Mostly working packing, just handle memory and check for duplicate packed chars

freetype.go

using import "core:c.odin"

foreign import ftlib "freetype271.lib";
/*
when ODIN_OS == "windows" do foreign import ftlib "freetype271.lib";
else do _ :: compiler_assert(false);
*/

FT_Library_ :: struct {}
FT_Library  :: ^FT_Library_;

FT_Size_Internal :: rawptr;
FT_Size_Metrics :: struct {
    x_ppem      : u16,
    y_ppem      : u16,
    x_scale     : c_long,
    y_scale     : c_long,
    ascender    : c_long,
    descender   : c_long,
    height      : c_long,
    max_advance : c_long,
}

FT_Generic_Finalizer :: proc "c" (object: rawptr);
FT_Generic :: struct {
    data: rawptr,
    finalizer: FT_Generic_Finalizer,
}

FT_SizeRec :: struct {
    face     : FT_Face,
    generic  : FT_Generic,
    metrics  : FT_Size_Metrics,
    internal : FT_Size_Internal,
}
FT_Size :: ^FT_SizeRec;

FT_Bitmap_Size :: struct {
    height : i16,
    width  : i16,
    size   : c_long,
    x_ppem : c_long,
    y_ppem : c_long,
}

FT_Encoding :: enum i32 #export {
    FT_ENCODING_NONE      = 0,
    FT_ENCODING_MS_SYMBOL = ('s' << 24) | ('y' << 16) | ('m' << 8) | 'b',
    FT_ENCODING_UNICODE   = ('u' << 24) | ('n' << 16) | ('i' << 8) | 'c',
    FT_ENCODING_SJIS      = ('s' << 24) | ('j' << 16) | ('i' << 8) | 's',
    FT_ENCODING_PRC       = ('g' << 24) | ('b' << 16) | (' ' << 8) | ' ',
    FT_ENCODING_BIG5      = ('b' << 24) | ('i' << 16) | ('g' << 8) | '5',
    FT_ENCODING_WANSUNG   = ('w' << 24) | ('a' << 16) | ('n' << 8) | 's',
    FT_ENCODING_JOHAB     = ('j' << 24) | ('o' << 16) | ('h' << 8) | 'a',

    /* for backward compatibility */
    FT_ENCODING_GB2312     = FT_ENCODING_PRC,
    FT_ENCODING_MS_SJIS    = FT_ENCODING_SJIS,
    FT_ENCODING_MS_GB2312  = FT_ENCODING_PRC,
    FT_ENCODING_MS_BIG5    = FT_ENCODING_BIG5,
    FT_ENCODING_MS_WANSUNG = FT_ENCODING_WANSUNG,
    FT_ENCODING_MS_JOHAB   = FT_ENCODING_JOHAB,

    FT_ENCODING_ADOBE_STANDARD = ('A' << 24) | ('D' << 16) | ('O' << 8) | 'B',
    FT_ENCODING_ADOBE_EXPERT   = ('A' << 24) | ('D' << 16) | ('B' << 8) | 'E',
    FT_ENCODING_ADOBE_CUSTOM   = ('A' << 24) | ('D' << 16) | ('B' << 8) | 'C',
    FT_ENCODING_ADOBE_LATIN_1  = ('l' << 24) | ('a' << 16) | ('t' << 8) | '1',
    FT_ENCODING_OLD_LATIN_2    = ('l' << 24) | ('a' << 16) | ('t' << 8) | '2',
    FT_ENCODING_APPLE_ROMAN    = ('a' << 24) | ('r' << 16) | ('m' << 8) | 'n',
}

FT_CharMapRec :: struct {
    face        : FT_Face,
    encoding    : FT_Encoding,
    platform_id : u16,
    encoding_id : u16,
}
FT_CharMap :: ^FT_CharMapRec;

FT_BBox :: struct {
    xMin, yMin: c_long,
    xMax, yMax: c_long,
}

FT_Glyph_Metrics :: struct {
    width        : c_long,
    height       : c_long,
    horiBearingX : c_long,
    horiBearingY : c_long,
    horiAdvance  : c_long,
    vertBearingX : c_long,
    vertBearingY : c_long,
    vertAdvance  : c_long,
}

