feat: Windows (CF_DIB) and macOS (AppleScript) clipboard image sync

internal/clipboard/clipboard_darwin.go

@@ -4,6 +4,7 @@ package clipboard
 
 import (
 	"fmt"
+	"os"
 	"os/exec"
 	"strings"
 )
@@ -43,3 +44,55 @@ func (c *darwinClipboard) Write(text string) error {
 	}
 	return nil
 }
+
+// ReadImage reads a PNG image from the clipboard via AppleScript, writing it to
+// a temporary file and reading it back.
+func (c *darwinClipboard) ReadImage() (string, []byte, error) {
+	tmp, err := os.CreateTemp("", "clip-sync-*.png")
+	if err != nil {
+		return "", nil, err
+	}
+	tmpPath := tmp.Name()
+	tmp.Close()
+	defer os.Remove(tmpPath)
+
+	// AppleScript type code PNGf, wrapped in the chevron quotes AppleScript uses.
+	script := `set f to (open for access POSIX file "` + tmpPath + `" with write permission)
+set eof f to 0
+write (the clipboard as «class PNGf») to f
+close access f`
+	if err := exec.Command("osascript", "-e", script).Run(); err != nil {
+		return "", nil, ErrNoImage
+	}
+
+	data, err := os.ReadFile(tmpPath)
+	if err != nil || len(data) == 0 {
+		return "", nil, ErrNoImage
+	}
+	return "image/png", data, nil
+}
+
+// WriteImage writes a PNG image to the clipboard via AppleScript.
+func (c *darwinClipboard) WriteImage(mime string, data []byte) error {
+	if mime != "" && mime != "image/png" {
+		return fmt.Errorf("clipboard: unsupported image mime %q (only PNG)", mime)
+	}
+	tmp, err := os.CreateTemp("", "clip-sync-*.png")
+	if err != nil {
+		return err
+	}
+	if _, err := tmp.Write(data); err != nil {
+		tmp.Close()
+		os.Remove(tmp.Name())
+		return err
+	}
+	tmpPath := tmp.Name()
+	tmp.Close()
+	defer os.Remove(tmpPath)
+
+	script := `set the clipboard to (read (POSIX file "` + tmpPath + `") as «class PNGf»)`
+	if err := exec.Command("osascript", "-e", script).Run(); err != nil {
+		return fmt.Errorf("clipboard write image (osascript): %w", err)
+	}
+	return nil
+}