Lastic Limited ::: Lastic Screen Handler ::: Key Features

	Lastic Screen Handler Overview Key Features ::: Benefits Interface Design Licensing / Prices

	You are here: Home > Products > Lastic Screen Handler > Key Features Key Features Interface Design Lastic Terminal Builder is the visual interface design facility for Lastic Screen Handler, providing complete form construction within a character terminal environment. A rich array of standard and specialised Windows-based controls are supported, allowing for the development of rich application interfaces. Click here for further details Context-Sensitive Help Lastic Terminal Builder also contains help file authoring facilities, enabling your applications to be supported by context-sensitive online help information at both the form and individual control level. All help information is held centrally within the Caché / M database. Form Layering A form is defined as an area of the screen and contains one or more controls for display and/or amendment. The form and it's contents are held as parameters within the Caché / M database. When a form is invoked these parameters are loaded by the Screen Handler which draws the form and it’s controls and then actions those controls’ parameters in the nominated sequence. The application program invokes a form by issuing a call (DO) to the Screen Handler, passing parameters of the system and form required. Additional run-time options are available via a switch parameter, and further controls can be defined for such as item skipping, visibility, start control, etc. Once invoked the form will be processed until terminated either by the user or by the application. It is common practice to call new forms from within application events. The system retains knowledge of the previous forms, though control values are displayed and edited directly from the nominated application variables. By use of the 'new' instruction, encapsulated applications can be developed such that applications can be invoked at any point from within one another, yet permitting full re-instatement of the original application (and screen) upon completion. Invoking further forms from within events is usually used for sub-actions of the same application - for example an order entry (header, items and footer). A second method for calling other application routines does not require application program intervention and permits re-configuration of application access. This method uses drop-down menus. A form is terminated when the application ceases to process the form as a result of either the user 'exiting' the form or by the application instruction upon return from an event. At this point the form is still visible and the parameters are retained. This enables the application to quickly re-enter that form should it be required. The form is removed if the application returns to the event within the lower level form or calls a different form. Menus This feature enables a list of routines to be attached to any form as a menubar such that they may be selected and actioned from within that form. Upon completion, the original form is automatically re-instated and processing of that application continues where it left off. These menu selections may be cascaded so that an application called by such a method may itself provide a menu from which further applications may be invoked. Again re-instatement of each application is achieved automatically back through the levels of the original path. A system-wide 'Utilities' menu may also appear on the menubar enabling commonly used applications to be invoked from within any form without needing to set that application onto each form’s menubar. This enables applications such as E-Mail, Desk Diary, etc., to be accessed at any time. Application Events Lastic Screen Handler provides event handling at both the form and control level. Form level events include pre-form (form-activate), pre-exit (queryunload) and application (a Lastic special). The pre-form event is invoked once the form is initially painted but before any control receives focus. The pre-exit event is invoked when the form is about to be terminated. It is possible, from within this event, to override the form 'exit' and to return to that form. The application event enables control and value sensitive processing to be performed while any control has focus on that form. Control level events include gotFocus, click, doubleClick, change and lostFocus. They may have validation and library function calls to reduce the level of application level coding required and can automatically repaint nominated controls upon return from that event. Control Functionality Lastic Screen Handler enables the behaviour and functionality of each control within a form to be precisely defined, including: look-up lists data validation display / re-display field editing