The TApxTerminal Component

HierarchyPropertiesMethods

Unit:

AxTerm

Description:

The TApxTerminal component represents the visual part of a terminal. It is the only visual component in the Async Professional CLX family of terminal classes. It is responsible for maintaining the window handle and for performing the low-level processing to get all the possible keystrokes available on a PC keyboard.

Apart from this, it performs next to no work itself, handing off most of the display and other capabilities to an emulator component (a descendant of TApxTerminalEmulator). Essentially, the terminal component acts as a conduit between the PC screen and keyboard and the other classes that perform all of the work.

The main behaviors of the terminal component and its associated objects are as follows:

·Receives characters from the serial device and passes them onto the emulator for interpretation and processing.

·Traps all keystrokes and passes them onto the emulator for conversion into their terminal equivalents.

·The emulator maintains a buffer of several matrices, one for each of text, background color, text color, attributes, and character sets. This buffer stores the information needed to show the visual representation of the terminal.

·The terminal has the capability of maintaining a scrollback buffer to enable the user to scroll back through old data that has scrolled off the display. The terminal will automatically show scrollbars in that case.

·The terminal will automatically display scrollbars if the client window is smaller than the terminal display.

·If the terminal component is dropped onto a form and there is no existing emulator component on that form, the terminal will create an internal instance of a TTY (teletype) emulator. This means that the terminal component can be used as is for simple tasks.