Add copy example

examples/copy/main.go

@@ -0,0 +1,73 @@
+// Example copy shows how to place text data in the CLIPBOARD selection.
+package main
+
+import "os"
+import "io"
+import "log"
+import "bytes"
+import "github.com/jezek/xgbutil"
+import "github.com/jezek/xgb/xproto"
+import "git.tebibyte.media/tomo/xgbsel"
+import "github.com/jezek/xgbutil/xprop"
+import "github.com/jezek/xgbutil/xevent"
+import "github.com/jezek/xgbutil/xwindow"
+
+// data is a very basic implementation of xgbsel.Data that only serves data of
+// one type.
+type data struct {
+	buffer io.ReadSeekCloser
+	mime   string
+}
+
+func (this *data) Convert (target xgbsel.Target) (io.ReadSeekCloser, bool) {
+	if mime, _ := target.ToMime(); mime == this.mime {
+		return this.buffer, true
+	} else {
+		return nil, false
+	}
+}
+
+func (this *data) Supported () []xgbsel.Target {
+	return xgbsel.MimeToTargets(this.mime)
+}
+
+// nopSeekCloser is like io.NopCloser but for an io.ReadSeeker.
+type nopSeekCloser struct { io.ReadSeeker }
+func (nopSeekCloser) Close () error { return nil }
+
+func main () {
+	// get data from user
+	log.Println("enter data, ^D when done: ")
+	buffer, _ := io.ReadAll(os.Stdin)
+	data := &data {
+		buffer: nopSeekCloser {
+			ReadSeeker: bytes.NewReader(buffer),
+		},
+		mime: "text/plain",
+	}
+
+	// establish connection
+	X, err := xgbutil.NewConn()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// create window
+	window, err := xwindow.Generate(X)
+	if err != nil {
+		log.Fatalln("could not generate a new window X id:", err)
+	}
+	window.Create(X.RootWin(), 0, 0, 500, 500, xproto.CwBackPixel, 0xffffffff)
+
+	// obtain claim on CLIPBOARD
+	log.Println("obtaining claim")
+	clipboard, _ := xprop.Atm(X, "CLIPBOARD")
+	claim := xgbsel.NewClaim(window, clipboard, data)
+
+	// listen for events
+	window.Listen(xproto.EventMaskPropertyChange)
+	xevent.SelectionRequestFun(claim.HandleSelectionRequest).Connect(X, window.Id)
+	
+	log.Println("running main event loop")
+	xevent.Main(X)
+}