TForm class

In unit Forms

Implements a form used in an LCL application.

Declaration

pascal

TForm = class(TCustomForm)

Inheritance

Descends from it: TCalculatorForm TCalendarPopupForm TCustomCopyToClipboardDialog TFindDialogForm TLazarusFileDialogForm TLazMessageDialog TLCLTaskDialog TLoginDialog TReplaceDialogForm TTimePopupForm

Description

TForm is a TCustomForm descendant which implements a form displayed in an LCL application. It sets the visibility and default values for properties introduced in ancestor classes. It also adds methods needed for use as an MDI form in an application. LCL version information is available in the LCLVersion property, and is streamed to to the component resource file when a Parent is not assigned for the form.

Forms created at design-time using the Lazarus IDE are TForm descendants. A form can be used as the main form in an application, or it can be displayed as a MDI forms, dialog box, or tool window. Controls can added to the form, such as: TEdit, TLabel, TButton, TCheckBox, TComboBox, TListView, TTreeView, et. al.

Properties

`ClientHandle`	public	The Handle of the MDIForm client (container for MDI children).
`DockManager`	public	The docking layout manager for this control.
`Action`	published	The Action associated with the control.
`ActiveControl`	published	Gets or sets the active control on the form.
`Align`	published	Specifies the placement of the control on its Parent control.
`AllowDropFiles`	published	Specifies whether files can be dropped onto this form.
`AlphaBlend`	published	Allows the form to be drawn with translucency.
`AlphaBlendValue`	published	The translucence level for the form (0=transparent, 255=opaque).
`Anchors`	published	The set of anchor definitions for this control.
`AutoScroll`	published	Indicates if the form can automatically show or hide scroll bars.
`AutoSize`	published	Allows automatic adjustment of the size for the control, according to its content.
`BiDiMode`	published	Indicates whether text controls use in bi-directional reading.
`BorderIcons`	published	Specifies the icons which appear in the title bar for the form.
`BorderStyle`	published	The border style affects the title bar, border, icon(s), and resize behavior for the form.
`BorderWidth`	published	Width of the Border around the control; default is zero.
`Caption`	published	The text displayed in the title bar for the form.
`ChildSizing`	published	Provides a grid (table) layout for the children of this control.
`ClientHeight`	published	The height for the client area on the control.
`ClientWidth`	published	The width of the client area for the control.
`Color`	published	The background color for the form.
`Constraints`	published	Contains the minimum and maximum Width and Height for the control.
`DefaultMonitor`	published	The monitor on which the form is displayed.
`DesignTimePPI`	published	Design-time Pixels Per Inch for the designer surface.
`DockSite`	published	Allows controls to be drag-and-dock-ed into this control.
`DoubleBuffered`	published	When enabled, it reduces flicker when the control is painted.
`DragKind`	published	Indicates the action performed for a drag operation: drag-and-drop or drag-and-dock.
`DragMode`	published	Determines how a drag operation is started for the control.
`Enabled`	published	Determines whether the control responds to mouse or keyboard input.
`Font`	published	The font to be used for text display in this control.
`FormStyle`	published	Indicates the style for the form.
`HelpFile`	published	The name of the help file for the form.
`Icon`	published	The Icon associated with this Form (in minimized state).
`KeyPreview`	published	Allows the form to intercept keystrokes in child controls.
`Menu`	published	The main menu for the form instance.
`ParentBiDiMode`	published	Indicates whether the BiDiMode settings in the Parent control are used.
`ParentDoubleBuffered`	published	Value for the DoubleBuffered property in a Parent control.
`ParentFont`	published	Uses the font from the Parent when enabled.
`PixelsPerInch`	published	Run-time Pixels Per Inch for the designer surface.
`PopupMenu`	published	A context-sensitive menu that pops up when the right mouse button is clicked over this control.
`PopupMode`	published	Defines where pop-up menus are shown.
`PopupParent`	published	Parent form which owns the current form instance when displayed as a pop-up window.
`Position`	published	The initial placement for the form.
`SessionProperties`	published	Delimited list of form and / or component properties saved to and restored from an external storage mechanism.
`ScreenSnap`	published	Indicates whether the form instance can be snapped to an edge on the monitor.
`ShowHint`	published	Enables Hint display for the control.
`ShowInTaskBar`	published	Indicates if the form should be displayed on the system Task Bar.
`SnapBuffer`	published	Distance from (or proximity to) an edge on a snap target where the snapping behavior is automatically engaged.
`SnapOptions`	published	Contains the form and screen snapping options for the form instance.
`UseDockManager`	published	Determines whether a DockManager is used for this DockSite.
`LCLVersion`	published	The LCL version number as a String type.
`Scaled`	published	Indicates if the design surface is scaled to reflect changes in display density (Pixels Per Inch).
`TileMode`	published	Controls the layout order for MDI child forms for a MDI form instance.
`Visible`	published	Indicates if the control is visible on its parent.
`WindowState`	published	Indicates whether the form is displayed in a minimized, maximized, full-screen or normal state.

