LedControls - a Lazarus Visual Component Library

Background

The LED as light-emitting semiconductors was invented in 1962. I have been invented a year before so I could follow the development from the beginning. In 1992 Shuji Nakamura invented a blue LED which was the base for the latest revolution of illumination. He got the Nobel prize. Around 2014 I decided to bring the LED-7-Segment modules to modern computer displays in web applications. They refused to reward me with a Nobel price, so I decided to bring LEDs to Lazarus.

Intro - 4 LED-style visual Controls

The following 4 components may be used to visualize any processes behaviour. Iam using the Led component in many Delphi applications to signal states like incomming data, saving processes or processing results (green for ok, yellow for critical, red for alert). The 7-segment-led display may be usefull to display numeric values of measurments. The LedMeter component displays single values tendencies graphically with their possible limits.

TBlinker	Select an existing leds image with one of 7 colors or define a .png file with an image designed with Greenfish Icon Editor, Inkscape or whatever. Let your Led blink continuously or once.	Intro Reference
TSegmentDisplay	Define 7-segment-led modules and assign them a text to display. There are many styles and design details you can configure to give them an individual look.	Intro Reference
TLedMeter	A control with many styles to display single analogue values or vectors of values.	Intro Reference
TSignalStrength	Displays a signals strength or whatever.	Intro Reference

Download

LEDControls is available on GitHub:
https://github.com/Atomek61/LEDControls

Installation

I developed and tested the components with Windows 10 but I dont see a reason not to use them under other graphical operating systems.

Make sure you have installed the BGRABitmapPack. It is used by TSegmentDisplay.
Create a folder in your Lazarus source directory like Atomek.Controls/
Copy all the downloaded files to this directory
Open the package with Package|Open Package File...|ledcontrols.lpk
Install the package with Use|Install

TBlinker

A Blinker lets an image toggle periodically between two images - a bright one and a dark one. So you need an ImageList control which contains pairs of images.

Place the Blinker from palette Atomek on your form
Place an ImageList (palette Common Controls) on your form
Double-click the ImageList, Add.. the file LEDs.png from Atomek.Controls and split it
Select the Blinker and set the ImageList property with the newly created ImageList
Select the LED to be displayed with the properties ImageIndexOff and ImageIndexOn (0 and 1)
Activate the Blinker with property Active := true

Key features of the Blinker component are the boolean Active property and the Mode (bmContinuously or bmKeepAlive).

Find all details in the TBlinker reference.

TSegmentDisplay

After placing the control on your form two steps are important:

Define the modules , example SegmentDisplay.Modules := '8.8.8.8.';
Display a text wich matches the defined modules, example SegmentDisplay.Text := '234.5';

The default modules definition is "8.8.8.8". This means there are 4 8-segment modules. An 8-segment module can display all 7 cipher segments and a dot. A matching text may be "-1.23". The modules are filled from right to left. Missing symbols are interprated as SPACE, missing modules are ignored.

Examples for module definitions:

Clock, long form	'8888888888_88:88:88.888'
Text	'2018-05-03 07:23:45.678'
Clock, short form	'88:88'
Text	'12:34' or '12 34'

There are really a lot of design features available to enable you to create an individual LED segment style. For details see the TSegmentDisplay reference.

Use one of the predefined color sets or use your own colors for bright segments, dark segments and for the background.

Available modules are

"8"	7-segment module
"8."	8-segment module
":"	Double dot (for clocks)
"_"	Spacer

Displayable symbols are "0123456789AbCdEF-.:" and SPACE. You can define other symbols in the OnDrawSegments-event.

TLedMeter

This control displays one or more numerical values as colored bars made of discrete led elements.

Define the controls styles, define the colors and their ranges and set the levels to be displayed.

BarCount defines the number of bars
Orientation is loVertical or loHorizontal
Style is lsNormal or lsBiDirectional
Levels[] contains the bars levels as single precision values
ColorNodes is a collection containing color/level pairs
SegmentSize defines the height/width of the segments. 0 means quadratic.
MinLevel defines the minimum level (Mode=lsNormal only)

Hint: many technical values (audio pressure) are displayed logarithmic (dB). Its a good idea to assign Levels[i] := Log10(Value); instead of a linear scaling.

TSignalStrength

This control displays a signal strength level. You can define the colors and the minimum and maximum levels.

BarCount defines the number of bars
Level is the current level
MinLevel defines the lower limit
MaxLevel defines the upper limit
OnColor defines the bright segments color
OffColor defines the dark segments color
GapSize defines the width of the slit between segments.

Hint: many technical values (audio pressure) are displayed logarithmic (dB). Its a good idea to assign Level := Log10(Value); instead of a linear scaling. Dont forget to enter meaningfull limits for this level.