android 自定义圆形图片

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public class CircleImageView extends ImageView {    private Paint paint;    private boolean isgray;    public CircleImageView(Context context) {        this(context, null);    }    public CircleImageView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public CircleImageView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    private void init() {        paint = new Paint();        paint.setAntiAlias(true);    }    public void setGray(boolean isgray){        this.isgray = isgray;        invalidate();    }    @Override    protected void onDraw(Canvas canvas) {        //获得ImageView显示的图片        Drawable drawable = getDrawable();        if(drawable != null && drawable instanceof BitmapDrawable){            BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;            Bitmap bitmap = bitmapDrawable.getBitmap();//获得当前ImageView显示的Bitmap对象            //获得圆形的Bitmap            Bitmap circleBitmap = getCirleBitmap(bitmap);            //摆放圆形ImageView            int viewWidth = getWidth();            int viewHeight = getHeight();            //设置图片显示的返回            Rect rect1 = new Rect(0, 0, circleBitmap.getWidth(), circleBitmap.getHeight());            Rect rect2 = null;            if(viewWidth > viewHeight){                rect2 = new Rect(                        viewWidth/2 - viewHeight/2,                        0,                        viewWidth/2 + viewHeight/2,                        viewHeight                );            } else {                rect2 = new Rect(                        0,                        viewHeight/2 - viewWidth/2,                        viewWidth,                        viewHeight/2 + viewWidth/2                );            }            canvas.drawBitmap(circleBitmap, rect1, rect2, null);        } else {            super.onDraw(canvas);        }    }    /**     * 传一个矩形的Bitmap进去，返回一个圆形的Bitmap     * @param bitmap     * @return     */    private Bitmap getCirleBitmap(Bitmap bitmap){        int s = bitmap.getWidth() > bitmap.getHeight() ? bitmap.getHeight() : bitmap.getWidth();        //获得一个宽高都为s的空白Bitmap        Bitmap newBitmap = Bitmap.createBitmap(s, s, Bitmap.Config.ARGB_8888);        //将该空白的Bitmap转化为画布        Canvas canvas = new Canvas(newBitmap);        //设置画布的抗锯齿        canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG                | Paint.FILTER_BITMAP_FLAG));        //绘制圆形        canvas.drawCircle(s/2, s/2, s/2, paint);        //设置画笔的混合模式        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));        //设置图片的黑白程度        if(this.isgray) {            ColorMatrix colorMatrix = new ColorMatrix();            colorMatrix.setSaturation(0);            ColorMatrixColorFilter colorMatrixFilter = new ColorMatrixColorFilter(colorMatrix);            paint.setColorFilter(colorMatrixFilter);        }        //将有内容的bitmap压缩至画布等宽高，然后绘制在画布上        Rect rect1 = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());        Rect rect2 = new Rect(0, 0, s, s);        canvas.drawBitmap(bitmap, rect1, rect2, paint);        //重置画笔        paint.reset();        return newBitmap;    }}
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