ImageItemData class (gdiplusimaging.h)

The ImageItemData class is used to store and retrieve custom image metadata. Windows GDI+ supports custom metadata for JPEG, PNG, and GIF image files.

ImageItemData has these types of members:

Remarks

To retrieve custom metadata from an image file, call Image::GetItemData. To store custom metadata in an image file, follow these steps:

1. Create and initialize an ImageItemData object.
2. Create an EncoderParameters object that has an array of one or more EncoderParameter objects.
3. For one of the EncoderParameter objects in the array, set the Value member to the address of your ImageItemData object. Set the other members as follows: Guid = EncoderImageItems, Type = EncoderParameterValueTypePointer, NumberOfValues = 1.
4. Pass the address of the EncoderParameters object to the Image::Save method of an Image object.

Examples

The following example saves a piece of custom metadata in a JPEG file. The code relies on a helper function, GetEncoderClsid, to get the class identifier for the JPEG encoder. To see the source code for GetEncoderClsid, see Retrieving the Class Identifier for an Encoder.

CHAR myData[] = "Byte sequence of your choice";
BYTE description = 0xE4;

ImageItemData itemData;
itemData.Size = sizeof(itemData);
itemData.DescSize = 1;
itemData.Desc = &description;
itemData.DataSize = 28;
itemData.Data = (VOID*)myData;
itemData.Position = ItemDataPositionAfterHeader;

// Get the Clsid of the JPEG encoder.
CLSID encoderClsid;
GetEncoderClsid(L"image/jpeg", &encoderClsid);

EncoderParameters encoderParameters;
encoderParameters.Count = 1;
encoderParameters.Parameter[0].Guid = EncoderImageItems;
encoderParameters.Parameter[0].Type = EncoderParameterValueTypePointer;
encoderParameters.Parameter[0].NumberOfValues = 1; 
encoderParameters.Parameter[0].Value = &itemData;

Image image(L"River.jpg");
image.Save(L"River2.jpg", &encoderClsid, &encoderParameters);

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	gdiplusimaging.h (include Gdiplus.h)