internal void Dispose(bool disposing)
{
bool deletedHandle = false;
if (ownHandle)
{
if (!ownedByCacheManager || !disposing)
{
// If we were ever owned by the CacheManger and we're being disposed
// we can be sure that we're not in use by any DC's (otherwise Dispose() wouldn't have been called)
// skip the check IsFontInUse check in this case.
// Also skip the check if disposing == false, because the cache is thread-static
// and that means we're being called from the finalizer.
if (everOwnedByCacheManager || !disposing || !DeviceContexts.IsFontInUse(this))
{
Debug.Assert(hFont != IntPtr.Zero, "Unexpected null hFont.");
DbgUtil.AssertFinalization(this, disposing);
IntUnsafeNativeMethods.DeleteObject(new HandleRef(this, hFont));
#if TRACK_HFONT
Debug.WriteLine(DbgUtil.StackTraceToStr(String.Format("DeleteObject(HFONT[0x{0:x8}]))", (int)this.hFont)));
#endif
hFont = IntPtr.Zero;
ownHandle = false;
deletedHandle = true;
}
}
}
if (disposing && (deletedHandle || !ownHandle))
{
GC.SuppressFinalize(this);
}
}
public static WindowsFont GetWindowsFont(Font font, WindowsFontQuality fontQuality)
{
if (font == null)
{
return(null);
}
// First check if font is in the cache.
int count = 0;
int index = currentIndex;
// Search by index of most recently added object.
while (count < WindowsFontCache.Count)
{
if (WindowsFontCache[index].Key.Equals(font)) // don't do shallow comparison, we could miss cloned fonts.
{
// We got a Font in the cache, let's see if we have a WindowsFont with the same quality as required by the caller.
// WARNING: It is not expected that the WindowsFont is disposed externally since it is created by this class.
Debug.Assert(WindowsFontCache[index].Value.Hfont != IntPtr.Zero, "Cached WindowsFont was disposed, enable GDI_FINALIZATION_WATCH to track who did it!");
WindowsFont wf = WindowsFontCache[index].Value;
if (wf.Quality == fontQuality)
{
return(wf);
}
}
index--;
count++;
if (index < 0)
{
index = CacheSize - 1;
}
}
// Font is not in the cache, let's add it.
WindowsFont winFont = WindowsFont.FromFont(font, fontQuality);
KeyValuePair <Font, WindowsFont> newEntry = new KeyValuePair <Font, WindowsFont>(font, winFont);
currentIndex++;
if (currentIndex == CacheSize)
{
currentIndex = 0;
}
if (WindowsFontCache.Count == CacheSize) // No more room, update current index.
{
WindowsFont wfont = null;
// Go through the existing fonts in the cache, and see if any
// are not in use by a DC. If one isn't, replace that. If
// all are in use, new up a new font and do not cache it.
bool finished = false;
int startIndex = currentIndex;
int loopIndex = startIndex + 1;
while (!finished)
{
if (loopIndex >= CacheSize)
{
loopIndex = 0;
}
if (loopIndex == startIndex)
{
finished = true;
}
wfont = WindowsFontCache[loopIndex].Value;
if (!DeviceContexts.IsFontInUse(wfont))
{
currentIndex = loopIndex;
finished = true;
break;
}
else
{
loopIndex++;
wfont = null;
}
}
if (wfont != null)
{
WindowsFontCache[currentIndex] = newEntry;
winFont.OwnedByCacheManager = true;
#if GDI_FONT_CACHE_TRACK
Debug.WriteLine("Removing from cache: " + wfont);
Debug.WriteLine("Adding to cache: " + winFont);
#endif
wfont.OwnedByCacheManager = false;
wfont.Dispose();
}
else
{
// do not cache font - caller is ALWAYS responsible for
// disposing now. If it is owned by the CM, it will not
// disposed.
winFont.OwnedByCacheManager = false;
#if GDI_FONT_CACHE_TRACK
Debug.WriteLine("Creating uncached font: " + winFont);
#endif
}
}
else
{
winFont.OwnedByCacheManager = true;
WindowsFontCache.Add(newEntry);
#if GDI_FONT_CACHE_TRACK
Debug.WriteLine("Adding to cache: " + winFont);
#endif
}
return(winFont);
}
