Python的DXT压缩

Question

我目前使用的是图片，有些是DXT压缩的，我需要一种简单的方法来用Python来解压缩这些文件。不幸的是，我找不到任何为我这样做的图书馆。

有没有人知道一个好的Python DXT压缩库，或者一个压缩库的接口？

-- dav1d

编辑：

libsquish是这里的方法，但不幸的是Python绑定不起作用，所以这里是解决方案。

在C++中制作一个压缩包装器，导出内部访问libsquish的函数：

#include <squish.h>

typedef unsigned char u8;

extern "C" {
    void CompressMasked( u8 const* rgba, int mask, void* block, int flags ) {
        squish::CompressMasked(rgba, mask, block, flags);
    }

    void Compress( u8 const* rgba, void* block, int flags ) {
        squish::Compress(rgba, block, flags);
    }

    void Decompress( u8* rgba, void const* block, int flags ) {
        squish::Decompress(rgba, block, flags);
    }

    int GetStorageRequirements( int width, int height, int flags ) {
        return squish::GetStorageRequirements(width, height, flags);
    }

    void CompressImage( u8 const* rgba, int width, int height, void* blocks, int flags ) {
        squish::CompressImage(rgba, width, height, blocks, flags);
    }

    void DecompressImage( u8* rgba, int width, int height, void const* blocks, int flags ) {
        squish::DecompressImage(rgba, width, height, blocks, flags);
    }
}

创建一个动态库( windows上的dll或linux上的so，我称之为libsquishc.so)并使用ctypes打开它。

我的方法(只是导出我需要的函数)：

from ctypes import CDLL, c_int, byref, create_string_buffer
import os.path

libsquish_path = os.path.join(os.path.split(os.path.abspath(__file__))[0], 'libsquishc.so')
libsquish = CDLL(libsquish_path)


DXT1 = 1 << 0 
DXT3 = 1 << 1 
DXT5 = 1 << 2 

COLOR_ITERATIVE_CLUSTER_FIT = 1 << 8    
COLOR_CLUSTER_FIT = 1 << 3    
COLOR_RANGE_FIT = 1 << 4
WEIGHT_COLOR_BY_ALPHA = 1 << 7


GetStorageRequirements = libsquish.GetStorageRequirements
GetStorageRequirements.argtypes = [c_int, c_int, c_int]
GetStorageRequirements.restype = c_int

def compress_image(rgba, width, height, flags):
    rgba = create_string_buffer(rgba)

    c = GetStorageRequirements(width, height, flags)
    buffer = create_string_buffer(c)

    libsquish.Compress(byref(rgba), byref(buffer), c_int(flags))

    return buffer.raw

def decompress_image(block, width, height, flags):
    block = create_string_buffer(block)

    c = width*height*4
    rgba = create_string_buffer(c)

    libsquish.DecompressImage(byref(rgba), c_int(width), c_int(height), byref(block), c_int(flags))

    return rgba.raw

Answer 1

libSquish有添加Python绑定的修补程序。

编辑：安装过程似乎是

1. 下载squish-1.11.zip
2. 解压缩和编译--应该会产生一个libsquish.file
3. 下载并安装Cython (听起来你这样做了)
4. 创建一个临时目录并“应用”修补程序-它会删除一堆新文件，这些文件是绑定代码。
5. 运行安装程序(sudo python setup.py安装)

如果您这样做了，并且仍然有错误，那么您可能应该(a)共享实际的错误消息，这样我们就可以找出原因，或者(b)直接联系补丁作者- mat (at) kivy.org。

Edit2:编译错误足够短，因此我将在这里包括它：

running install
running build
running build_ext
skipping 'squish.c' Cython extension (up-to-date)
building 'squish' extension
gcc -pthread -fno-strict-aliasing -march=i686 -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2 -DNDEBUG -march=i686 -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2 -fPIC -I.. -I/usr/include/python2.7 -c squish.c -o build/temp.linux-i686-2.7/squish.o
In file included from squish.c:274:0:
/usr/include/squish.h:32:1: error: unknown type name 'namespace'
/usr/include/squish.h:32:18: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
squish.c: In function '__pyx_pf_6squish_compressImage':
squish.c:790:22: error: 'squish' undeclared (first use in this function)
squish.c:790:22: note: each undeclared identifier is reported only once for each function it appears in
squish.c:790:28: error: expected ';' before ':' token
squish.c:866:10: error: expected expression before ':' token
squish.c: In function '__pyx_pf_6squish_2decompressImage':
squish.c:1202:10: error: expected expression before ':' token
error: command 'gcc' failed with exit status 1

H的相关部分看起来

#ifndef SQUISH_H
#define SQUISH_H

//! All squish API functions live in this namespace.
namespace squish {

// -----------------------------------------------------------------------------

看起来它被namespace关键字堵住了，我会说这意味着它正在编译为C，而它应该被编译为C++。

Answer 2

libsquish有一些有贡献的python绑定:但是，http://code.google.com/p/libsquish/issues/detail?id=17我还没有使用它们。