Cthulhu is no longer a fork. Now it is a screen reader written in Golang.

internal/clipboard/watch.go

@@ -0,0 +1,100 @@
+// Copyright (c) 2026 Storm Dragon
+// Authors: Storm Dragon, Angus Kola
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package clipboard
+
+/*
+#include "watch.h"
+*/
+import "C"
+
+import (
+	"bufio"
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"runtime"
+	"time"
+)
+
+type WatchSettings struct {
+	Enabled bool
+	Epoch   uint64
+}
+
+type TextChange struct {
+	Text      string
+	Epoch     uint64
+	Timestamp uint32
+	Ready     bool
+}
+
+// WatchText keeps a GTK selection connection warm so successive clipboard
+// changes are captured asynchronously and emitted in arrival order. Disabled
+// applications never request clipboard targets or contents.
+func WatchText(ctx context.Context, input io.Reader, output io.Writer) error {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	settings := make(chan WatchSettings, 1)
+	inputDone := make(chan error, 1)
+	go func() {
+		scanner := bufio.NewScanner(input)
+		scanner.Buffer(make([]byte, 1024), 4096)
+		for scanner.Scan() {
+			var request WatchSettings
+			if err := json.Unmarshal(scanner.Bytes(), &request); err != nil {
+				inputDone <- err
+				return
+			}
+			select {
+			case settings <- request:
+			case <-ctx.Done():
+				return
+			}
+		}
+		inputDone <- scanner.Err()
+	}()
+	if C.clipboard_watch_init() == 0 {
+		return errors.New("cannot watch clipboard on this display")
+	}
+	encoder := json.NewEncoder(output)
+	if err := encoder.Encode(TextChange{Ready: true}); err != nil {
+		return err
+	}
+	ticker := time.NewTicker(time.Millisecond)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case err := <-inputDone:
+			return err
+		case request := <-settings:
+			enabled := C.int(0)
+			if request.Enabled {
+				enabled = 1
+			}
+			C.clipboard_watch_enable(enabled, C.ulonglong(request.Epoch))
+			if err := encoder.Encode(TextChange{Ready: true, Epoch: request.Epoch}); err != nil {
+				return err
+			}
+		case <-ticker.C:
+			C.clipboard_watch_iterate()
+			for {
+				change := C.clipboard_watch_next()
+				if change == nil {
+					break
+				}
+				value := TextChange{Text: C.GoString(change.text), Epoch: uint64(change.epoch), Timestamp: uint32(change.timestamp)}
+				C.clipboard_watch_free(change)
+				if err := encoder.Encode(value); err != nil {
+					return err
+				}
+			}
+		}
+	}
+}