internal static bool IsCombinationDefined(string className, int part)
{
bool returnVal = false;
if (!IsSupported)
{
if (!VisualStyleInformation.IsEnabledByUser)
{
throw new InvalidOperationException(SR.VisualStyleNotActive);
}
else
{
throw new InvalidOperationException(SR.VisualStylesDisabledInClientArea);
}
}
if (className == null)
{
throw new ArgumentNullException(nameof(className));
}
IntPtr hTheme = GetHandle(className, false);
if (hTheme != IntPtr.Zero)
{
// IsThemePartDefined doesn't work for part = 0, although there are valid parts numbered 0. We
// allow these explicitly here.
if (part == 0)
{
returnVal = true;
}
else
{
returnVal = UxTheme.IsThemePartDefined(hTheme, part, 0).IsTrue();
}
}
//if the combo isn't defined, check the validity of our theme handle cache
if (!returnVal)
{
using (ThemeHandle tHandle = ThemeHandle.Create(className, false))
{
if (tHandle != null)
{
returnVal = UxTheme.IsThemePartDefined(tHandle, part, 0).IsTrue();
}
//if we did, in fact get a new correct theme handle, our cache is out of date -- update it now.
if (returnVal)
{
RefreshCache();
}
}
}
return(returnVal);
}
