python-webm 0.2.2-2.1 / usr / lib / python2.7 / dist-packages / webm / encode.py

# -*- coding: utf-8 -*-
"""
Copyright (c) 2011, Daniele Esposti <expo@expobrain.net>
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * The name of the contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

from ctypes import (c_int, c_float, c_void_p, byref, memmove,
    create_string_buffer)
from webm import _LIBRARY
from webm.handlers import WebPHandler


# -----------------------------------------------------------------------------
# Exceptions
# -----------------------------------------------------------------------------

class EncodeError(Exception):
    """
    Exception for encoding errors
    """
    pass


# -----------------------------------------------------------------------------
# Internal functions
# -----------------------------------------------------------------------------

# Set argument types
LOSSY_ARGS = [c_void_p, c_int, c_int, c_int, c_float, c_void_p]
_LIBRARY.WebPEncodeRGB.argtypes = LOSSY_ARGS
_LIBRARY.WebPEncodeBGR.argtypes = LOSSY_ARGS
_LIBRARY.WebPEncodeRGBA.argtypes = LOSSY_ARGS
_LIBRARY.WebPEncodeBGRA.argtypes = LOSSY_ARGS

HAS_LOSSLESS = False
try:
    LOSSLESS_ARGS = [c_void_p, c_int, c_int, c_int, c_void_p]
    _LIBRARY.WebPEncodeLosslessRGB.argtypes = LOSSLESS_ARGS
    _LIBRARY.WebPEncodeLosslessBGR.argtypes = LOSSLESS_ARGS
    _LIBRARY.WebPEncodeLosslessRGBA.argtypes = LOSSLESS_ARGS
    _LIBRARY.WebPEncodeLosslessBGRA.argtypes = LOSSLESS_ARGS

    # Set return types
    _LIBRARY.WebPEncodeRGB.restype = c_int
    _LIBRARY.WebPEncodeBGR.restype = c_int
    _LIBRARY.WebPEncodeRGBA.restype = c_int
    _LIBRARY.WebPEncodeBGRA.restype = c_int
    _LIBRARY.WebPEncodeLosslessRGB.restype = c_int
    _LIBRARY.WebPEncodeLosslessBGR.restype = c_int
    _LIBRARY.WebPEncodeLosslessRGBA.restype = c_int
    _LIBRARY.WebPEncodeLosslessBGRA.restype = c_int

    HAS_LOSSLESS = True
except AttributeError:
    #lossless is missing!
    pass


def _lossy(func, image, quality):
    """
    Encode the image with the given quality using the given encoding
    function

    :param func: The encoding function
    :param image: The image to be encoded
    :param quality: The encode quality factor

    :type function: function
    :type image: BitmapHandler
    :type quality: float
    """
    # Call encode function
    data = str(image.bitmap)
    width = c_int(image.width)
    height = c_int(image.height)
    stride = c_int(image.stride)
    q_factor = c_float(quality)
    output_p = c_void_p()

    size = func(data, width, height, stride, q_factor, byref(output_p))

    # Check return size
    if size == 0:
        raise EncodeError

    # Convert output
    output = create_string_buffer(size)

    memmove(output, output_p, size)

    return WebPHandler(bytearray(output), image.width, image.height)


def _lossless(func, image):
    """
    Encode the image losslessly using the given encoding
    function

    :param func: The encoding function
    :param image: The image to be encoded

    :type function: function
    :type image: BitmapHandler
    """
    assert HAS_LOSSLESS, "this version of the webp library does not support lossless modes!"
    # Call encode function
    data = str(image.bitmap)
    width = c_int(image.width)
    height = c_int(image.height)
    stride = c_int(image.stride)
    output_p = c_void_p()

    size = func(data, width, height, stride, byref(output_p))

    # Check return size
    if size == 0:
        raise EncodeError

    # Convert output
    output = create_string_buffer(size)

    memmove(output, output_p, size)

    return WebPHandler(bytearray(output), image.width, image.height)




# -----------------------------------------------------------------------------
# Public functions
# -----------------------------------------------------------------------------

def EncodeRGB(image, quality=100):
    """
    Encode the given RGB image with the given quality

    :param image: The RGB image
    :param quality: The encode quality factor

    :type image: BitmapHandler
    :type quality: float
    """
    return _lossy(_LIBRARY.WebPEncodeRGB, image, quality)

def EncodeRGBA(image, quality=100):
    """
    Encode the given RGBA image with the given quality

    :param image: The RGBA image
    :param quality: The encode quality factor

    :type image: BitmapHandler
    :type quality: float
    """
    return _lossy(_LIBRARY.WebPEncodeRGBA, image, quality)

def EncodeBGRA(image, quality=100):
    """
    Encode the given BGRA image with the given quality

    :param image: The BGRA image
    :param quality: The encode quality factor

    :type image: BitmapHandler
    :type quality: float
    """
    return _lossy(_LIBRARY.WebPEncodeBGRA, image, quality)

def EncodeBGR(image, quality=100):
    """
    Encode the given BGR image with the given quality

    :param image: The BGR image
    :param quality: The encode quality factor

    :type image: BitmapHandler
    :type quality: float
    """
    return _lossy(_LIBRARY.WebPEncodeBGR, image, quality)

def EncodeLosslessRGB(image):
    """
    Encode the given RGB image losslessly

    :param image: The RGB image

    :type image: BitmapHandler
    """
    return _lossless(_LIBRARY.WebPEncodeLosslessRGB, image)

def EncodeLosslessRGBA(image):
    """
    Encode the given RGBA image losslessly

    :param image: The RGBA image

    :type image: BitmapHandler
    """
    return _lossless(_LIBRARY.WebPEncodeLosslessRGBA, image)

def EncodeLosslessBGRA(image):
    """
    Encode the given BGRA image losslessly

    :param image: The BGRA image

    :type image: BitmapHandler
    """
    return _lossless(_LIBRARY.WebPEncodeLosslessBGRA, image)

def EncodeLosslessBGR(image):
    """
    Encode the given BGR image losslessly

    :param image: The BGR image

    :type image: BitmapHandler
    """
    return _lossless(_LIBRARY.WebPEncodeLosslessBGR, image)