Contains definitions and descriptions for constructing the Forms which are the basis of the Lazarus Graphical User Interface Represents the Position and Size on Screen of an Form poDesigned - The Form appears exactly as it is positioned and sized in the Form Designer
poDefault - The window manager decides how the form is to appear, in a default position and size
poDefaultPosOnly - keeps the Designed size, but position determined by windowmanager
poDefaultSizeOnly - keeps the Designed position, but size determined by windowmanager
poScreenCenter - Centers the form on screen
poDeskTopCenter - Centers the form on desktop
poMainFormCenter - Centers the Form on the Main Form
poOwnerFormCenter - Centers the Form on Owner form Represents the actual State of the window on the screen wsNormal - The window appears normal
wsMinimized - The window appears minimized
wsMaximized - The window appears maximized TCustomForm.OnClose Scrolling Window Control Scrolling Window Control: A window control with scroll bars.
An ancestor class for many forms with scrolling windows Exception in Scroll Bar Exception class for Scroll Bar Control Scroll Bar Control Scroll Bar: Scroll Bar control for adding to windows. Can be horizontal or vertical.
This is an ancestor class for many form types and classes of windowed controls Create an instance of a Scroll Bar Control The identity of the windowed control in which the scroll bar is found Whether this is a horizontal or a vertical scrollbar Assigns the contents of the source object to the current object; in particular finds the increment, position, range and whether smooth scrolling is to be feature and whether the scroll bar is visible The object that called this instance of the class Visibility of scroll bar Returns 'True' if scroll bar visible Position of the indicator cursor on the scroll bar Returns position of the scroll cursor as an integer Finds which kind of scroll bar this is: horizontal or vertical Reads a flag to determine which kind of scroll bar Finds out details of the other scroll bar Returns a link to the details of the other scroll bar Find out details about the horizontal scroll bar Returns details of the horizontal scroll bar as a pointer to a structure Find out details of the vertical scroll bar Returns details of the vertical scroll bar as a pointer to a structure Determine the size of the scroll bar Reads or writes a flag to determine the size; by default the size is not stored The size of the scrolling increment The amount by which the scroll indicator moves if the triangle at either end of the bar is selected.
Read or write a flag to determine the increment, an integer with a default value of 8 (pixels) The size of the paging increment for scrolling The amount by which the scroll indicator moves if the cursor selects the scroll bar above, below or on either side of the scroll indicator.
Reads or writes a flag to determine paging increment; default value is 80 pixels Determine whether smooth scrolling is to be implemented Reads or writes a flag to determine smooth scrolling, and sets a flag is the scrolling status is stored Position of the scroll bar Reads or writes a flag with the position; default is zero The range (extent) of the scroll bar Reads or writes a flag to determine the range; default is zero Is the scroll bar visible? Reads or writes flag to determine visibility, and sets a flag if the property is stored Create an instance of a scrolling window control This constructor can override the constructor of an ancestor class Destroy this instance of scrolling window control, and free its resources Can override destructor of parent class Update the position of the scroll indicatores in the scroll bars Checks if the scroll bars are in process of being loaded or destroyed;
if so, or if there is no valid handle, exit.
If the indicators are valid, re-computes position etc Whether the scroll bars are visible Does auto-scrolling apply? Reads or writes a flag to determine auto-scrolling The properties of the horizontal scroll bar The properties of the vertical scroll bar Scroll Box: A box with scroll bars Custom Frame: The base type for Frame Frame - a container for all the other components on a form, or for a group of components within a form Specifies which icon appears on the top border of the Form biSystemMenu - The form has a System menu (Maybe not all windowmanager supports this)
biMinimize - The form has an minimize button
biMaximize - The form has a maximize button
biHelp - When you click this button a Question Cursor appears and the help routines are called if you click on an control TCustomForm - the base type for TForm Asks every visible control to Execute the specified action ExeAction.

DoExecuteAction asks every visible control to Execute the specified action ExeAction. If some control executes it and returns true, then the traversal of visible components is stopped. All child controls (and its children etc) are queried too.

For example you have

TForm
   TPanel
     TButton
     TCheckBox
   TMemo

then the following controls are queried in this order: TPanel, TButton, TCheckBox, TMemo.

But first of all, the Form itself and the ActiveControl are asked to execute the given action.

