rdpq_font: add builtin fonts for debugging purposes

include/rdpq_font.h

@@ -8,6 +8,7 @@
 #define LIBDRAGON_RDPQ_FONT_H
 
 #include "graphics.h"
+#include "debug.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -16,6 +17,8 @@ extern "C" {
 ///@cond
 typedef struct rdpq_font_s rdpq_font_t;
 typedef struct rdpq_paragraph_char_s rdpq_paragraph_char_t;
+rdpq_font_t* __rdpq_font_load_builtin_0(void);
+rdpq_font_t* __rdpq_font_load_builtin_1(void);
 ///@endcond
 
 /**
@@ -45,6 +48,48 @@ rdpq_font_t* rdpq_font_load(const char *fn);
  */
 rdpq_font_t* rdpq_font_load_buf(void *buf, int sz);
 
+/** 
+ * @brief Builtin fonts, shipped with libdragon
+ * 
+ * All builtin fonts are licensed under CC0 or similar license that effectively
+ * place them into public domain, so there are no restrictions on their usage.
+ */
+typedef enum {
+    /// ASCII Debug font, outlined, monospace (8x8 pixels, plus outline)
+    /// Monogram by datagoblin (https://datagoblin.itch.io/monogram)
+    /// License: CC0
+    FONT_BUILTIN_DEBUG_MONO = 0,
+
+    /// ASCII Debug font, outlined, variable width (7x9 pixels, plus outline)
+    /// At01 by GrafxKid (https://grafxkid.itch.io/at01)
+    /// License: CC0
+    FONT_BUILTIN_DEBUG_VAR = 1,
+} rdpq_font_builtin_t;
+
+/**
+ * @brief Load a builtin font provided by libdragon.
+ * 
+ * Builtin fonts are simple debug fonts shipped with libdragon itself, to let
+ * people quickly write something on the screen without much hassle. They are
+ * meant mainly for debug purposes.
+ * 
+ * See #rdpq_font_builtin_t for a list of available builtin fonts.
+ * 
+ * @param font              Builtin font to load
+ * 
+ * @return rdpq_font_t*     Loaded font
+ */
+inline rdpq_font_t* rdpq_font_load_builtin(rdpq_font_builtin_t font) {
+    switch (font) {
+        case FONT_BUILTIN_DEBUG_MONO:
+            return __rdpq_font_load_builtin_0();
+        case FONT_BUILTIN_DEBUG_VAR:
+            return __rdpq_font_load_builtin_1();
+        default:
+            assertf(false, "Invalid builtin font");
+    }
+}
+
 /**
  * @brief Free a font.
  * 

src/rdpq/rdpq_font.c

@@ -19,6 +19,9 @@
 #include "fmath.h"
 #include "utils.h"
 
+// Include the built-in font data
+#include "rdpq_font_builtin.c"
+
 #define MAX_STYLES   256
 
 _Static_assert(sizeof(glyph_t) == 16, "glyph_t size is wrong");
@@ -306,5 +309,17 @@ int rdpq_font_render_paragraph(const rdpq_font_t *fnt, const rdpq_paragraph_char
     return ch - chars;
 }
 
-// extern inline void rdpq_font_print(rdpq_font_t *fnt, const char *text, const rdpq_parparms_t *parms);
+rdpq_font_t *__rdpq_font_load_builtin_0(void)
+{
+    return rdpq_font_load_buf((void*)__fontdb_monogram, __fontdb_monogram_len);
+}
+
+rdpq_font_t *__rdpq_font_load_builtin_1(void)
+{
+    return rdpq_font_load_buf((void*)__fontdb_at01, __fontdb_at01_len);
+}
+
+
 extern inline void __rdpq_font_glyph_metrics(const rdpq_font_t *fnt, int16_t index, float *xadvance, int8_t *xoff, int8_t *xoff2, bool *has_kerning, uint8_t *sort_key);
+extern inline rdpq_font_t* rdpq_font_load_builtin(rdpq_font_builtin_t font);
+