Canvas, Window and Alert Definition

CANVAS

This object represents a background entity on which you place interface items, such as check boxes, radio groups, and text items. There are four types of canvas objects: Content, Stacked, Horizontal Toolbar, and Vertical Toolbar.

1.Content Canvas

The most common canvas type is the content canvas (the default type). A content canvas is the "base" view that occupies the entire content pane of the window in which it is displayed. You must define at least one content canvas for each window you create.

2.Stacked Canvas

A stacked canvas is displayed atop—or stacked on—the content canvas assigned to the current window. Stacked canvases obscure some part of the underlying content canvas, and often are shown and hidden programmatically. You can display more than one stacked canvas in a window at the same time.

3.Tab Canvas

A tab canvas—made up of one or more tab pages —allows you to group and display a large amount of related information on a single dynamic Form Builder canvas object. Like stacked canvases, tab canvases are displayed on top of a content canvas, partly obscuring it. Tab pages (that collectively comprise the tab canvas) each display a subset of the information displayed on the entire tab canvas.

4.Toolbar Canvas

A toolbar canvas often is used to create toolbars for individual windows. You can create two types of toolbar canvases: horizontal or vertical. Horizontal toolbar canvases are displayed at the top of a window, just under its menu bar, while vertical toolbars are displayed along the far left edge of a window.

Showing and hiding a canvas programmatically

SHOW_VIEW('a_stack'); or SET_VIEW_PROPERTY('a_stack', visible, property_true);

HIDE_VIEW('a_stack'); or SET_VIEW_PROPERTY('a_stack', visible, property_false);

WINDOW

A window is a container for all visual objects that make up a Form Builder application, including canvases. A single form can include any number of windows. While every new form automatically includes a default window named WINDOW1, you can create additional windows as needed by inserting them under the Windows node in the Object Navigator.

There are two window styles:

Document

Document Windows Document windows typically display the main canvases and work areas of your application where most data entry, and data retrieval is performed.

Dialog

Dialog Windows Dialog windows are free-floating, containers typically used for modal dialogs that require immediate user interaction.

Window Modality

1.Modal Windows

Modal windows are usually used as dialogs, and have restricted functionality compared to modeless windows. On some platforms, for example, end users cannot resize, scroll, or iconify a modal window. Modal windows are often displayed with a platform-specific border unique to modal windows. On some platforms, modal windows are "always-ontop" windows that cannot be layered behind modeless windows.

2. Modeless Windows

You can display multiple modeless windows at the same time, and end users can navigate freely among them (provided your application logic allows it). On most GUI platforms, you can layer modeless windows so that they appear either in front of or behind other windows.

Hide on Exit property

For a modeless window, determines whether Form Builder hides the window automatically when the end user navigates to an item in another window.

MDI and SDI windows

1. Multiple Document Interface

MDI applications display a default parent window, called the application window. All other windows in the application are either document windows or dialog windows. Document windows always are displayed within the MDI application window frame.

2. Single Document Interface

Although MDI is the default system of window management during Forms Runtime, Form Builder also provides support for an SDI root window on Microsoft Windows.REPLACE_CONTENT_VIEW built-in Replaces the content canvas currently displayed in the indicated window with a different content canvas.

REPLACE_CONTENT_VIEW (window_name VARCHAR2, view_name VARCHAR2);

** Built-in: REPLACE_CONTENT_VIEW

** Example: Replace the 'salary' view with the 'history'

** view in the 'employee_status' window. */

BEGIN

Replace_Content_View('employee_status','history');

END;

Trigger - Windows

When-Window-Activated , When-Window-Deactivated , When-Window-Closed , When- Window-Resized

ALERT

An alert is a modal window that displays a message notifying the operator of some application condition.

Use alerts to advise operators of unusual situations or to warn operators who are about to perform an action that might have undesirable or unexpected consequences.

There are three styles of alerts: Stop, Caution, and Note. Each style denotes a different level of message severity. Message severity is represented visually by a unique icon that displays in the alert window.