line endings switch, and add missed stubs / go.mod update

backend/smtc_unsupported.go

@@ -1,32 +1,47 @@
-//go:build !windows
-
-package backend
-
-import "errors"
-
-type SMTCPlaybackState int
-
-const (
-	SMTCPlaybackStateStopped SMTCPlaybackState = 0
-	SMTCPlaybackStatePlaying SMTCPlaybackState = 1
-	SMTCPlaybackStatePaused  SMTCPlaybackState = 2
-)
-
-type SMTC struct{}
-
-var smtcUnsupportedErr = errors.New("SMTC is not supported on this platformo")
-
-func InitSMTCForWindow(hwnd uintptr) (*SMTC, error) {
-	return nil, smtcUnsupportedErr
-}
-
-func (s *SMTC) UpdatePlaybackState(state SMTCPlaybackState) error {
-	return smtcUnsupportedErr
-}
-
-func (s *SMTC) UpdateMetadata(title, artist string) error {
-	return smtcUnsupportedErr
-}
-
-func (s *SMTC) Shutdown() {
-}
+//go:build !windows
+
+package backend
+
+import "errors"
+
+type SMTCPlaybackState int
+type SMTCButton int
+
+const (
+	// constants from smtc.h in github.com/supersonic-app/smtc-dll
+	SMTCPlaybackStateStopped SMTCPlaybackState = 2
+	SMTCPlaybackStatePlaying SMTCPlaybackState = 3
+	SMTCPlaybackStatePaused  SMTCPlaybackState = 4
+
+	SMTCButtonPlay     SMTCButton = 0
+	SMTCButtonPause    SMTCButton = 1
+	SMTCButtonStop     SMTCButton = 2
+	SMTCButtonPrevious SMTCButton = 4
+	SMTCButtonNext     SMTCButton = 5
+)
+
+type SMTC struct{}
+
+var smtcUnsupportedErr = errors.New("SMTC is not supported on this platformo")
+
+func InitSMTCForWindow(hwnd uintptr) (*SMTC, error) {
+	return nil, smtcUnsupportedErr
+}
+
+func (s *SMTC) OnButtonPressed(func(SMTCButton)) {}
+
+func (s *SMTC) OnSeek(f func(millis int)) {}
+
+func (s *SMTC) Shutdown() {}
+
+func (s *SMTC) UpdatePlaybackState(state SMTCPlaybackState) error {
+	return smtcUnsupportedErr
+}
+
+func (s *SMTC) UpdateMetadata(title, artist string) error {
+	return smtcUnsupportedErr
+}
+
+func (s *SMTC) UpdatePosition(positionMillis, durationMillis int) error {
+	return smtcUnsupportedErr
+}