From 530c80c63c1559c1d9bc754fbb188e45cc3f5d0c Mon Sep 17 00:00:00 2001
From: bjorn <tie.372@gmail.com>
Date: Tue, 7 Feb 2017 22:11:20 -0800
Subject: [PATCH] Kerning;

---
 src/graphics/font.c | 34 +++++++++++++++++++++++++++++++---
 src/graphics/font.h |  2 ++
 src/loaders/font.c  |  9 +++++++++
 src/loaders/font.h  |  3 ++-
 4 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/src/graphics/font.c b/src/graphics/font.c
index 27f7fb17..5386d8bf 100644
--- a/src/graphics/font.c
+++ b/src/graphics/font.c
@@ -15,6 +15,7 @@ Font* lovrFontCreate(FontData* fontData) {
 
   font->fontData = fontData;
   vec_init(&font->vertices);
+  map_init(&font->kerning);
 
   // Atlas
   int padding = 1;
@@ -40,6 +41,7 @@ void lovrFontDestroy(const Ref* ref) {
   lovrFontDataDestroy(font->fontData);
   lovrRelease(&font->texture->ref);
   map_deinit(&font->atlas.glyphs);
+  map_deinit(&font->kerning);
   vec_deinit(&font->vertices);
   free(font);
 }
@@ -55,29 +57,40 @@ void lovrFontPrint(Font* font, const char* str) {
   int length = strlen(str);
   const char* end = str + length;
   size_t bytes;
+  unsigned int previous = '\0';
   unsigned int codepoint;
 
   vec_reserve(&font->vertices, length * 30);
   vec_clear(&font->vertices);
 
   while ((bytes = utf8_decode(str, end, &codepoint)) > 0) {
+
+    // Newlines
     if (codepoint == '\n') {
       x = 0;
       y -= font->fontData->size;
+      previous = '\0';
       str += bytes;
       continue;
     }
 
-    Glyph* glyph = lovrFontGetGlyph(font, codepoint);
+    // Kerning
+    x += lovrFontGetKerning(font, previous, codepoint);
+    previous = codepoint;
 
+    // Glyph geometry
+    Glyph* glyph = lovrFontGetGlyph(font, codepoint);
     int gx = glyph->x;
     int gy = glyph->y;
     int gw = glyph->w;
     int gh = glyph->h;
+    int dx = glyph->dx;
+    int dy = glyph->dy;
 
+    // Triangles
     if (gw > 0 && gh > 0) {
-      float x1 = x + glyph->dx;
-      float y1 = y + glyph->dy;
+      float x1 = x + dx;
+      float y1 = y + dy;
       float x2 = x1 + gw;
       float y2 = y1 - gh;
       float s1 = gx / u;
@@ -97,6 +110,7 @@ void lovrFontPrint(Font* font, const char* str) {
       vec_pusharr(&font->vertices, v, 30);
     }
 
+    // Advance cursor
     x += glyph->advance;
     str += bytes;
   }
@@ -117,6 +131,20 @@ int lovrFontGetDescent(Font* font) {
   return font->fontData->descent;
 }
 
+int lovrFontGetKerning(Font* font, unsigned int left, unsigned int right) {
+  char key[12];
+  snprintf(key, 12, "%d,%d", left, right);
+
+  int* entry = map_get(&font->kerning, key);
+  if (entry) {
+    return *entry;
+  }
+
+  int kerning = lovrFontDataGetKerning(font->fontData, left, right);
+  map_set(&font->kerning, key, kerning);
+  return kerning;
+}
+
 Glyph* lovrFontGetGlyph(Font* font, uint32_t codepoint) {
   char key[6];
   snprintf(key, 6, "%d", codepoint);
diff --git a/src/graphics/font.h b/src/graphics/font.h
index e535e881..af7fce8c 100644
--- a/src/graphics/font.h
+++ b/src/graphics/font.h
@@ -42,6 +42,7 @@ typedef struct {
   FontData* fontData;
   Texture* texture;
   FontAtlas atlas;
+  map_int_t kerning;
   vec_float_t vertices;
 } Font;
 
@@ -51,6 +52,7 @@ void lovrFontPrint(Font* font, const char* str);
 int lovrFontGetHeight(Font* font);
 int lovrFontGetAscent(Font* font);
 int lovrFontGetDescent(Font* font);
+int lovrFontGetKerning(Font* font, unsigned int a, unsigned int b);
 Glyph* lovrFontGetGlyph(Font* font, uint32_t codepoint);
 void lovrFontAddGlyph(Font* font, Glyph* glyph);
 void lovrFontExpandTexture(Font* font);
diff --git a/src/loaders/font.c b/src/loaders/font.c
index 0a526821..f3a2512c 100644
--- a/src/loaders/font.c
+++ b/src/loaders/font.c
@@ -81,3 +81,12 @@ void lovrFontDataLoadGlyph(FontData* fontData, uint32_t character, Glyph* glyph)
 
   FT_Done_Glyph(slot);
 }
+
+int lovrFontDataGetKerning(FontData* fontData, uint32_t left, uint32_t right) {
+  FT_Face face = fontData->rasterizer;
+  FT_Vector kerning;
+  left = FT_Get_Char_Index(face, left);
+  right = FT_Get_Char_Index(face, right);
+  FT_Get_Kerning(face, left, right, FT_KERNING_DEFAULT, &kerning);
+  return kerning.x >> 6;
+}
diff --git a/src/loaders/font.h b/src/loaders/font.h
index 820fb45e..1398a69f 100644
--- a/src/loaders/font.h
+++ b/src/loaders/font.h
@@ -3,4 +3,5 @@
 
 FontData* lovrFontDataCreate(void* data, int size, int height);
 void lovrFontDataDestroy(FontData* fontData);
-void lovrFontDataLoadGlyph(FontData* fontData, uint32_t characer, Glyph* glyph);
+void lovrFontDataLoadGlyph(FontData* fontData, uint32_t character, Glyph* glyph);
+int lovrFontDataGetKerning(FontData* fontData, uint32_t left, uint32_t right);