How to use IVsFontAndColorEvents?

Question

Microsoft's own site does not explain in details how to use this interface. They claim that this is the way to get notified if the Fonts & Colors change in Visual Studio.

I tried what seemed to be an obvious choice and implemented the interface on my package, but there were no attributes mentioned I should set on my VSPackage. Unfortunately that doesn't seem to be enough.

Here's a sample of what I did:

public class SceVSIPackage : Package, IVsFontAndColorEvents
{
    public int OnApply()
    {
        return VSConstants.S_OK;
    }

    public int OnFontChanged(ref Guid rguidCategory, FontInfo[] pInfo, LOGFONTW[] pLOGFONT, uint HFONT)
    {
        return VSConstants.S_OK;
    }

    public int OnItemChanged(ref Guid rguidCategory, string szItem, int iItem, ColorableItemInfo[] pInfo, uint crLiteralForeground, uint crLiteralBackground)
    {
        return VSConstants.S_OK;
    }

    public int OnReset(ref Guid rguidCategory)
    {
        return VSConstants.S_OK;
    }

    public int OnResetToBaseCategory(ref Guid rguidCategory)
    {
        return VSConstants.S_OK;
    }
}

Unfortunately none of the IVsFontAndColorEvent members (all the methods above) get called.

Do I miss something else? Like an attribute? Or proffering the service?

I also tried serviceContainer.AddService(typeof(IVsFontAndColorEvent), this, true); but it didn't help either.

Answer 1

Workaround

Unfortunately I couldn't make IVsFontAndColorEvents working. However, I could achieve the same (getting notified when the Fonts change in Tools\\Options\\Fonts and Colors\\Text Editor ) with the code found here .

The idea is to use TextManagerEvents instead of IVsFontAndColorEvents :

//using Microsoft.VisualStudio.TextManager.Interop;
IVsTextManager textManager = GetService(typeof(SVsTextManager)) as IVsTextManager;
if (textManager != null)
{
    IConnectionPointContainer container = textManager as IConnectionPointContainer;
    if (container != null)
    {
        IConnectionPoint textManagerEventsConnection;
        Guid eventGuid = typeof(IVsTextManagerEvents).GUID;
        container.FindConnectionPoint(ref eventGuid, out textManagerEventsConnection);
        if (textManagerEventsConnection != null)
        {
            TextManagerEvents textManagerEvents = new TextManagerEvents();
            uint textManagerCookie;
            textManagerEventsConnection.Advise(textManagerEvents, out textManagerCookie);
            if (textManagerCookie != 0)
            {
                textManagerEvents.FontColorPreferencesChanged += OnFontColorPreferencesChanged;
            }
        }
    }
}

---

Notes

1. OnFontColorPreferencesChanged

Just in case you are also interested in how to extract the font and color information, here is how I did it:

private FontInfo prevFontInfo;  // Store previous FontInfo to prevent execution of the event handler multiple times.

private void OnFontColorPreferencesChanged(object sender, EventArgs e)
{
    IVsFontAndColorStorage fontAndColorStorage = GetService(typeof(SVsFontAndColorStorage)) as IVsFontAndColorStorage;
    if (fontAndColorStorage != null)
    {
        // GlobalValues.FontsAndColors_TextEditor is found in the registry: HKEY_USERS\.DEFAULT\Software\Microsoft\VisualStudio\[VS_VER]_Config\FontAndColo‌​rs\Text Editor, where VS_VER is the actual Visual Studio version: 10.0, 11.0, 12.0, 14.0, etc.
        if (fontAndColorStorage.OpenCategory(GlobalValues.FontsAndColors_TextEditor, (uint)__FCSTORAGEFLAGS.FCSF_LOADDEFAULTS) == VSConstants.S_OK)
        {
            LOGFONTW[] logFontw = new LOGFONTW[1];  // Only 1 item expected
            FontInfo[] fontInfo = new FontInfo[1];  // Only 1 item expected
            if (fontAndColorStorage.GetFont(logFontw, fontInfo) == VSConstants.S_OK &&
                !prevFontInfo.Equals(fontInfo[0]))
            {
                prevFontInfo = fontInfo[0];

                // FontInfo uses pixels as units, WPF uses points. Conversion between the two is required.
                double fontSize = (double)new FontSizeConverter().ConvertFrom(string.Format("{0}pt", fontInfo.wPointSize));    
                FontFamily fontFamily = new FontFamily(fontInfo.bstrFaceName);
                // There you go, you have the FontFamily and size ready to use.
            }
            fontAndColorStorage.CloseCategory();
        }
    }
}

2. Limitations

Although this solutions is a usable workaround for me, it has some problems:

• when changing the font of the Text Editor, the OnFontColorPreferencesChanged event is raised multiple times. I can't tell if IVsFontAndColorEvents would raise the event only once or had the same problem (as I never got it working.) I solved this issue by introducing prevFontInfo and don't invoke my logic unless this value is different from fontInfo[0], the values I just read.
• the event fires only when the Text Editor fonts and colors are changed, but not when any of the rest (eg Environment Font or Output Window )
• the event does not fire when the bold option is changed. Nevertheless, the font weight is not seemed to be used by the IDE anyway...
• the event does not fire when "Use Defaults" is selected in Options/Fonts and Colors . As a matter of fact it doesn't fire either when it's reset to the default values by manually entering them (eg: font size to 10)

I hope some of these might be useful for someone stumbling upon this question.