背景圖拉升后，畫(huà)到上面的位圖中
  canvasBg.drawBitmap(this.bitmap,null,new Rect(0,0,getWidth(),getHeight()),this.paint);
 }
 if(this.mX!=-1 && this.mY!=-1){
  //填充模式為上面講的第二種，就是復(fù)制粘貼的填充模式，但這里不會(huì)執(zhí)行
  //因?yàn)槲覀兩厦鎻?qiáng)制設(shè)置了圖片的大小為整個(gè)屏幕，所以屏幕沒(méi)有空白區(qū)域
  this.paint.setShader(new BitmapShader(this.bgBitmap,  Shader.TileMode.REPEAT,Shader.TileMode.REPEAT));
   canvas.drawCircle(this.mX,this.mY,200,this.paint);
 }
}