Action#

Qualified name: delphivcl.Action

class Action#

Bases: CustomAction

TAction is the base class for VCL action objects. TAction implements actions to be used with menu items and controls. The published properties and events of TAction actions can be managed in the Object Inspector at design time. The TAction class is almost the same as TCustomAction. TAction extends only the following features of TCustomAction:

Changes the public scope to published for the AutoCheck, Caption, Checked, Enabled, GroupIndex, HelpType, HelpContext, HelpKeyword, Hint, ImageIndex, SecondaryShortCuts, ShortCut, and Visible properties. Sets the published scope for the OnExecute, OnUpdate, and OnHint events. The published scope of these properties and events provides the possibility to use the Object Inspector assistance for editing values of these properties and events. The DisableIfNoHandler property is set to True while an action is created, that is, the action is inaccessible if it does not have an OnExecute event handler. TAction is a generic action component. It can be added to action lists when there is no predefined action class that implements the desired response to user commands. Unlike predefined action classes, which have built-in methods that respond when users click the client controls, TAction has no built-in response to user commands. Instead, when using TAction, you can provide the response when the action “fires” by writing (using the Object Inspector’s assistance) an OnExecute event handler, and configure the properties of TAction to reflect the current conditions by writing an OnUpdate event handler. Action objects are used to centralize the response to user commands (actions) and to represent user interface elements in applications that use action lists or action bands. TAction can also act as a base class for predefined action classes. You can derive from TAction if you want to retain the published scope of the supported properties and events. If you want to use the public scope to some of the supported properties and events, you can derive from TCustomAction. For predefined actions that augment the behavior of TAction, see the action classes in the Vcl.StdActns, Vcl.DBActns, and Vcl.ExtActns units.

Methods

`Create`	Creates and initializes a TAction object.
`Execute`	Generates an OnExecute event.
`Update`	Provides an opportunity to execute centralized code when an application is idle.

Attributes

`ActionComponent`	Indicates the client component that caused this action to execute.
`ActionList`	Holds the action list to which the action belongs.
`AutoCheck`	Controls whether the Checked property toggles when the action executes.
`Caption`	Represents the caption of the action.
`Category`	Group or category where the action belongs.
`Checked`	Indicates whether client controls and menu items appear checked.
`ClassName`	Returns the TObject.ClassName
`ComObject`	Specifies the interface reference implemented by the component.
`ComponentCount`	Indicates the number of components owned by the component.
`ComponentIndex`	Indicates the position of the component in its owner's Components property array.
`ComponentState`	Describes the current state of the component, indicating when a component needs to avoid certain actions.
`ComponentStyle`	Governs the behavior of the component.
`Components`	<Delphi indexed property Components of type TComponent at 21141642500>
`DesignInfo`	Contains information used by the Form designer.
`DisableIfNoHandler`	Indicates whether the action's clients should be disabled if no OnExecute event handler is found.
`Enabled`	Specifies the enabled state for the action.
`GroupIndex`	Indicates a group of actions in one action list.
`HelpContext`	Keeps the integer context ID that identifies the Help topic for the action.
`HelpKeyword`	Contains the keyword string that identifies the Help topic for the action.
`HelpType`	Keeps whether to use the HelpContext or HelpKeyword property to identify the Help topic.
`Hint`	Stores the Help hint text.
`ImageIndex`	Stores an index in a list of images.
`ImageName`	Displays the name of linked items from the Image Collection.
`Images`	Embarcadero Technologies does not currently have any additional information.
`Index`	Specifies the index of the action in its action list.
`Name`	Specifies the name of the component as referenced in code.
`Observers`	Indicates the TObservers object added to the TComponent.
`OnExecute`	<Delphi property OnExecute of type TAction at 2114145F2D0>
`OnHint`	<Delphi property OnHint of type TAction at 2114145F3A0>
`OnUpdate`	<Delphi property OnUpdate of type TAction at 2114145F470>
`Owner`	Indicates the component that is responsible for streaming and freeing this component.
`SecondaryShortCuts`	Stores shortcuts (in addition to ShortCut) for triggering the action.
`ShortCut`	Shortcut that triggers the action.
`StatusAction`	Stores the status for an input field in an action.
`Tag`	Stores a NativeInt integral value as a part of a component.
`VCLComObject`	Represents information used internally by components that support COM.
`Visible`	Stores whether the action representation is visible.

ActionComponent#: Indicates the client component that caused this action to execute.

AutoCheck#: Controls whether the Checked property toggles when the action executes. AutoCheck causes the Checked property to toggle when the action executes. This allows the Checked property of the action to remain in sync with the Checked property of the client (or an equivalent). If the client has an AutoCheck property of its own, the AutoCheck property of the action is propagated to the AutoCheck property of the client.

Caption#: Represents the caption of the action. Caption holds the string that is used as the caption of the action, when it is set. The value of Caption can be propagated to all client controls and client menu items linked to the action.

Checked#

Indicates whether client controls and menu items appear checked. Checked specifies the checked state for the action. The value of Checked can be propagated to all client controls and client menu items linked to the action.

Note: If the action has a GroupIndex value greater than 0, then setting Checked to True sets to False the Checked properties of all other actions in the GroupIndex group. Tip: Use the AutoCheck property to ensure that the action’s Checked property toggles when the action executes.

