JFace Data Binding/Scenarios
These scenarios are designed to provide the core functional requirements for the binding framework and prove the binding API by covering a set of patterns that commonly occur in a data bound GUI. In their simplest form they will be written using SWT controls including the support for structured JFace controls (e.g., ComboViewer, ListViewer, TreeViewer, ListViewer and Progress Viewer).
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Initially each scenario will be built with as little surrounding framework as possible, so they could be classes that open a Shell in their main or they could be RCP views. Validation exceptions that occur will be fed back via console messages. In the later examples Eclipse frameworks will be used such as building a preference page, where the validation provided by JFace will be used to provide a richer user interface experience.
Property Binding (Boris)
Binding simple values, in essence is the ability to bind a property of one object to another. This is typically done to bind a text control to a portion of a domain model. The expectation is to have a simple, one line, intuitive API:
- Binding the name property of an Adventure object to the contents of Text controls, no conversion, no validation.
- Binding the name property of an Adventure object to the contents of Text controls, no conversion, no validation. The Text widget editable is set to false.by the developer (can not change the name)
- Binding of a read-only property of an Adventure object to the contents of Text controls, no conversion, no validation. Text control is not editable as a side effect of binding to a read-only property..
- Binding a nested property of an Adventure object to the content of a Text control, no conversion, no validation.
- Binding the name property of an Adventure object to the contents of Text controls where conversion occurs – the model data is held all in uppercase and displayed in lowercase with the first letter capitalized.
- Binding the name property of an Adventure object to the contents of Text controls where validation occurs and the name cannot be longer than 15 characters and cannot contain spaces
- Binding the price property of an Adventure to a Text control. Price is a double and Text accepts String so conversion will have to occur. Validation ensure that the value is positive.
- Binding the price property of an Adventure to a Text control but with custom conversion – the double will be validated to only have two decimal places and displayed with a leading currency symbol, and can be entered with or without the currency symbol.
- Binding a boolean property to a CheckBox. Adventure will have a Boolean property “petsAllowed”
- Binding a Transportation departure time to a Text control that formats and validates the time to and from a String. There are property bindings that bind elements of the GUI to elements to GUI and also elements of the domain to elements of the domain.
- Binding the max value of a spinner to another spinner.
- Binding the enabled state of several Text controls to a check box. There will be two check boxes, so as each is enabled/disabled the other one follows as do the states of the Text controls.
- Changing the update policy to be not automatic, but on explicit method call (e.g. triggered by a button click)
- Bind an Adventure's name to two Text fields. Update the first Text field's name, and ensure that both the Adventure's name, and the second textfieds are updated currently only once.
- Binding the name property of an Adventure object to the contents of Text controls where the update of the Adventure model object occurs on key stroke, occurs on focus being lost, and occurs with an explicit “Apply” button.
- Binding a boolean property to a Radio Button set of Yes/No
- Binding an int property that accepts different static values to a radio button set that displays the values. Adventure will have an int property called “transport” with int values of 0=”Bus”, 2=”Self Drive”, 3=”Taxi”. This could also be done with a 1.5 version using an Enum.
- Binding the enabled state of a Text control to a radio button set that represents the states “enabled” and “disabled”. There will be a check box as well that shadows the enabled state and also drives it that affects the radio button set as well as the radio button set affecting the check box.
Custom Binding (Joe)
- Binding the price property of an Adventure to two spinner controls – one that shows the dollar portion and one that shows the cents.
- Binding a derived aggregate property of an Adventure that does not exist to a text field. For example, the name and description combined together with a comma separating them. Also combined together on a multi line text field with a line feed separating them. The text would render the combined property, as well as accept input and change the Adventure, and also the derived property would refresh itself if either of the properties that make it up (name and description) change.
- Binding a Transportation departure time to two Text controls, one that shows the hours and one for the minutes, both of which validate the entry.
- Binding a Transportation departure time to two Spinner controls, one that shows the hours and one for the minutes. When the minutes spinner changes from 59 to 00, the hours spinner should be incremented; when it changes from 00 to 59, the hours spinner should be decremented.
- Binding a custom control (one that is not part of SWT already) for editing time to a Transportation departure time.
Binding to a read-only Combo or List (Gili)
- Binding the current selection of a read-only combo to the country property (of type String) of an Account object. The list of possible values does not come from a model object, it is given as a list or array of String objects.
- Binding the current selection of a read-only combo viewer to the country property (of type String) of an Account object. The list of possible values does not change dynamically, it is given as a list of Country objects. The Country object's name property is used for displaying in the combo viewer, and it is used as the value that is set on the Account object.
- Do the same for CCombo, and List
- Binding the current selection of a read-only combo viewer to a given adventure's default lodging. The combo items display the Lodging's name property. To set the default lodging to null, there is an empty entry in the list of combo items. The list of available lodgings can change over time, as can the name of any lodging. Both kinds of updates should update the combo viewer, updating the name of a selected lodging should preserve the selection.
