pygame / docs / reST / ref / bufferproxy.rst

Full commit


:class:`BufferProxy` is a Pygame support type, designed as the return value of the :meth:`Surface.get_buffer` and :meth:`Surface.get_view` methods. For all Python versions a :class:`BufferProxy` object exports a C struct and Python level array interface on behalf of its parent object's buffer. For CPython 2.6 and later a new buffer interface is also exported. In Pygame, :class:`BufferProxy` is key to implementing the :mod:`pygame.surfarray` module.

:class:`BufferProxy` instances can be created directly from Python code, either for a parent that exports an interface, or from a Python dict describing an object's buffer layout. The dict entries are based on the Python level array interface mapping. The following keys are recognized:

"shape" : tuple
The length of each array dimension as a tuple of integers. The length of the tuple is the number of dimensions in the array.
"typestr" : string
The array element type as a length 3 string. The first character gives byteorder, '<' for little-endian, '>' for big-endian, and '|' for not applicable. The second character is the element type, 'i' for signed integer, 'u' for unsigned integer, 'f' for floating point, and 'V' for an chunk of bytes. The third character gives the bytesize of the element, from '1' to '9' bytes. So, for example, "<u4" is an unsigned 4 byte little-endian integer, such as a 32 bit pixel on a PC, while "|V3" would represent a 24 bit pixel, which has no integer equivalent.
"data" : tuple
The physical buffer start address and a read-only flag as a length 2 tuple. The address is an integer value, while the read-only flag is a bool—False for writable, True for read-only.
"strides" : tuple : (optional)
Array stride information as a tuple of integers. It is required only of non C-contiguous arrays. The tuple length must match that of "shape".
"parent" : object : (optional)
The exporting object. It can be used to keep the parent object alive while its buffer is visible.
"before" : callable : (optional)
Callback invoked when the :class:`BufferProxy` instance exports the buffer. The callback is given one argument, the "parent" object if given, otherwise None. The callback is useful for setting a lock on the parent.
"after" : callable : (optional)
Callback invoked when an exported buffer is released. The callback is passed on argument, the "parent" object if given, otherwise None. The callback is useful for releasing a lock on the parent.

The BufferProxy class supports subclassing, instance variables, and weak references.

New in Pygame 1.8.0, extended in Pygame 1.9.2