Teach Yourself Borland C++ in 14 Days - portal

158 Day 5
Standard Component Classes
The standard components are those components that encapsulate the most common
Windows controls. The standard component classes include TButton, TEdit, TListBox,
TMemo, TMainMenu, TPopupMenu, TCheckBox, TRadioButton, TRadioGroup, TGroupBox, and
TPanel.
Most of these classes encapsulate a Windows control, so I won’t discuss all of them right now.
The TMainMenu class encapsulates an application’s main menu. At design time, doubleclicking
the MainMenu component’s icon brings up the Menu Editor. TMainMenu has properties
that control whether the menu item is grayed out, whether it is checked, the help context ID,
the item’s hint text, and others. Each menu item has a single event, OnClick, so that you can
attach a function to a menu item being selected. I’ll discuss menus and the Menu Editor in
more detail on Day 7, “Working with the Form Designer and the Menu Designer.”
Another of the standard components of interest is TPanel.
A panel represents a rectangular region on a form, usually with its own components,
that can be treated as a single unit.
NEW TERM
For instance, if you wanted to build a speedbar for an application, you would start with a
panel and then place speed buttons on the panel. If you move the panel, the speed buttons
move with it. Panels can be used for a wide variety of tasks in C++Builder. You could use a
panel to build a status bar, for example. Panels have properties that control what type of edge
the panel should have; whether the panel is raised, sunken, or flat; and the width of the border.
Combinations of these properties can be used to create a variety of 3D panels.
C++Builder has another group of components that I’ll throw in with the standard controls.
These controls can be found under the Additional tab on the Component Palette. The classes
representing these components include TBitBtn, TSpeedButton, TMaskEdit, TStringGrid,
TDrawGrid, TImage, TShape, TBevel, and TScrollBox. The TBitBtn class represents a button
that has an image on it. TSpeedButton is also a button with an image, but this component is
designed to be used as a speed button on a control bar. A TSpeedButton is not a true button,
but rather a graphical depiction of a button. This allows you to have a large number of speed
buttons and not consume Windows resources for each of the buttons. The TImage component
allows you to place an image on a form that can then be selected from a file on disk. The
TBevel component can be used to create boxes and lines that are raised (bumps) or lowered
(dips). Bevels can be used to divide up a form into visual regions and generally to provide an
aesthetically pleasing form.
Windows 95 Custom Control Classes
VCL has component classes that encapsulate many of the Windows 32-bit custom controls.
These classes include TListView, TTreeView, TProgressBar, TTabControl, TPageControl,