Datasheet

Chapter 1 Customization and MEL Scripting

determined by a closing curly bracket }. In the case of newcam.mel, the closing curly bracket is

on the last line of the script.

A procedure is not activated until it is called. Executing the procedure name in the

Script Editor work area is one way to call a procedure. This assumes that the procedure

is global, which is determined by the inclusion of the word

global. Once a procedure is

global, you can call it from any part of a script that is not part of the procedure. That is,

you can call global procedures from non-procedure parts of the script, from other pro-

cedures, or as a command listed by a button or menu item. If variables (symbolic names

that hold values) are set up correctly within the script, the

global option is not necessary

and procedures become local. For a deeper discussion of global and local variables and

when to use them, see Chapter 3.

Another feature of the

newcam.mel script is the use of three collapsible frames (indicated

by the down-pointing arrows on the left side of the window). To create a collapsible frame,

code similar to the following is needed:

frameLayout -collapsable true -label “frame name”

-width 250;

rowLayout -numberOfColumns 3 -columnWidth3 100 100 100;

[text, buttons, or fields go here]

setParent ..;

The two setParent commands are necessary for the frame to function. You can place as

many frames as you like in a window so long as each

frameLayout command has two match-

ing

setParent commands. In addition, each frame must have its own layout command; in

this example,

rowLayout is used. The -numberOfColumns flag indicates the number of columns

within the frame. The

-columnWidth3 flag indicates the pixel width of each column; a pixel

width of 100 is set by including

100 100 100 after the flag. Although these are optional flags,

they make the results much cleaner.

Retrieving Values from Fields

One of the trickier aspects of MEL scripting is the creation of numeric fields in which users

can enter new values.

newcam.mel creates two of these: one in the Lens frame and one in the

Clip frame. The following line creates the Lens field and establishes the size of the camera lens:

string $holdera =`intField -width 45 -value 25

-minValue 25 -maxValue 250

-changeCommand “int $cam_lens = `intField -query

-value enteredValuea`” enteredValuea`;

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