TApplication class

In unit Forms

Application management and configuration for a GUI application.

Declaration

pascal

TApplication = class(TCustomApplication)

Inheritance

Description

TApplication is a TCustomApplication descendant which provides facilities used to manage and configure a GUI application. Properties, methods, and event handlers are provided which allow a program to create, execute, monitor, maintain and destroy an application and its forms. Every GUI application contains an Application variable that represents the TApplication or descendent class instance.

TApplication provides a message processing loop that includes hooks for event handlers and exception handling, and supports dispatching messages for TCustomAction instances used in application forms. TApplication provides support for hints and content-sensitive help for forms and controls used in the application. Convenience methods, like MessageBox, are provided to simplify access to dialogs and error messages in the application.

For the macOS Carbon widgetset, an application is executed via the Application Bundle. As a result, command line parameters are not available to the application instance. The OnDropFiles event handler must be used to detected when associated files need to be opened.

Properties

`Active`	public	True if the application is focused.
`ActiveFormHandle`	public
`ApplicationType`	public	The type of the application (i.e. the sort of device for which it is intended).
`BidiMode`	public	The bidirectional mode to use.
`CaptureExceptions`	public	Enables exception handling in the Application.
`DoubleBuffered`	public	Indicates if the application uses double buffering.
`ExtendedKeysSupport`	public	Controls whether extended key codes are available in key down and key up messages.
`ExceptionDialog`	public	Indicates the dialog type used for an exception in the application.
`FindGlobalComponentEnabled`	public	Enables searching for global components by name.
`Flags`	public	Contains state flags for the application.
`GlyphDrawEffectsEnabled`	public	Indicates whether drawing effects are enabled for mouse-over and mouse-down events for button glyphs in the application.
`Handle`	public	Provides access to the handle for the application instance.
`Hint`	public	The current Hint text active for the application.
`HintColor`	public	The background color for a Hint window.
`HintHidePause`	public	Indicates how long a Hint remains visible after the mouse pointer is moved.
`HintHidePausePerChar`	public	Indicates how long a keystroke extends the time a Hint remains visible (added to HintHidePause).
`HintPause`	public	The delay before a Hint is shown for a form or control.
`HintShortCuts`	public	Enables or disables display of keyboard shortcuts (e. g. on menu items).
`HintShortPause`	public	The pause before a different Hint is displayed.
`Icon`	public	The icon associated with this application.
`LayoutAdjustmentPolicy`	public	Indicates the layout and sizing policy used for forms and controls in the application.
`Navigation`	public	Allows switching between controls using keyboard navigation.
`MainForm`	public	Contains the main form for the application.
`MainFormHandle`	public	Window handle for the MainForm in the application.
`MainFormOnTaskBar`	public	Controls whether a button is displayed on the task bar for the main form in the application.
`ModalLevel`	public	The number of modal forms shown.
`MoveFormFocusToChildren`	public	Indicates if an active control is focused when a form receives focus.
`MouseControl`	public	Contains the control currently under the mouse pointer.
`TaskBarBehavior`	public	Indicates how forms are represented in the task bar.
`UpdateFormatSettings`	public	Indicates if application format settings are updated when changed in a widgetset class.
`ShowButtonGlyphs`	public	Allows the platform defaults for glyphs on buttons to be overridden.
`ShowMenuGlyphs`	public	Sets the default policy for showing or hiding glyph images in menus.
`ShowHint`	public	Indicates if Hints are displayed for the application.
`ShowMainForm`	public	Allows the main form to be shown or hidden when an application is started.
`Title`	public	Contains the title for the application.
`Scaled`	public	Indicates if forms and controls in the application can be scaled to different display densities (Pixels per Inch).

