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#ifndef AMR_FONTS_H
#define AMR_FONTS_H
#define LATIN_BASIC_START_INDEX 32
#define LATIN_BASIC_END_INDEX 126
typedef struct amr_letter_details_debug {
i32 advance;
i32 lsb;
i32 x0, y0, x1, y1;
i32 byte_offset;
// @TODO: check if offsets are in PX
f32 StartingYOffset;
f32 StartingXOffset;
} amr_letter_details_debug;
typedef struct amr_font_state_debug {
stbtt_fontinfo font_info;
amr_letter_details_debug font_details;
// font metrics
f32 font_size;
f32 scale_factor;
i32 ascent;
i32 descent;
i32 line_gap;
// glyphs
u32 charset_start_index;
u32 charset_end_index;
// @TODO: make this array
u32 *glyph_index_array;
u32 glyph_count;
// text specific metrics
// @TODO: these should probably be moved to an array or remain out of this struct
f32 Baseline;
f32 MaxLineWidthPx;
// font bitmap info
unsigned char *FontBitmap;
u32 FontBitmapWidth;
u32 FontBitmapHeight;
} amr_font_state;
// initialise a font and loads the font in the fontbuffer
// input:
// - font path
// - font buffer, must be initialised by caller
// - size of the font file, must be known beforehand
// output:
// - error code
u32 amr_InitFont(const u8 *FontPath, u8 *FontBuffer, u32 FontFz);
void amr_LoadFontMetrics(amr_font_state font, u32 FontSize);
void amr_LoadGlyphsFromFont(amr_DebugArena *MemoryArena, amr_font_state *font);
u32 amr_GetGlyphIdFromCodepoint(amr_font_state font, u32 Codepoint);
//////////////////////////////////////////////////////////////////////////////
/// Naive Font Bitmap generation
/// This approach is fast but usese more memory
/// We make a single draw call, but load the entire text in a single bitmap
//////////////////////////////////////////////////////////////////////////////
void amr_MakeFontBitmapNaive(GameState *State, amr_font_state *Font, char *Text, u32 TextSize);
u32 amr_InitFont(stbtt_fontinfo *font_info, const char *FontPath, u8 *FontBuffer, u32 FontSz)
{
PlatformDebugFileRead(FontPath, FontBuffer, FontSz);
if (!stbtt_InitFont(font_info, FontBuffer, 0))
{
printf("ERROR: failed to read arial font");
assert(1 == 0);
}
return 0;
}
void amr_LoadFontMetrics(amr_font_state *Font, f32 FontSize)
{
// get a SF (scale factor)
Font->scale_factor = stbtt_ScaleForPixelHeight(&(Font->font_info), FontSize);
// get vertical metrics
stbtt_GetFontVMetrics(&(Font->font_info), &(Font->ascent),
&(Font->descent), &(Font->line_gap));
}
void amr_LoadGlyphsFromFont(amr_DebugArena *MemoryArena, amr_font_state *Font)
{
Font->glyph_count = Font->charset_end_index - Font->charset_start_index;
Font->glyph_index_array = (u32 *)amr_ArenaAlloc(MemoryArena,
sizeof(Font->glyph_count) * Font->glyph_count);
u32 *array_iter = Font->glyph_index_array;
for (u32 i = 0; i < Font->glyph_count; i++)
{
u32 offset_codepoint = Font->charset_start_index + i;
*array_iter = stbtt_FindGlyphIndex(&(Font->font_info), offset_codepoint);
array_iter++;
}
}
u32 amr_GetGlyphIdFromCodepoint(amr_font_state Font, u32 Codepoint)
{
u32 glyph_id = *(Font.glyph_index_array + (Codepoint - Font.charset_start_index));
return glyph_id;
}
void amr_MakeFontBitmapNaive(GameState *State, amr_font_state *Font, char *Text, u32 TextSize)
{
Font->MaxLineWidthPx = 0.0f;
Font->Baseline = roundf(Font->ascent * Font->scale_factor);
u32 fd_sz = sizeof(amr_letter_details_debug)*TextSize;
amr_letter_details_debug *fd_arr = (amr_letter_details_debug *)amr_ArenaAlloc(&(State->Memory.Arena), fd_sz);
amr_letter_details_debug *_fi = fd_arr;
f32 RunningXOffset = 0.0f;
// convert str to font
for (i32 i = 0; i < TextSize; ++i)
{
_fi->StartingXOffset = RunningXOffset;
if (Text[i] == '\n')
{
// if new line, move baseline down
Font->Baseline += (i32)roundf((Font->ascent - Font->descent
+ Font->line_gap) * Font->scale_factor);
RunningXOffset = 0;
++_fi;
continue;
}
u32 GlyphId = amr_GetGlyphIdFromCodepoint(*Font, Text[i]);
stbtt_GetGlyphHMetrics(&(Font->font_info), GlyphId,
&_fi->advance, &_fi->lsb);
stbtt_GetGlyphBitmapBox(&(Font->font_info), GlyphId,
Font->scale_factor, Font->scale_factor,
&_fi->x0, &_fi->y0, &_fi->x1, &_fi->y1);
_fi->StartingYOffset = (f32)(Font->Baseline + _fi->y0);
RunningXOffset += (_fi->advance * Font->scale_factor);
if (i < TextSize - 1 && Text[i+1] != '\n')
{
i32 kern = stbtt_GetGlyphKernAdvance(&(Font->font_info),
GlyphId, amr_GetGlyphIdFromCodepoint(*Font, Text[i+1]));
RunningXOffset += roundf(kern * Font->scale_factor);
}
if (RunningXOffset > Font->MaxLineWidthPx)
{
Font->MaxLineWidthPx = RunningXOffset;
}
++_fi;
}
// make all the glyphs into bitmaps.
_fi = fd_arr;
Font->FontBitmapWidth = (u32)Font->MaxLineWidthPx;
Font->FontBitmapHeight = (u32)(Font->Baseline -
roundf(Font->scale_factor * Font->descent));
u32 bitmap_size = sizeof(unsigned char)*Font->FontBitmapWidth*Font->FontBitmapHeight;
Font->FontBitmap = (unsigned char *)amr_ArenaAlloc(&(State->Memory.Arena), bitmap_size);
_fi = fd_arr;
for (int i = 0; i < TextSize; i++)
{
if (Text[i] == '\n') {
++_fi;
continue;
}
_fi->byte_offset = (i32)(_fi->StartingXOffset + roundf(_fi->lsb * Font->scale_factor) +
(_fi->StartingYOffset * Font->FontBitmapWidth)) ;
// store image data in bitmap
stbtt_MakeGlyphBitmap(&(Font->font_info), Font->FontBitmap + _fi->byte_offset,
_fi->x1 - _fi->x0, _fi->y1 - _fi->y0, Font->FontBitmapWidth,
Font->scale_factor, Font->scale_factor,
amr_GetGlyphIdFromCodepoint(*Font, Text[i]));
_fi++;
}
}
#endif
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