JPEG (.JPG) adding user tags values to a photo file via a program API (C/C++) ?

Question

Hello everyone

I am using Windows 10 (soon Windows 11?).

I am aware that I can add user Tags values (separated by semi-colons) to a JPEG photo file (.JPG file) via editing Properties, click on Add Tag, etc.

However, I have tens of thousands of JPG files to which I want to add various user tags via a program (such as Visual C/C++ API)

What set of Windows API calls can I use to do this?

I also want to be able to read/retrieve and add/remove user Tags from JPG files via C/C++ API.

If anyone can link a Visual C++ code sample dealing with JPG Tags (read and write) it would help me greatly.

I suspect WIC (Windows Imaging Component) may be the "winner" in Windows 10/11 but I dont know specifically which methods/functions to use for this task. https://learn.microsoft.com/en-us/windows/win32/wic/-wic-lh

thank you

Answer 1

Following example shows reading and writing tags to the properties of a .jpg image -

#include <ShlObj.h>  
#include <propvarutil.h>  
#include <propkey.h>  
  
#pragma comment(lib, "propsys")  
  
#include <stdio.h>  
#include <tchar.h>  
  
HRESULT ReadTags(PCWSTR szImage)  
{  
    HRESULT hr;  
    IPropertyStore* pStore{};  
    hr = SHGetPropertyStoreFromParsingName(szImage, nullptr, GPS_DEFAULT, IID_PPV_ARGS(&pStore));  
    if (SUCCEEDED(hr) && pStore)  
    {  
        PROPVARIANT propTags;  
  
        PropVariantInit(&propTags);  
        hr = pStore->GetValue(PKEY_Keywords, &propTags);  
        if (SUCCEEDED(hr))  
        {  
            switch (propTags.vt)  
            {  
            case VT_EMPTY:  
                wprintf_s(L"Image %s has no tags\n", szImage);  
                break;  
  
            case VT_VECTOR | VT_LPWSTR:  
            {  
                PWSTR pwszTags[10]{};  
                ULONG cElem{ 0 };  
                hr = PropVariantToStringVector(propTags, pwszTags, ARRAYSIZE(pwszTags), &cElem);  
                if (SUCCEEDED(hr))  
                {  
                    wprintf_s(L"Image %s contained %d tags\n", szImage, cElem);  
                    for (ULONG i = 0; i < cElem; i++)  
                    {  
                        wprintf_s(L"Tag %d is %s\n", i, pwszTags[i]);  
                        CoTaskMemFree(pwszTags[i]);  
                    }  
                }  
                else  
                    wprintf_s(L"PropVariantToStringVector failed error was 0x%X\n", hr);  
  
                PropVariantClear(&propTags);  
            }  
            break;  
  
            default:  
                wprintf(L"Unexpected type %d in propvariant\n", propTags.vt);  
            }  
  
        }  
        pStore->Release();  
    }  
  
    return hr;  
}  
  
HRESULT WriteTags(PCWSTR szImage)  
{  
    HRESULT hr;  
    IPropertyStore* pStore{};  
    hr = SHGetPropertyStoreFromParsingName(szImage, nullptr, GPS_READWRITE, IID_PPV_ARGS(&pStore));  
    if (SUCCEEDED(hr) && pStore)  
    {  
        PROPVARIANT propTags;  
        PCWSTR aTags[] =  
        {  
            L"First",  
            L"Second",  
            L"Third"  
        };  
  
        PropVariantInit(&propTags);  
  
        hr = InitPropVariantFromStringVector(aTags, ARRAYSIZE(aTags), &propTags);  
        if (SUCCEEDED(hr))  
        {  
            hr = pStore->SetValue(PKEY_Keywords, propTags);  
            if (SUCCEEDED(hr))  
            {  
                hr = pStore->Commit();  
                if (SUCCEEDED(hr))  
                    wprintf_s(L"Property Tags Written to %s\n", szImage);  
                else  
                    wprintf_s(L"IPropertyStore::Commit failed error was 0x%X\n", hr);  
            }  
            else  
                wprintf_s(L"IPropertyStore::SetValue failed error was 0x%X\n", hr);  
        }  
  
        PropVariantClear(&propTags);  
  
        pStore->Release();  
    }  
  
    return hr;  
}  
  
int main()  
{  
    if (SUCCEEDED(CoInitialize(NULL)))  
    {  
        PCWSTR pwszImage = L"C:\\Users\\Rlwa32\\Pictures\\IMG_1874.jpg";  
        ReadTags(pwszImage);  
        WriteTags(pwszImage);  
        ReadTags(pwszImage);  
    }  
  
    CoUninitialize();  
  
    return 0;  
}  
  

Properties before -

Program output -

Properties after -

Answer 2

With IPropertyStore

Answer 3

many thanks!!