Methods

`GetConsoleApplication`	protected	Always returns False for a GUI application.
`NotifyIdleHandler`	protected	Signals all idle handlers for the application.
`NotifyIdleEndHandler`	protected	Notifies all Idle End handlers when a new message has arrived.
`NotifyActivateHandler`	protected	Notifies all Activate handlers for the application.
`NotifyDeactivateHandler`	protected	Notifies all Deactivate handlers for the application.
`NotifyCustomForms`	protected	Performs the specified message for all custom forms in the application.
`IsHintMsg`	protected	Exists for Delphi compatibility only.
`DoOnHelp`	protected	Signals an OnHelp event handler.
`DoOnMouseMove`	protected	OnMouseMove message handler, updates the Hint.
`ShowHintWindow`	protected	Shows or hides the hint window for a control in the application.
`OnHintTimer`	protected	Implements an event handler signalled when the timer for a hint display has elapsed.
`SetTitle`	protected	Sets the value for the Title property.
`StartHintTimer`	protected	Starts the timer for display of a hint message.
`UpdateVisible`	protected	Asks the widgetset to update its task bar entries.
`DoIdleActions`	protected	Updates all Actions and hides splash screens.
`MenuPopupHandler`	protected	Implements the OnMenuPopupHandler for the application.
`HasAsyncCallQueued`	protected	Indicates whether there are unprocessed asynchronous calls pending in the application queue.
`ProcessAsyncCallQueue`	protected	Calls all methods queued in QueueAsyncCall.
`DoDecLCLRefcountToZero`	protected	Performs actions needed when the reference count for a TLCLComponent instance reaches 0 in the application.
`FreeComponent`	protected	Destroys all components marked for release.
`ReleaseComponents`	protected	Destroys all components marked for release.
`DoBeforeFinalization`	protected	Destroys all components.
`GetParams`	protected	Returns the command line argument at the specified ordinal position.
`DoLog`	protected	Performs actions needed to implement the Log method.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destructor for the class instance.
`ActivateHint`	public	Configures a hint window for the specified mouse position.
`GetControlAtMouse`	public	Gets the control under the mouse pointer.
`GetControlAtPos`	public	Gets the control which contains the specified position, and optionally updates the internal tracking members for mouse capture when needed.
`ControlDestroyed`	public	Clears all references to the destroyed control.
`BigIconHandle`	public	Returns the Handle for the large application Icon.
`SmallIconHandle`	public	Returns the Handle for the small application Icon.
`BringToFront`	public	Asks the widgetset to bring the last form for the application in front of all other programs.
`CreateForm`	public	Creates a Form or component owned by the Application instance.
`UpdateMainForm`	public	Makes the specified form the MainForm in the Application.
`QueueAsyncCall`	public	Inserts an asynchronous call into the queue.
`RemoveAsyncCalls`	public	Removes all calls added via QueueAsyncCall.
`ReleaseComponent`	public	Safely destroys a component used in the application.
`ExecuteAction`	public	Signals an OnActionExecute handler (when assigned).
`UpdateAction`	public	Signals an OnActionUpdate handler (when assigned).
`HandleException`	public	HandleException method for handling an exception; attempts to maintain program execution if possible, otherwise exits gracefully.
`HandleMessage`	public	Handles pending messages, and enters the Idle state.
`HelpCommand`	public	Show help.
`HelpContext`	public	Shows context-sensitive help for the application.
`HelpKeyword`	public	Shows help for the specified keyword.
`HelpShowTableOfContents`	public	Displays the Help Table of Contents using the Help Manager for the application.
`ShowHelpForObject`	public	When Sender is a TControl, invoke its ShowHelp method.
`RemoveStayOnTop`	public	Removes the StayOnTop attribute from all visible forms in the application.
`RestoreStayOnTop`	public	Restores StayOnTop for all forms changed by RemoveStayOnTop.
`IsWaiting`	public	True if the application is waiting for a message event.
`CancelHint`	public	Called when the Hint timer has expired to stop showing the Hint.
`HideHint`	public	Hides the Hint window.
`HintMouseMessage`	public	Called when the mouse is over a control with a Hint.
`Initialize`	public	Initializes the widgetset (and more).
`MessageBox`	public	Display an message dialog with response buttons.
`Minimize`	public	Asks the widgetset to minimize the application.
`ModalStarted`	public	Called when a modal form display is started.
`ModalFinished`	public	Called when a modal form is closed.
`Restore`	public	Restores a previously minimized application.
`Notification`	public	Performs actions when a component is added to or removed from the application.
`ProcessMessages`	public	Call this method during lengthy operations to ensure the GUI remains responsive.
`Idle`	public	Called when the application enters the idle state.
`Run`	public	Loads the form and passes control to the event loop for the application.
`ShowException`	public	Shows the message for the specified exception and asks the user to abort or continue.
`Terminate`	public	The application is terminated and the component engine is shutdown.
`DisableIdleHandler`	public	Disables Idle handling.
`EnableIdleHandler`	public	Resumes Idle handling.
`NotifyUserInputHandler`	public	Notifies all user input handlers of the specified message.
`NotifyKeyDownBeforeHandler`	public	Notifies all ahtKeyDownBefore handlers.
