如何将HSB转换为RGB [英] How to convert HSB to RGB

问题描述

我有一个Delphi XE2项目使用 Timer04 更改 Label01字体颜色。所以我写了以下代码：

I having one Delphi XE2 Project to change Label01 Font Color using Timer04. So I have written the following codes:

procedure TMainForm.FormCreate(Sender: TObject);
begin
  Timer04.Enabled := true;
end;
..
..
..
..
..
procedure TMainForm.Timer04Timer(Sender: TObject);
var
  StartColor, RedColor, GreenColor, BlueColor: integer;
begin
  StartColor := ColorToRGB(Label01.Font.Color);
  RedColor := GetRValue(StartColor);
  GreenColor := GetGValue(StartColor);
  BlueColor := GetBValue(StartColor);
  if RedColor <= 251 then Inc(RedColor, 1) else RedColor := 1;
  if GreenColor <= 252 then Inc(GreenColor, 2) else GreenColor := 2;
  if BlueColor <= 253 then Inc(BlueColor, 3) else BlueColor := 3;
  Label01.Font.Color := RGB(RedColor, GreenColor, BlueColor);
end;

这段代码工作完美。 Label01字体颜色不同颜色之间的变化。

This codes work perfectly. Label01 Font Color changes between different colors.

现在我试图实现 Label02颜色将被修改（如绿色），亮点的值将从 0 增加到 100 。如果值达到 100 ，它将会降低到 0 ，并且循环将持续。

Now I am trying to implement that Label02 Color will be fixed (say Green) and the value of brightnees will be increase from 0 to 100. If the value reaches to 100 it will be decreased to 0 and it will be continuous to a loop.

对于我的情况，我选择了 HUE = 135 ， SATURATION = 85 和 BRIGHTNESS = 50 。 BRIGHTNESS 的值将从 50 增加到 100 ，然后将从 100 至 0 ，并将继续。
但是问题是没有这样的函数 HSB 转换为 RGB ，反之亦然， Delphi XE2 。我已经走了但是我发现任何函数为 HSBToRGB 。只有一些 Delphi Unit 可用。我已经阅读了他们的重新发现，发现每个人都有一些错误。

For my case I have chosen HUE=135, SATURATION=85 and BRIGHTNESS=50. The value of BRIGHTNESS will be increased from 50 to 100 and then will be decreased from 100 to 0 and it will be continued. But the problem is that there is no such Function available to convert HSB to RGB and vice versa in Delphi XE2. I have Gooled it. But I have found any Function as HSBToRGB. Only some Delphi Unit is availabe. I have read their revoews and found that every one is having some bugs.

推荐答案

这是一个Delphi翻译的C代码这里： http://www.cs.rit.edu/~ncs/color /t_convert.html

Here is a Delphi a translation of C code found here: http://www.cs.rit.edu/~ncs/color/t_convert.html

function RGBFP(R, G, B: Double): TColor;
const
  RGBmax = 255;
begin
  Result := RGB(Round(RGBmax * R), Round(RGBmax * G), Round(RGBmax * B));
end;

function HSVtoRGB(H, S, V: Double): TColor;
var
  i: Integer;
  f, p, q, t: Double;
begin
  Assert(InRange(H, 0.0, 1.0));
  Assert(InRange(S, 0.0, 1.0));
  Assert(InRange(V, 0.0, 1.0));

  if S = 0.0 then
  begin
    // achromatic (grey)
    Result := RGBFP(V, V, V);
    exit;
  end;

  H := H * 6.0; // sector 0 to 5
  i := floor(H);
  f := H - i; // fractional part of H
  p := V * (1.0 - S);
  q := V * (1.0 - S * f);
  t := V * (1.0 - S * (1.0 - f));
  case i of
  0:
    Result := RGBFP(V, t, p);
  1:
    Result := RGBFP(q, V, p);
  2:
    Result := RGBFP(p, V, t);
  3:
    Result := RGBFP(p, q, V);
  4:
    Result := RGBFP(t, p, V);
  else
    Result := RGBFP(V, p, q);
  end;
end;

我给了这个最小的测试。请确保双重检查。

I've given this minimal testing. Please do feel free to double check it.

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