Updated font rendering code.

Source/Examples/Tutorial/Fonts.cs

@@ -24,7 +24,7 @@ namespace Examples.Tutorial
             this.VSync = VSyncMode.On;
         }
 
-        TextureFont serif;
+        TextureFont serif = new TextureFont(new Font(FontFamily.GenericSerif, 16.0f));
 
         string[] poem = new StreamReader("Data/Poem.txt").ReadToEnd().Replace('\r', ' ').Split('\n');
         float scroll_speed;
@@ -33,24 +33,56 @@ namespace Examples.Tutorial
         float warparound_position;
         float current_position;
 
+        int display_list;
+
         public override void OnLoad(EventArgs e)
         {
             GL.Enable(GL.Enums.EnableCap.TEXTURE_2D);
-            serif = new TextureFont(new Font(FontFamily.GenericSerif, 24, FontStyle.Regular, GraphicsUnit.Pixel));
+            serif.LoadGlyphs("ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz,.!?;()\'- ");
-            serif.LoadGlyphs("ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz,.!?");
 
-            scroll_speed = 4/(float)Height;
-            initial_position = -1.0f - 64 / (float)Height;  // 64 pixels below the bottom of the screen;
-            warparound_position = 7.0f;
             current_position = initial_position;
+            scroll_speed = -1.0f;
+
+            display_list = GL.GenLists(1);
+            GL.NewList(1, GL.Enums.ListMode.COMPILE);
+
+            GL.PushMatrix();
+
+            GL.MatrixMode(GL.Enums.MatrixMode.PROJECTION);
+            GL.LoadIdentity();
+            GL.Ortho(0.0, Width, Height, 0.0, 0.0, 1.0);
+            GL.MatrixMode(GL.Enums.MatrixMode.MODELVIEW);
+            GL.LoadIdentity();
+            
+            int i = 0, line = 0;
+            float x_pos, accum_x_pos = 0.0f;
+            foreach (string str in poem)
+            {
+                GL.Translate(0.0f, serif.LineSpacing * line, 0.0f);
+                foreach (char c in str)
+                {
+                    serif.PrintFast(c);
+                    x_pos = serif.MeasureWidth(str.Substring(i++, 1));
+                    accum_x_pos += x_pos;
+
+                    GL.Translate((int)(x_pos + 0.5f), 0.0f, 0.0f);
+                }
+                GL.LoadIdentity();
+                i = 0;
+                ++line;
+            }
+
+            GL.PopMatrix();
+
+            GL.EndList();
         }
 
         protected override void OnResize(OpenTK.Platform.ResizeEventArgs e)
         {
             GL.Viewport(0, 0, Width, Height);
-            GL.MatrixMode(GL.Enums.MatrixMode.PROJECTION);
+
-            GL.LoadIdentity();
+            initial_position = Height + serif.LineSpacing;
-            GL.Ortho(-1.0, 1.0, -1.0, 1.0, 0.0, 16.0);
+            warparound_position = -(poem.Length + 1) * serif.LineSpacing;
         }
 
         public override void OnUpdateFrame(UpdateFrameEventArgs e)
@@ -58,38 +90,29 @@ namespace Examples.Tutorial
             if (Keyboard[Key.Space])
                 scroll_speed = 0.0f;
             if (Keyboard[Key.Down])
-                scroll_speed -= 1 / (float)Height;
+                scroll_speed += 1;
             if (Keyboard[Key.Up])
-                scroll_speed += 1 / (float)Height;
+                scroll_speed -= 1;
             if (Keyboard[Key.Escape])
                 this.Exit();
         }
 
         public override void OnRenderFrame(RenderFrameEventArgs e)
         {
-            GL.MatrixMode(GL.Enums.MatrixMode.MODELVIEW);
-            GL.LoadIdentity();
-
             // We'll start printing from the lower left corner of the screen. The text
             // will slowly move updwards - the user can control the movement speed with
             // the keyboard arrows and the space bar.
             current_position += scroll_speed * (float)e.ScaleFactor;
-            if (current_position > 0.0f && current_position > warparound_position)
+            if (scroll_speed > 0.0f && current_position > initial_position)
-                current_position = initial_position;
-            else if (current_position < 0.0f && current_position < initial_position)
                 current_position = warparound_position;
-            scroll_position = ((int)(current_position * (float)Height)) / (float)Height;    // Round to closest pixel.
+            else if (scroll_speed < 0.0f && current_position < warparound_position)
-
+                current_position = initial_position;
-            GL.Translate(-1.0f, scroll_position, 0.0f);
+            scroll_position = current_position;
 
