Opentk/Source/OpenTK/Fonts/TextureFont.cs

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C#
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using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Text;
using OpenTK.Math;
using OpenTK.OpenGL;
using System.Drawing.Imaging;
using OpenTK.Platform;
namespace OpenTK.Fonts
{
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public class TextureFont : IDisposable
{
Font font;
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Dictionary<char, int> loaded_glyphs = new Dictionary<char, int>(36);
Graphics gfx = Graphics.FromImage(new Bitmap(1, 1));
static int texture;
static TexturePacker<Glyph> pack;
static int texture_width, texture_height;
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float[] viewport = new float[6];
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/// <summary>
/// Constructs a new TextureFont object, using the specified System.Drawing.Font.
/// </summary>
/// <param name="font"></param>
public TextureFont(Font font)
{
if (font == null)
throw new ArgumentNullException("font", "Argument to TextureFont constructor cannot be null.");
this.font = font;
}
/// <summary>
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/// Prepares the specified glyphs for rendering.
/// </summary>
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/// <param name="glyphs">The glyphs to prepare for rendering.</param>
public void LoadGlyphs(string glyphs)
{
foreach (char c in glyphs)
{
if (!loaded_glyphs.ContainsKey(c))
LoadGlyph(c);
}
}
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private int LoadGlyph(char c)
{
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if (pack == null)
PrepareTexturePacker();
Glyph g = new Glyph(c, font);
Rectangle rect = pack.Add(g);
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using (Bitmap bmp = new Bitmap(g.Width, g.Height, PixelFormat.Format32bppArgb))
using (Graphics gfx = Graphics.FromImage(bmp))
{
// Upload texture and create Display List:
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GL.BindTexture(GL.Enums.TextureTarget.TEXTURE_2D, texture);
gfx.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
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//gfx.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAliasGridFit;
gfx.Clear(Color.Transparent);
gfx.DrawString(g.Character.ToString(), g.Font, Brushes.White, 0.0f, 0.0f);
BitmapData data = bmp.LockBits(new Rectangle(0, 0, g.Width, g.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
GL.TexSubImage2D(GL.Enums.TextureTarget.TEXTURE_2D, 0, rect.Left, rect.Top, rect.Width, rect.Height,
GL.Enums.PixelFormat.RGBA, GL.Enums.PixelType.UNSIGNED_BYTE, data.Scan0);
bmp.UnlockBits(data);
float left = rect.Left / (float)texture_width;
float bottom = rect.Bottom / (float)texture_height;
float right = rect.Right / (float)texture_width;
float top = rect.Top / (float)texture_height;
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float width = rect.Right - rect.Left;
float height = rect.Bottom - rect.Top;
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int list = GL.GenLists(1);
GL.NewList(list, GL.Enums.ListMode.COMPILE);
GL.Enable(GL.Enums.EnableCap.BLEND);
GL.BlendFunc(GL.Enums.BlendingFactorSrc.ONE, GL.Enums.BlendingFactorDest.ONE_MINUS_SRC_ALPHA);
GL.Begin(GL.Enums.BeginMode.QUADS);
GL.TexCoord2(left, top);
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//GL.Vertex2(0.375f, 0.375f);
GL.Vertex2(0.0f, 0.0f);
GL.TexCoord2(right, top);
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//GL.Vertex2(0.375f + 2 * width, 0.375f);
GL.Vertex2(width, 0.0f);
GL.TexCoord2(right, bottom);
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//GL.Vertex2(0.375f + 2 * width, 0.375f + 2 * height);
GL.Vertex2(width, height);
GL.TexCoord2(left, bottom);
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//GL.Vertex2(0.375f, 0.375f + 2 * height);
GL.Vertex2(0.0f, height);
GL.End();
GL.EndList();
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loaded_glyphs.Add(g.Character, list);
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return list;
}
}
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/// <summary>
/// Calculates the optimal size for the font texture and TexturePacker, and creates both.
