Implement wxInputStream.

Can now be used to load images from a io.BytesIO.

Author: amauryfa

etg/cffi/stream.py

@@ -1,3 +1,59 @@
+import etgtools
+import etgtools.tweaker_tools as tools
+
+from etgtools.extractors import ClassDef, CppMethodDef_cffi, ParamDef
+
 def run(module):
-    # TODO: replicate functions added in etg/sip/stream.py
-    pass
+    # Include a C++ class that can wrap a Python file-like object so it can
+    # be used as a wxInputStream
+    c = ClassDef(name='wxPyInputStream')
+    c.includeCppCode('src/cffi/stream_input.cpp')
+    module.addItem(c)
+    c.addItem(CppMethodDef_cffi(
+        c.name, isCtor=True,
+        pyArgs=etgtools.ArgsString('(WL_Self self, WL_Object file)'),
+        pyBody="""\
+        with wrapper_lib.get_refcounted_handle(file) as handle:
+            self._cpp_obj = call(handle)
+        """,
+        cReturnType='void*',
+        cArgsString='(void *handle)',
+        cBody="return new WL_CLASS_NAME(handle);",
+        originalCppArgs=etgtools.ArgsString('(void *handle)'),
+    ))
+
+    # Add the following code to the class body to initialize the callback
+    module.addCdef_cffi("""\
+    size_t (*PyInputStream_OnSysRead)(void*, void*, size_t);
+    int (*PyInputStream_IsSeekable)(void*);
+    size_t (*PyInputStream_TellI)(void*);
+    size_t (*PyInputStream_SeekI)(void*, size_t, int);
+    """)
+    c.pyCode_cffi = """\
+    @ffi.callback('size_t(*)(void*, void*, size_t)')
+    def _PyInputStream_OnSysRead(handle, buffer, bufsize):
+        file = ffi.from_handle(handle)
+        data = file.read(bufsize)
+        ffi.cast('char*', buffer)[0:len(data)] = data
+        return len(data)
+    clib.PyInputStream_OnSysRead = _PyInputStream_OnSysRead
+ 
+    @ffi.callback('int(*)(void*)')
+    def _PyInputStream_IsSeekable(handle):
+        file = ffi.from_handle(handle)
+        return hasattr(file, 'seek')
+    clib.PyInputStream_IsSeekable = _PyInputStream_IsSeekable
+
+    @ffi.callback('size_t(*)(void*)')
+    def _PyInputStream_TellI(handle):
+        file = ffi.from_handle(handle)
+        return file.tell()
+    clib.PyInputStream_TellI = _PyInputStream_TellI
+
+    @ffi.callback('size_t(*)(void*, size_t, int)')
+    def _PyInputStream_SeekI(handle, pos, whence):
+        file = ffi.from_handle(handle)
+        return file.seek(pos, whence)
+    clib.PyInputStream_SeekI = _PyInputStream_SeekI
+    """
+

etg/stream.py

@@ -85,6 +85,12 @@ def run():
         *sipCppPtr = new wxPyInputStream(sipPy);
         return sipGetState(sipTransferObj);
         """
+    c.convertFromPyObject_cffi = """\
+    return PyInputStream(py_obj)
+    """
+    c.instanceCheck_cffi = """\
+    return hasattr(py_obj, 'read')
+    """
 
 
 

src/cffi/stream_input.cpp

@@ -0,0 +1,55 @@
+extern "C" size_t (*PyInputStream_OnSysRead)(void*, void*, size_t);
+extern "C" int (*PyInputStream_IsSeekable)(void*);
+extern "C" size_t (*PyInputStream_TellI)(void*);
+extern "C" size_t (*PyInputStream_SeekI)(void*, size_t, int);
+
+// This class can wrap a Python file-like object and allow it to be used 
+// as a wxInputStream.
+class wxPyInputStream : public wxInputStream
+{
+private:
+    void* m_file_handle;
+
+public:
+
+    wxPyInputStream(void* file_handle)
+	: m_file_handle(file_handle)
+    { 
+	WL_ADJUST_REFCOUNT(m_file_handle, 1);
+    }
+    
+    virtual ~wxPyInputStream()
+    {
+	WL_ADJUST_REFCOUNT(m_file_handle, -1);
+    }
+
+    wxPyInputStream(const wxPyInputStream& other) 
+	: m_file_handle(other.m_file_handle)
+    {
+	WL_ADJUST_REFCOUNT(m_file_handle, 1);
+    }
+    
+protected:
+
+    // implement base class virtuals
+    virtual size_t OnSysRead(void *buffer, size_t size)
+    {
+	return (*PyInputStream_OnSysRead)(m_file_handle, buffer, size);
+    }
+
+    bool IsSeekable() const 
+    {
+	return (*PyInputStream_IsSeekable)(m_file_handle);
+    }
+
+    wxFileOffset TellI() const 
+    {
+	return (*PyInputStream_TellI)(m_file_handle);
+    }
+
+    wxFileOffset SeekI(wxFileOffset pos, wxSeekMode mode = wxFromStart)
+    {
+	return (*PyInputStream_SeekI)(m_file_handle, pos, mode);
+    }
+
+};