haskell - 如何从 WxHaskell 面板中删除小部件

Question

我的 google-fu 让我失望了。如何删除已添加到的小部件Panel ()？例如，在下面，我希望controls-panel 再次变为空。

buildGUI = do
  f <- frame [ text := "Hello" ]

  controls <- panel f []
  ctext <- staticText controls [ text := "Foo" ]
  set controls [ layout := margin 5 (widget ctext) ]

  set f [ layout := widget controls ]
  {- delete ctext ? How? -}
  return ()

（我正在尝试构建一个动态 GUI，当它更新时我需要摆脱旧控件）。

Answer 1

您可以使其不可见并将其从布局中删除。这实际上并没有删除它，但会动态更改 UI：

import Graphics.UI.WX

buildGUI = do
  f <- frame [ text := "Hello" ]

  controls <- panel f []
  ctext <- staticText controls [ text := "Foo" ]
  butn <- button controls [text := "Remove the Foo"]        -- I've added a button to remove Foo
  set controls [ layout := row 0 [margin 5 (widget ctext),
                                  margin 5 (widget butn) ]]

  set f [ layout := widget controls ]

  set butn [on command := do
      set ctext [visible := False]                          -- so ctext doesn't show
      set controls [layout := margin 5 (widget butn) ]]     -- so ctext doesn't take up space
  return ()

main = start buildGUI