Methods

`WSRegisterClass`	protected	Creates an association between the class type and its widgetset class.
`CreateWnd`	protected	Creates the handle for the widgetset class and updates it menu and icons.
`Loaded`	protected	Performs actions when LCL component streaming has been completed for the form instance.
`Create`	public	Constructor for the class instance.
`Cascade`	public	Arranges MDI child forms so they overlap.
`Next`	public	Activates the next MDI child form (fsMDIChild) in the form sequence.
`Previous`	public	Activates the previous MDI child form (fsMDIChild) in the form sequence.
`Tile`	public	Arranges MDI child forms using the TileMode for the MDI form.
`ArrangeIcons`	public	Arranges the icons for minimized forms in a MDI form.

Events

`OnActivate`	published	Handler signalled when the form instance receives focus.
`OnChangeBounds`	published	Event handler signalled when the Bounds for the control have been changed.
`OnClick`	published	Notification handler for mouse clicks.
`OnClose`	published	Handler called when the form is closed. It determines what happens to the form (destroy, hide, etc.).
`OnCloseQuery`	published	Event handler signalled when trying to close a form.
`OnConstrainedResize`	published	This handler can supply specific Constraints (size limits), when the control is resized.
`OnContextPopup`	published	Invoked when a context-sensitive pop-up menu is requested.
`OnCreate`	published	Handler called when the form has been created.
`OnDblClick`	published	Event handler signalled when a mouse double click occurs in the control.
`OnDeactivate`	published	Handler signalled when the form is deactivated (loses focus).
`OnDestroy`	published	Handler called when the form is destroyed.
`OnDockDrop`	published	Event handler signalled for the drop of a control to be docked.
`OnDockOver`	published	Event handler signalled when a control is moved over a docksite; determines whether the drop event is accepted or rejected.
`OnDragDrop`	published	Event handler signalled when an object is dropped onto the control.
`OnDragOver`	published	Event handler signalled when a control is dragged over the control instance.
`OnDropFiles`	published	Handler called when files have been dropped.
`OnEndDock`	published	Event handler signalled for the end of a drag-dock operation.
`OnGetSiteInfo`	published	Provides information about the DockSite for the control.
`OnHelp`	published	Handler called when Help is requested.
`OnHide`	published	Handler called when the form is being hidden.
`OnKeyDown`	published	Event handler signalled for key down keyboard events.
`OnKeyPress`	published	Event handler signalled for character data entered by the user.
`OnKeyUp`	published	Event handler signalled when a key up event has occurred for the control.
`OnMouseDown`	published	Event handler signalled when a mouse down event is handled for the control.
`OnMouseEnter`	published	Event handler signalled when the mouse pointer has entered the control.
`OnMouseLeave`	published	Event handler signalled when the mouse pointer has left the control.
`OnMouseMove`	published	Event handler signalled when the mouse pointer is moved in the control.
`OnMouseUp`	published	Event handler signalled when a mouse up event is handled for the control.
`OnMouseWheel`	published	Event handler for mouse wheel turned.
`OnMouseWheelDown`	published	Event handler signalled for a downward movement of the mouse wheel.
`OnMouseWheelUp`	published	Event handler signalled for an upward movement of the mouse wheel.
`OnMouseWheelHorz`	published	Event handler signalled for a horizontal movement of the mouse wheel.
`OnMouseWheelLeft`	published	Event handler signalled for a leftward movement of the mouse wheel.
`OnMouseWheelRight`	published	Event handler signalled for a rightward movement of the mouse wheel.
`OnPaint`	published	Event handler signalled to paint the control.
`OnResize`	published	Event handler signalled when the size for the form is changed.
`OnShortCut`	published	Event handler signalled when a key is pressed, before further handling of the key.
`OnShow`	published	Handler called when the form becomes visible.
`OnShowHint`	published	Event handler signalled when a hint window is displayed for the control.
`OnStartDock`	published	Event handler for the start of a docking operation.
`OnUnDock`	published	Event handler signalled before a control is undocked from its DockSite.
`OnUTF8KeyPress`	published	Handler for a character entered by the user.
`OnWindowStateChange`	published	Handler called when the form is minimized, maximized or restored.