Changing Colors in Bitmaps and Making Icons from Them

Environment: MFC/GDI

The day has come when I need to have a large number of identical icons with only one difference—some colors will change from icon to icon. I found the solution for making all of my icons from a single bitmap, and changing colors on the fly. So, I wrote my CCloneBitmap class. It is derived from CBitmap and is able to change colors and export 32x32 icons.

It is very simple to use. Just follow these steps:

  1. Load the bitmap using the LoadBitmap() function.
  2. Make a clone of this bitmap by calling a Clone() method.
  3. Change colors of the bitmap by calling a ChangeColor() method.
  4. You can make a 32x32 icon from this bitmap (if bitmap is 32x32).

Here is a simple example of how to use this class:

HBITMAP hBmp;
CCloneBitmap bmpClone;
HICON hIcon;
hBmp=LoadBitmap(AfxGetResourceHandle(),
     MAKEINTRESOURCE(ID_LIGHTCAR));
if(hBmp!=NULL)
{
  bmpClone.Clone(hBmp);
  DeleteObject(hBmp);
  bmpClone.ChangeColor(IRGB(0,0,0), IRGB(255,0,0));
  // change BLACK pixels to RED ones.
  hIcon=bmpClone.MakeIcon(IRGB(255,255,255));
  // make icon, using WHITE color as transparent.
}
Note: Remember to use the IRGB() macro instead of RGB().

If you have a color in the COLORREF variable, use the INVERSECOLOR() macro:

bmpClone.ChangeColor(IRGB(0,0,0), INVERSECOLOR(myColor));

Downloads

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Comments

  • Help with dynamic bitmap

    Posted by Legacy on 02/10/2004 12:00am

    Originally posted by: VIjay Shan

    Hi,
    I found your article to be extremely helpful, though had a couplea questions how do i use this class if i have a modified bitmap (cbitmap*). when i paste this bitmap into the clipboard it works fine but when i get a handle and pass it to the clone function and use makeicon it just gives me a black square back. whereas when i try the samething with a preproduced bitmap it works fine. Any kinda help would be appreciated.

    Vijay

    Reply
  • Great, but if you (or someone) would please....

    Posted by Legacy on 05/30/2003 12:00am

    Originally posted by: Chris

    Hello, I'm a Borland C++ Builder programmer and I'd love to use that code, I have MSVC++ and have dabbled in it... I've managed to convert most of the code, but I'm having problems, I was wondering if you could convert it into standard Windows SDK code(nothing like CDC or CBitmap used) and then post it for all programmers to use.
    Thanks and have a nice day. :)

    Reply
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