private static extern uint GetGlyphOutline(IntPtr hdc, uint ch, uint format, out GLYPHMETRICS gm, uint cb, IntPtr buffer, ref MAT2 mat2);
public static Image GetGlyphOutlineImage(Font font, char ch, out GLYPHMETRICS gm)
{
byte[] alpha;
int size;
using (FontDC dc = new FontDC(font))
{
MAT2 mat = new MAT2();
mat.eM11.value = 1;
mat.eM22.value = 1;
size = (int)GetGlyphOutline(dc.handle, ch, (uint)GlyphOutline.GGO_GRAY8_BITMAP, out gm, 0, IntPtr.Zero, ref mat);
if (size <= 0)
{
return null;
}
IntPtr bufptr = Marshal.AllocHGlobal(size);
try
{
alpha = new byte[size];
GetGlyphOutline(dc.handle, ch, (uint)GlyphOutline.GGO_GRAY8_BITMAP, out gm, (uint)size, bufptr, ref mat);
Marshal.Copy(bufptr, alpha, 0, size);
}
finally
{
Marshal.FreeHGlobal(bufptr);
}
}
int stride = (int)(gm.gmBlackBoxX + 3) & ~3; // dword alinged
Bitmap bmp = new Bitmap(stride, (int)gm.gmBlackBoxY, PixelFormat.Format32bppArgb);
BitmapData bd = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
int bmpSize = bd.Stride * bd.Height;
byte[] bmpValues = new byte[bmpSize];
Marshal.Copy(bd.Scan0, bmpValues, 0, bmpSize);
const int bias = 0x40;
for (int i = 0; i < size; i++)
{
byte v = (byte)((int)alpha[i] * 255 / bias);
bmpValues[i * 4 + 0] = 0xff;
bmpValues[i * 4 + 1] = 0xff;
bmpValues[i * 4 + 2] = 0xff;
bmpValues[i * 4 + 3] = v;
}
Marshal.Copy(bmpValues, 0, bd.Scan0, bmpSize);
bmp.UnlockBits(bd);
return bmp;
}