True, if any control handles the action. Action to execute. This constructor can override the constructor of an ancestor class Find the handle for the Icon Close the form and release its resources Is the associated query to be closed? Set free the resources of the form Shows, brings to front and activates the form Shows this form as the top (nearest) item of any stack of windows or images. Ensure that this form is always visible, if necessary moving it to the top (front) of the stack of images Show this form as modal - ie control cannot be resumed by another form until the current form is closed IsShortcut - if True, the specified Key and Message are active as a shortcut Is true when the form has the focus Use active to check if the form has the focus Specifies the active control on the form Use this to get or set the active control on this form Specifies the active default control on the Form Specifies if files are allowed to be dropped on this form. Set AllowDropFiles event to True to allow dropping files on this form. It is set to False by default. Specifies which icons appear on the top of the form Use bordericons flags to get or set the icons that appear on the top border of the form.
By default we see down-triangle or other generic icon on the left,
which activates a pop-up system menu allowing closure or re-sizing of the form,
and on the right end we see the minimise and re-size/maximise buttons,
but of course these can be customised by the application programmer. The border style for this Form

Use borderstyle to get or set the appearance of the form's border.

By default it is a sizeable window, but it could, for example, be a dialog form or a tool window, or could be non-sizeable

This property is slightly different (has a differert base type) from the TCustomControl.BorderStyle

The control associated with the cancel action

Determines the control associated with the Cancel action (exit from the control without changing anything).

This is usually a button with the caption 'Cancel', but might be an 'Exit' button or anything else the application programmer decides.

This control is selected either by explicitly clicking with the mouse, or by hitting the 'Esc' key

The form's colour; by default it is the same as the colour specified for button faces. The form's colour; by default it is the same as the colour specified for button faces. The control associated with the default action for this form Reads or sets a flag determining the default control.
This is typically a button such as 'Accept' which is highlighted in some way on-screen to indicate that this is the default action, and is selected either by hitting 'Return' or 'Enter' or by selecting that control with the mouse Determines the state of the form Reads or writes a flag to determine the form's state:
is it being created, is this its first showing, is the border style being changed, etc.
FormState is a set, so could take zero or more of possible values. Determinates the style of the form

Reads or writes flag to determine the style of the form.

Default is 'normal', but could be MDIChild or MDINormal, could stay on top or could be a 'Splash' form.

FormStyle is a set, so could take zero or more of these values.

Specifies the help file that is used by the form Reads or writes a flag to determine identity of Help file,
and to determine whether its name is stored.
Property contains filename as a string. The Icon associated with this Form (which may appear in menus, directories, ListBoxes etc) Specifies a MainMenu for this form Drop a TMainMenu on the form and select it here to show it on the form.
Specifies the return value of an modal form Reads or writes a flag to determine whether there is a modal resut.
If the form is modal, returns an integer value. Event handler for activation (opening) of the form Event handler for closing the form Event handler for closing the query associated with the form Event handler for creating the form Event handler for deactivating the form Event handler when the form is being destroyed The event invoked when file is dropped on this form. The OnDropFiles event is invoked when user drops one or multiple files on this form. You enable this feature by setting AllowDropFiles property. Event handler when Help is required Event handler if form is being hidden Event handler if shortcut key is pressed Event handler if form is to be shown Event handler for a change in the window state The scaling of the form in absolute terms

Reads or writes a flag to determine the scaling factor (a longinteger).

Not normally stored locally

The position of the form on the screen Reads or writes a flag to determine screen position of form.
By default it is in the position that it was placed in the Form Designer The position of the left edge of the form when it is restored (ie changes from minimised or maximised) The position of the top edge of the form when it is restored (ie changes from minimised or maximised) The width of the form when it is restored (ie changes from minimised or maximised) The height of the form when it is restored (ie changes from minimised or maximised) Should the form be shown in the system Task Bar? Indicates if the form is visible Set or get this to set the form visible/hidden or get the status of the form Represents how the form appears on the screen Reads or write flag to determine state of the window on screen.
Default is 'normal' (ie not minimised or maximised) Form - the fundamental visual object that appears in every application with a Graphical User Interface.

Form - the fundamental visual object that appears in every GUI application.

