使用Canvas和Paint制作圆角矩形头像

前言:最近需要做一个带边框用户的圆角头像,然后搜索了下,发现大部分都是使用shape来做的,于是使用Canvas做了个头像处理

Demo:https://github.com/459905207/rounded-rectangle

效果图:

实现代码

    //return:Bitmap    //参数:原图,圆角大小,边框大小    private Bitmap createCircleImage(Bitmap bitmap, int roundPx, int framePx) {        Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_4444);        //创建画板        Canvas canvas = new Canvas(newBitmap);        //画板drawARGB必须与Bitmap的Config一致        canvas.drawARGB(0, 0, 0, 0);        Paint paint = new Paint();        //抗锯齿        paint.setAntiAlias(true);        //左上右下位置        Rect rect = new Rect(framePx / 2, framePx / 2, bitmap.getWidth() - framePx / 2, bitmap.getHeight() - framePx / 2);        RectF rectF = new RectF(rect);        //RectF对象,X矩形圆角大小,Y矩形圆角大小,画笔        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);        //设置两张图片相交时的模式为Mode.SRC_IN        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));        canvas.drawBitmap(bitmap, rect, rect, paint);        //创建画边框的画笔        Paint paintFrame = new Paint();        paintFrame.setAntiAlias(true);        //设置空心画笔        paintFrame.setStyle(Paint.Style.STROKE);        //设置边框颜色        paintFrame.setColor(Color.WHITE);        //设置边框宽度        paintFrame.setStrokeWidth(framePx);        //画圆角矩形边框        canvas.drawRoundRect(rectF, roundPx, roundPx, paintFrame);        return newBitmap;    }    public int dip2px(float dpValue) {        final float scale = getApplication().getResources()            .getDisplayMetrics().density;        return (int) (dpValue * scale + 0.5f);    }

核心:

主要用到了Canvas的drawRoundRect(RectF rect, float rx, float ry,Paint paint)方法,用来生成圆角矩形,根据float rx, float ry的大小决定X,Y轴矩形圆角的大小
还有Paint的setXfermode方法来生成圆角矩形头像
(参考文章:http://folksy.iteye.com/blog/1488629)
最后使用空心画笔画一个边框即可