import android.app.Activity; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.PorterDuff; 
import android.graphics.PorterDuff.Mode; 
import android.graphics.PorterDuffXfermode; 
import android.graphics.Rect; 
import android.graphics.RectF; 
import android.graphics.drawable.Drawable; 
import android.os.Bundle; 
import android.view.View; 

public class MyCanvasActivity extends Activity { 
 /** Called when the activity is first created. */ 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(new ImageEffect(this)); 
 } 

 class ImageEffect extends View{ 
  Paint paint; 
  public ImageEffect(Context context){ 
   super(context); 
   paint= new Paint(); //初始化画笔，为后面阴影效果使用。  
   paint.setAntiAlias(true);//去除锯齿。  
   paint.setShadowLayer(5f, 5.0f, 5.0f, Color.BLACK); //设置阴影层，这是关键。  
   paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 

  } 
  public void onDraw(Canvas canvas){ 
   super.onDraw(canvas); 
   int posX = 20; 
   int posY = 50; 
   int PicWidth,PicHeight; 

  Drawable drawable = getResources().getDrawable(R.drawable.pic); 
  Drawable dbe = getResources().getDrawable(R.drawable.pic).mutate();//如果不调用mutate方法，则原图也会被改变，因为调用的资源是同一个，所有对象是共享状态的。  
  Drawable drawTest = getResources().getDrawable(R.drawable.pic); 
  Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.pic); 
  PicWidth = drawable.getIntrinsicWidth(); 
  PicHeight = drawable.getIntrinsicHeight(); 

  drawTest.setBounds(posX, (2 * posY) + PicHeight, posX + PicWidth, (2 * posY) + 2 * PicHeight ); 
  drawable.setBounds(posX,posY,posX+PicWidth,posY+PicHeight); 
  dbe.setBounds(0, 0, PicWidth, PicHeight); 

  canvas.drawColor(Color.WHITE);//设置画布颜色  
  canvas.save(Canvas.MATRIX_SAVE_FLAG); 
  dbe.setColorFilter(0x7f000000,PorterDuff.Mode.SRC_IN); 
  canvas.translate(posX + (int)(0.9 * PicWidth/2), posY + PicHeight/2);//图像平移为了刚好在原图后形成影子效果。  
  canvas.skew(-0.9F, 0.0F);//图像倾斜效果。  
  canvas.scale(1.0f, 0.5f);//图像（其实是画布）缩放，Y方向缩小为1/2。  
  dbe.draw(canvas);//此处为画原图像影子效果图，比原图先画，则会在下层。  
  drawable.clearColorFilter(); 
  canvas.restore(); 

  canvas.save(Canvas.MATRIX_SAVE_FLAG); 
  drawable.draw(canvas);//此处为画原图像，由于canvas有层次效果，因此会盖在影子之上。  
  canvas.restore(); 

  //默认无效果原图  
  canvas.save(Canvas.MATRIX_SAVE_FLAG); 
  drawTest.draw(canvas); 
  canvas.restore(); 

  //图片阴影效果  
  Rect rect = new Rect(2*posX + PicWidth + 3, 2*posY + PicHeight + 3, 2*posX + 2*PicWidth - 2, 2*posY + 2*PicHeight - 2); 
  //由于图片的实际尺寸比显示出来的图像要大一些，因此需要适当更改下大小，以达到较好的效果  

  RectF rectF = new RectF(rect); 
  canvas.drawRoundRect(rectF, 10f, 10f, paint);//在原有矩形基础上，画成圆角矩形，同时带有阴影层。  
  canvas.drawBitmap(bmp, 2*posX + PicWidth, 2*posY + PicHeight, null);//画上原图。  
  canvas.restore(); 
  } 
 }