android中的位图循环裁剪

2018-06-10 15:52:22

我有一个正方形的位图显示在一个半透明的圆下面。用户可以触摸并拖动位图来定位它。我希望能够裁剪位于圆下的位图的任何部分。我怎样才能做到这一点？

看看支持库中的RoundedBitmapDrawable

所有你需要做的就是给它的位图和角半径

RoundedBitmapDrawable img = RoundedBitmapDrawableFactory.create(getResources(),bitmap);
img.setCornerRadius(radius);

imageView.setImageDrawable(img);

你可以使用RoundedBitmapDrawable使你的imageview循环

这里是实现roundedImageview的代码：

ImageView profilePic=(ImageView)findViewById(R.id.user_image);
//get bitmap of the image
Bitmap imageBitmap=BitmapFactory.decodeResource(getResources(),  R.drawable.large_icon);
RoundedBitmapDrawable roundedBitmapDrawable=
  RoundedBitmapDrawableFactory.create(getResources(), imageBitmap);
roundedBitmapDrawable.setCornerRadius(50.0f);
roundedBitmapDrawable.setAntiAlias(true);
profilePic.setImageDrawable(roundedBitmapDrawable);

您可以使用PorterDuff的力量来获取您的位图任何形状或路径...

这里是一个例子：

public static Bitmap getCircular(Bitmap bm, int cornerRadiusPx) {
    int w = bm.getWidth();
    int h = bm.getHeight();

    int radius = (w < h) ? w : h;
    w = radius;
    h = radius;

    Bitmap bmOut = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bmOut);

    Paint paint = new Paint();
    paint.setAntiAlias(true);
    paint.setColor(0xff424242);

    Rect rect = new Rect(0, 0, w, h);
    RectF rectF = new RectF(rect);

    canvas.drawARGB(0, 0, 0, 0);
    canvas.drawCircle(rectF.left + (rectF.width()/2), rectF.top + (rectF.height()/2), radius / 2, paint);

    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bm, rect, rect, paint);

    return bmOut;
}

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