用于把普通图片转换为圆角图像的工具类RoundRect类（复制即可使用）：
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.PorterDuffXfermode;import android.graphics.RectF;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;public class RoundRect { private int width; private int height; private float cornerRadius; /** * 用于初始化圆角矩形基本参数 * * @param width 图片宽度 * @param height 图片高度 * @param cornerRadius 圆角半径 */ public RoundRect(int width, int height, float cornerRadius) { this.width = width; this.height = height; this.cornerRadius = cornerRadius; } /** * 用于把普通图片转换为圆角矩形图像 * * @param path 图片路径 * @return output 转换后的圆角矩形图像 */ Bitmap toRoundRect(String path) { //创建位图对象 Bitmap photo = lessenUriImage(path); return Transformation(photo); } /** * 用于把普通图片转换为圆角矩形图像 * * @param imageID 图片资源ID * @param context 上下文对象 * @return output 转换后的圆角矩形图像 */ Bitmap toRoundRect(Context context, int imageID) { //创建位图对象 Bitmap photo = BitmapFactory.decodeResource(context.getResources(), imageID); return Transformation(photo); } /** * 用于把Uri图片转换为Bitmap对象 * * @param path 图片URI地址 * @return 生成的Bitmap对象 */ public final static Bitmap lessenUriImage(String path) { BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; Bitmap bitmap = BitmapFactory.decodeFile(path, options); //此时返回 bm 为空 options.inJustDecodeBounds = false; //缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可 int be = (int) (options.outHeight / (float) 320); if (be <= 0) be = 1; options.inSampleSize = be; //重新读入图片，注意此时已经把 options.inJustDecodeBounds 设回 false 了 bitmap = BitmapFactory.decodeFile(path, options); int w = bitmap.getWidth(); int h = bitmap.getHeight(); System.out.println(w + " " + h); //after zoom return bitmap; } /** * 用于把Bitmap图像转换为圆角图像 * * @param photo 需要转换的Bitmap对象 * @return 转换成圆角的Bitmap对象 */ private Bitmap Transformation(Bitmap photo) { //根据源文件新建一个darwable对象 Drawable imageDrawable = new BitmapDrawable(photo); // 新建一个新的输出图片 Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(output); // 新建一个矩形 RectF outerRect = new RectF(0, 0, width, height); // 产生一个红色的圆角矩形 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); paint.setColor(Color.RED); canvas.drawRoundRect(outerRect, cornerRadius, cornerRadius, paint); // 将源图片绘制到这个圆角矩形上 paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); imageDrawable.setBounds(0, 0, width, height); canvas.saveLayer(outerRect, paint, Canvas.ALL_SAVE_FLAG); imageDrawable.draw(canvas); canvas.restore(); return output; }} 测试效果：
创建矩形图标：
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.image); ImageView image = (ImageView)findViewById(R.id.image); RoundRect roundRect = new RoundRect(500,500,100); Bitmap photo = roundRect.toRoundRect(this,R.drawable.kms); image.setImageBitmap(photo); }} 
创建圆形头像：
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.image); ImageView image = (ImageView)findViewById(R.id.image); RoundRect roundRect = new RoundRect(500,500,300); Bitmap photo = roundRect.toRoundRect(this,R.drawable.indark); image.setImageBitmap(photo); }} 