Changed how the bitmap font prepares characters.

Playground was updated to reflect this.

src/SlatedGameToolkit.Framework/Graphics/Text/BitmapFont.cs

@@ -67,9 +67,33 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
             return textures[index];
         }
 
-        public unsafe void Draw(MeshBatch batch, float x, float baseLine, string text, Color color) {
+        /// <summary>
+        /// Prepares the characters for rendering. All characters to be rendered in one frame should be loaded using this method.
+        /// This will also ensure that the bitmap font is big enough.
+        /// Calling this multiple times per frame is not good for performance as multiple texture uploads are occurring.
+        /// </summary>
+        /// <param name="characters">An array of characters to load. Won't load if already loaded.</param>
+        public void PrepareCharacterGroup(params char[] characters) {
             int textureChanges = 0;
+            foreach (char c in characters)
+            {
+                if (!glyphTexLocations.ContainsKey((c, scale)) || !textures[glyphTexLocations[(c, scale)]].ContainsChar(c, scale)) {
+                    glyphTexLocations.Remove((c, scale));
+                    if (!textures[drawingTo].Upload(scale, c)) {
+                        drawingTo++;
+                        if (drawingTo >= textures.Length) drawingTo = 0;
+                        FontTexture fontTexture = textures[drawingTo];
+                        fontTexture.Clear();
+                        fontTexture.Upload(scale, c);
+                        textureChanges++;
+                        if (textureChanges > textures.Length) throw new FrameworkUsageException(string.Format("Character group \"{0}\" takes up too much texture space! Consider increasing decreasing font size, or increasing texture lengths, or number of backing textures.", new string(characters)));
+                    }
+                    glyphTexLocations.Add((c, scale), drawingTo);
+                }
+            }
+        }
 
+        public unsafe void Draw(MeshBatch batch, float x, float baseLine, string text, Color color) {
             float currentPoint = x;
             char[] chars = text.ToCharArray();
             for (int i = 0; i < chars.Length; i++) {
@@ -80,19 +104,9 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
                 context.GetViewport(out vX, out vY, out viewWidth, out viewHeight);
 
                 if (c != ' ') {
-                    //Check if glyph is loaded, if not, load it.
+                    //Check if glyph is loaded, if not, throw exception.
                     if (!glyphTexLocations.ContainsKey((c, scale)) || !textures[glyphTexLocations[(c, scale)]].ContainsChar(c, scale)) {
-                        glyphTexLocations.Remove((c, scale));
+                        throw new FrameworkUsageException(string.Format("Character \'{0}\' was not prepared and is missing!", c));
-                        if (!textures[drawingTo].Upload(scale, c)) {
-                            drawingTo++;
-                            if (drawingTo >= textures.Length) drawingTo = 0;
-                            FontTexture fontTexture = textures[drawingTo];
-                            fontTexture.Clear();
-                            fontTexture.Upload(scale, c);
-                            textureChanges++;
-                            if (textureChanges > textures.Length) throw new FrameworkUsageException(string.Format("String \"{0}\" takes up too much texture space! Consider increasing decreasing font size, or increasing texture lengths, or number of backing textures. Attempted to swap {1} times within draw call.", text, textureChanges));
-                        }
-                        glyphTexLocations.Add((c, scale), drawingTo);
                     }
 
                     FontTexture texture = textures[glyphTexLocations[(c, scale)]];

src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs

@@ -80,6 +80,7 @@ namespace SlatedGameToolkit.Tools.Utilities.Playground
 
             font = new BitmapFont("Resources/Playground/earwig_factory_rg.ttf");
             font.PixelHeight = 128;
+            font.PrepareCharacterGroup("ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890".ToCharArray());
         }
 
         public void Render(double delta)