Add on-redraw hook command (gokcehan#1479)

* Add `on-redraw` hook command

* Add documentation

doc.go

@@ -208,6 +208,7 @@ The following special shell commands are used to customize the behavior of lf wh
 	pre-cd
 	on-cd
 	on-select
+	on-redraw
 	on-quit
 
 The following commands/keybindings are provided by default:
@@ -1110,6 +1111,10 @@ This shell command can be defined to be executed after changing a directory.
 
 This shell command can be defined to be executed after the selection changes.
 
+	on-redraw
+
+This shell command can be defined to be executed after the screen is redrawn or if the terminal is resized.
+
 	on-quit
 
 This shell command can be defined to be executed before quit.

eval.go

@@ -1151,6 +1151,12 @@ func onChdir(app *app) {
 	}
 }
 
+func onRedraw(app *app) {
+	if cmd, ok := gOpts.cmds["on-redraw"]; ok {
+		cmd.eval(app, nil)
+	}
+}
+
 func onSelect(app *app) {
 	if cmd, ok := gOpts.cmds["on-select"]; ok {
 		cmd.eval(app, nil)
@@ -1944,6 +1950,7 @@ func (e *callExpr) eval(app *app, args []string) {
 			dir.boundPos(app.nav.height)
 		}
 		app.ui.loadFile(app, true)
+		onRedraw(app)
 	case "load":
 		if !app.nav.init {
 			return

lf.1

@@ -231,6 +231,7 @@ The following special shell commands are used to customize the behavior of lf wh
     pre-cd
     on-cd
     on-select
+    on-redraw
     on-quit
 .EE
 .PP
@@ -1332,6 +1333,12 @@ This shell command can be defined to be executed after changing a directory.
 .PP
 This shell command can be defined to be executed after the selection changes.
 .PP
+.EX
+    on-redraw
+.EE
+.PP
+This shell command can be defined to be executed after the screen is redrawn or if the terminal is resized.
+.PP
 .EX
     on-quit
 .EE