             GL.Clear(GL.Enums.ClearBufferMask.COLOR_BUFFER_BIT);
 
-            float line_spacing = -2.0f * serif.LineSpacing / (float)Height;
+            //GL.Translate(0.0f, scroll_position, 0.0f);
-            foreach (string line in poem)
+            GL.CallList(display_list);
-            {
-                serif.Print(line);
-                GL.Translate(0.0f, line_spacing, 0.0f);   // Move to the next line.
-            }
 
             SwapBuffers();
         }
@@ -99,7 +122,7 @@ namespace Examples.Tutorial
 
         public void Launch() 
         {
-            Run(30.0, 85.0);
+            Run(30.0, 0.0);
         }
 
         public static readonly int order = 6;

Source/OpenTK/Fonts/TextureFont.cs

@@ -11,65 +11,33 @@ using OpenTK.Platform;
 
 namespace OpenTK.Fonts
 {
-    public class TextureFont
+    public class TextureFont : IDisposable
     {
         Font font;
-        Dictionary<char, LoadedGlyph> loaded_glyphs = new Dictionary<char, LoadedGlyph>(36);
+        Dictionary<char, int> loaded_glyphs = new Dictionary<char, int>(36);
-        Graphics gfx;
+        Graphics gfx = Graphics.FromImage(new Bitmap(1, 1));
-
-        struct LoadedGlyph
-        {
-            public int List;
-            public float Width, Height;
-        }
 
         static int texture;
         static TexturePacker<Glyph> pack;
         static int texture_width, texture_height;
+        float[] viewport = new float[6];
 
+        /// <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;
-
-            if (pack == null)
-            {
-                // 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;
-
-                PrepareTexturePacker(size, size);
-                gfx = Graphics.FromImage(new Bitmap(1, 1));
-            }
         }
 
         /// <summary>
-        /// Not ready yet.
+        /// Prepares the specified glyphs for rendering.
         /// </summary>
-        /// <param name="width"></param>
+        /// <param name="glyphs">The glyphs to prepare for rendering.</param>
-        /// <param name="height"></param>
-        private void PrepareTexturePacker(int width, int height)
-        {
-            texture_width = width;
-            texture_height = height;
-            pack = new TexturePacker<Glyph>(texture_width, texture_height);
-            
-            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.LINEAR);
-
-            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);
-        }
-
         public void LoadGlyphs(string glyphs)
         {
             foreach (char c in glyphs)
@@ -79,16 +47,22 @@ namespace OpenTK.Fonts
             }
         }
 
-        private LoadedGlyph LoadGlyph(char c)
+        private int LoadGlyph(char c)
         {
+            if (pack == null)
+                PrepareTexturePacker();
+
             Glyph g = new Glyph(c, font);
             Rectangle rect = pack.Add(g);
 
-            using (Bitmap bmp = new Bitmap(g.Width, g.Height))
+            using (Bitmap bmp = new Bitmap(g.Width, g.Height, PixelFormat.Format32bppArgb))
             using (Graphics gfx = Graphics.FromImage(bmp))
             {
                 // Upload texture and create Display List:
+                GL.BindTexture(GL.Enums.TextureTarget.TEXTURE_2D, texture);
+
                 gfx.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
+                //gfx.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAliasGridFit;
 
                 gfx.Clear(Color.Transparent);
                 gfx.DrawString(g.Character.ToString(), g.Font, Brushes.White, 0.0f, 0.0f);
@@ -101,17 +75,11 @@ namespace OpenTK.Fonts
                 float bottom = rect.Bottom / (float)texture_height;
                 float right = rect.Right / (float)texture_width;
                 float top = rect.Top / (float)texture_height;
-                float width = (rect.Right - rect.Left); // / (float)screen_width;
+                float width = rect.Right - rect.Left;
-                float height = (rect.Top - rect.Bottom); // / (float)screen_height;
+                float height = rect.Bottom - rect.Top;
 
-                //width /= 2.0f;
+                int list = GL.GenLists(1);
-
+                GL.NewList(list, GL.Enums.ListMode.COMPILE);
-                LoadedGlyph lg = new LoadedGlyph();
-                
-                lg.List = GL.GenLists(1);
-                GL.NewList(lg.List, GL.Enums.ListMode.COMPILE);
-
-                //GL.PushAttrib(GL.Enums.AttribMask.ALL_ATTRIB_BITS);
 