Create(AOwner: Component)#: Creates and initializes a TAction object. Applications do not usually create action objects explicitly. Actions are created automatically when you add them to an action manager or action list component at design time. When instantiating TAction at run time, assign a TActionList or TActionManager component to the new action’s ActionList property after calling Create. Create sets the DisableIfNoHandler to True, that is, the action is inaccessible if it does not have an OnExecute event handler.

Enabled#: Specifies the enabled state for the action. The value of Enabled can be propagated to all client controls and client menu items linked to the action.

Execute()#: Generates an OnExecute event.

GroupIndex#

Indicates a group of actions in one action list. Actions in this group act like the group of radio buttons. The value of GroupIndex is used to define groups of actions. Actions in each group act like groups of radio buttons. When GroupIndex is greater than 0, this value identifies the group to which some actions belong. The value of GroupIndex can be propagated to all client controls and client menu items linked to the action. When the Checked property of any action in that group is set to True, the Checked properties of all other actions in the group are set to False. That is, only one action in the group can be checked at a time.

Note: All actions in a group must be listed by the same action list.

HelpContext#

Keeps the integer context ID that identifies the Help topic for the action. HelpContext specifies the integer context ID to identify the Help topic to show when invoking Help for the action. The value of HelpContext can be propagated to all client controls and client menu items linked to the action. See also IsHelpLinked. HelpContext is only used when htContext is selected in the HelpType property.

Note: To use Help, you need to enable Help in your application. When your application supports usage of the appropriate Help system, then it can show Help topics from the associated Help file. When a client control has focus and the user presses the F1 key, the control uses the value of the HelpContext property to invoke the online Help that shows the topic with this context ID. The target topic is uniquely identified by a HelpContext context ID value.

HelpKeyword#

Contains the keyword string that identifies the Help topic for the action. The value of HelpKeyword can be propagated to all client controls and client menu items linked to the action. HelpKeyword is only used when htKeyword is selected in the HelpType property.

Note: To use Help, you need to enable Help in your application. When your application supports usage of the appropriate Help system, then it can show Help topics from the associated Help file. When a client control has focus and the user presses the F1 key, the control uses the HelpKeyword property’s value to invoke the online Help showing the topic with this keyword.

HelpType#

Keeps whether to use the HelpContext or HelpKeyword property to identify the Help topic. The value of HelpType can be propagated to all client controls and client menu items linked to the action. HelpType can keep one of the following constants:

htContext ? instructs to use the HelpContext property to identify the Help topic to show when invoking Help. htKeyword ? instructs to use the HelpKeyword property to identify the Help topic to show when invoking Help.

Hint#

Stores the Help hint text. Hint holds the hint string indicating the hint text for the action. Hint contains the text strings that appear in a pop-up box (or in a status bar) when the user moves the mouse over screen elements. This hint string can be propagated to clients of the action ? to controls, menu items, and other GUI elements.

Note: VCL controls support hint strings containing three parts that can be shown in separate locations (see Vcl.Controls.TControl.Hint).

ImageIndex#

Stores an index in a list of images. ImageIndex is a zero-based index in a list of images. TContainedAction does not provide the actual list of images, only implementations of actions in GUI application frameworks provide such a property. In general, this list of images contains images that are associated with controls and menu items that use this action. The value of ImageIndex can be propagated to all client controls and client menu items linked to the action.

Note: When ImageIndex is -1, this means that the list does not contain any images. In typical implementations of controls, an image is drawn at the leftmost position in the control, and a control’s text is drawn to the right of the image. If ImageIndex is -1, then a control does not offset the text to the right to reserve a placeholder for the image. Otherwise, if ImageIndex is not -1, then the control’s text is always drawn with the offset to the right to reserve a place for drawing an image.

ImageName#: Displays the name of linked items from the Image Collection.

OnExecute#: <Delphi property OnExecute of type TAction at 2114145F2D0>

OnHint#: <Delphi property OnHint of type TAction at 2114145F3A0>

OnUpdate#: <Delphi property OnUpdate of type TAction at 2114145F470>

SecondaryShortCuts#: Stores shortcuts (in addition to ShortCut) for triggering the action. Actions can execute in response to multiple shortcut key combinations. SecondaryShortCuts lists all the shortcut key combinations (other than the one specified by the ShortCut property) that can trigger the action. This lets you provide additional, secondary shortcuts. When the user types one of the key combinations listed in SecondaryShortCuts, the action’s Execute method is called.

ShortCut#: Shortcut that triggers the action. The value of Shortcut can be propagated to all client controls and client menu items linked to the action.

Update()#: Provides an opportunity to execute centralized code when an application is idle.

Visible#: Stores whether the action representation is visible. Visible specifies the visible state for the action (True means visible, False means invisible). This Visible value is propagated to a client of the action if IsVisibleLinked method of the action link linking the client to the action returns True. If the Visible of an action is False and IsVisibleLinked of an action link returns True, then the Visible of the client (a control, menu item, or others) is also set False and this client is also invisible. Typically, IsVisibleLinked of an action link returns False if the action belongs to TCustomViewAction. Otherwise, when the action belongs to TAction, then IsVisibleLinked of an action link returns True. That is, TCustomViewAction is used when one need to provide visible representation of clients of actions that have Visible set True.