Progressbar color fade?

[entrisity]

Hey guys,

I'm making a school project (game) and want to have a hp bar. I want it to be green if you have full health and go over to red if you have low hp (so it should fade/ have a gradient). I wanted to ask if there is any way to do that (I'm fine to download a package that support that kind of progress bar). I know that I can just do loads of if statements and the more i have the better the fade is but i want a other method that takes less work.

Thanks in advance!

[Handoko]

There is no ready-to-use color fade progress bar. But you can easily create the effect. For example you can try the test.zip below:

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Forms, Graphics, ExtCtrls, BGRAFlashProgressBar;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     BGRAFlashProgressBar1: TBGRAFlashProgressBar;
16.     Timer1: TTimer;
17.     procedure Timer1Timer(Sender: TObject);
18.   end;
19.  
20. var
21.   Form1: TForm1;
22.  
23. implementation
24.  
25. {$R *.lfm}
26.  
27. { TForm1 }
28.  
29. procedure TForm1.Timer1Timer(Sender: TObject);
30. var
31.   HP: Integer;
32.   ValRed, ValGreen, ValBlue: Byte;
33. begin
34.  
35.   HP := BGRAFlashProgressBar1.Value;
36.   if HP  > 0 then
37.     Dec(HP)
38.   else
39.     HP := BGRAFlashProgressBar1.MaxValue;
40.   BGRAFlashProgressBar1.Value := HP;
41.  
42.   ValRed   := Round((1 - HP/BGRAFlashProgressBar1.MaxValue) * 255);
43.   ValGreen := Round(HP / BGRAFlashProgressBar1.MaxValue * 255);
44.   ValBlue  := Round(255 - abs(ValRed-ValGreen));
45.   BGRAFlashProgressBar1.Color := RGBToColor(ValRed, ValGreen, ValBlue);
46.  
47. end;
48.  
49. end.

The code uses TBGRAFlashProgressBar from BGRAControl package:
http://wiki.freepascal.org/BGRAControls

You can manually install the package or you can install it using Online Package Manager:
Lazarus main menu > Package > Online Package Manager

[entrisity]

Hey, thanks for responding,

I'm kind of a newbie when it comes to open other projects. When im opening yours im getting following error message (see in picture). How do i fix that?
https://imgur.com/a/Hdd62yO

[Handoko]

Just tested, I have no problem with the download and opening the project. Have you installed BGRAControl package properly?

The image you provided shows that you're opening the file directly from temporary folder. You should unzip all the files to a new location (maybe Desktop) first, then you open the project from there.

[wp]

[...] want to have a hp bar. I want it to be green if you have full health and go over to red if you have low hp (so it should fade/ have a gradient).

The Lazarus port of the JVCL library contains a TJvSpecialProgressbar which can be configured to display a continuous color gradient. Unfortunately the component is not completely self-contained and you must install the packages JvCoreLazR, JvCoreLazD, JvMMLazR, JvMMLazD - you can find them in the Online-Package-Manager as subitems of the JVCLLaz entry.

Or if you can live with a little modfied version you can try the one in the attachment which is ready to use - you only copy it into your project folder and create it and set its properties at run-time, just like in the demo project.

[sash]

I know that I can just do loads of if statements and the more i have the better the fade is

You don't have to. For simple color transition use color blending / interpolation.

Code: Pascal  [Select][+][-]

1. function ColorLerp(col1, col2 : TColor; factor : single {0.0 .. 1.0}) : TColor;
2.  
3.   function ByteLerp(val1, val2 : byte; factor : single) : byte;
4.   begin
5.     Result := Round( (val1 * factor) + ( (1 - factor) * val2) );
6.   end;
7. begin
8.   Result := RGBToColor
9.   (
10.       ByteLerp(Red(col1), Red(col2), factor ),
11.       ByteLerp(Green(col1), Green(col2), factor ),
12.       ByteLerp(Blue(col1), Blue(col2), factor )
13.   );
14. end;
15.  

You can create your own Class/Helper utility function based on provided demo form, where TShape is simply resized according to scale factor.
No ifs were used