How to Add 'Comments' to a JPEG File Using MFC - mfc

Question

Within the property window of a JPEG image, there is a tab called 'Summary'. Within this tab, there is a field called 'Comments' I would like to write some MFC code which will add a given string to this field e.g "This is a photo".
Does some kind soul out there know how to do this?
Many thanks.

Answer 1

MFC doesn't provide this functionality, however you can use GDI+ for the task. The Image class is capable of reading and writing Exif metadata.
This is almost trivial, and explained under Reading and Writing Metadata. However, since the UserComment metadata tag allows for different character encodings, things get a little more involved. The following code1) implements a command line utility that allows to set (or replace if present) the UserComment field:
#include <windows.h>
#include <gdiplus.h>
using namespace Gdiplus;
#pragma comment(lib, "Gdiplus.lib")
int wmain( int argc, const wchar_t* argv[] ) {
// Input format: AddExifComment "<input filename>" "<comment>" "<output filename>"
if (argc != 4)
return -1;
// Initialize GDI+
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken{ 0 };
GdiplusStartup( &gdiplusToken, &gdiplusStartupInput, nullptr );
// Load image
Image* img = new Image(argv[1]);
// Construct Unicode comment
const auto& comment = MakeUnicodeComment(argv[2]);
// Assign the UserComment property
PropertyItem propertyItem;
propertyItem.id = PropertyTagExifUserComment;
propertyItem.length = comment.size();
propertyItem.type = PropertyTagTypeUndefined;
propertyItem.value = (void*)comment.data();
img->SetPropertyItem(&propertyItem);
// Save image
CLSID clsid;
GetEncoderClsid(L"image/jpeg", &clsid);
img->Save(argv[3], &clsid);
// Cleanup
delete img;
GdiplusShutdown(gdiplusToken);
return 0;
}
Constructing an appropriately formatted comment takes a bit of work. This is implemented in the following function:
#include <vector>
using std::vector;
#include <iterator>
using std::back_inserter;
vector<BYTE> MakeUnicodeComment(const wchar_t* text){
// Exif 2.2 header for Unicode (UCS-2): 'U', 'N', 'I', 'C', 'O', 'D', 'E', '\0'
static const char header[]{"UNICODE"};
static const size_t headerSize{ sizeof(header) / sizeof(header[0]) };
// UserComment field contains the 8-byte header followed by UTF-16LE encoded code units
vector<BYTE> buffer;
std::copy(header, header + headerSize, back_inserter(buffer));
// Append comment text (NUL terminator is not required)
auto current = text;
while (*current) {
buffer.push_back(*current & 0xFF);
buffer.push_back((*current >> 8) & 0xFF);
++current;
}
return buffer;
}
Retrieving the JPEG encoder from its MIME type is copied from Retrieving the Class Identifier for an Encoder for reference:
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid) {
UINT num = 0; // number of image encoders
UINT size = 0; // size of the image encoder array in bytes
ImageCodecInfo* pImageCodecInfo = NULL;
GetImageEncodersSize(&num, &size);
if (size == 0)
return -1; // Failure
pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
if (pImageCodecInfo == NULL)
return -1; // Failure
GetImageEncoders(num, size, pImageCodecInfo);
for (UINT j = 0; j < num; ++j) {
if (wcscmp(pImageCodecInfo[j].MimeType, format) == 0) {
*pClsid = pImageCodecInfo[j].Clsid;
free(pImageCodecInfo);
return j; // Success
}
}
free(pImageCodecInfo);
return -1; // Failure
}
1) Error handling elided for brevity.

Answer 2

OK,Finally I manage to solove the problem!There is the code:
OK,Finally I manage to solove the problem!There is the code:
#include "stdafx.h"
#include <windows.h>
#include <gdiplus.h>
#include <stdio.h>
using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
UINT num= 0;
UINT size= 0;
ImageCodecInfo* pImageCodecInfo= NULL;
GetImageEncodersSize(&num, &size);
if(size== 0)
{
return -1;
}
pImageCodecInfo= (ImageCodecInfo*)(malloc(size));
if(pImageCodecInfo== NULL)
{
return -1;
}
GetImageEncoders(num, size, pImageCodecInfo);
for(UINT j=0; j< num; ++j)
{
if(wcscmp(pImageCodecInfo[j].MimeType, format)== 0)
{
*pClsid= pImageCodecInfo[j].Clsid;
free(pImageCodecInfo);
return j;
}
}
free(pImageCodecInfo);
return -1;
}
// load bitmap from memory,sync way
Bitmap* LoadBitmapFromMemory(const void* memory, DWORD size)
{
Bitmap* bmp = NULL;
IStream* stream = NULL;
if (CreateStreamOnHGlobal(NULL, TRUE, &stream) == S_OK)
{
ULARGE_INTEGER uli;
uli.QuadPart = size;
stream->SetSize(uli);
if (stream->Write(memory, size, NULL) == S_OK)
bmp = new Bitmap(stream);
stream->Release();
}
return bmp;
}
// load bitmap from file,sync way
Bitmap* LoadBitmapFromFile(const TCHAR* file_name)
{
Bitmap* bmp = NULL;
HANDLE file_handle = CreateFile(file_name, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if (file_handle != INVALID_HANDLE_VALUE)
{
DWORD temp = 0;
DWORD file_size = GetFileSize(file_handle, &temp);
if (file_size && !temp) // the file must be less than 4G
{
unsigned char* buffer = new unsigned char[file_size];
if (ReadFile(file_handle, buffer, file_size, &temp, NULL))
bmp = LoadBitmapFromMemory(buffer, temp);
delete [] buffer;
}
CloseHandle(file_handle);
}
return bmp;
}
int _tmain(int argc, _TCHAR* argv[])
{
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
Status stat;
CLSID clsid;
char propertyValue[] = "Fake Photograph";
Bitmap* bitmap = LoadBitmapFromFile(L"E:/sandbox/stone.jpg");
PropertyItem* propertyItem = new PropertyItem;
// Get the CLSID of the JPEG encoder.
GetEncoderClsid(L"image/jpeg", &clsid);
propertyItem->id = PropertyTagCopyright;
propertyItem->length = 16; // string length including NULL terminator
propertyItem->type = PropertyTagTypeASCII;
propertyItem->value = propertyValue;
bitmap->SetPropertyItem(propertyItem);
stat = bitmap->Save(L"E:/sandbox/stone.jpg", &clsid, NULL);
if(stat == Ok)
printf("FakePhoto2.jpg saved successfully.\n");
delete propertyItem;
delete bitmap;
GdiplusShutdown(gdiplusToken);
return 0;
return 0;
}