实现圆形图片

逃离我推掉我的手 2022-07-16 15:07 224阅读 0赞

![SouthEast][]

实现原理：

1.  得到原图的宽高，计算出圆心，取图片的短边为基准半径。
2.  创建空白Bitmap，大小为基准半径的正方形。
3.  位移原图，使其中心点和创建的空白图中心点重合。
4.  利用Android的Paint绘制叠加图，只绘制重叠部分
5.  效果完成。

public class CircleImageView extends ImageView{ 
        public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }
        public CircleImageView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }
        public CircleImageView(Context context) {
            super(context);
        }
        @Override
        public void setBackgroundDrawable(Drawable background) {
            super.setBackgroundDrawable(getCircleDrawable(getResources(), background));
        }
        @Override
        public void setBackgroundResource(int resid) {
            //Don't worry, we don't need to override it,because it will be call 
            //setBackgroundDrawable(Drawable background)
            super.setBackgroundResource(resid);
        }
        @Override
        public void setImageBitmap(Bitmap bm) {
            //Don't worry, we don't need to override it,because it will be call 
            //setImageDrawable(Drawable drawable)
            super.setImageBitmap(bm);
        }
        @Override
        public void setImageDrawable(Drawable drawable) {
            super.setImageDrawable(getCircleDrawable(getResources(), drawable));
        }
        @Override
        public void setImageURI(Uri uri) {
          //cheat it, let's change the way to implement
            super.setImageURI(uri);
            Drawable img = getCircleDrawable(getResources(), getDrawable());
            super.setImageDrawable(img);
        }
        @Override
        public void setImageResource(int resId) {
            //cheat it, let's change the way to implement
            Drawable img = getCircleDrawable(getResources(), resId);
            super.setImageDrawable(img);
        }
        private static final int SPACING_LINE = 2;
        private static Paint mCirclePaint = null;
        private static Paint mLinePaint = null;
        private static Paint getCirclePaint(){
            if(mCirclePaint == null){
                mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            }
            return mCirclePaint;
        }
        private static Paint getLinePaint(){
            if(mLinePaint == null){
                mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
                mLinePaint.setStyle(Style.STROKE);
                //You can use it to change the width of the line
                mLinePaint.setStrokeWidth(1);
                //You can use it to change the color of the line
                mLinePaint.setColor(Color.BLACK);
            }
            return mLinePaint;
        }
        /** * You can call this method to generate the circular bitmap, * even if you don't use this class */
        public static Bitmap getCircleBitmap(Bitmap src){
            if(src == null){
                return null;
            }
            int width  = src.getWidth();
            int height = src.getHeight();
            int centerX = width / 2;
            int centerY = height / 2;
            int radius  = Math.min(centerX, centerY) / 2;
            Bitmap result = Bitmap.createBitmap(radius * 2, radius * 2, Config.ARGB_8888);
            Canvas canvas = new Canvas(result);
            canvas.drawCircle(radius, radius, radius - SPACING_LINE, getCirclePaint());
            getCirclePaint().setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
            canvas.drawBitmap(src, -(centerX - radius), -(centerY - radius), getCirclePaint());
            //outer 
            canvas.drawCircle(radius, radius, radius, getLinePaint());
            //inner
            canvas.drawCircle(radius, radius, radius - SPACING_LINE, getLinePaint());
            //reset
            getCirclePaint().setXfermode(null);
            //recycle
            src.recycle();
            return result;
        }
        public static Bitmap getCircleBitmap(Drawable src){
            if(src instanceof BitmapDrawable){
                return getCircleBitmap(((BitmapDrawable)src).getBitmap());
            }else{
                //now, i don't know how to do...
                throw new UnsupportedException("Unsupported");
            }
        }
        public static Bitmap getCircleBitmap(Resources res,int id){
            return getCircleBitmap(BitmapFactory.decodeResource(res, id));
        }
        public static Drawable getCircleDrawable(Resources res, Bitmap src){
            return new BitmapDrawable(res,getCircleBitmap(src));
        }
        public static Drawable getCircleDrawable(Resources res, Drawable src){
            return new BitmapDrawable(res,getCircleBitmap(src));
        }
        public static Drawable getCircleDrawable(Resources res, int id) {
            return new BitmapDrawable(res, getCircleBitmap(res, id));
        }
        static class UnsupportedException extends RuntimeException{        
            private static final long serialVersionUID = 1L;
            public UnsupportedException(String str){
                super(str);
            }
        }
    }

[SouthEast]: /images/20220709/ddf80255ebed4d548cf080a2d358bfde.png