超簡潔代碼實現CircleImageView

public class CircleView extends ImageView {
    private Paint mPaint = new Paint();


public CircleView(Context context, AttributeSet attrs) {
    super(context, attrs);
}


@Override
protected void onDraw(Canvas canvas) {
    Drawable mDrawable = getDrawable();//獲取xml文件設置的圖片
    if (null == mDrawable) super.onDraw(canvas);//如果為空，交給父類處理
    Bitmap mBitmap = ((BitmapDrawable) mDrawable).getBitmap();//將圖片轉化成bitmap

    int len = getWidth() < getHeight() ? getWidth() : getHeight();//獲取xml的長寬屬性值，選擇較小的

    Bitmap tempBitmap = Bitmap.createBitmap(len, len, Bitmap.Config.ARGB_8888);//新建一個bitmap對象，作為緩存
    Canvas mCanvas = new Canvas(tempBitmap);//新建畫布緩存bitmap對象

    mPaint.setAntiAlias(true);//抗鋸齒
    mCanvas.drawCircle(len / 2, len / 2, len / 2, mPaint);//畫一個圓

    mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));//設置畫筆的覆蓋類型

    Matrix matrix = new Matrix(); // 初始化Matrix對象
    matrix.setScale((float) len / mBitmap.getWidth(), (float) len / mBitmap.getHeight()); //設置縮放比例
    mCanvas.drawBitmap(mBitmap, matrix, mPaint);//畫出縮放后的圖片

    mPaint.reset();//重置畫筆
    canvas.drawBitmap(tempBitmap, 0, 0, mPaint);//繪制緩存圖片
}


}</pre>