switch resize algo; document odd window size behavior

main.go

@@ -140,14 +140,18 @@ func updateImage(file string, img *tk.LabelWidget) {
 		// -50 to give some space to breathe around the edges
 		must(strconv.Atoi(tk.WinfoScreenWidth(tk.App)))-50,
 		must(strconv.Atoi(tk.WinfoScreenHeight(tk.App)))-50,
-		imaging.Linear,
+		imaging.CatmullRom,
 	)
 	repaint(img, filepath.Base(file), tk.Data(i))
 	directoryState.currentFile = filepath.Base(file)
 }
 
-func repaint(img *tk.LabelWidget, name string, opt tk.Opt) {
-	img.Configure(tk.Image(tk.NewPhoto(opt)))
+func repaint(img *tk.LabelWidget, name string, data tk.Opt) {
+	// TODO: sometimes, when going from a big image to a smaller one,
+	// the window remains the same height as the big image,
+	// even as the width shrinks to fit the smaller image.
+	// This only seems to happen when the large image was full-screen height.
+	img.Configure(tk.Image(tk.NewPhoto(data)))
 	if name != "" {
 		tk.App.WmTitle(fmt.Sprintf("why | %s", name))
 	} else {