add descratcher example

README.md

@@ -66,7 +66,10 @@ func main() {
 }
 ```
 
-Also take a look into the **_examples** folder for more examples.
+Also take a look into the **_examples** folder for more examples. For
+a more comprehensive and practical example look at the
+`_examples/descratcher` program which you can use to selectively
+retrieve a window from the scratchpad.
 
 You may take a look at the [tool swaycycle](https://github.com/tlinden/swaycycle)
 which is using this module.

_examples/descratch/descratcher-rofi.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+descratch \
+    | rofi -matching fuzzy -dmenu -p "Select window from scratchpad to show" \
+    | cut -d' ' -f1 | xargs -I{} --no-run-if-empty "descratch" {}

_examples/descratch/main.go

@@ -0,0 +1,106 @@
+package main
+
+/*
+   This is a more practical example. With sway you can move windows to
+   a "scratchpad", i.e. like iconify it. There may be an official way
+   to get back such windows, but I didn't find a good one. There's the
+   "scratchpad show" command, but it doesn't allow you to select a
+   window, it just shows the next one (and it keeps it in the floating
+   state).
+
+   So, this example program lists all windows currently garaged on the
+   scratchpad. When called with a windows id, it gets back the window
+   to the current workspace and gives it focus - thus descratching it.
+
+   To add comfort to the process I  added a small script which you can
+   use as a ui to it. It uses  rofi which makes a handy ui. To use it,
+   compile descratch  with "go  build", copy  the descratch  binary to
+   some location within your $PATH and run the script.
+*/
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+
+	"github.com/alecthomas/repr"
+	"github.com/tlinden/swayipc"
+)
+
+func main() {
+	// we need a session to sway via IPC
+	ipc := swayipc.NewSwayIPC()
+
+	err := ipc.Connect()
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer ipc.Close()
+
+	// first, retrieve the whole sway root node
+	root, err := ipc.GetTree()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// get the hidden scratchpad workspace
+	scratch := getScratch(root)
+
+	if len(os.Args) > 1 {
+		// called with an arg, consider it to be a container id
+		id, err := strconv.Atoi(os.Args[1])
+		if err != nil {
+			log.Fatalf("failed to convert arg %s to integer: %w", os.Args[1], err)
+		}
+
+		// switch to it
+		retrieveWindow(ipc, scratch, id)
+	} else {
+		// no args, just list scratched windows
+		listScratchedContainer(scratch)
+	}
+}
+
+func retrieveWindow(ipc *swayipc.SwayIPC, scratch *swayipc.Node, id int) {
+	// make sure the id exists
+	var exists bool
+	for _, con := range scratch.FloatingNodes {
+		if con.Id == id {
+			exists = true
+		}
+	}
+
+	if !exists {
+		log.Fatalf("no window with id %d exists on the scratchpad", id)
+	}
+
+	// scratched windows are floating, so we move it to current
+	// workspace, disable the floating state and switch focus to it
+	responses, err := ipc.RunContainerCommand(id, "move workspace current, floating toggle, focus")
+	if err != nil {
+		repr.Println(responses)
+		log.Fatal(err)
+	}
+
+}
+
+func listScratchedContainer(scratch *swayipc.Node) {
+	// list the windows
+	for _, con := range scratch.FloatingNodes {
+		fmt.Printf("%d %s\n", con.Id, con.Name)
+	}
+}
+
+func getScratch(root *swayipc.Node) *swayipc.Node {
+	// the root node only has output nodes, we iterate over them and
+	// look for the internal one named__i3. This in turn only has one
+	// workspace, the scratchpad workspace, which we return.
+	for _, output := range root.Nodes {
+		if output.Name == "__i3" {
+			return output.Nodes[0]
+		}
+	}
+
+	return nil
+}