unsafe void InitializeFont(GDIFont font)
{
IntPtr hdc = myTempGraphics.GetHdc();
IntPtr hfont = font.ToHfont();
SelectObject(hdc, hfont);
if (!GetCharWidth32(hdc, 0, 255, CharacterWidths))
throw new SystemException("Unable to measure character widths.");
tagTEXTMETRIC metrics = new tagTEXTMETRIC();
GetTextMetrics(hdc, ref metrics);
myLeadingSpace = metrics.tmInternalLeading;
myTrailingSpace = metrics.tmExternalLeading;
myTempGraphics.ReleaseHdc(hdc);
int width = 0;
for (int i = myFirstCharacterOfInterest; i <= myLastCharacterOfInterest; i++)
{
CharacterWidths[i] += myLeadingSpace + myTrailingSpace;
width += CharacterWidths[i];
}
myHeight = (int)Math.Round(myTempGraphics.MeasureString(myCharactersOfInterest, font).Height);
int squareDim = (int)Math.Ceiling(Math.Sqrt(width * myHeight));
squareDim = BitmapSource.GetValidTextureDimensionFromSize(squareDim);
int squareWidth = squareDim;
int squareHeight = squareDim;
float fSquareWidth = squareWidth;
float fSquareHeight = squareHeight;
Bitmap bitmap;
bool fit;
do
{
bitmap = new Bitmap(squareWidth, squareHeight, System.Drawing.Imaging.PixelFormat.Format16bppRgb565);
using (Graphics g = Graphics.FromImage(bitmap))
{
int x = 0;
int y = 0;
for (char i = myFirstCharacterOfInterest; i <= myLastCharacterOfInterest; i++)
{
if (x + CharacterWidths[i] >= fSquareWidth)
{
y += myHeight;
x = 0;
}
CharacterLocations[i] = new Point(x, y);
float uStart = x / fSquareWidth;
float uEnd = (x + CharacterWidths[i]) / fSquareWidth;
float vStart = y / fSquareHeight;
float vEnd = (y + myHeight) / fSquareHeight;
int offset = i * 4;
TextureCoordinates[offset] = new TextureCoordinate(uStart, vEnd);
TextureCoordinates[offset+ 1] = new TextureCoordinate(uStart, vStart);
TextureCoordinates[offset + 2] = new TextureCoordinate(uEnd, vEnd);
TextureCoordinates[offset + 3] = new TextureCoordinate(uEnd, vStart);
g.DrawString(i.ToString(), font, myWhiteBrush, x, y);
// adding a 1 pixel extra margin on the left seems to clear up some artifacting
// that occurs as a result of glyphs being too close together.
x += CharacterWidths[i] + 1;
}
fit = y + myHeight < fSquareHeight;
if (!fit)
{
squareWidth <<= 1;
fSquareWidth = squareWidth;
}
}
}
while (!fit);
byte[] alphaBytes = new byte[bitmap.Width * bitmap.Height];
BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format16bppRgb565);
int pixCount = 0;
for (int y = 0; y < bitmap.Height; y++)
{
short* yp = (short*)((int)data.Scan0 + data.Stride * y);
for (int x = 0; x < bitmap.Width; x++, pixCount++)
{
short* p = (short*)(yp + x);
short pixel = *p;
byte b = (byte)((pixel & 0x1F) << 3);
byte g = (byte)(((pixel >> 5) & 0x3F) << 2);
byte r = (byte)(((pixel >> 11) & 0x1F) << 3);
byte totalAlpha = (byte)((r + g + b) / 3);
alphaBytes[pixCount] = totalAlpha;
}
}
bitmap.UnlockBits(data);
bitmap.Dispose();
uint tex = 0;
gl.GenTextures(1, &tex);
gl.BindTexture(gl.GL_TEXTURE_2D, tex);
fixed (byte* alphaBytesPointer = alphaBytes)
{
gl.TexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_ALPHA, squareWidth, squareHeight, 0, gl.GL_ALPHA, gl.GL_UNSIGNED_BYTE, (IntPtr)alphaBytesPointer);
}
gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR);
gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR);
gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_WRAP_S, gl.GL_CLAMP_TO_EDGE);
gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_WRAP_T, gl.GL_CLAMP_TO_EDGE);
mySource = new BitmapSource();
mySource.myWidth = squareWidth;
mySource.myHeight = squareHeight;
mySource.myName = tex;
mySource.myIsTransparent = true;
}
static extern bool GetTextMetrics(IntPtr hdc, ref tagTEXTMETRIC lptm);
