从Python调用cpp函数时出现分段错误

安东尼

我正在尝试从python调用此cpp函数：

TESS_API BOOL TESS_CALL TessBaseAPIProcessPages(TessBaseAPI* handle, const char* filename, 
  const char* retry_config, int timeout_millisec, TessResultRenderer* renderer)
{
    if (handle->ProcessPages(filename, retry_config, timeout_millisec, renderer))
        return TRUE;
    else
        return FALSE;
}

此函数的最后一个参数是TessResultRenderer。还有另一个用于创建的cpp函数TessResultRenderer

TESS_API TessResultRenderer* TESS_CALL TessTextRendererCreate(const char* outputbase)
{
    return new TessTextRenderer(outputbase);
}

现在，当从我的python调用它时，我做了以下工作：

outputbase = "stdout"
renderer = tesseract.TessTextRendererCreate(outputbase)
text_out = tesseract.TessBaseAPIProcessPages(api, 
     ctypes.create_string_buffer(path), 
     None, 0, renderer) //Segmentation fault (core dumped) error on this line

但我总是Segmentation fault出错。

我的问题是如何TessBaseAPIProcessPages从Python调用？

更多参考链接到代码库：

推荐人API

实现processPages（...）

编辑

尝试评论的建议后，我做了以下操作，但出现错误： item 1 in _argtypes_ has no from_param method

PTessResultRenderer = ctypes.POINTER(TessResultRenderer)
self.tesseract.TessTextRendererCreate.restype = PTessResultRenderer
outputbase = "stdout"
self.tesseract.TessTextRendererCreate.argtypes = [outputbase] #error here
self.tesseract.TessTextRendererCreate

ReturnVal = ctypes.c_bool
self.tesseract.TessBaseAPIProcessPages.argtypes = [self.api, path, None, 0, PTessResultRenderer]
self.tesseract.TessBaseAPIProcessPages.restype = ReturnVal
self.tesseracto.TessBaseAPIProcessPages

class TessResultRenderer(ctypes.Structure):
    pass

食囊龙

有一个使用contrib文件夹中ctypes的tesseract C-API的示例。但是，似乎有些过时了。contrib / tesseract-c_api-demo.py

您需要设置restype和argtypes一些方法。另外，不要忘记在处理程序上调用init函数。以下示例对我有用。它从英语中名为“ test.bmp”的文件中读取文本到text变量中。

from ctypes import *
from ctypes.util import find_library

lang = b"eng"
filename = b"test.bmp"
TESSDATA_PREFIX = b"/usr/local/Cellar/tesseract/3.04.01_1/share/tessdata"

path = find_library("libtesseract.dylib")
tesseract = CDLL(path)

class TessBaseAPI(Structure):
    pass
class TessResultRenderer(Structure):
    pass

tesseract.TessBaseAPICreate.restype = POINTER(TessBaseAPI)
tesseract.TessBaseAPIInit3.argtypes = [POINTER(TessBaseAPI), c_char_p, c_char_p]
tesseract.TessBaseAPIInit3.restype = c_bool
tesseract.TessBaseAPIProcessPages.argtypes = [POINTER(TessBaseAPI), c_char_p, c_char_p, c_int, POINTER(TessResultRenderer)]
tesseract.TessBaseAPIProcessPages.restype = c_bool
tesseract.TessBaseAPIGetUTF8Text.argtypes = [POINTER(TessBaseAPI)]
tesseract.TessBaseAPIGetUTF8Text.restype = c_char_p

api = tesseract.TessBaseAPICreate()
rc = tesseract.TessBaseAPIInit3(api, TESSDATA_PREFIX, lang);
if (rc):
    tesseract.TessBaseAPIDelete(api)
    print("Could not initialize tesseract.\n")
    exit(3)

success = tesseract.TessBaseAPIProcessPages(api, filename, None , 0, None)

if success:
    text = tesseract.TessBaseAPIGetUTF8Text(api)
    print("="*78)
    print(text.decode("utf-8").strip())
    print("="*78)

输出如下：

==============================================================================
This is a lot of 12 point text to test the
ocr code and see if it works on all types
of file format.

The quick brown dog jumped over the
lazy fox. The quick brown dog jumped
over the lazy fox. The quick brown dog
jumped over the lazy fox. The quick
brown dog jumped over the lazy fox.
==============================================================================

编辑：c_void_peryksun建议使用不透明类型替换。谢谢！

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