通過給定的Mask來確定顯示圖片的形狀

直接貼上程式碼

/**
 * @author Momo
 * */
public class XCRoundImageView extends ImageView {
    private Paint paint;

    public XCRoundImageView(Context context) {
        this(context, null);
    }

    public XCRoundImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0
 
);
    }

    public XCRoundImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        paint = new Paint();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Drawable drawable = getDrawable();
        if (null != drawable) {
            //獲得原始image
 

            Bitmap src = ((BitmapDrawable) drawable).getBitmap();
            //建立矩陣來放大或者縮小原始圖片
            //postScale（<這裡面為放大或者縮小的引數>）
            Matrix matrix = new Matrix();
            float srcLength = pxTodp(Math.min(src.getWidth(),src.getHeight()));
            matrix.postScale(1 / (srcLength / 44
 
), 1 / (srcLength / 44));
            //獲得mask
            //quick_settings_personal_center_mask -->這裡是mask的資原始檔
            Bitmap mask = BitmapFactory.decodeResource(getResources(),R.drawable.quick_settings_personal_center_mask);
            //建立符合要求大小的原始圖片
            Bitmap bitmap = Bitmap.createBitmap(((BitmapDrawable) drawable).getBitmap(), 0, 0, src.getWidth(),src.getHeight(),matrix,true);
            //設定層級
            int sr = canvas.saveLayer(0, 0, src.getWidth(),src.getHeight(), null, Canvas.ALL_SAVE_FLAG);
            canvas.drawBitmap(bitmap,0,0,paint);
            paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
            canvas.drawBitmap(mask, 0, 0, paint);
            paint.setXfermode(null);
            canvas.restoreToCount(sr);
        } else {
            super.onDraw(canvas);
        }
    }

    public int pxTodp(float px){
        final float scale = getContext().getResources().getDisplayMetrics().density;
        return (int) (px / scale + 0.5f);
    }