public static Bitmap toRoundImage(Bitmap bitmap) {
float roundPx = 0;
int rectStartX=0;
int rectStartY=0;
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Bitmap.Config.ARGB_8888);
Rect rect=null;
/**
截取宽高较小的图片,就是截取正中间的正方形
*/
if (bitmap.getWidth()>bitmap.getHeight()){
roundPx=bitmap.getHeight()/2;//半径
rectStartX=(bitmap.getWidth()-bitmap.getHeight())/2; //矩形x开始位置
rect = new Rect(rectStartX, 0, bitmap.getWidth()-rectStartX, bitmap.getHeight());//取中间部分
}else{
roundPx=bitmap.getWidth()/2;//半径
rectStartY=(bitmap.getHeight()-bitmap.getWidth())/2; //矩形Y开始位置
rect = new Rect(0, rectStartY, bitmap.getWidth(), bitmap.getHeight()-rectStartY);//取中间部分
}
Canvas canvas = new Canvas(output);
int color = 0xff424242;
Paint paint = new Paint();
RectF rectF = new RectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint); //画拐角,拐角的半径为正方形的边长一半
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
//下面上图来解释,就一目了然