Most of the properties are inherited from the ancestors

Create a Window Control to contain the Form The operating system handle for the client Use active control to set or get the control that has the focus on this form TCustomDockForm - Base class for docking forms Hint Window - the popup box containing helpful information that appears when the mouse pointer hovers over an object Allow the hint message to be displayed in the specified rectangular space Allow the hint message to be displayed, with a pointer to further data Work out the size of the rectangle required to display the specified hint message Release the handle for the hint message and return it to the system Does the hint disappear (get hidden) after a while? If AutoHide is TRUE, the hint disappears afer an interval specified by HideInterval The time after which the displayed hint disappears Screen - the visible area Specifies which style the form border has Create an instance of TScreen Destroy this instance of TScreen The Index number of a Custom Form on the screen The Index number of the Custom Form, stored as an integer The Custom Form to which the Index refers The index number of a Form on the Screen The index number of the Form, stored as an integer The Form to which the Index refers Method for updating screen The identity of the active control on this screen Reads a flag to determine the active control The identity of the active Custom Form on this screen Reads a flag to determine the active Custom Form The identity of the active Form on this Screen Reads a flag to determine the active Form The cursor currently being used in this screen Reads or writes a flag to determine the cursor.
This can take any integer value, but there are several pre-determined cursor styles
listed as constants in 'Controls',
and these should be used to define the cursor for the current screen The indexed list of available cursors for this screen The number of Custom Forms on this screen Reads flag to determine number of Custom Forms (integer) The list of Custom Forms on the screen The total available height of the desktop in which the screen is to be placed The total available width of the desktop in which the screen is to be placed The number of Forms on this screen Reads a flag to determine the number of Forms (integer) The list of Forms in this Screen Index number of a Form, stored as an integer The fonts to be used in this screen Reads a flag to determine the fonts to be used; their names are stored as a list of strings The height of the screen Reads a flag to determine screen height; stored as an integer The font to be used to display hints Reads a flag to determine the font to be used (font name stored as a string) The width of the screen Reads flag to determine screen width, stored as an integer Event handler for change in the active control Event handler for a change in the active form on the screen Scaling factor for displaying graphic information on the screen Reads a flag to determine number of pixels per inch (integer) Application - the whole current program, described as an object

Application - the whole current program, described as an object.

Includes the useful function MessageBox, a simple dialog intended for displaying error messages internally, but available as an alternative to the various Message Dialogs

Make the application run in a loop, ie it starts again when it has finished Create an instance of TApplication This instance of the constructor performs most of the setting up of the environment for the application. The instances of Create that occur in some of the ancestor classes are place holders rather than actual instructions for constructing the object The Owner object that invoked this instance of TApplication Destroy this instance of TApplication and free its resources Method for dealing with a control that has been destroyed Use the selected widget set's method to bring the application's form(s) to the front Create Form or any other kind of component Note: The name is confusing and only kept for Delphi compatibility.
It can actually create any kind of component

Creates a Component instance, sets the pointer to the component variable and loads the component.
If it is a form it will be added to the application's forms list Insert a given asynchronous call into the queue The method to be used for the asynchronous call The data structure used by the asynchronous call method The method to be used to execute the action associated with the Application This is a function that should be supplied by the application programmer, to override the placeholders declared in ancestor classes Exception handler - methods to be followed in response to exceptions Individual exception handler methods should be supplied by the application programmer, to override place-holder entries declared in ancestor classes.
This method checks whether the application is required to halt if an exception occurs, or invokes the appropriate handler.
It also writes details of the exception to the appropriate place for debugging. Process all events according to the method defined for the widget set Cancels a request for a hint, if there is no hint timer or no hint to display Don't display the hint The icon to be associated with this application Initialize any forms associated with the application Finds the appropriate widget set, reads the application's icon (if any) from the Lazarus Resource file, initialises the screen, and leaves it ready for processing. Message Box: a useful function to display a message.

Message Box: a useful function to display a message.

The function is used internally to display messages during the handling of Exceptions , but is also available to application programmers as an alternative to some of the message dialogs found in Dialogs

The argument Flags is a long integer constructed by adding together various constants to define the contents and behaviour of the box, for example:

MB_ABORTRETRYIGNORE + MR_ICONQUESTION will cause the application to display a query (?) icon in a box with three buttons:

ABORT RETRY IGNORE.

The following button constants are available:

MB_OK

MB_OKCANCEL

MB_ABORTRETRYIGNORE

MB_YESNOCANCEL

MB_YESNO

MB_RETRYCANCEL

And the following icon constants:

MB_ICONHAND

MB_ICONQUESTION

MB_ICONEXCLAMATION

MB_ICONASTERICK

MB_ICONWARNING = MB_ICONEXCLAMATION

MB_ICONERROR = MB_ICONHAND

MB_ICONSTOP = MB_ICONHAND

MB_ICONINFORMATION = MB_ICONASTERICK

These constants are declared on the LCLType unit.

