CColor – RGB and HLS combined in one class

CodeGuru content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More.

The CColor class emerged from the need to manipulate color
in the HLS modell, this means to directly change attributes like luminance or saturation.
The HLS modell makes it very easy, to draw such things as color
gradients between any color, too. Perhaps NT 5.0 will support the HLS (or the similary
HSB) color modell, but I do not want to wait until the release, on the other side, my code
should also work under NT 4.0 and Win95/98. The CColor class
encapsulates the long known type COLORREF and extends it with the HLS color modell. An CColor object represents a color, whose RGB and HLS properties
can be directly read and manipulated. It makes the use of type COLORREF and the associated
macros superfluous.

Another handy feature, which I miss since long in the Win32 API, are named colors:
frequent common colors can be used by name (instead of using a RGB value). If you use only
a small number of colors, for example to emphasize portions of text, the use of named
colors makes code more understandible (in my humble opinion). X11 supports named colors
since I remeber X11, though optimal use of the limited hardware palette was probably the
original motive in those days. In the Html documentation of the Internet Explorer I
discovered again name colors and decided, to integrate excactly the same into the CColor class.

Demo Source (19k)
The source of the sample application.

CColor Reference
The detailled documentation of the CColor class.

Sample 2: Drawing of a color gradient with CColor

void DrawGradient(CDC& dc, int x, int y, CColor c1, CColor c2, int width, int height)
{
  ASSERT(width > 0);

  float dh = (c2.GetHue() - c1.GetHue()) / width;
  float dl = (c2.GetLuminance() - c1.GetLuminance()) / width;
  float ds = (c2.GetSaturation() - c1.GetSaturation()) / width;

  for (int i = 0; i < width; ++i)
  {
    CPen pen(PS_SOLID, 1, c1);
    CPen* pOld = dc.SelectObject(&pen);
    dc.MoveTo(x + i, y);
    dc.LineTo(x + i, y + height);
    dc.SelectObject(pOld);
    c1.SetHue(c1.GetHue() + dh);
    c1.SetLuminance(c1.GetLuminance() + dl);
    c1.SetSaturation(c1.GetSaturation() + ds);
  }
}

) 1999 by Christian
Rodemeyer