FT_Glyph_Format :: enum i32 #export {
    FT_GLYPH_FORMAT_NONE      = 0,
    FT_GLYPH_FORMAT_COMPOSITE = ('c' << 24) | ('o' << 16) | ('m' << 8) | 'p',
    FT_GLYPH_FORMAT_BITMAP    = ('b' << 24) | ('i' << 16) | ('t' << 8) | 's',
    FT_GLYPH_FORMAT_OUTLINE   = ('o' << 24) | ('u' << 16) | ('t' << 8) | 'l',
    FT_GLYPH_FORMAT_PLOTTER   = ('p' << 24) | ('l' << 16) | ('o' << 8) | 't',
}

FT_Bitmap :: struct {
    rows         : u32,
    width        : u32,
    pitch        : int,
    buffer       : ^u8,
    num_grays    : u16,
    pixel_mode   : u8,
    palette_mode : u8,
    palette      : rawptr,
}

FT_Vector :: struct {
    x: c_long,
    y: c_long,
}

FT_Outline :: struct {
    n_contours : i16,
    n_points   : i16,
    points     : ^FT_Vector,
    tags       : ^u8,
    contours   : ^i16,
    flags      : i32,
}

FT_SubGlyph :: rawptr;
FT_Slot_Internal :: rawptr;

FT_GlyphSlotRec :: struct {
    library           : FT_Library,
    face              : FT_Face,
    next              : FT_GlyphSlot,
    reserved          : u32,
    generic           : FT_Generic,
    metrics           : FT_Glyph_Metrics,
    linearHoriAdvance : c_long,
    linearVertAdvance : c_long,
    advance           : FT_Vector,
    format            : FT_Glyph_Format,
    bitmap            : FT_Bitmap,
    bitmap_left       : i32,
    bitmap_top        : i32,
    outline           : FT_Outline,
    num_subglyphs     : u32,
    subglyphs         : FT_SubGlyph,
    control_data      : rawptr,
    control_len       : c_long,
    lsb_delta         : c_long,
    rsb_delta         : c_long,
    other             : rawptr,
    internal          : FT_Slot_Internal,
}
FT_GlyphSlot :: ^FT_GlyphSlotRec;

FT_Driver :: rawptr;

FT_Alloc_Func   :: proc"c"(memory: FT_Memory, size: c_long) -> rawptr;
FT_Free_Func    :: proc"c"(memory: FT_Memory, block: rawptr);
FT_Realloc_Func :: proc"c"(memory: FT_Memory, cur_size: c_long, new_size: c_long, block: rawptr) -> rawptr;

FT_MemoryRec :: struct {
    user    : rawptr,
    alloc   : FT_Alloc_Func,
    free    : FT_Free_Func,
    realloc : FT_Realloc_Func,
}
FT_Memory :: ^FT_MemoryRec;

FT_Stream_IoFunc    :: proc"c"(stream: FT_Stream, offset: c_ulong, buffer: ^u8, count: c_ulong) -> c_ulong;
FT_Stream_CloseFunc :: proc"c"(stream: FT_Stream);

FT_StreamDesc :: struct #raw_union {
    value: c_long,
    pointer: rawptr,
}

FT_StreamRec :: struct {
    base       : ^u8,
    size       : c_ulong,
    pos        : c_ulong,
    descriptor : FT_StreamDesc,
    pathname   : FT_StreamDesc,
    read       : FT_Stream_IoFunc,
    close      : FT_Stream_CloseFunc,
    memory     : FT_Memory,
    cursor     : ^u8,
    limit      : ^u8,
}
FT_Stream :: ^FT_StreamRec;

FT_ListNode :: rawptr;
FT_ListRec :: struct {
    head : FT_ListNode,
    tail : FT_ListNode,
}
FT_List :: ^FT_ListRec;

FT_Face_Internal :: rawptr;

FT_FaceRec :: struct {
    num_faces       : c_long,
    face_index      : c_long,
    face_flags      : c_long,
    style_flags     : c_long,
    num_glyphs      : c_long,
    family_name     : ^u8,
    style_name      : ^u8,
    num_fixed_sizes : i32,
    available_sizes : ^FT_Bitmap_Size,
    num_charmaps    : i32,
    charmaps        : ^FT_CharMap,
    generic         : FT_Generic,
    
    /*# The following member variables (down to `underline_thickness') */
    /*# are only relevant to scalable outlines; cf. @FT_Bitmap_Size    */
    /*# for bitmap fonts.                                              */
    bbox                : FT_BBox,
    units_per_EM        : u16,
    ascender            : i16,
    descender           : i16,
    height              : i16,
    max_advance_width   : i16,
    max_advance_height  : i16,
    underline_position  : i16,
    underline_thickness : i16,
    glyph               : FT_GlyphSlot,
    size                : FT_Size,
    charmap             : FT_CharMap,
    
