Initializes the receiver, a newly allocated NSBitmapImageRep object, with bitmap data read from a rendered image.
A rectangle that specifies an area of the current window in the current coordinate system.
Returns the initialized object or nil If for any reason the new object can’t be initialized.
This method uses imaging operators to read the image data into a buffer; the object is then created from that data. The object is initialized with information about the image obtained from the window server.