transition fileList management to deiconify/withdraw

main.go

@@ -105,9 +105,12 @@ func newBrowse(file string) {
 		}
 		return 1
 	})
+	clearFileList()
 	for i, v := range directoryState.images {
+		insertIntoFileList(directoryState.images[i])
 		if v == filepath.Base(file) {
 			directoryState.i = i
+			moveSelectionInFileList(i)
 		}
 	}
 	updateImage(file)
@@ -158,53 +161,18 @@ func repaint(name string, data tk.Opt) {
 	tk.App.Center()
 }
 
-// TODO: make this use withdraw/deiconify
-func destroyFileList(destroy bool) {
-	if destroy {
-		tk.Destroy(fileList)
-	}
-	fileList = nil
-	lb = nil
-	fileListBindVar.Set("0")
-}
-
-func constructFileList() {
-	fileList = tk.Toplevel()
-	fileList.WmTitle("Files")
-	lb = fileList.Listbox(tk.Height(0))
-	for i := range directoryState.images {
-		lb.Insert("end", directoryState.images[i])
-		if i == directoryState.i {
-			lb.SelectionSet(i)
-		}
-	}
-	tk.Pack(lb)
-	tk.Bind(lb, "<<ListboxSelect>>", tk.Command(func() {
-		selection := lb.Curselection()
-		updateImage(directoryState.pathToImageAtIndex(selection[0]))
-	}))
-	tk.Bind(fileList, "<Destroy>", tk.Command(func(e *tk.Event) {
-		// list closed by user click on <x>
-		destroyFileList(false)
-	}))
-	fileListBindVar.Set("1")
-}
-
 func menuSelect() {
-	if fileListBindVar.Get() == "1" && fileList == nil {
-		constructFileList()
-	} else if fileListBindVar.Get() == "0" && fileList != nil {
-		destroyFileList(true)
+	if fileListBindVar.Get() == "1" {
+		showFileList()
+	} else if fileListBindVar.Get() == "0" {
+		hideFileList()
 	}
 }
 
-func moveSelectInFileList(target int) {
+func updateSelection(target int) {
 	directoryState.i = target
-	if lb != nil {
-		lb.SelectionClear("0", "end")
-		lb.SelectionSet(target)
-		lb.See(target)
-	}
+	updateImage(directoryState.pathToImageAtIndex(target))
+	moveSelectionInFileList(target)
 }
 
 // TODO: by default, the event callback loop in TK is fully synchronous;
@@ -227,28 +195,85 @@ func keyPress(e *tk.Event) {
 	case "d":
 		newDirectory()
 	case "a":
-		if fileList == nil {
-			constructFileList()
+		if fileListBindVar.Get() == "0" {
+			showFileList()
 		} else {
-			destroyFileList(true)
+			hideFileList()
 		}
 	case "Up", "Left":
 		if curr > 0 {
-			updateImage(directoryState.pathToImageAtIndex(curr - 1))
-			moveSelectInFileList(curr - 1)
+			updateSelection(curr - 1)
 		}
 	case "Down", "Right":
 		if curr < len(directoryState.images)-1 && curr != -1 {
-			updateImage(directoryState.pathToImageAtIndex(curr + 1))
-			moveSelectInFileList(curr + 1)
+			updateSelection(curr + 1)
 		}
 	}
 }
 
+func constructFileList() {
+	fileList = tk.Toplevel()
+	fileList.WmTitle("Files")
+	tk.WmWithdraw(fileList.Window)
+	lb = fileList.Listbox(tk.Height(0))
+	tk.Pack(lb)
+	tk.Bind(lb, "<<ListboxSelect>>", tk.Command(func() {
+		updateSelection(lb.Curselection()[0])
+	}))
+	tk.Bind(fileList, "<Destroy>", tk.Command(func(e *tk.Event) {
+		// wipe the reference so next show event recreates
+		fileList = nil
+		fileListBindVar.Set("0")
+	}))
+}
+
+func showFileList() {
+	if fileList == nil {
+		constructFileList()
+		// repopulate
+		lb.Delete("0", "end")
+		for i := range directoryState.images {
+			lb.Insert("end", directoryState.images[i])
+			if directoryState.i == i {
+				lb.SelectionSet(i)
+			}
+		}
+	}
+	tk.WmDeiconify(fileList.Window)
+	fileListBindVar.Set("1")
+}
+
+func hideFileList() {
+	tk.WmWithdraw(fileList.Window)
+	fileListBindVar.Set("0")
+}
+
+func insertIntoFileList(filename string) {
+	if fileList != nil {
+		lb.Insert("end", filename)
+	}
+}
+
+func clearFileList() {
+	if fileList != nil {
+		lb.Delete("0", "end")
+	}
+}
+
+func moveSelectionInFileList(target int) {
+	if fileList != nil {
+		lb.SelectionClear("0", "end")
+		lb.SelectionSet(target)
+		lb.See(target)
+	}
+}
+
 func main() {
 	tk.App.IconPhoto(tk.NewPhoto(tk.Data(icon)))
 	tk.MacOpenDocument(newBrowse)
 
+	constructFileList()
+
 	menubar := tk.Menu()
 	fileMenu := menubar.Menu()
 	fileMenu.AddCommand(tk.Lbl("Open File"), tk.Accelerator("O"), tk.Command(newFileInDirectory))
@@ -259,6 +284,7 @@ func main() {
 	fileMenu.EntryConfigure(checkbox, fileListBindVar)
 	menubar.AddCascade(tk.Lbl("File"), tk.Underline(0), tk.Mnu(fileMenu))
 	tk.App.Configure(tk.Mnu(menubar))
+	fileListBindVar.Set("0")
 
 	tk.Bind(fileMenu, "<<MenuSelect>>", tk.Command(menuSelect))
 	tk.Bind(tk.App, "<KeyPress>", tk.Command(keyPress))