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4539 :: still no success binding DLL's callback function

• oyster (orginal) [2019-01-07T11:02:41+01:00] view original

  I have posted days ago https://forum.nim-lang.org/t/4522 in which I try to bind xcgui which is a free 32bits dll for windows

  Now I try to bind FLTK(http://www.fltk.org). I can compile FLTK, test, examples and fluid with my MSYS2+MingW64 on Win7 64 bits I know there is already https://github.com/Skrylar/nfltk, but so bad, the test.nim can not be compiled, my msys2 halted for hours on lines

  
  Hint: nimwidget [Processing]
  CC: fltk_test
  CC: fltk_enumerations
  Run

  However I am not trying to translated the official FLTK C header by myself again. C's pointer are always beats me, and I found a nice FLTK binding( and tons of examples) for freebasic by D.J.Peters on https://www.freebasic.net/forum/viewtopic.php?f=14&t=24547 In the work of D.J.Peters, there are prebuilt

  
  fltk-c-1.3.3-32.dll
  fltk-c-1.3.3-64.dll
  libfltk-c-1.3.3-32-arm.so
  libfltk-c-1.3.3-32-syslib.so
  libfltk-c-1.3.3-32.so
  libfltk-c-1.3.3-64-syslib.so
  libfltk-c-1.3.3-64.so
  Run

  so I just mimicked and got the following code

  import winim # for the L""
  
  type
      long = int16
      Fl_Widget = int16
      Fl_Window = int16
      Fl_Button = int16
      #~ Fl_Callback = int16
  
  const
      fltk* = "fltk-c-1.3.3-64.dll"
  
  
  type
    Ihandle = object
    PIhandle* = ptr Ihandle
    
    Icallback* = proc (arg: PIhandle): cint {.cdecl.}
    
    Fl_Callback* = proc(widget: ptr Fl_Widget, pData: ptr any)
  
  proc Fl_WindowNew(byval: long, h: long, title:cstring):  ptr Fl_Window{.
      cdecl, importc: "Fl_WindowNew", dynlib: fltk, discardable.}
  
  proc Fl_ButtonNew(x: long, y: long, w: long, h: long, label: cstring) :  ptr Fl_Button{.
      cdecl, importc: "Fl_ButtonNew", dynlib: fltk, discardable.}
  
  proc Fl_WidgetSetCallback(wgt:  ptr Fl_Widget, cb:Fl_Callback){.
      cdecl, importc: "Fl_WidgetSetCallback", dynlib: fltk, discardable.}
  
  proc Fl_WindowShow(win:  ptr Fl_Window){.
      cdecl, importc: "Fl_WindowShow", dynlib: fltk, discardable.}
  
  proc Fl_Run(): long{.
      cdecl, importc: "Fl_Run", dynlib: fltk, discardable.}
  
  proc Fl_WidgetCopyLabel(wgt:  ptr Fl_Widget; caption: ptr WCHAR){.
      cdecl, importc: "Fl_WidgetCopyLabel", dynlib: fltk, discardable.}
  
  proc ButtonClick (button: ptr FL_WIDGET, arg: ptr any):cint  {.cdecl.} =
    Fl_WidgetCopyLabel(button, "do it again")
  
  var Win = Fl_WindowNew(320, 200, "What a shiny Window :-)")
  var Btn = Fl_ButtonNew(10, 10, 120, 32, "click me")
  #~ Fl_WidgetSetCallback(Btn, ButtonClick)
  #~ Fl_WidgetSetCallback(cast[ptr Fl_Widget](Btn), (ButtonClick))
  #~ Fl_WidgetSetCallback(cast[ptr Fl_Widget](Btn), cast[Fl_Callback](ButtonClick))
  Fl_WindowShow(Win)
  Fl_Run()
  Run

  this code can run without the Fl_WidgetSetCallback line.

  If I use

  Fl_WidgetSetCallback(Btn, ButtonClick)
  Run

  I get

  
  a.nim(45, 21) Error: type mismatch: got <ptr Fl_Button, proc (button: ptr Fl_Widget, arg: ptr GenericParam): cint{.cdecl.}>
  but expected one of:
  proc Fl_WidgetSetCallback(wgt: ptr Fl_Widget; cb: Fl_Callback)
    first type mismatch at position: 2
    required type: Fl_Callback
    but expression 'ButtonClick' is of type: proc (button: ptr Fl_Widget, arg: ptr GenericParam): cint{.cdecl.}
  
  expression: Fl_WidgetSetCallback(Btn, ButtonClick)
  Run

  elif I use

  Fl_WidgetSetCallback(cast[ptr Fl_Widget](Btn), (ButtonClick))
  Run

  I get

  
  a.nim(46, 21) Error: type mismatch: got <ptr Fl_Widget, proc (button: ptr Fl_Widget, arg: ptr GenericParam): cint{.cdecl.}>
  but expected one of:
  proc Fl_WidgetSetCallback(wgt: ptr Fl_Widget; cb: Fl_Callback)
    first type mismatch at position: 2
    required type: Fl_Callback
    but expression 'ButtonClick' is of type: proc (button: ptr Fl_Widget, arg: ptr GenericParam): cint{.cdecl.}
  
  expression: Fl_WidgetSetCallback(cast[ptr Fl_Widget](Btn), ButtonClick)
  Run

  elif I use

  Fl_WidgetSetCallback(cast[ptr Fl_Widget](Btn), cast[Fl_Callback](ButtonClick))
  Run

  I get

  
  a.nim(47, 53) Error: cannot cast to a non concrete type: 'Fl_Callback'
  Run

  Please, can anyone give clear help? Thanks

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• moerm (orginal) [2019-01-07T16:09:39+01:00] view original

  Here is your problem:

  Fl_Callback* = proc(widget: ptr Fl_Widget, pData: ptr any)
  
  # ...
  proc ButtonClick (button: ptr FL_WIDGET, arg: ptr any):**cint  {.cdecl.}** =
  Run

  In other words, Fl_Callback is not cdecl and its return type is void while ButtonClick is cdecl and its return type is cint.

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• cumulonimbus (orginal) [2019-01-07T20:42:35+01:00] view original

  FLTK's widgets are full on pointers, and coordinates in FLTK-1.3 are at least 32-bit (they were 16-bit in FLTK-1.0 and FLTK-1.1); You might have problems from the int16<>ptr mismatch, as well as the int16<->int32 mismatch if you ever use coordianates > 32768.

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• oyster (orginal) [2019-01-08T05:49:53+01:00] view original

  Let me ignore the data type first ;) I hope there is a VisualBasic-Freebasic-C-Nim data type comparasion sheet

  type
    Fl_Callback* = proc(widget: ptr Fl_Widget, pData: ptr any):cint {.cdecl.}
  
  proc ButtonClick (button: ptr FL_WIDGET, arg: ptr any):cint {.cdecl.} =
    Fl_WidgetCopyLabel(button, "do it again")
  
  Fl_WidgetSetCallback(Btn, ButtonClick)
  Run

  says

  
  a.nim(45, 27) template/generic instantiation of `ButtonClick` from here
  a.nim(40, 42) Error: cannot instantiate: 'arg:type'
  Run

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• Araq (orginal) [2019-01-08T11:10:49+01:00] view original

  Don't use ptr any, use pointer instead.

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