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ui/font.sx

@@ -0,0 +1,104 @@
+#import "modules/std.sx";
+#import "ui/types.sx";
+
+FIRST_CHAR :s32: 32;
+NUM_CHARS  :s32: 96;
+ATLAS_W    :s32: 512;
+ATLAS_H    :s32: 512;
+
+// Matches stbtt_bakedchar memory layout
+BakedChar :: struct {
+    x0, y0, x1, y1: u16;
+    xoff, yoff, xadvance: f32;
+}
+
+// Matches stbtt_aligned_quad memory layout
+AlignedQuad :: struct {
+    x0, y0, s0, t0: f32;
+    x1, y1, s1, t1: f32;
+}
+
+FontAtlas :: struct {
+    texture_id: u32;
+    font_size: f32;
+    char_data: [*]BakedChar;
+    bitmap: [*]u8;
+    ascent: f32;
+    descent: f32;
+    line_height: f32;
+
+    // Bake font glyphs into a bitmap. Call upload_texture() after GL is ready.
+    init :: (self: *FontAtlas, path: [:0]u8, size: f32) {
+        file_size : s32 = 0;
+        font_data := read_file_bytes(path, @file_size);
+        if xx font_data == 0 {
+            out("Failed to load font: ");
+            out(path);
+            out("\n");
+            return;
+        }
+
+        self.font_size = size;
+
+        // Allocate baked char data (96 entries for ASCII 32..127)
+        self.char_data = xx context.allocator.alloc(xx NUM_CHARS * size_of(BakedChar));
+
+        // Bake font bitmap (512x512 single-channel alpha)
+        bitmap_size : s64 = xx ATLAS_W * xx ATLAS_H;
+        self.bitmap = xx context.allocator.alloc(bitmap_size);
+        stbtt_BakeFontBitmap(font_data, 0, size, self.bitmap, ATLAS_W, ATLAS_H, FIRST_CHAR, NUM_CHARS, xx self.char_data);
+
+        // Get font vertical metrics
+        fontinfo : [256]u8 = ---;
+        stbtt_InitFont(xx @fontinfo, font_data, 0);
+        ascent_i : s32 = 0;
+        descent_i : s32 = 0;
+        linegap_i : s32 = 0;
+        stbtt_GetFontVMetrics(xx @fontinfo, @ascent_i, @descent_i, @linegap_i);
+        scale := stbtt_ScaleForPixelHeight(xx @fontinfo, size);
+        self.ascent = xx ascent_i * scale;
+        self.descent = xx descent_i * scale;
+        self.line_height = self.ascent - self.descent + xx linegap_i * scale;
+
+        font_data_ptr : *void = xx font_data;
+        free(font_data_ptr);
+
+        out("Font loaded: ");
+        out(path);
+        out("\n");
+    }
+
+    measure_text :: (self: *FontAtlas, text: string, font_size: f32) -> Size {
+        if self.char_data == null { return Size.zero(); }
+        scale := font_size / self.font_size;
+        xpos : f32 = 0.0;
+        ypos : f32 = 0.0;
+        q : AlignedQuad = ---;
+        i : s64 = 0;
+        while i < text.len {
+            ch : s32 = xx text[i];
+            if ch >= FIRST_CHAR and ch < FIRST_CHAR + NUM_CHARS {
+                stbtt_GetBakedQuad(xx self.char_data, ATLAS_W, ATLAS_H, ch - FIRST_CHAR, @xpos, @ypos, xx @q, 1);
+            }
+            i += 1;
+        }
+        Size.{ width = xpos * scale, height = self.line_height * scale };
+    }
+}
+
+// Global font atlas pointer for views (Label, Button) to access
+g_font : *FontAtlas = xx 0;
+
+set_global_font :: (font: *FontAtlas) {
+    g_font = font;
+}
+
+// Convenience measurement function for views
+measure_text :: (text: string, font_size: f32) -> Size {
+    if xx g_font == 0 {
+        // Fallback approximate measurement
+        scale := font_size / 16.0;
+        return Size.{ width = xx text.len * 8.0 * scale, height = font_size };
+    }
+    g_font.measure_text(text, font_size);
+}