1 files changed, 61 insertions, 0 deletions
diff --git a/nexgb/examples/get-active-window/main.go b/nexgb/examples/get-active-window/main.go
new file mode 100644
index 0000000..48e020c
--- /dev/null
+++ b/nexgb/examples/get-active-window/main.go
@@ -0,0 +1,61 @@
+// Example get-active-window reads the _NET_ACTIVE_WINDOW property of the root
+// window and uses the result (a window id) to get the name of the window.
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/BurntSushi/xgb"
+	"github.com/BurntSushi/xgb/xproto"
+)
+
+func main() {
+	X, err := xgb.NewConn()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the window id of the root window.
+	setup := xproto.Setup(X)
+	root := setup.DefaultScreen(X).Root
+
+	// Get the atom id (i.e., intern an atom) of "_NET_ACTIVE_WINDOW".
+	aname := "_NET_ACTIVE_WINDOW"
+	activeAtom, err := xproto.InternAtom(X, true, uint16(len(aname)),
+		aname).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the atom id (i.e., intern an atom) of "_NET_WM_NAME".
+	aname = "_NET_WM_NAME"
+	nameAtom, err := xproto.InternAtom(X, true, uint16(len(aname)),
+		aname).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Get the actual value of _NET_ACTIVE_WINDOW.
+	// Note that 'reply.Value' is just a slice of bytes, so we use an
+	// XGB helper function, 'Get32', to pull an unsigned 32-bit integer out
+	// of the byte slice. We then convert it to an X resource id so it can
+	// be used to get the name of the window in the next GetProperty request.
+	reply, err := xproto.GetProperty(X, false, root, activeAtom.Atom,
+		xproto.GetPropertyTypeAny, 0, (1<<32)-1).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+	windowId := xproto.Window(xgb.Get32(reply.Value))
+	fmt.Printf("Active window id: %X\n", windowId)
+
+	// Now get the value of _NET_WM_NAME for the active window.
+	// Note that this time, we simply convert the resulting byte slice,
+	// reply.Value, to a string.
+	reply, err = xproto.GetProperty(X, false, windowId, nameAtom.Atom,
+		xproto.GetPropertyTypeAny, 0, (1<<32)-1).Reply()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Active window name: %s\n", string(reply.Value))
+}