bitmap circular crop in android

问题:

i have a square bitmap being displayed underneath a semi transparent circle. The user can touch and drag the bitmap to position it. I want to be able to crop what ever part of the bitmap is under the circle. How can i do this?

回答1:

have a look at RoundedBitmapDrawable in the support library

all you have to do is give it the bitmap and the corner radius

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

imageView.setImageDrawable(img);

回答2:

You Can make your imageview circular using RoundedBitmapDrawable

here is the code for achieving roundedImageview:

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);

回答3:

You can use the power of PorterDuff to get your bitmap in any shape or path...

Here is an example:

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;
}

回答4:

Here is a link to a sample project. It has a transparent square over an image. You can pinch zoom or drag the bottom image and can corp it.

https://github.com/tcking/ImageCroppingView.

The square is made by using canvas. you can change it to any shape as u desired by changing canvas. Hop it helps you.