圆形图片实现2种方式

package com.example.testandroid;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.Shader.TileMode;
import android.util.AttributeSet;
import android.view.View;

public class MyProgress extends View
{

 private float scale;
 private float dx;
 private float dy;
 private int mBorderWidth;

 public MyProgress(Context context, AttributeSet attrs)
 {
  super(context, attrs);
 }

 @Override
 protected void onDraw(Canvas canvas)
 {
  super.onDraw(canvas);
  Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
    R.drawable.hello);
  //圆形图片实现方式001
  bitmap = getRoundedCornerBitmap(bitmap, 1);
  Rect rect2 = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
  Rect rect3 = new Rect(200, 200, 400, 400);
  Paint paint4 = new Paint();
  paint4.setAntiAlias(true);
  canvas.drawBitmap(bitmap, rect2, rect3, paint4);
  //圆形图片实现方式002
        //中点cx,cy,半径radius
  canvas.drawCircle(500, 300, 200, getPaint(bitmap));
 }

 private Paint getPaint(Bitmap bitmap)
 {
  int outWidth = 200;
  int outHeight = 200;
  int width = bitmap.getWidth();
  int height = bitmap.getHeight();
  Paint paint = new Paint();
  paint.setAntiAlias(true);
  Shader shader = new BitmapShader(bitmap, TileMode.CLAMP, TileMode.CLAMP);
  Matrix localM = new Matrix();

  if (width * outHeight > outWidth * height)
  {
   scale = outHeight / (float) height;
   dx = (outWidth - width * scale) * 0.5f;
  } else
  {
   scale = outWidth / (float) width;
   dy = (outHeight - height * scale) * 0.5f;
  }

  //localM.setScale(scale, scale);
  //localM.postTranslate((int) (dx + 0.5f) + mBorderWidth,
  //  (int) (dy + 0.5f) + mBorderWidth);
        System.out.println("缩放比例:"+scale);
  shader.setLocalMatrix(localM);
  paint.setShader(shader);
  return paint;
 }

 /**
  * 将图片截取为圆角图片
  *
  * @param bitmap
  *            原图片
  * @param ratio
  *            截取比例，如果是8，则圆角半径是宽高的1/8，如果是2，则是圆形图片
  * @return 圆角矩形图片
  */
 public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, float ratio)
 {

  int width = bitmap.getWidth();
  int height = bitmap.getHeight();
  Bitmap output = Bitmap.createBitmap(width,
    height, Config.ARGB_8888);
  Canvas canvas = new Canvas(output);

  final Paint paint = new Paint();
  final Rect rect = new Rect(0, 0, width, height);
  final RectF rectF = new RectF(rect);

  paint.setAntiAlias(true);
  canvas.drawARGB(0, 0, 0, 0);
  // 不能少.........
  canvas.drawRoundRect(rectF, width / ratio,
    height / ratio, paint);
  // 圆形,少了就不是圆形.............
  // 圆形,少了就不是圆形.............
  paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
  canvas.drawBitmap(bitmap, rect, rect, paint);
  return output;
 }

}