The function returns an integer value corresponding to the button that was pressed; its value can be determined by reference to the constants [IDOK..IDHELP]

It can be invoked like a procedure call (ie as a 'MessageBox()' statement rather than as a 'Variable := MessageBox()' function call)

MessageDlg Result Result: integer value returned by the function to signify which box was selected

Can be one of the following values:

IDOK
IDCANCEL
IDABORT
IDRETRY
IDIGNORE
IDYES
IDNO
IDCLOSE
IDHELP Text: the string that is displayed as a prompt or instruction in the Box Caption: the string label at the top of the message box Flags - a long integer constructed by adding together various constants to define the contents and behaviour of the box Flags: longint - an integer constructed by adding together various constants to define the contents and behaviour of the box, for example
MB_ABORTRETRYIGNORE + MR_ICONQUESTION will cause the application to display a query (?) icon in a box with three buttons:
ABORT RETRY IGNORE.

The following button constants are available:

MB_OK
MB_OKCANCEL
MB_ABORTRETRYIGNORE
MB_YESNOCANCEL
MB_YESNO
MB_RETRYCANCEL

And the following icon constants:

MB_ICONHAND
MB_ICONQUESTION
MB_ICONEXCLAMATION
MB_ICONASTERICK
MB_ICONWARNING = MB_ICONEXCLAMATION
MB_ICONERROR = MB_ICONHAND
MB_ICONSTOP = MB_ICONHAND
MB_ICONINFORMATION = MB_ICONASTERICK

These constants are declared on the LCLType unit. Minimise the form using the widget set's method Restore the application's form to the size it was before minimisation or maximisation The method to be used to make the application execute. This method should be supplied by the application programmer, and should be the main process control procedure for the application Show any exception that has occurred The exception that is to be displayed Procedure to end the application If exceptions have occurred, find out what they are, ready for processing The hint associated with the main application A hint is a small pop-up mesage that appears briefly while the mouse hovers over a specified area of the screen. It usually displays useful information about how to use an object or what data should be entered, etc

Reads or writes a flag to determine the hint associated with the application The colour used to display the hint The delay period after mouse entry before the hint becomes visible The length of time for which the hint is displayed Determine how the form is to be navigated Reads or writes a flag to determine the navigation method:
Is Tab used to move to next control?
Does Enter or Ret activate the default action?
Does Esc perform the cancel action?
Does F1 activate a Help system?

Navigation Options is a set, so can take zero or more of the available values The Main Form used by the application for process control and for data input/output Reads a flag to get particulars of the main form Event handler for executing the form's main action Event handler for activation of the application Event handler for deactivation of the application Event handler for ending a session of the application Event handler for minimising the application's form Event handler for restoring the application's form from minimised or maximised condition The event invoked when file is dropped on one of the application forms. The OnDropFiles event is invoked when user drops one or multiple files on one of the application forms. You must enable this feature by setting AllowDropFiles property of form. Event handler when help is required Event handler when a hint is required Event handler when a shortcut key is pressed Event handler for showing a hint Event handler when user input is required or is occurring Event handler for destruction of the application Is a hint required to be shown? Is the main form for the application to be shown? Default TRUE The Title to be displayed in the top border of the Main Window of the application The type of the application (ie the sort of device for which it is intended)

The type of the application:

Default, Desktop, Handheld, PDA, Smartphone

Application Properties: The properties of the current application

TApplication Properties can be set as a local default set of properties to be used for any new instance fo TApplication

Determine whether exceptions are being captured Boolean property (true if exceptions are being captured); reads or writes flag to see if they are being captured Determines which file to use for Help Reads or writes flag to determine name of Help file - name is stored as a string Determines Hint to be used Reads or writes flag to determine Hint - stored as a string Colour to be used when displaying Hint Reads or writes flag to determine Hint colour (stored as a TColor integer) Determines whether a hint is to be displayed Read or write flag to determine whether to display hint (stored as boolean, True if hint is to be displayed) Determines whether main form is to be displayed Title to be shown in Application's top Border Event handler for exceptions Event handler for the end of the session Event handler for the end of a query session Event handler for minimising the form Eent handler for restoring a form which has been minimised or maximised Event handler when files are dropped on the form Event handler when help is needed Event handler when a hint is needed Event handler for showing a hint Event handler when user input is received Data Module Data Module: for interfacing to the database The version of the LCL as string. Used to distinguish form streams of different versions. The number of data modules on the screen The list of Data Modules