    /*@private begin */    
    driver      : FT_Driver,
    memory      : FT_Memory,
    stream      : FT_Stream,
    sizes_list  : FT_ListRec,
    autohint    : FT_Generic,
    extensions  : rawptr,
    internal    : FT_Face_Internal,
}
FT_Face     :: ^FT_FaceRec;

FT_Load_Flags :: enum i32 #export {
    FT_LOAD_DEFAULT                     = 0x0,
    FT_LOAD_NO_SCALE                    = 1 << 0,
    FT_LOAD_NO_HINTING                  = 1 << 1,
    FT_LOAD_RENDER                      = 1 << 2,
    FT_LOAD_NO_BITMAP                   = 1 << 3,
    FT_LOAD_VERTICAL_LAYOUT             = 1 << 4,
    FT_LOAD_FORCE_AUTOHINT              = 1 << 5,
    FT_LOAD_CROP_BITMAP                 = 1 << 6,
    FT_LOAD_PEDANTIC                    = 1 << 7,
    FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH = 1 << 9,
    FT_LOAD_NO_RECURSE                  = 1 << 10,
    FT_LOAD_IGNORE_TRANSFORM            = 1 << 11,
    FT_LOAD_MONOCHROME                  = 1 << 12,
    FT_LOAD_LINEAR_DESIGN               = 1 << 13,
    FT_LOAD_NO_AUTOHINT                 = 1 << 15,
    FT_LOAD_COLOR                       = 1 << 20,
    FT_LOAD_COMPUTE_METRICS             = 1 << 21,
    FT_LOAD_BITMAP_METRICS_ONLY         = 1 << 22,


}

FT_Render_Mode :: enum i32 #export {
    FT_RENDER_MODE_NORMAL = 0,
    FT_RENDER_MODE_LIGHT,
    FT_RENDER_MODE_MONO,
    FT_RENDER_MODE_LCD,
    FT_RENDER_MODE_LCD_V,
    FT_RENDER_MODE_MAX,
}

FT_Kerning_Mode :: enum u32 #export {
    FT_KERNING_DEFAULT = 0,
    FT_KERNING_UNFITTED,
    FT_KERNING_UNSCALED,
}

@(default_calling_convention="c")
foreign ftlib {
    FT_Init_FreeType :: proc(lib: ^FT_Library) -> i32 ---;
    FT_Done_FreeType :: proc(lib: FT_Library)  -> i32 ---;
    
    FT_New_Face  :: proc(library: FT_Library, path: ^u8, face_index: c_long, face: ^FT_Face) -> i32 ---;
    FT_Done_Face :: proc(face: FT_Face) -> i32 ---;
    FT_Set_Pixel_Sizes :: proc(face: FT_Face, pixel_width: u32, pixel_height: u32) -> i32 ---;

    FT_Load_Glyph      :: proc(face: FT_Face, glyph_index: u32, load_flags: FT_Load_Flags) -> i32 ---;
    FT_Load_Char       :: proc(face: FT_Face, char_code: c_ulong, load_flags: FT_Load_Flags) -> i32 ---;
    FT_Render_Glyph    :: proc(slot: FT_GlyphSlot, render_mode: FT_Render_Mode) -> i32 ---;

    FT_Get_Char_Index  :: proc(face: FT_Face, charcode: c_ulong) -> u32 ---;
    FT_Get_Kerning     :: proc(face: FT_Face, left_glyph, right_glyph: u32, kern_mode: u32, kerning: ^FT_Vector) -> i32 ---;
    FT_Get_Glyph_Name  :: proc(face: FT_Face, glyph_index: u32, buffer: ^u8, buffer_max: u32) -> i32 ---;
}

import "core:fmt.odin"

/*    face: FT_Face;
    path := "fonts/arial.ttf\x00";
    if FT_New_Face(lib, &path[0], 0, &face) != 0 {
        fmt.println("Failed to create face!\n");
    }
    FT_Set_Pixel_Sizes(face, 0, 16);

    print_rune(face, '£');*/

print_rune :: proc(face: FT_Face, r: rune) {
    if FT_Load_Char(face, auto_cast r, FT_LOAD_RENDER) != 0 {
        fmt.println("Failed to load char!\n");
    }

    chars := " .:ioV#@";
    bitmap := face.glyph.bitmap;
    pixels := mem.slice_ptr(bitmap.buffer, int(bitmap.rows*bitmap.width));
    for y in 0..bitmap.rows {
        for x in 0..bitmap.width {
            v := pixels[x+y*bitmap.width] >> 5;
            fmt.printf("%c", chars[v]);
        }
        fmt.println();
    }
    fmt.println();
}

using import "shared:odin-stb/stb_rect_pack.odin"
import "core:strings.odin"
import "core:mem.odin"

