Cache font heights in a static fixed array.

This is to avoid significant per-call overhead to get font heights,
as this is performed very frequently.

src/fontcache.cpp

@@ -43,6 +43,7 @@ FontCache::FontCache(FontSize fs) : parent(FontCache::Get(fs)), fs(fs), height(_
 {
 	assert(parent == NULL || this->fs == parent->fs);
 	FontCache::caches[this->fs] = this;
+	font_height_cache[this->fs] = this->height;
 	Layouter::ResetFontCache(this->fs);
 }
 
@@ -54,18 +55,6 @@ FontCache::~FontCache()
 	Layouter::ResetFontCache(this->fs);
 }
 
-
-/**
- * Get height of a character for a given font size.
- * @param size Font size to get height of
- * @return     Height of characters in the given font (pixels)
- */
-int GetCharacterHeight(FontSize size)
-{
-	return FontCache::Get(size)->GetHeight();
-}
-
-
 /** Font cache for fonts that are based on a freetype font. */
 class SpriteFontCache : public FontCache {
 private:
@@ -151,6 +140,7 @@ void SpriteFontCache::InitializeUnicodeGlyphMap()
 			this->SetUnicodeGlyph(_default_unicode_map[i].code, sprite);
 		}
 	}
+	font_height_cache[this->fs] = this->GetHeight();
 }
 
 /**
@@ -197,6 +187,7 @@ bool SpriteFontCache::GetDrawGlyphShadow()
 }
 
 /* static */ FontCache *FontCache::caches[FS_END] = { new SpriteFontCache(FS_NORMAL), new SpriteFontCache(FS_SMALL), new SpriteFontCache(FS_LARGE), new SpriteFontCache(FS_MONO) };
+int font_height_cache[FS_END];
 
 #ifdef WITH_FREETYPE
 #include <ft2build.h>
@@ -312,6 +303,8 @@ FreeTypeFontCache::FreeTypeFontCache(FontSize fs, FT_Face face, int pixels) : Fo
 		/* Both FT_Set_Pixel_Sizes and FT_Select_Size failed. */
 		DEBUG(freetype, 0, "Font size selection failed. Using FontCache defaults.");
 	}
+
+	font_height_cache[this->fs] = this->GetHeight();
 }
 
 /**

src/fontcache.h

@@ -19,6 +19,8 @@
 typedef uint32 GlyphID;
 static const GlyphID SPRITE_GLYPH = 1U << 30;
 
+extern int font_height_cache[FS_END]; ///< Cache of font heights
+
 /** Font cache for basic fonts. */
 class FontCache {
 private:

src/gfx_func.h

@@ -158,7 +158,17 @@ byte GetCharacterWidth(FontSize size, uint32 key);
 byte GetDigitWidth(FontSize size = FS_NORMAL);
 void GetBroadestDigit(uint *front, uint *next, FontSize size = FS_NORMAL);
 
-int GetCharacterHeight(FontSize size);
+extern int font_height_cache[FS_END];
+
+/**
+ * Get height of a character for a given font size.
+ * @param size Font size to get height of
+ * @return     Height of characters in the given font (pixels)
+ */
+inline int GetCharacterHeight(FontSize size)
+{
+	return font_height_cache[size];
+}
 
 /** Height of characters in the small (#FS_SMALL) font. */
 #define FONT_HEIGHT_SMALL  (GetCharacterHeight(FS_SMALL))