/// </summary>
private void PrepareTexturePacker()
{
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// Calculate the size of the texture packer. We want a power-of-two size
// that is less than 1024 (supported in Geforce256-era cards), but large
// enough to hold at least 256 (16*16) font glyphs.
int size = (int)(font.Size * 16);
size = (int)System.Math.Pow(2.0, System.Math.Ceiling(System.Math.Log((double)size, 2.0)));
if (size > 1024)
size = 1024;
texture_width = size;
texture_height = size;
pack = new TexturePacker<Glyph>(texture_width, texture_height);
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GL.GenTextures(1, out texture);
GL.BindTexture(GL.Enums.TextureTarget.TEXTURE_2D, texture);
GL.TexParameter(GL.Enums.TextureTarget.TEXTURE_2D, GL.Enums.TextureParameterName.TEXTURE_MIN_FILTER, (int)GL.Enums.All.LINEAR);
GL.TexParameter(GL.Enums.TextureTarget.TEXTURE_2D, GL.Enums.TextureParameterName.TEXTURE_MAG_FILTER, (int)GL.Enums.All.NEAREST);
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byte[] data = new byte[texture_height * texture_width * 4];
GL.TexImage2D(GL.Enums.TextureTarget.TEXTURE_2D, 0, 4, texture_width, texture_height, 0,
GL.Enums.PixelFormat.RGBA, GL.Enums.PixelType.UNSIGNED_BYTE, data);
}
/// <summary>
/// Prints a glyph.
/// </summary>
/// <param name="c">The character corresponding to the glyph to print.</param>
/// <remarks>
/// The print position is specified by the active Modelview matrix.
/// <para>
/// To print pixel perfect fonts, you must setup a Projection matrix that is maps one texel to one pixel. This
/// can be achieved by calling GL.Ortho with width/height set to the actual viewport size, or alternatively,
/// by calling GL.Scale(1.0f/viewport_width, 1.0f/viewport_height, 0.0f).
/// </para>
/// <para>
/// To avoid filtering artifacts, avoid positioning characters on fractional pixels.
/// This is usually achieved by adding 0.5f to the glyph's position and extracting the integer component,
/// i.e. GL.Translate((int)(x_pos + 0.5f), (int)(y_pos + 0.5f), 0.0f);
/// </para>
/// </remarks>
/// <seealso cref="PrintFast"/>
public void Print(char c)
{
int list;
if (loaded_glyphs.TryGetValue(c, out list))
{
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GL.CallList(list);
}
else
{
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GL.CallList(LoadGlyph(c));
}
}
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/// <summary>
/// Prints a previously loaded glyph.
/// </summary>
/// <param name="c">The character corresponding to the glyph to print.</param>
/// <remarks>
/// You must call the LoadGlyphs function with the corresponding glyph, before using
/// PrintFast. Otherwise, this function works exactly like Print.
/// </remarks>
/// <see cref="Print"/>
/// <seealso cref="LoadGlyphs"/>
public void PrintFast(char c)
{
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GL.CallList(loaded_glyphs[c]);
}
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/// <summary>
/// Gets a float indicating the default line spacing of this font.
/// </summary>
public float LineSpacing
{
get { return font.Height; }
}
/// <summary>
/// Measures the width of the specified string.
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public float MeasureWidth(string str)
{
float distance = gfx.MeasureString(str, font, 16384, StringFormat.GenericTypographic).Width;
if (distance == 0)
distance = font.SizeInPoints * 0.5f;
return distance;
}
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#region IDisposable Members
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bool disposed;
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/// <summary>
/// Releases all resources used by this OpenTK.Fonts.TextureFont.
/// </summary>
public void Dispose()
{
GC.SuppressFinalize(this);
Dispose(true);
}
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private void Dispose(bool manual)
{
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if (!disposed)
{
pack = null;
if (manual)
{
GL.DeleteTextures(1, ref texture);
font.Dispose();
gfx.Dispose();
}
disposed = true;
}
}
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~TextureFont()
{
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Dispose(false);
}
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#endregion
}
}