/// <devdoc>
/// Selects the specified object into the dc. If the specified object is the same as the one currently selected
/// in the dc, the object is not set and a null value is returned.
/// </devdoc>
public IntPtr SelectFont(WindowsFont font)
{
// Fonts are one of the most expensive objects to select in an hdc and in many cases we are passed a Font that is the
// same as the one already selected in the dc so to avoid a perf hit we get the hdc font's log font and compare it
// with the one passed in before selecting it in the hdc.
// Also, we avoid performing GDI operations that if done on an enhanced metafile DC would add an entry to it, hence
// reducing the size of the metafile.
if (font.Equals(this.Font))
{
return(IntPtr.Zero);
}
IntPtr result = SelectObject(font.Hfont, GdiObjectType.Font);
WindowsFont previousFont = selectedFont;
selectedFont = font;
hCurrentFont = font.Hfont;
// the measurement DC always leaves fonts selected for pref reasons.
// in this case, we need to diposse the font since the original
// creator didn't fully dispose.
if (previousFont != null)
{
#if DEBUG
//Disabling this assert until DevDiv Bugs 95968 gets fixed
//Debug.Assert(previousFont.Hfont != IntPtr.Zero, "A font has been disposed before it was unselected from the DC. This will leak a GDI handle on Win9x! Call ResetFont()");
#endif
if (MeasurementDCInfo.IsMeasurementDC(this))
{
previousFont.Dispose();
}
}
#if OPTIMIZED_MEASUREMENTDC
// once we've changed the font, update the last used font.
if (MeasurementDCInfo.IsMeasurementDC(this))
{
if (result != IntPtr.Zero)
{
MeasurementDCInfo.LastUsedFont = font;
}
else
{
// there was an error selecting the Font into the DC, we dont know anything about it.
MeasurementDCInfo.Reset();
}
}
#endif
return(result);
}
/// <devdoc>
/// Restores the device context to the specified state. The DC is restored by popping state information off a
/// stack created by earlier calls to the SaveHdc function.
/// The stack can contain the state information for several instances of the DC. If the state specified by the
/// specified parameter is not at the top of the stack, RestoreDC deletes all state information between the top
/// of the stack and the specified instance.
/// Specifies the saved state to be restored. If this parameter is positive, nSavedDC represents a specific
/// instance of the state to be restored. If this parameter is negative, nSavedDC represents an instance relative
/// to the current state. For example, -1 restores the most recently saved state.
/// See MSDN for more info.
/// </devdoc>
public void RestoreHdc()
{
#if TRACK_HDC
bool result =
#endif
// Note: Don't use the Hdc property here, it would force handle creation.
IntUnsafeNativeMethods.RestoreDC(new HandleRef(this, this.hDC), -1);
#if TRACK_HDC
// Note: Winforms may call this method during app exit at which point the DC may have been finalized already causing this assert to popup.
Debug.WriteLine(DbgUtil.StackTraceToStr(String.Format("ret[0]=DC.RestoreHdc(hDc=0x{1:x8})", result, unchecked ((int)this.hDC))));
#endif
Debug.Assert(contextStack != null, "Someone is calling RestoreHdc() before SaveHdc()");
if (contextStack != null)
{
GraphicsState g = (GraphicsState)contextStack.Pop();
hCurrentBmp = g.hBitmap;
hCurrentBrush = g.hBrush;
hCurrentPen = g.hPen;
hCurrentFont = g.hFont;
#if !DRAWING_NAMESPACE
if (g.font != null && g.font.IsAlive)
{
selectedFont = g.font.Target as WindowsFont;
}
else
{
WindowsFont previousFont = selectedFont;
selectedFont = null;
if (previousFont != null && MeasurementDCInfo.IsMeasurementDC(this))
{
previousFont.Dispose();
}
}
#endif
}
#if OPTIMIZED_MEASUREMENTDC
// in this case, GDI will copy back the previously saved font into the DC.
// we dont actually know what the font is in our measurement DC so
// we need to clear it off.
MeasurementDCInfo.ResetIfIsMeasurementDC(this.hDC);
#endif
}
internal void DisposeFont(bool disposing)
{
if (disposing)
{
DeviceContexts.RemoveDeviceContext(this);
}
if (selectedFont != null && selectedFont.Hfont != IntPtr.Zero)
{
IntPtr hCurrentFont = IntUnsafeNativeMethods.GetCurrentObject(new HandleRef(this, hDC), IntNativeMethods.OBJ_FONT);
if (hCurrentFont == selectedFont.Hfont)
{
// select initial font back in
IntUnsafeNativeMethods.SelectObject(new HandleRef(this, this.Hdc), new HandleRef(null, hInitialFont));
hCurrentFont = hInitialFont;
}
selectedFont.Dispose(disposing);
selectedFont = null;
}
}
/// <devdoc>
/// <para>
/// Calculates the spacing required for drawing text w/o clipping parts of a glyph.
/// </para>
/// </devdoc>
public float GetOverhangPadding(WindowsFont font)
{
// Some parts of a glyphs may be clipped depending on the font & font style, GDI+ adds 1/6 of tmHeight
// to each size of the text bounding box when drawing text to account for that; we do it here as well.
WindowsFont tmpfont = font;
if (tmpfont == null)
{
tmpfont = this.dc.Font;
}
float overhangPadding = tmpfont.Height / 6f;
if (tmpfont != font)
{
tmpfont.Dispose();
}
return(overhangPadding);
}
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);
}
