Actions are instructions written that automate desktop tasks
such as running applications and opening data files. Actions work
much like application macros or programming functions. Each action
has a name that is used to run the action.
Once you define an action, it can be used to adapt the desktop
user interface so that tasks are easier to do. The desktop provides
the ability to attach user interface components such as icons, Front
Panel controls, and menu items to actions.
For example, the Desktop_Tools application group in Application
Manager contains icons that start various utilities.
Each of these icons runs an action when the icon is double-clicked.
For example, here's a portion of the definition of the action that
runs when the user double-clicks the icon labeled Xwd Display. The
action is defined in the configuration file /usr/dt/appconfig/types/language/xclients.dt:
ACTION Xwud
{
LABEL Xwd Display
TYPE COMMAND
EXEC_STRING /usr/bin/X11/xwud -noclick -in \
%(File)Arg_1"Xwd File To Display:"%
...
} |
The command in the action's EXEC_STRING
is run when the user double-clicks the icon.
The
Front Panel also uses actions. For example, here's a portion of
the definition of the control labeled Terminal in the Personal Applications
subpanel. The control is defined in the configuration file /usr/dt/appconfig/types/language/dtwm.fp:
CONTROL Term
{
ICON Fpterm
LABEL Terminal
PUSH_ACTION Dtterm
...
} |
The PUSH_ACTION field
specifies the action to run when the user clicks the control—in
this case, an action named Dtterm.
Another common use for actions is
in menus. Data files usually have actions in their Selected menu
in File Manager. For example, XWD files (files with names ending
in.xwd or.wd)
have an Open action that displays the screen image by running the
Xwud action.
The actions in the Selected menu are specified in the data
type definition for XWD files. The definition is located in the
configuration file /usr/dt/appconfig/types/language/xclients.dt.
DATA_ATTRIBUTES XWD
{
ACTIONS Open,Print
ICON Dtxwd
...
} |
The XWD data type, and its associated Open and Print actions,
are explained in “How
Data Types Connect Data Files to Actions”.
How Actions Create Icons for
Applications |
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Consider the Xwd Display icon in the Desktop_Tools application
group. Double-clicking this icon runs the X client xwud.
However, this icon does not directly represent the actual xwud
executable /usr/bin/X11/xwud.
The icon labeled Xwd Display appears in the application group
because there is a file in that directory named Xwud
(see Figure 8-4 “Application (action)
icon representing an action file”)
This file represents an underlying action with the same name—Xwud.
In the action definition, the action name is the name following
the ACTION keyword:
ACTION Xwud
{
LABEL Xwd Display
TYPE COMMAND
WINDOW_TYPE NO_STDIO
EXEC_STRING /usr/bin/X11/xwud -noclick -in \
%(File)Arg_1"Xwd File To Display:"%
DESCRIPTION The Xwd Display (Xwud) XwdDisplay action \
displays an xwd file that was created using the \
Xwd Capture (Xwd) action. It uses \
the xwud command.
} |
The
file is called an action file because it represents
an action. A file is an action file when it is an executable file
with the same name as an action. Its icon in Application Manager
(or File Manager) is called an action icon, or
application icon, because double-clicking it
starts an application.
When Application Manager detects an executable file, it looks
through the actions database to see if there are any actions whose
names match the file name. If a match is found, Application Manager
knows that the file is an action file.
The
content of the action file is irrelevant; action files usually contain
comments describing their desktop function.
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|
 | NOTE: The action file is not the same
as the action definition file. The action
file is a file with the same name as the action. It is
used to create the application icon in File
Manager or Application Manager. The action definition
file is the file named name.dt
containing the definition of the action. |
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| |
|
Once the desktop determines that a file is an action file,
the underlying action definition is used to define the appearance
and behavior of the action file.
The EXEC_STRING
field specifies the behavior of the application icon. In the case
of the Xwd Display icon, the EXEC_STRING
specifies that the action icon runs the xwud
X client with certain command-line arguments.
The LABEL field
specifies the label for the application icon.
The DESCRIPTION
field describes the text displayed when the user requests On Item
help.
The Xwud application icon uses the default icon
image for actions because its action definition does contain an
ICON field to specify a different
image.
In contrast, the icon labeled Compress File uses a different
icon image because its underlying action definition contains an
ICON field:
For example:
ACTION Compress
LABEL Compress File
ICON Dtcmprs
...
} |
The Xwud action is called a command
action because its definition contains the command (EXEC_STRING)
to be run. The TYPE field in
the action definition defines the action type.
Initially, the Xwd Display icon appears in the Desktop_Tools
application group. However, you can create additional copies of
the action icon in any directory for which you have write permission.
As long as the Xwud action definition is part of the database, any
executable file you create named Xwud
will be an action file representing that action, and its icon in
File Manager or Application Manager can be used to run the action.
How
Actions Use Data Files as Arguments |
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An argument
of a command is the thing, usually a
file, that the command acts upon. Actions can be written to accept
file arguments.
For example, the EXEC_STRING
of the Xwud action specifies that a file argument is required:
EXEC_STRING /usr/bin/X11/xwud -noclick -in \
%(File)Arg_1"Xwd File To Display:"% |
The term Arg stands for
the word argument.
The syntax
Arg_1 means the first argument,
and (File) means that the
action treats that argument as a file.
The
easiest way for the user to provide a file argument is to drop a
data file on the application icon. The desktop determines the path
of the dropped file and substitutes it into the command line in
place of the text between the %
symbols (%(File)Arg_1"Xwd File To Display:"%).
Thus, the command that gets executed is:
/usr/bin/X11/xwud -noclick -in file_path |
When the user double-clicks the application icon, the desktop
determines from the EXEC_STRING
that a file argument is required, and displays a dialog box prompting
the user to enter a file name or path. In the case of the Xwud action,
the prompt is:
The file name or path supplied by the user is used as the
file argument.
Additional Uses for Actions |
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In addition to starting applications, actions are used throughout
the desktop to create functionality in:
The Front Panel.
The definition for a Front Panel control includes fields that
specify the action that runs when the user clicks the control or
drops a file on it. For more information, see “Defining
Front Panel Controls”.
Menus.
The syntax for the Window and Workspace menu definitions allows
you to specify the action to be run by a menu item. For more information,
see “Workspace
Manager Menus” and the
dtwmrc(4) man page.
Communication between applications.
An application can be designed to send and receive information
using a special type of action called ToolTalk message (TT_MSG).
TT_MSG actions are described
in the developer environment documentation for the desktop.
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