Default laptop key set to capslock. Keys that can be set to fenrir key or script key selectable via checkbox.

internal/input/bindings.go

@@ -26,6 +26,12 @@ import (
 	"github.com/pelletier/go-toml/v2"
 )
 
+type Layout struct {
+	Version    int       `toml:"version"`
+	FenrirKeys []string  `toml:"fenrir_keys"`
+	Bindings   []Binding `toml:"bindings"`
+}
+
 type Binding struct {
 	Name          string     `toml:"name"`
 	Keys          []string   `toml:"keys"`
@@ -71,24 +77,48 @@ type chord struct {
 var modifierNames = map[string]modifiers{"FENRIR": fenrirModifier, "CTRL": ctrlModifier, "SHIFT": shiftModifier, "ALT": altModifier}
 
 // Decode_bindings rejects unsupported keys, commands and duplicate chords.
-func Decode_bindings(data []byte) ([]Binding, error) {
-	var file struct {
-		Version  int       `toml:"version"`
-		Bindings []Binding `toml:"bindings"`
-	}
+func Decode_bindings(data []byte) (Layout, error) {
+	var file Layout
 	if err := toml.NewDecoder(bytes.NewReader(data)).DisallowUnknownFields().Decode(&file); err != nil {
-		return nil, err
+		return Layout{}, err
 	}
 	if file.Version != 1 {
-		return nil, fmt.Errorf("unsupported keyboard version %d", file.Version)
+		return Layout{}, fmt.Errorf("unsupported keyboard version %d", file.Version)
 	}
-	_, err := New_router(file.Bindings)
-	return file.Bindings, err
+	_, err := New_router(file)
+	return file, err
 }
 
 // New_router compiles a private layout. Reset and capture preserve these bindings.
-func New_router(bindings []Binding) (Router, error) {
+func New_router(layout Layout) (Router, error) {
+	bindings := layout.Bindings
 	router := Router{bindings: make(map[chord]command.ID), doubleBindings: make(map[chord]command.ID), tripleBindings: make(map[chord]command.ID), multiPressTimeout: DefaultMultiPressTimeout}
+	keys := layout.FenrirKeys
+	if len(keys) == 0 {
+		keys = []string{"INSERT", "SUPER", "KP0"}
+	}
+	router.readerKeys = make(map[uint16]bool)
+	for _, name := range keys {
+		var codes []uint16
+		switch name {
+		case "INSERT":
+			codes = []uint16{KeyInsert}
+		case "SUPER":
+			codes = []uint16{KeyMeta, KeyRightMeta}
+		case "CAPSLOCK":
+			codes = []uint16{KeyCapsLock}
+		case "KP0":
+			codes = []uint16{KeyKP0}
+		default:
+			return Router{}, fmt.Errorf("unsupported Fenrir modifier %q", name)
+		}
+		for _, code := range codes {
+			if router.readerKeys[code] {
+				return Router{}, fmt.Errorf("duplicate Fenrir modifier %q", name)
+			}
+			router.readerKeys[code] = true
+		}
+	}
 	if len(bindings) == 0 {
 		return Router{}, fmt.Errorf("keyboard layout has no bindings")
 	}