From 1f8d37a1602a26df5dff2fcde1c0db41618fb72b Mon Sep 17 00:00:00 2001
From: bjorn <mail@bjornbyt.es>
Date: Wed, 29 Jun 2022 21:49:55 -0700
Subject: [PATCH] Font:getKerning;

---
 src/api/api.h                   |  1 +
 src/api/l_data_rasterizer.c     | 28 ++++++++++++++--------------
 src/api/l_graphics_font.c       | 11 +++++++++++
 src/modules/graphics/graphics.c |  6 +++---
 src/modules/graphics/graphics.h |  1 +
 5 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/api/api.h b/src/api/api.h
index cd20ad54..26cd782f 100644
--- a/src/api/api.h
+++ b/src/api/api.h
@@ -142,6 +142,7 @@ struct Blob;
 struct Image;
 struct Blob* luax_readblob(struct lua_State* L, int index, const char* debug);
 struct Image* luax_checkimage(struct lua_State* L, int index);
+uint32_t luax_checkcodepoint(struct lua_State* L, int index);
 #endif
 
 #ifndef LOVR_DISABLE_EVENT
diff --git a/src/api/l_data_rasterizer.c b/src/api/l_data_rasterizer.c
index 0fb84699..950acc8b 100644
--- a/src/api/l_data_rasterizer.c
+++ b/src/api/l_data_rasterizer.c
@@ -6,6 +6,20 @@
 #include <lauxlib.h>
 #include <math.h>
 
+uint32_t luax_checkcodepoint(lua_State* L, int index) {
+  size_t length;
+  const char* str;
+  uint32_t codepoint;
+  switch (lua_type(L, index)) {
+    case LUA_TSTRING:
+      str = lua_tolstring(L, index, &length);
+      return utf8_decode(str, str + length, &codepoint) ? codepoint : 0;
+    case LUA_TNUMBER:
+      return luax_checku32(L, index);
+    default: return luax_typeerror(L, index, "string or number"), 0;
+  }
+}
+
 static int l_lovrRasterizerGetFontSize(lua_State* L) {
   Rasterizer* rasterizer = luax_checktype(L, 1, Rasterizer);
   float size = lovrRasterizerGetFontSize(rasterizer);
@@ -67,20 +81,6 @@ static int l_lovrRasterizerGetLeading(lua_State* L) {
   return 1;
 }
 
-static uint32_t luax_checkcodepoint(lua_State* L, int index) {
-  size_t length;
-  const char* str;
-  uint32_t codepoint;
-  switch (lua_type(L, index)) {
-    case LUA_TSTRING:
-      str = lua_tolstring(L, index, &length);
-      return utf8_decode(str, str + length, &codepoint) ? codepoint : 0;
-    case LUA_TNUMBER:
-      return luax_checku32(L, index);
-    default: return luax_typeerror(L, index, "string or number"), 0;
-  }
-}
-
 static int l_lovrRasterizerGetAdvance(lua_State* L) {
   Rasterizer* rasterizer = luax_checktype(L, 1, Rasterizer);
   uint32_t codepoint = luax_checkcodepoint(L, 2);
diff --git a/src/api/l_graphics_font.c b/src/api/l_graphics_font.c
index daaa3a4a..89189cfe 100644
--- a/src/api/l_graphics_font.c
+++ b/src/api/l_graphics_font.c
@@ -89,6 +89,16 @@ static int l_lovrFontGetHeight(lua_State* L) {
   return 1;
 }
 
+static int l_lovrFontGetKerning(lua_State* L) {
+  Font* font = luax_checktype(L, 1, Font);
+  uint32_t left = luax_checkcodepoint(L, 2);
+  uint32_t right = luax_checkcodepoint(L, 3);
+  float kerning = lovrFontGetKerning(font, left, right);
+  float density = lovrFontGetPixelDensity(font);
+  lua_pushnumber(L, kerning / density);
+  return 1;
+}
+
 static void online(void* context, const char* string, size_t length) {
   lua_State* L = context;
   int index = luax_len(L, -1) + 1;
@@ -117,6 +127,7 @@ const luaL_Reg lovrFont[] = {
   { "getAscent", l_lovrFontGetAscent },
   { "getDescent", l_lovrFontGetDescent },
   { "getHeight", l_lovrFontGetHeight },
+  { "getKerning", l_lovrFontGetKerning },
   { "getWrap", l_lovrFontGetWrap },
   { NULL, NULL }
 };
diff --git a/src/modules/graphics/graphics.c b/src/modules/graphics/graphics.c
index 17dcd8d7..1bb90a93 100644
--- a/src/modules/graphics/graphics.c
+++ b/src/modules/graphics/graphics.c
@@ -1970,13 +1970,13 @@ static Glyph* lovrFontGetGlyph(Font* font, uint32_t codepoint, bool* resized) {
   return glyph;
 }
 
-static float lovrFontGetKerning(Font* font, uint32_t previous, uint32_t codepoint) {
-  uint32_t codepoints[] = { previous, codepoint };
+float lovrFontGetKerning(Font* font, uint32_t left, uint32_t right) {
+  uint32_t codepoints[] = { left, right };
   uint64_t hash = hash64(codepoints, sizeof(codepoints));
   union { float f32; uint64_t u64; } kerning = { .u64 = map_get(&font->kerning, hash) };
 
   if (kerning.u64 == MAP_NIL) {
-    kerning.f32 = lovrRasterizerGetKerning(font->info.rasterizer, previous, codepoint);
+    kerning.f32 = lovrRasterizerGetKerning(font->info.rasterizer, left, right);
     map_set(&font->kerning, hash, kerning.u64);
   }
 
diff --git a/src/modules/graphics/graphics.h b/src/modules/graphics/graphics.h
index 78cdc4f1..77c00f74 100644
--- a/src/modules/graphics/graphics.h
+++ b/src/modules/graphics/graphics.h
@@ -353,6 +353,7 @@ float lovrFontGetPixelDensity(Font* font);
 void lovrFontSetPixelDensity(Font* font, float pixelDensity);
 float lovrFontGetLineSpacing(Font* font);
 void lovrFontSetLineSpacing(Font* font, float spacing);
+float lovrFontGetKerning(Font* font, uint32_t left, uint32_t right);
 void lovrFontGetWrap(Font* font, ColoredString* strings, uint32_t count, float wrap, void (*callback)(void* context, const char* string, size_t length), void* context);
 
 // Pass