`NotifyKeyDownHandler`	public	Notifies all ahtKeyDownAfter handlers, and eventually reacts to F1 (Help).
`ControlKeyDown`	public	Handles KeyDown events in a Control, e.g. handles navigation keys.
`ControlKeyUp`	public	Handles KeyUp events in a Control, e.g. handles Enter and Esc keys.
`AddOnIdleHandler`	public	Adds an application Idle handler to the list of handlers for the type.
`RemoveOnIdleHandler`	public	Removes an application Idle handler for the list of handlers for the type.
`AddOnIdleEndHandler`	public	Adds an application IdleEnd handler to the list of handlers for the type.
`RemoveOnIdleEndHandler`	public	Removes an application IdleEnd handler.
`AddOnUserInputHandler`	public	Adds an application user input handler to the list of handlers for the type.
`RemoveOnUserInputHandler`	public	Removes an application user input handler from the list of handlers for the type.
`AddOnKeyDownBeforeHandler`	public	Adds an application key down before interface handler.
`RemoveOnKeyDownBeforeHandler`	public	Removes an application key down before interface handler.
`AddOnKeyDownHandler`	public	Adds an application key down handler to the list for the type.
`RemoveOnKeyDownHandler`	public	Removes an application key down after interface handler.
`AddOnActivateHandler`	public	Adds an application activation handler.
`RemoveOnActivateHandler`	public	Removes an application activation handler.
`AddOnDeactivateHandler`	public	Adds an application deactivation handler.
`RemoveOnDeactivateHandler`	public	Removes an application deactivation handler.
`AddOnExceptionHandler`	public	Adds an application exception handler.
`RemoveOnExceptionHandler`	public	Removes an application exception handler.
`AddOnEndSessionHandler`	public	Adds an application logoff handler.
`RemoveOnEndSessionHandler`	public	Removes an application logoff handler.
`AddOnQueryEndSessionHandler`	public	Adds an application logoff query handler.
`RemoveOnQueryEndSessionHandler`	public	Removes an application logoff query handler.
`AddOnMinimizeHandler`	public	Adds an application minimizing handler.
`RemoveOnMinimizeHandler`	public	Removes an application minimizing handler.
`AddOnModalBeginHandler`	public	Adds an application becoming modal handler.
`RemoveOnModalBeginHandler`	public	Removes an application becoming modal handler.
`AddOnModalEndHandler`	public	Adds an application exiting modal state handler.
`RemoveOnModalEndHandler`	public	Removes an application exiting modal state handler.
`AddOnRestoreHandler`	public	Adds an application exiting minimized state handler.
`RemoveOnRestoreHandler`	public	Removes an application exiting minimized state handler.
`AddOnDropFilesHandler`	public	Adds an application dropped files handler.
`RemoveOnDropFilesHandler`	public	Removes an application dropped files handler.
`AddOnHelpHandler`	public	Adds an application Help handler.
`RemoveOnHelpHandler`	public	Removes an application Help handler.
`AddOnHintHandler`	public	Adds an application Hint handler.
`RemoveOnHintHandler`	public	Removes an application Hint handler.
`AddOnShowHintHandler`	public	Adds an application Hint show handler to the list for the handler type.
`RemoveOnShowHintHandler`	public	Removes an application Hint show handler from the list for the handler type.
`AddOnGetMainFormHandleHandler`	public	Adds a handler signalled when the application MainForm handle is retrieved.
`RemoveOnGetMainFormHandleHandler`	public	Removes a handler used to get the handle for the main form in the application.
`AddOnActionExecuteHandler`	public	Adds the specified routine to the list of ahtActionExecute handlers for the application.
`RemoveOnActionExecuteHandler`	public	Removes the specified routine from the list of ahtActionExecute handlers for the application.
`AddOnActionUpdateHandler`	public	Adds the specified routine to the list of ahtActionUpdate handlers for the application.
`RemoveOnActionUpdateHandler`	public	Removes the specified routine from the list of ahtActionUpdate handlers for the application.
`RemoveAllHandlersOfObject`	public	Removes all handlers implemented for the specified object.
`DoBeforeMouseMessage`	public	Performs actions needed before a mouse message is processed in the application.
`IsShortcut`	public	Checks whether a handler is available for the shortcut key in the message.
`IntfQueryEndSession`	public	Called by the interface to confirm the end of a session.
`IntfEndSession`	public	Called by the interface when the session ends.
`IntfAppActivate`	public	Called by the interface on application activation.
`IntfAppDeactivate`	public	Called by the interface on application deactivation.
`IntfAppMinimize`	public	Called by the interface when the application is minimized.
`IntfAppRestore`	public	Called by the interface when the application is restored.
`IntfDropFiles`	public	Called by the interface when files have been dropped.
`IntfSettingsChange`	public	Called when the WM_SETTINGCHANGE message is handled for the application.
`IntfThemeOptionChange`	public	Called by the interface when a theme option has changed.
`IsRightToLeft`	public	Indicates if BiDiMode contains a value other than bdLeftToRight.
`IsRTLLang`	public	Checks the given language name for use of right-to-left reading.
`Direction`	public	Gets the TBidiMode value with the direction for the specified language name.
`DoArrowKey`	public	Uses arrow keys for navigation, if enabled.
`DoTabKey`	public	Uses the Tab key for navigation, if enabled.
`DoEscapeKey`	public	Interprets Esc as Cancel action, if applicable.
`DoReturnKey`	public	Interprets Enter as the default action, if applicable.

