java类如下：

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.widget.ImageView;
import cn.dotcreate.tt.R;

public class RoundAngleImageView extends ImageView {

	private Paint paint;
	private int roundWidth = 5;
	private int roundHeight = 5;
	private Paint paint2;

	public RoundAngleImageView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init(context, attrs);
	}

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

	public RoundAngleImageView(Context context) {
		super(context);
		init(context, null);
	}
	
	private void init(Context context, AttributeSet attrs) {
		
		if(attrs != null) {   
			TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundAngleImageView); 
			roundWidth= a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundWidth, roundWidth);
			roundHeight= a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundHeight, roundHeight);
		}else {
			float density = context.getResources().getDisplayMetrics().density;
			roundWidth = (int) (roundWidth*density);
			roundHeight = (int) (roundHeight*density);
		} 
		
		paint = new Paint();
		paint.setColor(Color.WHITE);
		paint.setAntiAlias(true);
		paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
		
		paint2 = new Paint();
		paint2.setXfermode(null);
	}
	
	@Override
	public void draw(Canvas canvas) {
		Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);
		Canvas canvas2 = new Canvas(bitmap);
		super.draw(canvas2);
		drawLiftUp(canvas2);
		drawRightUp(canvas2);
		drawLiftDown(canvas2);
		drawRightDown(canvas2);
		canvas.drawBitmap(bitmap, 0, 0, paint2);
		bitmap.recycle();
	}
	
	private void drawLiftUp(Canvas canvas) {
		Path path = new Path();
		path.moveTo(0, roundHeight);
		path.lineTo(0, 0);
		path.lineTo(roundWidth, 0);
		path.arcTo(new RectF(
				0, 
				0, 
				roundWidth*2, 
				roundHeight*2), 
				-90, 
				-90);
		path.close();
		canvas.drawPath(path, paint);
	}
	
	private void drawLiftDown(Canvas canvas) {
		Path path = new Path();
		path.moveTo(0, getHeight()-roundHeight);
		path.lineTo(0, getHeight());
		path.lineTo(roundWidth, getHeight());
		path.arcTo(new RectF(
				0, 
				getHeight()-roundHeight*2, 
				0+roundWidth*2, 
				getHeight()),
				90, 
				90);
		path.close();
		canvas.drawPath(path, paint);
	}
	
	private void drawRightDown(Canvas canvas) {
		Path path = new Path();
		path.moveTo(getWidth()-roundWidth, getHeight());
		path.lineTo(getWidth(), getHeight());
		path.lineTo(getWidth(), getHeight()-roundHeight);
		path.arcTo(new RectF(
				getWidth()-roundWidth*2, 
				getHeight()-roundHeight*2, 
				getWidth(), 
				getHeight()), 0, 90);
		path.close();
		canvas.drawPath(path, paint);
	}
	
	private void drawRightUp(Canvas canvas) {
		Path path = new Path();
		path.moveTo(getWidth(), roundHeight);
		path.lineTo(getWidth(), 0);
		path.lineTo(getWidth()-roundWidth, 0);
		path.arcTo(new RectF(
				getWidth()-roundWidth*2, 
				0, 
				getWidth(), 
				0+roundHeight*2), 
				-90, 
				90);
		path.close();
		canvas.drawPath(path, paint);
	}

}

定义一个attr.xml的文件，放在values目录下面，内容如下：
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="RoundAngleImageView">
<attr name="roundWidth" format="dimension" />
<attr name="roundHeight" format="dimension" />
</declare-styleable>
</resources>
使用示例如下：
先要声明属性的名字空间：


效果如图：