                 GL.Enable(GL.Enums.EnableCap.BLEND);
                 GL.BlendFunc(GL.Enums.BlendingFactorSrc.ONE, GL.Enums.BlendingFactorDest.ONE_MINUS_SRC_ALPHA);
@@ -119,86 +87,159 @@ namespace OpenTK.Fonts
                 GL.Begin(GL.Enums.BeginMode.QUADS);
 
                 GL.TexCoord2(left, top);
-                GL.Vertex2(0.375f, 0.375f);
+                //GL.Vertex2(0.375f, 0.375f);
+                GL.Vertex2(0.0f, 0.0f);
 
                 GL.TexCoord2(right, top);
-                GL.Vertex2(0.375f + 2 * width, 0.375f);
+                //GL.Vertex2(0.375f + 2 * width, 0.375f);
+                GL.Vertex2(width, 0.0f);
 
                 GL.TexCoord2(right, bottom);
-                GL.Vertex2(0.375f + 2 * width, 0.375f + 2 * height);
+                //GL.Vertex2(0.375f + 2 * width, 0.375f + 2 * height);
+                GL.Vertex2(width, height);
 
                 GL.TexCoord2(left, bottom);
-                GL.Vertex2(0.375f, 0.375f + 2 * height);
+                //GL.Vertex2(0.375f, 0.375f + 2 * height);
+                GL.Vertex2(0.0f, height);
 
                 GL.End();
 
-                GL.PopAttrib();
-
                 GL.EndList();
 
-                lg.Width = 2 * width;
+                loaded_glyphs.Add(g.Character, list);
-                lg.Height = 2 * height;
 
-                loaded_glyphs.Add(g.Character, lg);
+                return list;
-                
-                return lg;
             }
         }
 
-        float[] viewport = new float[6];
+        /// <summary>
+        /// Calculates the optimal size for the font texture and TexturePacker, and creates both.
+        /// </summary>
+        private void PrepareTexturePacker()
+        {
+            // 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);
+
+            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);
+
+            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)
         {
-            LoadedGlyph lg;
+            int list;
-            GL.GetFloat(GL.Enums.GetPName.VIEWPORT, viewport);
+            if (loaded_glyphs.TryGetValue(c, out list))
-
-            GL.PushMatrix();
-
-            GL.Scale(1.0f / (viewport[2] - viewport[0]), 1.0f / (viewport[3] - viewport[1]), 1.0f);
-            if (loaded_glyphs.TryGetValue(c, out lg))
             {
-                GL.CallList(lg.List);
+                GL.CallList(list);
             }
             else
             {
-                GL.CallList(LoadGlyph(c).List);
+                GL.CallList(LoadGlyph(c));
             }
-            
-            GL.PopMatrix();
         }
 
-        public void Print(string str)
+        /// <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)
         {
-            GL.GetFloat(GL.Enums.GetPName.VIEWPORT, viewport);
+            GL.CallList(loaded_glyphs[c]);
-
-            GL.PushMatrix();
-
-            GL.Scale(1.0f / (viewport[2] - viewport[0]), 1.0f / (viewport[3] - viewport[1]), 1.0f);
-
-            LoadGlyphs(str);
-            int i = 0;
-            foreach (char c in str)
-            {
-                LoadedGlyph lg = loaded_glyphs[c];
-                GL.CallList(lg.List);
-
-                //GL.Translate(lg.Width, 0.0f, 0.0f);
-                float width = gfx.MeasureString(str.Substring(i, 1), font, 256, StringFormat.GenericTypographic).Width;
-                if (width == 0.0f) width = 8.0f;    // Spacebar.
-                GL.Translate(2 * width, 0.0f, 0.0f);
-                ++i;
-            }
-
-            GL.PopMatrix();
-        }
-
-        public void Print(string format, params object[] args)
-        {
-            Print(String.Format(format, args));
         }
 
+        /// <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;
+        }
+
+        #region IDisposable Members
+
+        bool disposed;
+
+        /// <summary>
+        /// Releases all resources used by this OpenTK.Fonts.TextureFont.
+        /// </summary>
+        public void Dispose()
+        {
+            GC.SuppressFinalize(this);
+            Dispose(true);
+        }
+
+        private void Dispose(bool manual)
+        {
+            if (!disposed)
+            {
+                pack = null;
+                if (manual)
+                {
+                    GL.DeleteTextures(1, ref texture);
+                    font.Dispose();
+                    gfx.Dispose();
+                }
+
+                disposed = true;
+            }
+        }
+
+        ~TextureFont()
+        {
+            Dispose(false);
+        }
+
+        #endregion
     }
 }