WIP: measure text in Font.

Voile/Source/Resources/Font.cs

@@ -34,6 +34,8 @@ public class Font : Resource, IDisposable
     internal nint FacePtr;
     internal nint LibraryPtr;
 
+    internal List<int> Codepoints => _glyphs.Keys.ToList();
+
     public Font(string path, byte[] buffer) : base(path)
     {
         Buffer = buffer;
@@ -62,12 +64,38 @@ public class Font : Resource, IDisposable
         }
     }
 
-    public void Measure(string text)
+    /// <summary>
+    /// Measures a given string using the font metrics.
+    /// </summary>
+    /// <param name="text">Text to measure.</param>
+    /// <returns>A <see cref="Rect"/> with the sizes of a given text using this font.</returns>
+    public Rect Measure(string text)
     {
+        if (string.IsNullOrEmpty(text))
+            return Rect.Zero;
+
+        float totalWidth = 0;
+        float maxAscent = 0;
+        float maxDescent = 0;
+
         foreach (char c in text)
         {
+            var glyph = GetGlyph(c);
 
+            totalWidth += glyph.Advance;
+
+            float ascent = glyph.Bearing.Y;
+            float descent = glyph.Height - glyph.Bearing.Y;
+
+            if (ascent > maxAscent)
+                maxAscent = ascent;
+
+            if (descent > maxDescent)
+                maxDescent = descent;
         }
+
+        float totalHeight = maxAscent + maxDescent;
+        return new Rect(totalWidth, totalHeight);
     }
 
     public Glyph GetGlyph(char character)
@@ -80,31 +108,29 @@ public class Font : Resource, IDisposable
         return loaded;
     }
 
-    internal void GetGlyphBoundingBox(Glyph glyph)
-    {
-
-    }
-
     private unsafe Glyph LoadGlyph(char character)
     {
         var face = (FT_FaceRec_*)FacePtr;
 
         // TODO: for now, we're loading glyphs for metrics, but when implementing WebGPU rendering, we want to somehow render them to SDF or bitmap.
-        FT_Error error = FT_Load_Char(face, character, FT_LOAD_NO_BITMAP);
+        FT_Error error = FT_Set_Pixel_Sizes(face, 0, (uint)Size);
+        error = FT_Load_Char(face, character, FT_LOAD_NO_BITMAP);
+
         if (error != 0)
             throw new Exception($"Failed to load glyph for '{character}'");
 
         var glyph = face->glyph;
         var bitmap = glyph->bitmap;
+        var metrics = glyph->metrics;
 
         return new Glyph
         {
-            Width = bitmap.width,
-            Height = bitmap.rows,
-            Bearing = new Vector2(glyph->bitmap_left, glyph->bitmap_top),
+            Width = metrics.width >> 6,
+            Height = metrics.height >> 6,
+            Bearing = new Vector2(metrics.horiBearingX >> 6, metrics.horiBearingY >> 6),
             Advance = (int)glyph->advance.x >> 6,
         };
     }
 
-    private Dictionary<char, Glyph> _glyphs = new();
+    private Dictionary<int, Glyph> _glyphs = new();
 }

Voile/Source/Resources/Loaders/ResourceLoader.cs

@@ -65,7 +65,12 @@ namespace Voile.Resources
             var resource = ResourceManager.LoadedResources[resourceGuid];
 
             ResourceManager.RemoveResource(resourceGuid);
-            resource.Dispose();
+
+            if (resource is IDisposable disposable)
+            {
+                disposable.Dispose();
+            }
+
 
             return true;
         }

Voile/Source/UI/Widgets/Label.cs

@@ -6,24 +6,29 @@ namespace Voile.UI.Widgets;
 
 public class Label : Widget
 {
-    public override Rect MinimumSize => throw new NotImplementedException();
+    public override Rect MinimumSize => _textSize;
 
-    public string Text { get; set; } = "Hello World!";
-
-    public Label(string text)
+    public string Text
     {
-        Text = text;
+        get => _text; set
+        {
+            _text = value;
+            MarkDirty();
+        }
     }
 
     public Label(string text, ResourceRef<Font> fontOverride)
     {
-        Text = text;
+        _text = text;
         _fontOverride = fontOverride;
+
+        MarkDirty();
+        Update();
     }
 
     protected override void OnInput(UIInputContext action)
     {
-        throw new NotImplementedException();
+
     }
 
     public override void Render(RenderSystem renderer, Style style)
@@ -31,13 +36,19 @@ public class Label : Widget
         // TODO: use style here.
         if (!_fontOverride.HasValue) return;
         renderer.SetTransform(GlobalPosition, Vector2.Zero);
-        renderer.DrawText(_fontOverride, Text, Color.White);
+        renderer.DrawText(_fontOverride, _text, Color.White);
     }
 
     protected override void OnUpdate()
     {
-        throw new NotImplementedException();
+        var font = _fontOverride.Value;
+        _textSize = font.Measure(_text);
+
+        Size = _textSize;
     }
 
     private ResourceRef<Font> _fontOverride = ResourceRef<Font>.Empty();
+
+    private string _text = "Hello, World!";
+    private Rect _textSize = Rect.Zero;
 }