Events

`OnActionExecute`	public	Default handler for unhandled Actions.
`OnActionUpdate`	public	Event handler signalled to update actions used in the application.
`OnActivate`	public	Event handler signalled when an Activate message is handled in the application.
`OnDeactivate`	public	Event handler signalled when a Deactivate message is handled in the application.
`OnGetMainFormHandle`	public	Event handler used to provide a value for the MainFormHandle property.
`OnIdle`	public	Event handler signalled when the application enters the idle state.
`OnIdleEnd`	public	Event handler signalled when the application leaves the Idle state.
`OnEndSession`	public	Event handler signalled when a session is ended in the application.
`OnQueryEndSession`	public	Event handler signalled to determine if the current session be be ended, and the application can be closed.
`OnMinimize`	public	Event handler signalled when the application is minimized.
`OnMessageDialogFinished`	public	Event handler signalled when a message dialog in the application has been completed.
`OnModalBegin`	public	Event handler signalled when a form in the application is displayed as a modal form.
`OnModalEnd`	public	Event handler signalled when the last modal form for the application has been exited.
`OnRestore`	public	Event handler signalled when the application is restored from a minimized / maximized state.
`OnDropFiles`	public	Event handler signalled when file(s) are dropped into the application.
`OnHelp`	public	Event handler signalled when help is requested in the application.
`OnHint`	public	Event handler signalled when a hint is requested in the application.
`OnShortcut`	public	Event handler signalled to determine if a keystroke message is a shortcut key in the application.
`OnShowHint`	public	Event handler signalled prior to displaying a hint window.
`OnUserInput`	public	Event handler signalled to handle user input messages.
`OnLog`	public	Event handler signalled for log messages written by the application.
`OnDestroy`	public	Event handler signalled when the application is freed.
`OnCircularException`	public	Event handler signalled when a circular exception occurs before the application is halted.