Menggunakan late binding di CPP

Prasyarat

Silakan daftarkan Aspose.PDF untuk .NET dengan COM Interop, silakan periksa artikel yang berjudul Gunakan Aspose.pdf untuk .NET via COM Interop.

Contoh

Ini adalah contoh kode C++ sederhana untuk mengekstrak teks dari PDF dengan menggunakan COM Interop melalui late binding. Untuk detail silakan lihat postingan ini.

#include "stdafx.h"
#include "comdef.h"

using namespace System;

String ^lateBinding(String ^file)
{
    String^ text;
    DISPID dispid;
    DISPPARAMS dp = { NULL, NULL, 0, 0};
    VARIANTARG vargs[1];
    VARIANT arg, result;
    WCHAR str[255];
    CLSID pclsid;

    // create ComHelper
    IDispatch* comHelperPtr;

    wcscpy_s(str, L"Aspose.PDF.ComHelper");
    CLSIDFromProgID(str, &pclsid);

    HRESULT hr = CoCreateInstance(pclsid, NULL, CLSCTX_ALL, IID_IDispatch, (void **)&comHelperPtr);
    if (FAILED(hr))
    {
        Console::WriteLine(L"Error occured");
    }
    else
    {
        // set license
        IDispatch* licPtr;
        wcscpy_s(str, L"Aspose.PDF.License");
        CLSIDFromProgID(str, &pclsid);

        HRESULT hr = CoCreateInstance(pclsid, NULL, CLSCTX_ALL, IID_IDispatch, (void **)&licPtr);

        OLECHAR* setLicense =  L"SetLicense";

        hr = licPtr->GetIDsOfNames(IID_NULL, &setLicense, 1, GetUserDefaultLCID(), &dispid);
        arg.vt = VT_BSTR;

        BSTR lic = SysAllocString(L"C:\\Temp\\Aspose.PDF.lic");

        arg.bstrVal = lic;

        vargs[0] = arg;

        dp.rgvarg = vargs;

        dp.cArgs = 1;

        hr = licPtr->Invoke(dispid, IID_NULL, GetUserDefaultLCID(), DISPATCH_METHOD, &dp, &result, NULL, NULL);

        SysFreeString(lic);

        licPtr.Release();

        // get Document

        OLECHAR* openFile =  L"OpenFile";

        hr = comHelperPtr->GetIDsOfNames(IID_NULL, &openFile, 1, GetUserDefaultLCID(), &dispid);

        arg.vt = VT_BSTR;

        arg.bstrVal = (BSTR)System::Runtime::InteropServices::Marshal::StringToBSTR(file).ToPointer();

        vargs[0] = arg;

        dp.rgvarg = vargs;

        dp.cArgs = 1;

        hr = comHelperPtr->Invoke(dispid, IID_NULL, GetUserDefaultLCID(), DISPATCH_METHOD, &dp, &result, NULL, NULL);

        IDispatch* docPtr = result.pdispVal;

        comHelperPtr.Release();

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

        // get Pages for the Document

        OLECHAR* pages =  L"Pages";

        hr = docPtr->GetIDsOfNames(IID_NULL, &pages, 1, GetUserDefaultLCID(), &dispid);

        dp.cArgs = 0;

        hr = docPtr->Invoke(dispid, IID_NULL, GetUserDefaultLCID(), DISPATCH_PROPERTYGET, &dp, &result, NULL, NULL);

        IDispatch* pagesPtr = result.pdispVal;

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

        // create Absorber

        IDispatch* absorberPtr;

        wcscpy_s(str, L"Aspose.PDF.Text.TextAbsorber");

        CLSIDFromProgID(str, &pclsid);

        hr = CoCreateInstance(pclsid, NULL, CLSCTX_ALL, IID_IDispatch, (void **)&absorberPtr);

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

        // browse text

        arg.vt = VT_DISPATCH;

        arg.pdispVal = absorberPtr;

        vargs[0] = arg;

        dp.rgvarg = vargs;

        dp.cArgs = 1;

        OLECHAR* accept_4 = L"Accept_4";

        hr = pagesPtr->GetIDsOfNames(IID_NULL, &accept_4, 1, GetUserDefaultLCID(), &dispid);

        hr = pagesPtr->Invoke(dispid, IID_NULL, GetUserDefaultLCID(), DISPATCH_METHOD, &dp, &result, NULL, NULL);

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

        // retrieve text

        OLECHAR* _text = L"Text";

        dp.cArgs = 0;

        hr = absorberPtr->GetIDsOfNames(IID_NULL, &_text, 1, GetUserDefaultLCID(), &dispid);

        hr = absorberPtr->Invoke(dispid, IID_NULL, GetUserDefaultLCID(), DISPATCH_PROPERTYGET, &dp, &result, 0, 0);

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

        text = gcnew String(result.bstrVal);

        docPtr.Release();

        pagesPtr.Release();

        absorberPtr.Release();

    }

    return text;

}

int main(array<System::String ^> ^args)
{
    if (args->Length != 1)
    {
        Console::WriteLine("Missing parameters\nUsage:testCOM <pdf file>");
        return 0;
    }

    CoInitialize(NULL);
    String ^text = lateBinding(args[0]);
    CoUninitialize();
    Console::WriteLine("Extracted text:");
    Console::WriteLine("---\n{0}", text != nullptr ? text->Trim() : "<empty>");
    Console::WriteLine("---");
    return 0;

}