为什么使用十六进制颜色值时，TPanel的颜色属性显示错误的颜色？

Question

I am using Delphi 2010 and if I create a new VCL application, drop a TPanel on the form and set its "color" property to "clInactiveCaptionText" it shows the correct color.

Correct color:

However, if I enter the hex value for this color ($00434E54 --- R 67,G 78,B 84) it shows up incorrectly. I should note that the result is the same whether I enable runtime themes or not.

Wrong color:

Any idea on why it won't correctly show this color when specifying its hex value?

Answer 1

RGB color values are actually specified as BGR.

So if you want:

• red you need to specify $000000FF
• green you need to specify $0000FF00
• blue you need to specify $00FF0000

Answer 2

As others have indicated, the RGB values are stored internally as BGR (ie TColor value, or what Windows calls a COLORREF ), that's why when you specify a custom color code you obtain a different color.

To maintain your sanity when specifying colors in RGB form you can use the RGB() function from the Windows unit; this accepts parameters in the "natural"/intuitive RGB order (as byte values) and yields an appropriate TColor / COLORREF value:

  MyPanel.Color := RGB(67, 78, 84);

or if hex is easier:

  MyPanel.Color := RGB($43, $4E, $54);

Answer 3

这是因为您要以RGB格式设置TColor值，而必须使用BGR。

Answer 4

Actually Tcolor is RGBA color format and also $FF000000 is the alpha channel so:

• To get red chanel you can get $000000FF
• To get green chanel you can get $0000FF00
• To get bluechanel you can get $00FF0000
• To get alpha chanel chanel you can get $FF000000

And easily you can convert the tcolor value to rgb by :

IntToHex(ColorPanel1.Color,1) 

this also work in cross platform FMX delphi apps.

Answer 5

function HexToColor(sColor : string) : TColor;
begin
   Result :=
     RGB(
       StrToInt('$'+Copy(sColor, 1, 2)),
       StrToInt('$'+Copy(sColor, 3, 2)),
       StrToInt('$'+Copy(sColor, 5, 2))
     ) ;
end;

With this simple function you can make easier:

Panel1.Color := HexToColor ('16a086');