/// <summary>
/// Creates a WindowsFont from the handle to a native GDI font and optionally takes ownership of managing
/// the lifetime of the handle.
/// </summary>
public unsafe static WindowsFont FromHfont(Gdi32.HFONT hFont, bool takeOwnership = false)
{
Gdi32.GetObjectW(hFont, out User32.LOGFONTW logFont);
FontStyle style = FontStyle.Regular;
if (logFont.lfWeight == Gdi32.FW.BOLD)
{
style |= FontStyle.Bold;
}
if (logFont.lfItalic == True)
{
style |= FontStyle.Italic;
}
if (logFont.lfUnderline == True)
{
style |= FontStyle.Underline;
}
if (logFont.lfStrikeOut == True)
{
style |= FontStyle.Strikeout;
}
WindowsFont wf = new WindowsFont(logFont, style, createHandle: false)
{
Hfont = hFont,
_ownHandle = takeOwnership // if true, hFont will be deleted on dispose.
};
return(wf);
}
/// <summary>
/// Creates a WindowsFont from the font selected in the supplied dc.
/// </summary>
public static WindowsFont FromHdc(Gdi32.HDC hdc)
{
Gdi32.HFONT hFont = (Gdi32.HFONT)Gdi32.GetCurrentObject(hdc, Gdi32.ObjectType.OBJ_FONT);
// don't call DeleteObject on handle from GetCurrentObject, it is the one selected in the hdc.
return(FromHfont(hFont));
}
private void Dispose(bool disposing)
{
if (!_handle.IsNull)
{
Gdi32.DeleteObject(_handle);
_handle = default;
}
}
public unsafe void CreateFontIndirect()
{
LOGFONTW logFont = default;
Gdi32.HFONT handle = Gdi32.CreateFontIndirectW(ref logFont);
Assert.False(handle.IsNull);
Assert.True(Gdi32.DeleteObject(handle).IsTrue());
}
/// <summary>
/// Constructs a WindowsFont object from an existing System.Drawing.Font object (GDI+), based on the screen dc
/// MapMode and resolution (normally: MM_TEXT and 96 dpi).
/// </summary>
private static Gdi32.HFONT FromFont(Font font, Gdi32.QUALITY quality = Gdi32.QUALITY.DEFAULT)
{
string familyName = font.FontFamily.Name;
// Strip vertical-font mark from the name if needed.
if (familyName != null && familyName.Length > 1 && familyName[0] == '@')
{
familyName = familyName.Substring(1);
}
// Now, creating it using the Font.SizeInPoints makes it GraphicsUnit-independent.
Debug.Assert(font.SizeInPoints > 0.0f, "size has a negative value.");
// Get the font height from the specified size. The size is in point units and height in logical units
// (pixels when using MM_TEXT) so we need to make the conversion using the number of pixels per logical
// inch along the screen height. (1 point = 1/72 inch.)
int pixelsY = (int)Math.Ceiling(DpiHelper.DeviceDpi * font.SizeInPoints / 72);
// The lfHeight represents the font cell height (line spacing) which includes the internal leading; we
// specify a negative size value (in pixels) for the height so the font mapper provides the closest match
// for the character height rather than the cell height.
User32.LOGFONTW logFont = new User32.LOGFONTW
{
lfHeight = -pixelsY,
lfCharSet = font.GdiCharSet,
lfOutPrecision = Gdi32.OUT_PRECIS.TT,
lfQuality = quality,
lfWeight = (font.Style & FontStyle.Bold) == FontStyle.Bold ? Gdi32.FW.BOLD : Gdi32.FW.NORMAL,
lfItalic = (font.Style & FontStyle.Italic) == FontStyle.Italic ? True : False,
lfUnderline = (font.Style & FontStyle.Underline) == FontStyle.Underline ? True : False,
lfStrikeOut = (font.Style & FontStyle.Strikeout) == FontStyle.Strikeout ? True : False,
FaceName = familyName
};
if (logFont.FaceName.IsEmpty)
{
logFont.FaceName = DefaultFaceName;
}
Gdi32.HFONT hfont = Gdi32.CreateFontIndirectW(ref logFont);
if (hfont.IsNull)
{
// Get the default font if we couldn't get what we requested.
logFont.FaceName = DefaultFaceName;
logFont.lfOutPrecision = Gdi32.OUT_PRECIS.TT_ONLY;
hfont = Gdi32.CreateFontIndirectW(ref logFont);
Debug.Assert(!hfont.IsNull);
}
return(hfont);
}
public static FontCache.Scope GetHFONT(Font?font, Gdi32.QUALITY quality, Gdi32.HDC hdc)
{
if (font != null)
{
return(GetHFONT(font, quality));
}
// Font is null, build off of the specified HDC's current font.
Gdi32.HFONT hfont = (Gdi32.HFONT)Gdi32.GetCurrentObject(hdc, Gdi32.OBJ.FONT);
return(new FontCache.Scope(hfont));
}
/// <summary>
/// Returns the Size of the given text using the specified font if not null, otherwise the font currently
/// set in the dc is used.
/// This method is used to get the size in points of a line of text; it uses GetTextExtentPoint32 function
/// which computes the width and height of the text ignoring TAB\CR\LF characters.
/// A text extent is the distance between the beginning of the space and a character that will fit in the space.
/// </summary>
public static Size GetTextExtent(this Gdi32.HDC hdc, string?text, Gdi32.HFONT hfont)
{
if (string.IsNullOrEmpty(text))
{
return(Size.Empty);
}
Size size = new Size();
using var selectFont = new Gdi32.SelectObjectScope(hdc, hfont);
Gdi32.GetTextExtentPoint32W(hdc, text, text.Length, ref size);
return(new Size(size.Width, size.Height));
}
internal FontHandleWrapper(Font font)
{
_handle = (Gdi32.HFONT)font.ToHfont();
}
