Image transforamtion and cropping in android 2.1

Question

Hey,

i would like to transform and crop a given image in android. Therefore i have 4 source and 4 destination points to specify the transformation matrix.

i use

    float[] src = new float[8];
    src[0] = rp[0].getX();
    src[1] = rp[0].getY();
    src[2] = rp[1].getX();
    src[3] = rp[1].getY();
    src[4] = rp[2].getX();
    src[5] = rp[2].getY();
    src[6] = rp[3].getX();
    src[7] = rp[3].getY();

    int width = image.getWidth();
    int height = image.getHeight();

    float[] dst = { 0, 0, width, 0, width, height, 0, height };

    Matrix trans = new Matrix();
    trans.setPolyToPoly(src, 0, dst, 0, 4);

rp contains 4 points specifying 4 corners of a quadrilateral

Then i use

    image = Bitmap.createBitmap(image, 0, 0, width, height, trans, false);

to transform the quadrilateral to an rectangle.

After that i would like to crop out the transformed rectangle. But i can not calculate the new position of the corners in the transformed image.

I would be pleased if anybody have a idea or solution for this problem.

greeting

Pascal