Add font containers for global and custom fonts

All global fonts and all custom fonts in a level are now loaded, and
added to their respective "vectors". The selected font is still always
as the global font.png, and the custom level font also isn't selected
yet, but it's now easier to implement that.

Also, I added FILESYSTEM_enumerateAssets, which #902 already has but I
needed it now. I also rewrote it to not use std::vector<std::string>.
That was my idea, it's also how FILESYSTEM_getLanguageCodes worked,
so for symmetry, that function is getting changed as well.

desktop_version/src/Font.cpp

@@ -9,6 +9,7 @@
 #include "Graphics.h"
 #include "Localization.h"
 #include "UtilityClass.h"
+#include "Vlogging.h"
 #include "XMLUtils.h"
 
 // Sigh... This is the second forward-declaration, we need to put this in a header file
@@ -17,7 +18,14 @@ SDL_Texture* LoadImage(const char *filename, const TextureLoadType loadtype);
 namespace font
 {
 
-Font temp_bfont; // replace with like, a vector of all loaded fonts
+static FontContainer fonts_main = {};
+static FontContainer fonts_custom = {};
+
+static size_t font_idx_interface = 0;
+static size_t font_idx_8x8 = 0;
+
+static bool font_idx_custom_is_custom = false;
+static size_t font_idx_custom = 0;
 
 static void codepoint_split(
     const uint32_t codepoint,
@@ -134,8 +142,19 @@ static bool decode_xml_range(tinyxml2::XMLElement* elem, unsigned* start, unsign
     return true;
 }
 
-static void load_font(Font* f, const char* name)
+static size_t load_font(FontContainer* container, const char* name)
 {
+    Font* new_fonts = (Font*) SDL_realloc(container->fonts, sizeof(Font)*(container->count+1));
+    if (new_fonts == NULL)
+    {
+        return 0;
+    }
+    container->fonts = new_fonts;
+    size_t f_idx = container->count++;
+    Font* f = &container->fonts[f_idx];
+
+    vlog_info("Loading font \"%s\"...", name);
+
     char name_png[256];
     char name_txt[256];
     char name_xml[256];
@@ -180,7 +199,7 @@ static void load_font(Font* f, const char* name)
 
     if (f->image == NULL)
     {
-        return;
+        return f_idx;
     }
 
     /* We may have a 2.3-style font.txt with all the characters.
@@ -300,17 +319,63 @@ static void load_font(Font* f, const char* name)
             }
         }
     }
+
+    return f_idx;
+}
+
+static void load_font_filename(bool is_custom, const char* filename)
+{
+    // Load font.png, and everything that matches *.fontmeta (but not font.fontmeta)
+    size_t expected_ext_start;
+    bool is_fontpng = SDL_strcmp(filename, "font.png") == 0;
+    if (is_fontpng)
+    {
+        expected_ext_start = SDL_strlen(filename)-4;
+    }
+    else
+    {
+        expected_ext_start = SDL_strlen(filename)-9;
+    }
+    if (is_fontpng || (endsWith(filename, ".fontmeta") && SDL_strcmp(filename, "font.fontmeta") != 0))
+    {
+        char font_name[128];
+        SDL_strlcpy(font_name, filename, sizeof(font_name));
+        font_name[SDL_min(127, expected_ext_start)] = '\0';
+
+        size_t f_idx = load_font(is_custom ? &fonts_custom : &fonts_main, font_name);
+
+        if (is_fontpng && !is_custom)
+        {
+            font_idx_8x8 = f_idx;
+        }
+    }
 }
 
 void load_main(void)
 {
-    // TODO PHYSFS_enumerateFiles, load everything that matches *.fontmeta or font.png (but not font.fontmeta)
-    load_font(&temp_bfont, "font");
+    // Load all global fonts
+    EnumHandle handle = {};
+    const char* item;
+    while ((item = FILESYSTEM_enumerate("graphics", &handle)) != NULL)
+    {
+        load_font_filename(false, item);
+    }
+    FILESYSTEM_freeEnumerate(&handle);
 }
 
 void load_custom(void)
 {
-    // Custom (level-specific assets) fonts NYI
+    // Load all custom (level-specific assets) fonts
+    unload_custom();
+    EnumHandle handle = {};
+    const char* item;
+    while ((item = FILESYSTEM_enumerateAssets("graphics", &handle)) != NULL)
+    {
+        load_font_filename(true, item);
+    }
+    FILESYSTEM_freeEnumerate(&handle);
+
+    // TODO: decide font_idx_custom
 }
 
 void unload_custom(void)
@@ -322,7 +387,7 @@ void unload_custom(void)
 void destroy(void)
 {
     /* Unload all fonts (main and custom) for exiting */
-    Font* f = &temp_bfont;
+    Font* f = &fonts_main.fonts[font_idx_8x8]; // TODO!
     VVV_freefunc(SDL_DestroyTexture, f->image);
 
     for (int i = 0; i < FONT_N_PAGES; i++)
@@ -358,7 +423,7 @@ static bool next_wrap(
             goto next;
         }
 
-        linewidth += get_advance(&font::temp_bfont, str[idx]);
+        linewidth += get_advance(&fonts_main.fonts[font_idx_8x8], str[idx]); // TODO get font via argument!
 
         switch (str[idx])
         {
@@ -581,7 +646,7 @@ static Font* fontsel_to_font(int sel)
 {
     /* Take font selection integer (0-31) and turn it into the correct Font */
     // TODO handle all these cases here like 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 etc
-    return &font::temp_bfont;
+    return &fonts_main.fonts[font_idx_8x8];
 }
 
 #define FLAG_PART(start, count) ((flags >> start) % (1 << count))