Defining action views in forms

How to define action views that will fire action events.

Actions views are form items that can be activated to fire an action event. The action event triggers user code in an ON ACTION block.

We distinguish action views defined explicitly in form files from default action views. A default action view will automatically appear when an action handler is implemented in the current dialog (if no explicit action view with the same name exists in the form). Default action view creation can be controlled with the DEFAULTVIEW action attribute.

To fire user code, action views are bound to action handlers by name.

Action view decoration attributes (IMAGE for icons, TEXT for label, COMMENT for hint) can be centralized in action defaults.

Action views can be items of form elements dedicated to action execution, such as TOOLBAR items (toolbar buttons) or TOPMENU options:

TOOLBAR
   ITEM accept
   ITEM cancel
   ...
END

Action views can be typical BUTTON items defined in the form LAYOUT:

LAYOUT
GRID
{
   [b1     ]
   ...
}
...
ATTRIBUTES
BUTTON b1 : print, IMAGE="printer";
...

Action views can be sub-elements of other elements, as when defining a BUTTONEDIT with an ACTION attribute:

LAYOUT
GRID
{
   [f1              ]
   ...
}
...
ATTRIBUTES
BUTTONEDIT f1 = customer.cust_city, ACTION=choose_city, IMAGE="zoom";
...

Action views can also be simple IMAGE items, when the ACTION attribute is specified:

LAYOUT
GRID
{
   [i1              ]
   ...
}
...
ATTRIBUTES
IMAGE i1: image1, ACTION=show_details, IMAGE="mylogo";
...

Note that IMAGE fields can be defined as TABLE columns and define the ACTION attribute to trigger user code:

LAYOUT
GRID
{
<TABLE t1          >
[c1  |c2       |c3 ]
[c1  |c2       |c3 ]
[c1  |c2       |c3 ]
...
}
...
ATTRIBUTES
...
IMAGE c3: FORMONLY.image, ACTION=delete;
...

For more details about image column actions see Image columns firing actions.

The row selection in a TABLE (or TREE) will be considered an action view when defining the DOUBLECLICK attribute:

DISPLAY ARRAY arr TO sr.*
        ATTRIBUTES(UNBUFFERED, DOUBLECLICK=select)
  ...
END DISPLAY

Action views can also be graphical elements that are standard action triggers on the front-end platform, such as the [x] cross button of desktop windows, that will automatically bind to a "close" action, or the FAB button of Android, which can be configured to trigger a specific action.