Windows Forms .NET 2.0: How to draw a PNG icon?

Question

Note: Question Using 256 x 256 Vista icon in application deals with using a \"Vista\" icon as the application\'s icon. This question deals with manually paintin

Answer 1

Today, I made a very nice function for extracting the 256x256 Bitmaps from Vista icons.

I use it to display the large icon as a Bitmap in "About" box.

This function takes Icon object as a parameter. So, you can use it with any icons - from resources, from files, from streams, and so on. It runs on any OS, because it does not use any Win32 API, it is 100% managed code :-)

Bitmap ExtractVistaIcon(Icon icoIcon)

I posted my function here: ExtractVistaIcon()

Answer 2

The ResourceManager loads the icon based on the bits stored in the resources. However, the way it handles loading won't let you access the 256x256 icon (this information does not make its way into the System.Drawing.Icon that you are getting back).

I am sorry to disappoint you, but the only way which works that I am aware of is to load the icon through a P/Invoke of LoadImage and working with a file (yes, I know, that's not what you were looking for). So the new question should be: how do I extract the bits of a given resource so that I can store them to a file? I fear that this isn't possible either, having done some stepping through System.Resources.ResourceReader, as the resource data seems to be a collection of serialized .NET objects.

Anyway, for those who can afford to load the icon from a .ICO file (and for myself, as a future reference on how to load 256x256 icons), call IconConverter.LoadIcon:

using System.Runtime.InteropServices;

static class IconConverter
{
    public static System.Drawing.Icon LoadIcon(string path, int width, int height)
    {
        System.IntPtr hIcon;
        hIcon = LoadImage (System.IntPtr.Zero, path, IMAGE_ICON, width, height,
                           LR_LOADFROMFILE);
        if (hIcon == System.IntPtr.Zero)
        {
            return null;
        }
        return System.Drawing.Icon.FromHandle (hIcon);
    }

    const int IMAGE_ICON = 1;
    const int LR_LOADFROMFILE = 0x0010;

    [DllImport ("user32.dll", SetLastError=true, CharSet=CharSet.Auto)]
    static extern System.IntPtr LoadImage(System.IntPtr hInstance,
                                          string lpszName, uint uType,
                                          int cxDesired, int cyDesired,
                                          uint fuLoad);
}

Once you have the System.Drawing.Icon in the expected size, just paint it using graphics.DrawIconUnstretched.

Answer 3

I asked a similar question a while ago but with not much luck. Some of the answers in my post may help you, there was one way but it looks pretty hard. Link to my post here