public class MyCirleImageView extends ImageView {
private static int RADIUS = 4; // 默认圆角的宽高是8dip,可以设置有参构造，传入需要的值public MyCirleImageView(Context context, AttributeSet attrs) {super(context, attrs);}@Overrideprotected void onDraw(Canvas canvas) {/**取得Drawable*/BitmapDrawable drawable = (BitmapDrawable) getDrawable();if (drawable == null) { return; }if (getWidth() == 0 || getHeight() == 0) { return; }/**取得对应bitmap*/Bitmap fullBitmap = drawable.getBitmap();/**取得View在parent view里面占的大小* getWidth得到的事某个View的实际尺寸。getMeasuredWidth是某个View想要在parent view里面占的大小*/int scaledWidth = getMeasuredWidth();int scaledHeight = getMeasuredHeight();Bitmap mScaledBitmap;if (scaledWidth == fullBitmap.getWidth() && scaledHeight == fullBitmap.getHeight()) {mScaledBitmap = fullBitmap;} else {mScaledBitmap = Bitmap.createScaledBitmap(fullBitmap, scaledWidth, scaledHeight, true);}try {Bitmap roundBitmap = getRoundedCornerBitmap(getContext(), mScaledBitmap, RADIUS, scaledWidth, scaledHeight, false, false, false, false);canvas.drawBitmap(roundBitmap, 0, 0, null);} catch (Exception e) {super.onDraw(canvas);}}/**取得圆角图片*/public static Bitmap getRoundedCornerBitmap(Context context, Bitmap input, int pixels, int w, int h, boolean squareTL, boolean squareTR, boolean squareBL, boolean squareBR) {Bitmap output = Bitmap.createBitmap(w, h, Config.ARGB_8888);Canvas canvas = new Canvas(output);final float mulitDensity = context.getResources().getDisplayMetrics().density;final int color = 0xff424242;final Paint paint = new Paint();final Rect rect = new Rect(0, 0, w, h);final RectF rectF = new RectF(rect);final float roundPx = pixels * mulitDensity;paint.setAntiAlias(true);canvas.drawARGB(0, 0, 0, 0);paint.setColor(color);canvas.drawRoundRect(rectF, roundPx, roundPx, paint);/**下面几个判断是实现：是否要保留对应直角*/if (squareTL) {canvas.drawRect(0, 0, w / 2, h / 2, paint);}if (squareTR) {canvas.drawRect(w / 2, 0, w, h / 2, paint);}if (squareBL) {canvas.drawRect(0, h / 2, w / 2, h, paint);}if (squareBR) {canvas.drawRect(w / 2, h / 2, w, h, paint);}/**设置两张图片相交时的模式。* 在正常的情况下，在已有的图像上绘图将会在其上面添加一层新的形状。如果新的Paint是完全不透明的，那么它将完全遮挡住下面的Paint；如果它是部分透明的，那么它将会被染上下面的颜色。* 而setXfermode就可以来解决这个问题* paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); * canvas.drawBitmap(srcBitmap, 0f, 0f, paint); canvas原有的图片可以理解为背景，就是dst；新画上去的图片可以理解为前景，就是src。* */paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));canvas.drawBitmap(input, 0, 0, paint);return output;}
}
———————–把MyCirleImageView 当成ImageView放到布局文件中使用就可以———————————–
，画龙画虎难画骨，知人知面不知心。
