From af641426fad35cd857c1f14bda523db3d85a70cd Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Sat, 4 May 2024 16:44:28 -0700
Subject: Initial commit.

---
 font/font.h | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 font/font.h

(limited to 'font/font.h')

diff --git a/font/font.h b/font/font.h
new file mode 100644
index 0000000..13ff1c3
--- /dev/null
+++ b/font/font.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include <assert.h>
+#include <stdint.h>
+
+static const unsigned char FontGlyphStart     = 32;  // Space.
+static const unsigned char FontGlyphEnd       = 127; // One past tilde.
+static const int           FontAtlasNumGlyphs = FontGlyphEnd - FontGlyphStart;
+
+/// Font atlas header.
+typedef struct FontHeader {
+  uint16_t glyph_width;
+  uint16_t glyph_height;
+  uint16_t num_glyphs;
+} FontHeader;
+
+/// Font atlas.
+///
+/// Pixels are stored in "glyph-major" order. First the rows of the first glyph,
+/// followed by the rows of the second glyph, etc. Thus, pixels should be viewed
+/// as a linear array, not a 2d array. This arrangement allows an application to
+/// render glyphs by scanning atlas memory linearly.
+typedef struct FontAtlas {
+  FontHeader    header;
+  unsigned char pixels[1];
+} FontAtlas;
+
+/// Load a font atlas from a file.
+FontAtlas* LoadFontAtlas(const char* path);
+
+/// Get the glyph into the atlas.
+static inline const unsigned char* FontGetGlyph(
+    const FontAtlas* atlas, unsigned char c) {
+  assert(atlas);
+  const int index = c - FontGlyphStart;
+  assert(index >= 0);
+  assert(index < FontAtlasNumGlyphs);
+  return atlas->pixels +
+         index * (atlas->header.glyph_width * atlas->header.glyph_height);
+}
-- 
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