ImageGear for C and C++ on Linux v20.0 - Updated
API Reference Guide > Core Component API Reference > Core Component Callback Functions Reference > LPAFT_IG_METAD_ITEM_GET_CB

This callback function is used to get information about metadata items received during a READ filter operation.


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        LPVOID lpPrivate, 
        AT_MODE FormatID, 
        LPCHAR ItemName,  
        DWORD ItemID, 
        AT_MODE ItemType, 
        LPVOID ItemValue, 
        AT_MODE ValueType,
        DWORD ValueLength,
        AT_BOOL ReadOnlyValue 


Name Type Description
lpPrivate LPVOID Private callback data.
FormatID AT_MODE The ID of the format filter that will send or get the item (IG_FORMAT_... constant).
ItemName LPCHAR Name of the item.
ItemID DWORD Numerical ID of the item.
ItemType AT_MODE Specifies the type of the item and reflects the status of the given record. Possible values are:
  • IG_METAD_VALUE_ITEM - this value specifies that the current item is a value of the simplest type, and the field Value contains the actual value of the item, and ValueType contains the identifier of the type of this item. ReadOnly can be either TRUE (read-only) or FALSE (read/write). Name and/or Id contains textual and numerical identification of item.
  • IG_METAD_LEVEL_START - this value specifies that the current item opens a sublevel of items, and all next items up to corresponding item with a IG_METAD_LEVEL_END value belong to this sublevel.
  • IG_METAD_LEVEL_END - this value closes the current sublevel and indicates that the next item belongs to a higher level.
ItemValue LPVOID If ItemType = IG_METAD_VALUE_ITEM then ItemValue contains the actual value of the item of the type specified by the ValueType parameter. Value is stored as array of elements where each element contains values of type ValueType. Length of array is provided in parameter ValueLength.
ValueType AT_MODE Type of element stored in array ItemValue.
ValueLength DWORD Length of array of elements stored in ItemValue.
ReadOnlyValue AT_BOOL If this argument is TRUE, then the actual value of the item cannot be changed by the callback function, and the value is passed for informational purposes only. If FALSE then the value of the item can be changed, and the application can provide a new value through the next three parameters.

Return Value:


Supported Raster Image Formats:

This function does not process image pixels.


See example for IG_fltr_metad_callback_set() function.


The ReadOnlyValue parameter is used to inform the application that the value of a given item is for information only and cannot be changed during future operations.

See also IG_fltr_metad_callback_get(), IG_fltr_metad_callback_set(), LPAFT_IG_METAD_ITEM_ADD_CB, LPAFT_IG_METAD_ITEM_SET_CB functions and the section Manipulating Image Data.

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