We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you two Citrix podcasts. Learn about 2020 trends and get answers to your biggest Citrix questions!Listen Now


Paletteindex() relates to RGB() as...

yonasb asked
Medium Priority
Last Modified: 2010-04-04

My question is: can some give the code for a procedure
BLA (Paletteindex: word; var Red,Green,Blue: word/integer?)

such that Shape1 will give the same color as Shape2


yields the same as

BLA(PaletteIndex(x), Red,GReen,Blue);
Watch Question

You'r have problem because each control can have different palette and when you type
Shape1.Brush.Color := paletteindex(n) then you specify number in logical palette but when you type
Shape1.Brush.Color := RGB( ....) then windows calculate which entry of this paleete need to use.

I don't fully understand your question. Do you need read RGB values for PaletteEntry which have Index=n ?
If this is true you need to use GetPaletteEntries which retrive palette RGB values.


To Mirek:

I know :
UINT GetPaletteEntries(
    HPALETTE  hpal,UINT  iStartIndex,      
    UINT  nEntries,    LPPALETTEENTRY  lppe );

-> But I do not understand how to use it.

I want the code for the following procedure.

Procedure GetRGBFromCurrentPalette
        (index: integer;
         var Red,Green,Blue: integer);
??? <-can someone write this





Shape1 en Shape2 must give the same color ON THE SCREEN.

Can you or someone else please write this little procedure for me?

Retrive RGB for palette - no problem, but you don't know palette  for tshape ! I think so you try make pogram with wrong way. Tell me what you are doing and i try help you more.

procedure GetRGBFromPalette( Hpal : HPalette; index : integer; var R,G,B : integer );
var lppe : TPaletteEntry;
  if HPal<>0 then
    GetPaletteEntries ( HPal, index, 1, lppe );
    r:= lppe.peRed;
    g:= lppe.peGreen;
    b:= lppe.peBlue;
    ShowMessage( 'no palette' );

p.s. When you Set color from PaletteIndex then you can't retrive values for R,G,B without Handle to palette.  VCL playing with this handle but you can't get acces to  this handle. This is because TShape is only for simple shape if you need more you need use own component as descendant of TGraphicControl.
Do you understand my comment?
Do you need more help ?



I don't understand. I need more help.

Do you mean this: ?????

I can set  Shape1.Brush.Color := $01000001
When I do, the color of Shape1.Brush.Color becomes
palette color 1 in Windows palette (if that is the
current palette).
You say: I cannot get the RGB value because I don't have
a handle to the palette.

How can I read the color of Shape1.Brush??

I must be able to use $010000xx because I want to read
the current palette color of Windows. In my program some
shapes must have the same color and when my program is running
and I change the colorscheme in Windows, I want to see
the new colors in my program.

I also must be able to calculate the difference between
two color.

You understand?
I have DynShape[1].Brush.Color:= $01000001, RGB=R1,G1,B1
I have DynShape[10].Brush.Color:=$01000011, RGB=R10,G10,B10

I calculate Rdelta:= (R10-R1) div (10 -9)
   {  Gdelta, Bdelta  same way}

Then I say, DynShape[2..9] you get the colors in between:

for x:=2 to 9
  DynShape[x].Brush.Color:=RGB(R1 + (x-1)*Rdelta,
                               G1  + (x-1) *Gdelta,
                               B1  + (x-1) * Bdelta).

Do you understand what I want Mirek?

I increase the points (only to 70, I don't have more).



Adjusted points to 70


Edited text of question
I think so now I know what you need, and as i say later you do this in bad way. If you set color as $01.... then you don't use system palette but current realized plette for control. You can read system palette entries with GetPaletteEntries (winapi) and then set color as $00BBGGRR where BB is blue GG is green RR is red. This can be done in TShape without limitation.

I post here example after some hours.
1.Change of color scheme don't change system palette! If you need use colors from Color scheme then you must usee constans defined in Graphics.Pas

clScrollBar = TColor(COLOR_SCROLLBAR or $80000000);
  clBackground = TColor(COLOR_BACKGROUND or $80000000);
  clActiveCaption = TColor(COLOR_ACTIVECAPTION or $80000000);
  clInactiveCaption = TColor(COLOR_INACTIVECAPTION or $80000000);
  clMenu = TColor(COLOR_MENU or $80000000);
and many other

2.If you need read system palette and use then this is example :

procedure TForm1.Button1Click(Sender: TObject);
  lk : integer;
  r,g,b : byte;

  function GetPalColor( nr : integer; var r,g,b : byte ) : TColor;
    PalEntries : array[0..255] of TPaletteEntry;
    HowMany    : integer;
    l : longint;
    DC : HDC;
    DC := GetDC( Handle );  { retrive DC for form, it can be any valid DC }
    HowMany := GetSystemPaletteEntries( DC, 0, 255, PalEntries );
    ReleaseDC( Handle, DC );
    if nr>HowMany then
      ShowMessage( 'Palette have only '+IntToSTr(HowMany)+' entries' );
    l := PalEntries[nr].peBlue;
    l := l*256+PalEntries[nr].peGreen;
    l := l*256+PalEntries[nr].peRed;
    result := l;
    r := PalEntries[nr].peRed;
    g := PalEntries[nr].peGreen;
    b := PalEntries[nr].peBlue;

  lk := 5;
  Shape1.Brush.Color := GetPalColor(lk,r,g,b);
  Shape2.Brush.Color := RGB( r,g,b );

Do you need more ? Ask !

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
Are you there ?
Do you understand the colors ?
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.