Glyph :: struct {
	bearingX, bearingY: int,
	width, height: int,
	advanceX: int,
}

Font :: struct {
	face: FT_Face,
	contex: stbrp_context,
	nodes: []stbrp_node,
	atlas_w, atlas_h: int,
	pixels: []u8,
	glyphs: map[rune]Glyph,
}

the_library: FT_Library;

load_font :: proc(path: string, pixel_size: int, atlas_width, atlas_height: int) -> ^Font {
	font := new(Font);
	font.atlas_w = atlas_width-1;
	font.atlas_h = atlas_height-1;
	using font;

	cpath := strings.new_c_string(path);
	defer free(cpath);
	if FT_New_Face(the_library, cpath, 0, &face) != 0 {
		return nil;
	}
	FT_Set_Pixel_Sizes(face, 0, auto_cast pixel_size);

	pixels = make([]u8, atlas_w*atlas_h);

	nodes = make([]stbrp_node, atlas_w);
	stbrp_init_target(&contex, i32(atlas_w), i32(atlas_h), &nodes[0], auto_cast len(nodes));

	pack_range(font, ' ', '~');

	return font;
}

pack_range :: proc(using font: ^Font, first, last: rune) -> (packed_all: bool = true) {
	glyph_count := int(last-first+1);
	reserve(&glyphs, glyph_count);
	rects := make([]stbrp_rect, glyph_count);
	defer free(rects);

	fmt.printf("glyph_count %v\n", glyph_count);
	
	// Get glyph data and setup packing
	for cp in first...last {
		if FT_Load_Char(face, auto_cast cp, FT_LOAD_RENDER) != 0 {
			assert(false, "Invalid font cp!");
		}
		glyph := face.glyph;
		g: Glyph;
		g.width = auto_cast glyph.metrics.width;
		g.height = auto_cast glyph.metrics.height;
		g.bearingX = auto_cast glyph.metrics.horiBearingX;
		g.bearingY = auto_cast glyph.metrics.horiBearingY;
		g.advanceX = auto_cast glyph.metrics.horiAdvance;
		glyphs[cp] = g;

		rects[cp-first].w = auto_cast (glyph.bitmap.width+1);
		rects[cp-first].h = auto_cast (glyph.bitmap.rows+1);

		fmt.printf("loop\n");
	}

	stbrp_pack_rects(&contex, &rects[0], i32(len(rects)));

	copy_to_atlas :: proc(using font: ^Font, r: ^stbrp_rect, bitmap: []u8) {
		for y in 0..r.h {
			yy := int(r.y+y);
			for x in 0..r.w {
				xx := int(r.x+x);
				font.pixels[xx+yy*font.atlas_w] = bitmap[x+y*r.w];
			}
		}
	}


	// Do packing and writing to atlas
	for cp in first...last {
		if FT_Load_Char(face, auto_cast cp, FT_LOAD_RENDER) != 0 {
			assert(false, "Invalid font cp!!??!?!");
		}
		r := &rects[cp-first];
		fmt.printf("r.was_packed %v %c\n", r.was_packed, cp);
		if r.was_packed == 0 {
			packed_all = false;
			continue;
		}

		r.x += 1;
		r.y += 1;
		r.w -= 1;
		r.h -= 1;

		pixels := mem.slice_ptr(face.glyph.bitmap.buffer, int(face.glyph.bitmap.width*face.glyph.bitmap.rows));
		copy_to_atlas(font, r, pixels);
	}

	return;
}

import stbiw "shared:odin-stb/stb_image_write.odin"

main :: proc() {
    FT_Init_FreeType(&the_library);
    defer FT_Done_FreeType(the_library);

    font := load_font("fonts/arial.ttf", 32, 512, 512);
    if font == nil {
    	assert(false, "failed to init font!");
    }
    pack_range(font, 0xA0, 0xFF);
    stbiw.write_png("test.png\x00", font.atlas_w, font.atlas_h, 1, font.pixels, 0);
}