TDBCustomNavigator class

In unit DBCtrls

TDBCustomNavigator is the base class for TDBNavigator, a tool for navigating through the records of a dataset.

Declaration

pascal

TDBCustomNavigator = class(TCustomPanel)

Inheritance

Descends from it: TDBNavigator

Description

TDBCustomNavigator is the parent class for TDBNavigator, an advanced tool for navigating through datasets generated by a query sent to the database. Most of the important properties are defined here in this base class.

It consists of a series of tool buttons used to perform navigation and maintenance for records in the linked dataset. For example:

Navigation: First, Prior, Next or Last
Maintenance: Insert, Delete, Edit, Post, Cancel or Refresh

Use the VisibleButtons property to specify which of the Buttons can be displayed in the control.

If used in conjunction with a data-aware controls, it controls which record is displayed, the position of the record selection cursor, and the initiation of changes to the dataset and ultimately the database.

Most of the functionality for the toolbar is built into the control, The programmer can specify actions to be associated with individual buttons using the OnClick event handler. It includes an argument can be sent with the index value of the button clicked, and the procedure chooses which action to call dependent on the button index.

The DataSource property must be assigned to link to the dataset for the control.

Properties

`BeforeAction`	public	BeforeAction - code to be executed before an action is performed.
`ConfirmDelete`	public	Indicates if the user is asked to confirm a record deletion.
`DataSource`	public	The Data Source to which the control must be linked in order to function.
`Direction`	public	Contains the orientation for buttons displayed on the control: horizontal or vertical.
`Flat`	public	Flat - if True, buttons have no 3-D effect.
`Hints`	public	A list of hints to be shown if the mouse hovers over a button.
`Options`	public	Options enabled for the navigator.
`VisibleButtons`	public	The set of visible buttons (some of them can be suppressed if their function appears redundant).
`ShowButtonHints`	public	Controls whether button hints are displayed for the control.
`Images`	public	Contains the images available for display on the navigator buttons.

Methods

`DataChanged`	protected	DataChanged - update status of all the buttons to reflect new data.
`EditingChanged`	protected	EditingChanged - the status of the buttons is set to CanModify.
`ActiveChanged`	protected	ActiveChanged - if datalink is active, calls DataChanged and EditingChanged.
`Loaded`	protected	Performs actions needed when the component has finished loading in the LCL streaming mechanism.
`Notification`	protected	Notification handler for insertion or deletion of components.
`UpdateButtons`	protected	UpdateButtons - if the position of the buttons need to be changed, does this, then updates the status of the buttons (see ActiveChanged).
`UpdateHints`	protected	UpdateHints - reloads the default hints and modifies any that have been changed.
`HintsChanged`	protected	HintsChanged - calls UpdateHints.
`ButtonClickHandler`	protected	ButtonClickHandler - performs BtnClick for the appropriate button.
`GetControlClassDefaultSize`	protected	Returns the default dimensions for new instances of the class.
`BeginUpdateButtons`	protected	BeginUpdateButtons - locks the buttons before updating them.
`EndUpdateButtons`	protected	EndUpdateButtons - unlocks each button in turn and updates it if needed.
`SetEnabled`	protected	Sets the value for the Enabled property.
`Create`	public	Create - constructor for TDBCustomNavigator: locks the buttons, calls inherited Create, sets default size, style, forms datalinks, initializes hints, updates the buttons.
`Destroy`	public	Destroy - destructor for TDBCustomNavigator: frees datalinks and hints, then calls inherited Destroy.
`BtnClick`	public	BtnClick - procedure to respond to button clicks, and select an action from a list according to the value of the Index of the clicked button.
`VisibleButtonCount`	public	Number of visible buttons on the control.

Events

OnClick public The action to be taken when a navigator button is clicked.

Fields

`Buttons`	protected	The list of Buttons included in the navigator tool.
`FocusableButtons`	protected	Contains the focusable button for the DB navigator control.