- For a given adventure editing its default activities by selecting from a list viewer (with SWT.MULTI) showing available activities displaying the Activities's name property. The list of available activities can change over time, as can the name of any activity. Both kinds of updates should update the list viewer, updating the name of a selected lodging should preserve the selection.
- Like the previous scenario, but use a Table with CHECK style
- Handle null entries in lists by displaying an empty item
A common scenario is that a control like a combo, List, Tree or
Table displays some data that represents a collection of objects.
Selection of a single object then makes that object the focus of the
GUI so that it can be edited. Bindings these kinds of controls implies
the need to bind the control’s content (list) and optionally binding
the control’s selection/s. As with the Property bindings, the goal is
to keep the API simple and intuitive.
These scenarios cover basic selection of an item in a list and editing it with different ways the list’s values are provided. The assumption here is a single selection.
- Displaying the catalog's list of Adventure objects in a list viewer, using their names. The name of the currently selected Adventure can be edited in a text widget. There is always a selected Adventure object.
- Selecting from the list of lodgings for an adventure and editing the properties of the selected lodging in text widgets. If no lodging is selected the input controls for name and adventure are disabled. There are two buttons "Add" and "Remove"; clicking on "Add" creates a new lodging and selects it so it can be edited, clicking on "Remove" removes the currently selected lodging from the list.
- List adventures and for the selected adventure allow its default lodging’s name and description to be changed in text controls. If there is no selected adventure or the default lodging is null the text controls are disabled. This is a nested property. The default lodging can be changed elsewhere, and the list
- Preventing selection changes in the master list if the detail widgets are dirty (or not valid). An example of this is Eclipse's launch configuration dialog.
- For a given catalog’s account objects show these in a Table viewer with columns that represent the first name, and last name and state. The table is read-only.
- For a given catalog’s account objects show these in a Table viewer with columns that represent the first name, and last name and state. The table is read-write.
- For a given catalog’s account objects show these in a Table viewer with columns that represent the first name, and time to read and state. Time to read requires a converter and validator. The table is read-write.
- For a given catalog’s account objects show these in a Table viewer with columns that represent the first and last name combined together, the state and phone. The phone should be formatted and the state displayed with the state description as well as two character identifier. (Non-editable)
- For a given catalog’s account objects show these in a Table viewer with columns for first name, state and phone. These are editable with text for name, combo or state and text for phone with validation.
- A scenario that demonstrates the use of virtual scrolling
- Handle null entries in tables by displaying an empty row that is not editable.
- Provide table filtering not all rows are to be listed.
- Handle table sorting.
- Binding to a custom table control such as CompositeTable.
- Table of adventure objects where one shows the name of the default lodging - make sure this refreshes when a lodging changes. Have a combo cell editor to change the default lodging
- A Tree of Catalogs and beneath it
- categories, with adventures beneath
- A tree that shows a directory structure over the file system, together with a Text input that validates a directory and drives the root of where the tree starts displaying its entries from.
- Provide element filtering (not every element is to be shown).
Error detection scenarios
- Binding to a non-existing (null) or disposed control should generate a BindingException.
- Binding to a non-existing feature id for a control (say, the max value of a text widget) should generate a BindingException.
- Binding to a null model object should throw a BindingException.
- Binding to a non-existing feature id for a model object (say, the foo feature of an Adventure object) should throw a BindingException.
- Providing converters that don't convert to or from the correct type should throw a BindingException.
Other event models
- The EMF event model has a build in event notification model which
helps the GUI to be notified of model changes. The binding framework
should be implemented against other models including
- A JavaBeans model that uses PropertyChangeListener
- A model that does not signal events. In this case, update to
bounded visuals will generate the proper events. The framework will
also provide a mechanism to fire a change event to induce proper
Preference page validation hookup
An Eclipse preference page is a good real world example to attempt to use the binding framework with. Two examples should be chosen.
One that takes an existing preference page (whose model is a preference store) and converts just the code concerned with model retrieval and update to the binding framework but leaving the rest of the code intact.
The second example would convert as much of the binding and validation as possible to the binding framework. The portions that could not be converted across would show the areas where the framework may be lacking. The validation feedback would be displayed in the preference page status bar and show the integration between binding validation and preference page feedback.
VE User admin
This is an example that allows editing of users, accounts, address and covers most model relationships and binding issues. It was used by the VE team before as the showcase example for their Swing data binding functionality and should be replicated in SWT using the binding framework.
User will be able to select a Visual, and bind it to a domain Object’s property. Properties will be reflected by their domain’s name (e.g., firstName).
User will be able to select a domain object and bind it to existing
(or generated) visual.
We re going to be using using the following data model, taken from the AdventureBuilder example application: