Android 倒影算法的实现代码

复制代码 代码如下:

public class MirrorView extends View {

 Paint m_paint;

 int m_nShadowH;

 Drawable m_dw;

 Bitmap m_bitmap;

 //xxxx

 Matrix mMatrix;

 int shadowHeight;

 public MirrorView(Context context, Bitmap bitmap) {

  super(context);

  m_bitmap = bitmap;

  _Init();

  // TODO Auto-generated constructor stub

 }

 private void _Init() {

  //m_dw = new BitmapDrawable(BitmapFactory.decodeResource(getResources(),  R.drawable.icon));

  m_dw = new BitmapDrawable(m_bitmap);

  m_dw.setBounds(0,0,m_dw.getIntrinsicWidth(),m_dw.getIntrinsicHeight());

  m_nShadowH = m_dw.getIntrinsicHeight()/1;

  m_paint = new Paint(Paint.ANTI_ALIAS_FLAG);

  LinearGradient lg = new LinearGradient(0, 0, 0, m_nShadowH, 0xB0FFFFFF, 0x00000000, Shader.TileMode.CLAMP);

  m_paint.setShader(lg);

  m_paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY)); 

  //xxxx

  mMatrix = new Matrix();

 }

 @Override

 public void onDraw(Canvas canvas) {

  super.onDraw(canvas);

  int nX = 0;

  int nY = 0;

  _DrawNormalImg(canvas, nX, nY);

  _DrawMirror(canvas, nX, nY);

 }

 private void _DrawNormalImg(Canvas canvas, int nX, int nY) {

  canvas.save(Canvas.MATRIX_SAVE_FLAG);

  canvas.translate(nX, nY);

  m_dw.draw(canvas);

  canvas.restore();

 }

 private void _DrawMirror(Canvas canvas, int nX, int nY) {

  int nW = m_dw.getIntrinsicWidth();

  int nH = m_dw.getIntrinsicHeight();

//  U.dout("nW="+nW+",nH="+nH);

  //xxxx

  shadowHeight=nH/2;

  //xxxx

  float[] src={0, nH, nW, nH, nW,nH - m_nShadowH, 0, nH - m_nShadowH};

  float[] dst={ 0, nH, nW, nH,nW, shadowHeight, 0, shadowHeight };

  //xxxx

  canvas.save();

  mMatrix.setPolyToPoly(src, 0, dst, 0, src.length >> 1);

  canvas.concat(mMatrix);

  //draw mirror image 

  canvas.save(Canvas.MATRIX_SAVE_FLAG);

  canvas.scale(1.0f, -1.0f);

  canvas.translate(nX, -(nY + nH * 2));

  canvas.clipRect(0, nH, nW, nH - m_nShadowH);

  m_dw.draw(canvas);

  canvas.restore();

  //draw mask 

  canvas.save();

  canvas.translate(nX, nY + nH);

  canvas.drawRect(0, 0, nW, m_nShadowH, m_paint);

  canvas.restore();

  //xxxx

  canvas.restore();

 }

}