我正在使用 python ctypes 和 libc 与供应商提供的 DLL 文件进行交互。 DLL 文件的目的是从相机获取图像。
图像采集似乎运行无误;我遇到的问题是访问数据。
图像采集函数将 ctypes.c_void_p 作为图像数据的参数。
简化如下:
"""
typedef struct AvailableData
{
void* initial_readout;
int64 readout_count;
} imageData;
"""
class AvailableData(ctypes.Structure):
_fields_ = [("initial_readout", ctypes.c_void_p),
("readout_count", ctypes.c_longlong)]
"""
Prototype
Acquire(
CamHandle camera,
int64 readout_count,
int readout_time_out,
AvailableData* available,
AcquisitionErrorsMask* errors );
"""
>>> imageData = AvailableData()
>>> Acquire.argtypes = CamHandle, ctypes.c_longlong, ctypes.c_int,
ctypes.POINTER(AvailableData), ctypes.POINTER(AcquisitionErrorsMask)
>>> Acquire.restype = ctypes.c_void_p
>>> status = Acquire(camera, readout_count, readout_time_out, imageData, errors)
我不完全理解这个函数到底在做什么,因为在我运行这个函数之后,imageData.initial_readout
似乎是一个“long”类型(甚至不是 ctypes.c_long:只是 '长')。然而,它也有与之相关的值(value)。我假设这是数据存储位置的起始地址。
>>> type(imageData.initial_readout)
<type 'long'>
>>> imageData.initial_readout
81002560L
我目前访问数据的方法是使用 libc.fopen、libc.fwrite、libc.fclose,如下所示:
>>> libc = ctypes.cdll.msvcrt
>>> fopen = libc.fopen
>>> fwrite = libc.fwrite
>>> fclose = libc.fclose
>>> fopen.argtypes = ctypes.c_char_p, ctypes.c_char_p
>>> fopen.restype = ctypes.c_void_p
>>> fopen.restype = ctypes.c_void_p
>>> fwrite.argtypes = ctypes.c_void_p, ctypes.c_size_t, ctypes.c_size_t, ctypes.c_void_p
>>> fwrite.restype = ctypes.c_size_t
>>> fclose = libc.fclose
>>> fclose.argtypes = ctypes.c_void_p,
>>> fclose.restype = ctypes.c_int
>>> fp = fopen('output3.raw', 'wb')
>>> print 'fwrite returns: ',fwrite(ctypes.c_void_p(imageData.initial_readout), readoutstride.value, 1, fp)
fwrite returns: 0
>>> fclose(fp)
其中 readoutstride = 2097152
对应于 16 位像素的 1024x1024 数组。
文件“output3.raw”出现在 Windows 资源管理器中,但是,它有 0 kbytes,当我尝试使用(例如使用图像查看器)打开它时,它说文件是空的。
我看到 fwrite
返回值 0(但应该返回值 1)
如果您对我在这里做错了什么有任何想法,我将不胜感激。提前谢谢你。
最佳答案
指定函数的argtypes
、restype
import ctypes
libc = ctypes.windll.msvcrt
fopen = libc.fopen
fopen.argtypes = ctypes.c_char_p, ctypes.c_char_p,
fopen.restype = ctypes.c_void_p
fwrite = libc.fwrite
fwrite.argtypes = ctypes.c_void_p, ctypes.c_size_t, ctypes.c_size_t, ctypes.c_void_p
fwrite.restype = ctypes.c_size_t
fclose = libc.fclose
fclose.argtypes = ctypes.c_void_p,
fclose.restype = ctypes.c_int
fp = fopen('output3.raw', 'wb')
fwrite('Hello', 5, 1, fp)
fclose(fp)
关于python - 使用 python ctypes 和 libc 将 void 指针写入二进制文件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17257137/