Start loading .fnt files. No display yet

internal/fonts/fonts.go

@@ -0,0 +1,133 @@
+package fonts
+
+import (
+	"fmt"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"ur.gs/ordoor/internal/util"
+	"ur.gs/ordoor/internal/util/asciiscan"
+)
+
+type Font struct {
+	Name string
+	// Contains the sprite data for the font. FIXME: load this?
+	ObjectFile string
+
+	// Maps ASCII bytes to a sprite offset in the ObjectFile
+	mapping map[int]int
+}
+
+func (f *Font) Entries() int {
+	return len(f.mapping)
+}
+
+// Returns the offsets required to display a given string, returning an error if
+// some of the runes in the string are unknown to the font
+func (f *Font) Indices(s string) ([]int, error) {
+	out := make([]int, 0, len(s))
+
+	for i, b := range []byte(s) {
+
+		offset, ok := f.mapping[int(b)]
+		if !ok {
+			return nil, fmt.Errorf("Unknown codepoint %v at offset %v in string %s", b, i, s)
+		}
+
+		out = append(out, offset)
+	}
+
+	return out, nil
+}
+
+func LoadFont(filename string) (*Font, error) {
+	scanner, err := asciiscan.New(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	defer scanner.Close()
+
+	// First, load the object file name
+	objFile, err := scanner.ConsumeString()
+	if err != nil {
+		return nil, err
+	}
+
+	out := &Font{
+		Name:       filepath.Base(filename),
+		ObjectFile: objFile,
+		mapping:    make(map[int]int),
+	}
+
+	for {
+		str, err := scanner.ConsumeString()
+		if err != nil {
+			return nil, err
+		}
+
+		parseErr := fmt.Errorf("Invalid entry in %v: %q", filename, str)
+		fields := strings.Fields(str)
+
+		switch fields[0] {
+		case "done":
+			goto out
+		case "r": // A range of codepoints
+			if len(fields) < 5 {
+				return nil, parseErr
+			}
+
+			cpStart, _ := strconv.Atoi(fields[1])
+			cpEnd, _ := strconv.Atoi(fields[2])
+			idxStart, _ := strconv.Atoi(fields[3])
+			idxEnd, _ := strconv.Atoi(fields[4])
+			size := idxEnd - idxStart
+
+			// FIXME: I'd love this to be an error but several .fnt files do it
+			if cpEnd-cpStart != size {
+				fmt.Printf("WARNING: %v has mismatched codepoints and indices: %q\n", filename, str)
+			}
+
+			for offset := 0; offset < size; offset++ {
+				out.mapping[cpStart+offset] = idxStart + offset
+			}
+		case "v": // A single codepoint, 4 fields
+			if len(fields) < 3 {
+				return nil, parseErr
+			}
+
+			cp, _ := strconv.Atoi(fields[1])
+			idx, _ := strconv.Atoi(fields[2])
+
+			out.mapping[cp] = idx
+		default:
+			return nil, parseErr
+		}
+	}
+
+out:
+	return out, nil
+}
+
+func LoadFonts(dir string) (map[string]*Font, error) {
+	files, err := util.DirByExt(dir, ".fnt")
+	if err != nil {
+		return nil, err
+	}
+
+	out := make(map[string]*Font, len(files))
+
+	for _, file := range files {
+		abs := filepath.Join(dir, file)
+		base := filepath.Base(file)
+		font, err := LoadFont(abs)
+		if err != nil {
+			return nil, fmt.Errorf("%s: %v", abs, err)
+		}
+
+		out[base] = font
+	}
+
+	return out, nil
+}