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6558 :: question on call callback function in C

• oyster (orginal) [2020-07-19T14:37:49+02:00] view original

  file https://github.com/lc-soft/LCUI/blob/develop/test/helloworld.c says

  Widget_BindEvent(btn, "click", OnBtnClick, NULL, NULL);
  
  Run

  And the corresponding function and types are

  typedef void(*LCUI_WidgetEventFunc)(LCUI_Widget, LCUI_WidgetEvent, void*);
  
  LCUI_API int Widget_BindEvent(LCUI_Widget widget, const char *event_name,
          LCUI_WidgetEventFunc func, void *data,
          void(*destroy_data)(void*));
  Run

  So I made my nimlang version:

  
  type
      LCUI_WidgetEvent* = pointer
      LCUI_WidgetEventFunc* = proc(widget: LCUI_Widget,
          widget_evt: LCUI_WidgetEvent, data: pointer) {.nimcall.}
      Tdestroy_data* = proc(d: pointer) {.nimcall.}
  
  proc Widget_BindEvent(widget: LCUI_Widget, event_name: string,
          fun: LCUI_WidgetEventFunc, data: pointer,
          destroy_data: Tdestroy_data): int {. importc: "Widget_BindEvent".}
  Run

  and call it as

  
      Widget_BindEvent(btn, "click",
          cast[LCUI_WidgetEventFunc](OnBtnClick),
          cast[pointer](nil), cast[Tdestroy_data](nil)
          );
  Run

  but the callback function does not been called. So what is the problem? Thanks

  btw. the full code is

  
  const dllname = "LCUI.dll"
  
  type
      #~ typedef struct LCUI_WidgetRec_* LCUI_Widget;
      LCUI_Widget = pointer
  
  {.push cdecl, importc, discardable, dynlib: dllname.}
  
  #~ LCUI_API void LCUI_Init(void);
  proc LCUI_Init*(){. importc: "LCUI_Init".}
  
  #~ LCUI_API int LCUI_Main(void);
  proc LCUI_Main*(): cint {. importc: "LCUI_Main".}
  
  #~ LCUI_API LCUI_Widget LCUIWidget_GetRoot(void);
  proc LCUIWidget_GetRoot*(): LCUI_Widget {. importc: "LCUIWidget_GetRoot".}
  
  #~ LCUI_API LCUI_Widget LCUIBuilder_LoadFile(const char *filepath);
  proc LCUIBuilder_LoadFile*(filepath: cstring): LCUI_Widget {. importc: "LCUIBuilder_LoadFile".}
  
  #~ LCUI_API int Widget_Append(LCUI_Widget container, LCUI_Widget widget);
  proc Widget_Append*(container: LCUI_Widget, widget: LCUI_Widget): int {. importc: "Widget_Append".}
  
  #~ LCUI_API int Widget_Unwrap(LCUI_Widget widget);
  proc Widget_Unwrap(widget: LCUI_Widget): int {. importc: "Widget_Unwrap".}
  
  #~ LCUI_API LCUI_Widget LCUIWidget_GetById(const char *id);
  proc LCUIWidget_GetById(id: cstring): LCUI_Widget {. importc: "LCUIWidget_GetById".}
  
  #~ typedef void(*LCUI_WidgetEventFunc)(LCUI_Widget, LCUI_WidgetEvent, void*);
  type
      LCUI_WidgetEvent* = pointer
      LCUI_WidgetEventFunc* = proc(widget: LCUI_Widget,
          widget_evt: LCUI_WidgetEvent, data: pointer) {.nimcall.}
      Tdestroy_data* = proc(d: pointer) {.nimcall.}
  
  #~ LCUI_API int Widget_BindEventById(LCUI_Widget widget, int event_id,
          #~ LCUI_WidgetEventFunc func, void *data,
          #~ void(*destroy_data)(void*));
  proc Widget_BindEventById(widget: LCUI_Widget, event_id: int,
          fun: LCUI_WidgetEventFunc,  data: pointer,
          destroy_data: Tdestroy_data): int {. importc: "Widget_BindEventById".}
  
  #~ LCUI_API int Widget_BindEvent(LCUI_Widget widget, const char *event_name,
          #~ LCUI_WidgetEventFunc func, void *data,
          #~ void(*destroy_data)(void*));
  proc Widget_BindEvent(widget: LCUI_Widget, event_name: string,
          fun: LCUI_WidgetEventFunc, data: pointer,
          destroy_data: Tdestroy_data): int {. importc: "Widget_BindEvent".}
  
  #~ LCUI_API size_t TextEdit_GetTextW(LCUI_Widget w, size_t start,
          #~ size_t max_len, wchar_t *buf);
  type size_t = int
  proc TextEdit_GetTextW(w: LCUI_Widget, start: size_t,
          max_len: size_t, buf: WideCString):  size_t {. importc: "TextEdit_GetTextW".}
  
  #~ LCUI_API int TextView_SetTextW(LCUI_Widget w, const wchar_t *text);
  proc TextView_SetTextW(w: LCUI_Widget, text: WideCString): int {. importc: "TextEdit_SetTextW".}
  
  {.pop.}
  
  proc OnBtnClick(self: LCUI_Widget, e: LCUI_WidgetEvent, arg: pointer) {.cdecl.}=
      echo 111
      var s = newWideCString("", 256)
      var edit = LCUIWidget_GetById("edit");
      var txt = LCUIWidget_GetById("text-hello");
      
      TextEdit_GetTextW(edit, 0, 255, s);
      TextView_SetTextW(txt, s);
  
  
  proc main(): int =
      
      var root, pack, btn: LCUI_Widget;
      
      LCUI_Init();
      root = LCUIWidget_GetRoot();
      pack = LCUIBuilder_LoadFile("helloworld.xml");
      if pack == nil:
          return -1
      Widget_Append(root, pack);
      Widget_Unwrap(pack);
      btn = LCUIWidget_GetById("btn");
      Widget_BindEvent(btn, "click",
          cast[LCUI_WidgetEventFunc](OnBtnClick),
          cast[pointer](nil), cast[Tdestroy_data](nil)
          );
      return LCUI_Main();
  
  discard main()
  
  Run

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• Stefan_Salewski (orginal) [2020-07-19T14:55:52+02:00] view original

  Maybe first error is in

  proc Widget_BindEvent(widget: LCUI_Widget, event_name: string,
  Run

  When it is a C lib, then event_name should be cstring, because compiler should not pass the Nim string but only the cstring, that is the data block.

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