Callbacks are low-level functions that provide control over the way that ART works. Each callback function must be "registered" in order to be automatically called by ART. ART_callback_register() registers ART callbacks.

Functions labeled as "Callback", when registered, are called by ART during certain events:

• When the user is about to create a new mark
• When they are going to delete a mark
• When the mouse is clicked over a mark

ART returns important data to you, and you can send data back to ART. This exchange of information determines whether or not to proceed with an operation. See the ART Component Callback Functions Reference section for specific information about the ART Component Callback Functions.

Currently there are two functions in this category: ART_control_option_set() and ART_control_option_get(). The former function modifies default library settings. The latter function gets a value of the control option.

Clipboard function names begin with ART_edit_ and allow you to copy and cut marks to the clipboard, and to paste marks into an image.

Undo function names begin with ART_edit_undo_. These functions record edits to marks, and undo a specified number of edits.

The ART component has two types of blocks:

• Global Named Blocks
• Named Blocks

Global Named Blocks hold values that act as defaults for the next mark created. Named Blocks can be used to set specific attributes for the current mark.

Global Named Blocks work with "Global Named Block Management" functions; these function names begin with ART_global_block_. Named Blocks work with "Named Block Management" functions; these function names begin with ART_mark_block_.

See the section ART Component Important Structures and Types.

These functions begin with ART_group_. They perform operations on groups of marks. You can form any number of groups and assign them names. You may choose to group all shapes together, and then send them "to the back" using the ART_group_send_to_back() function.

There is one function in this group, ART_image_burn_in(). This function causes marks to be "burned in" to an image when it is saved. There are many options for this function, including the ability to burn in only a specified list of the available marks.

The Internet group of functions can be used to load/transfer ART annotation files from/to FTP/GOPHER/HTTP(S).

These functions begin with ART_mark_. They modify and query marks. The ART_mark_modify() updates the values in the mark attributes structure. This structure is defined in ARTAPI.H and is illustrated in the section ART Component Important Structures and Types .

The ART_mark_query() function returns the values in the attributes structure.

The ART component has two types of blocks:

• Global Named Blocks
• Named Blocks

Global Named Blocks hold values that act as defaults for the next mark created. Named Blocks can be used to set specific attributes for the current mark.

Global Named Blocks work with "Global Named Block Management" functions; these function names begin with ART_global_block_. Named Blocks work with "Named Block Management" functions; these function names begin with ART_mark_block_.

See the section ART Component Important Structures and Types.

This group of functions provides the ability to work with marks in memory.