aled.txt

动态红绿灯控件

[hhALed], Freeware with source.

Replaces:  TAutoLed V2.01 by Chang Ting SU ([e-mail])
Author:    Howard Harvey
Date:      24/MAY/1999
Version:   1.10c
HISTORY
-------
V1.10c  24/05/99 Changed name to ThhALed
V1.10b  21/12/97 Changed palette name to "Howie"
V1.10   15/12/97 Added Border Colour property
V1.04	13/12/97 Added Border True/False property
V1.03a   4/10/97 Added details for using runtime arrays of ALed
V1.03    31/7/97 Added ShowHint property
V1.02    24/7/97 Fixed Timer identification
V1.01   Initial Release

DESCRIPTION
-----------
This component can show 6 different styles of LED:
  Round Large (the original in TAutoLed)
  Round Small
  Square Large
  Square Small
  Rectangular Horizontal
  Rectangular Vertical

Dynamic resizing is possible, but the 6 predefined sizes are best.
Resizing upwards is acceptable, but resizing downwards results in loss of clarity.
Resizing requires a definition of the form 
  hhALED1.width := NewWidth ;
  hhALED1.height := NewHeight ;
to be executed when the form is first drawn or after each change in the style
or colours.

Dynamic selection of the LED style is also possible (try doing that in hardware!)

Any defined system colour can be independently defined for the ON and OFF states.
Blinking (when ON state selected) is provided, with user selectable blink rate.

Each LED may appear to be mounted on a background pedestal or directly on the
background, and may be selected at design or execution time.
The colour for the direct background defaults to clBtnFace (usually = clSilver)
but may be changed to any other colour, either at design or execution time.

[Events]
    OnClick,
    *OnMouseEnter,
    *OnMouseLeave,
    *OnTimer (When Blink is true)
[Properties]
    BorderColor (You can select any defined color),
    Blink (True or False),
    Bordered (True or False),
    FalseColor (when Value is false) (You can select any defined color),
    Hint (string),
    Interval (Blink Interval),
    LedStyle (LEDSmall,LEDLarge,LEDSqSmall,LEDSqLarge,LEDVertical,LEDHorizontal),
    ShowHints (True or False),
    TrueColor (when Value is true) (You can select any defined color),
    Value (True or False);


Focus Colour Control for LEDs

The OnMouseEnter and OnMouseLeave events can be used to provide focus indication
by changing the LED colour (eg changing from Lime/Green to Red/Maroon when the
mouse enters the LED region and reverting to Lime/Green on exit)


Suggested True (ON) and False (OFF) Colours for LEDs are:

        TrueColor       FalseColor
        ---------       ----------
        Red             Maroon
        Yellow          Olive
        Lime            Green
        Fuchsia         Purple
        Aqua            Teal
        Blue            Navy
        White           Gray
        Silver          Black


Click Control

Using the OnClick event allows clicking the LED to initiate any desired action,
such as starting/stopping a timer or counter.


This component has been successfully tested on Delphi2 and Delphi3.
Test code is not included.  The component is simple and registers
as hhALed in the Extras component panel.


Specifying Multiple LEDs as an Array
------------------------------------

An email from Andre Nel ([e-mail]) provided the clue for how to
process a large array of LEDs at run time, rather than having to locate
each individual LED at design time.  Here is a 100 LED example:

unit Aled1;

{ The following unit processes 100 hhALEDs.  Any LED when clicked will change
  to Blue and place its array identifier in an Edit box.  All LEDs are
  accessed randomly, sequencing off-lime-red-off.  The "tag" field in the
  LEDa array is used to identify which LED was clicked.
  The LEDs are arranged as 4 rows of 25 LEDs }

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ALed, ExtCtrls, StdCtrls;

type
  TForm1 = class(TForm)
    Timer1: TTimer;
    Edit1: TEdit;
    procedure hhALedOnCLick(Sender: TObject) ;
    procedure FormCreate(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  LEDa : array [0..99] of ThhALed ;

implementation

{$R *.DFM}

procedure TForm1.hhALedOnCLick(Sender: TObject) ;

{ OnClick Handler }
{ Edit1 is placed at 200,72 on the form }

var
  index : integer ;
begin
  with sender as ThhALed do
  begin
    index := tag ;
    Edit1.text := IntToStr( index ) ;
    value := true ;
    truecolor := clBlue ;
  end ;
end ;

procedure TForm1.FormCreate(Sender: TObject);

{ Define all the LEDs }

VAR
  index : integer ;

begin
  Form1.clientwidth := 16*25 ;
  Form1.clientHeight := 16*4 + 40 ;
  for index := 0 to 99 do
  begin
    LEDa[index] := ThhALed.create(self) ;
    LEDa[index].parent := self ;
    LEDa[index].top := (index DIV 25)*16 ;
    LEDa[index].left := (index MOD 25)*16 ;
    LEDa[index].OnClick := hhALedOnCLick ;
    LEDa[index].blink := false ;
    LEDa[index].tag := index ;
    LEDa[index].show ;
  end ;
end;

procedure TForm1.Timer1Timer(Sender: TObject);

{ Timer to randomly autosequence the LEDs }

var
  index : integer ;
begin
  index := RANDOM(100) ;
  if LEDa[index].value
  then begin
    if LEDa[index].truecolor = clLime
    then LEDa[index].truecolor := clRed
    else begin
      LEDa[index].value := false ;
      LEDa[index].truecolor := clLime ;
    end ;
  end
  else LEDa[index].value := true ;
end;
end.


Howard Harvey
([e-mail])
(http://dove.net.au/~hharvey)