haskell - wx haskell 拖放示例

Question

我正在寻找一个 wx haskell 拖放示例。我还没有找到。

有可用的吗？或提示？

至今：

• 我可以看到一个on drag事件（但没有“on drop”）
• 鼠标只是给出一个left up目标

• 我看到一些评论，我应该在 object 上附加一个放置目标，但我看不到它是如何被调用的：

  Graphics.UI.WXCore.DragAndDrop

  大号 51

  -- | 创建'DropSource'。然后“dragAndDrop”用这个“DataObject”替换目标的“DataObject”。

  dropSource::DataObject a -> Window b -> IO (DropSource())

• 我看不到 Graphics.UI.WXCore.DragAndDrop 上方的 WX 层在哪里

• 我猜这（太）旧了：[0]：http ://bb10.com/haskell-wxhaskell-general/2007-08/msg00035.html

反正现在很模糊……

---

编辑：这就是我现在的立场：在拖动时不会被激活，所以也没有 dragAndDrop（在 xinput 中的鼠标上只是为了看看发生了什么）（dragger是我从 [O] 得到的），但我没有从中获取事件）

--- test where DnD from yinput to xinput
module Main where

import CustoWidget
import Graphics.UI.WX hiding (empty)
import Data.Graph.Inductive
import Data.Maybe
import Control.Monad
import Graphics.UI.WX.Events
import Graphics.UI.WXCore.WxcClassesMZ
import Graphics.UI.WXCore.WxcClassesAL
import Graphics.UI.WXCore.DragAndDrop
import Graphics.UI.WXCore.Events
import Debug.Trace
main
  = start ballsFrame
  -- @next : try andrun start within a state

ballsFrame
  = do

      f      <- frame  [text := "Layout test"]
      p      <- panel  f []                       -- panel for color and tab management.
      ok     <- button p [text := "Ok"]
      can    <- button p [text := "Cancel", on command := infoDialog f "Info" "Pressed 'Cancel'"]
      xinput <- textEntry p [text := "100", alignment := AlignRight]
      yinput <- textEntry p [text := "100", alignment := AlignRight]

      set f [defaultButton := ok
             ,layout := container p $
                        margin 10 $
                        column 5 [boxed "coordinates" (grid 5 5 [[label "x:", hfill $ widget xinput]
                                                                ,[label "y:", hfill $ widget yinput]])
                                 ,floatBottomRight $ row 5 [widget ok,widget can]]
                                 ]
      set xinput [    on mouse := showMe] --, on keyboard := showMeK
      set yinput [ ] --on mouse := showMe, on keyboard := showMeK ]
--      fileDropTarget xinput (\pt file ->  putStrLn $ show file )


      -- prepare the drop source

      textdata <- textDataObjectCreate ""
      drop <- dropTarget xinput textdata

      textdata' <- textDataObjectCreate "text"
      src <- dropSource textdata' yinput

      -- activate on drag the do drag drop
      set yinput [ on drag := onDrag src]
      set ok [ on command := onOk f textdata]




      return ()



onDrag s p =  trace ("on drag " ++ show s ++ " " ++ show p) 
    dragAndDrop s Default (\_ -> return ()) 



onOk f textdata = do

          txt <- textDataObjectGetText textdata
          infoDialog f "resultText" txt
          close f

showMe = \x -> do putStrLn $ show x

dragger win wout = do
          textdata <- textDataObjectCreate ""
          drop <- dropTarget wout textdata
          textdata' <- textDataObjectCreate "text"
          src <- dropSource textdata' win
          dragAndDrop src Default (\_ -> return ())
          txt <- textDataObjectGetText textdata
          infoDialog wout "resultText" txt

Answer 1

概括 ：

• 创建一个 dropTarget 和一个 dropSource ：来自 Graphics.UI.WXCore.DragAndDrop
• 在源小部件上使用事件“ on drag” ，您将从那里调用Graphics.UI.WXCore.EventsdragAndDrop

我的错误和错误假设：

• 我正在寻找目标上的“on drop”事件。不存在，也不需要，因为：
• 当“拖动”时，其他事件被暂停。没有更多mouse up或mouse down。如果未在 (DnD) 目标上释放，则拖动将中止并恢复正常事件。[0]
• 请注意， textEntry 需要一个焦点才能获得“粘贴”，但是仍然会发生下降。查看控制台上的“拖动激活”。
• 交换的文本是来自 DataObjects 的文本（而不是来自源，如果这将是一个 textEntry。）。请参阅“文本已删除”。

以下代码将事件转储到控制台上，以进行实验：

module Main where


import Graphics.UI.WX hiding (empty)

import Data.Maybe
import Control.Monad
import Graphics.UI.WX.Events
import Graphics.UI.WXCore.WxcClassesMZ
--import Graphics.UI.WXCore.WxcClassesAL
import Graphics.UI.WXCore.DragAndDrop
import Graphics.UI.WXCore.Events

main
  = start dndtest


dndtest
  = do

      f      <- frame  [text := "Drag And Drop test"]
      p      <- panel  f []                       
      ok     <- button p [text := "Ok"]
      xinput <- textEntry p [text := "here :"] 
      yinput <- staticText p [text := "drag me"]

      set f [defaultButton := ok
             ,layout := container p $
                        margin 10 $
                        column 5 [boxed "coordinates" (grid 5 5 [[label "source:", hfill $ widget yinput]
                                                                ,[label "target(focus first):", hfill $ widget xinput]
                                                                ])
                                 ,floatBottomRight $ row 5 [widget ok]]
                                 ]

      set xinput [ on enter := onEnter]

      set yinput [ ] 
---------------------------------------------------------
--- meaningful stuff starts here
---------------------------------------------------------

       -- prepare the drop source : create a DataObject and associate it with the source
      textdata' <- textDataObjectCreate "text dropped"
      src <- dropSource textdata' yinput

      -- prepare the drop target: create a DataObject (placeholder here) and associate it with the target
      textdata <- textDataObjectCreate ".."
      drop <- dropTarget xinput textdata 


      -- activate on drag the do dragdrop. this will replace the target dataObject with the source one.
      -- Try with and without giving focus to the textEntry field
      -- Try and source from your favorite editor also (focus first!)
      set yinput [ on drag := onDrag src ]
---------------------------------------------------------
--- meaningful stuff stops here
---------------------------------------------------------

      set ok [ on command := close f ]
      return ()





--onDrag:: Graphics.UI.WXCore.WxcClassTypes.DropSource a -> Point -> IO ()
onDrag s p  =  do
    dragAndDrop s Default (\_ -> return ())
    putStrLn "on Drag activated:"



showMeE :: EventMouse -> IO ()
showMeE (MouseMotion point mod) = putStr ""  --- discard meaningless Motion event
showMeE  e = putStrLn $ show e


onEnter p = putStrLn $ "on Enter:" ++ show p

我已经看到了我可能会探索的其他好东西，比如在拖动过程中更改光标，或者对不同的 drop 变体做出反应。

[0]：http ://docs.wxwidgets.org/2.8/wx_wxdndoverview.html