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CreateGrayscaleIcon which supports 24 and 32 bpp icons

, 3 May 2007 CPOL
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A c++ function which uses GDI to create a channel based version of an icon. Using all the channels you can create a gray scale one

Screenshot - shot.gif

Introduction

While I was working on the update for my Hyperlink control I faced with the problem of automatically creating a grayscale icon when the control is in disabled state. I searched on CodeProject and found the CreateGrayscaleIcon by Davide Calabro but I noticed that it doesn't support 32bpp icons. In addition, it s resource usage was a little too heavy in my opinion. So I decided to write one on my own and here's the result.

Curiously enough, I found that simply changing the palette filling loop a bit could create any channel scale icon, so I've re-written the function and overloaded it to support a custom palette parameter which lets you to make custom replacement. Look at the demo project to understand what I'm talking about. If you want to use this function in C programs, simply change the overloaded version with a default parameter one.

Using the code

The function is very simple to use. Just call CreateGrayscaleIcon passing your HICON and the function will return the new gray scale icon.

HICON myIcon = (HICON)::LoadImage(
        AfxFindResourceHandle(MAKEINTRESOURCE(ICON_ID), RT_GROUP_ICON),
        MAKEINTRESOURCE(ICON_ID), IMAGE_ICON, 0, 0, 0);

HICON grayIcon = CreateGrayscaleIcon(myIcon);

If you want to use the overloaded version simply create a palette and pass it to the function, like this:

COLORREF palette[256];

for(int i = 0; i < 256; i++)
{
    palette[i] = RGB(255-i, 255-i, 255-i);
}

HICON myIcon = (HICON)::LoadImage(
        AfxFindResourceHandle(MAKEINTRESOURCE(ICON_ID), RT_GROUP_ICON),
        MAKEINTRESOURCE(ICON_ID), IMAGE_ICON, 0, 0, 0);

HICON grayIcon = CreateGrayscaleIcon(myIcon,palette);

This will create a grayscale icon, like the default not overloaded CreateGrayscaleIcon.

Notes

I found that icon on my hard drive but sincerely don't know where does it come from, so if it is copyrighted material and the owner of the rights doesn't want to let me use it, just let me know and I will replace it with something else.

Conclusion

So, that's all, I think. If you have problems or questions don't hesitate to post.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Elia Sarti
Synved Ltd.
Ireland Ireland

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Comments and Discussions

 
Generalanother bug Pin
poxui12-Nov-07 7:48
memberpoxui12-Nov-07 7:48 
GeneralRe: another bug Pin
Gladstone12-Nov-07 18:00
memberGladstone12-Nov-07 18:00 
GeneralBug Pin
poxui10-Nov-07 4:58
memberpoxui10-Nov-07 4:58 

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