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Re: help with callbacks

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Jérôme Vuarand wrote:

Can you send the prototype of the C function you are calling to
register a callback, along with the prototype of that callback ?

here's one of the examples that comes with the lib, it's just a basic example that pops up a message box with a single button on it:
----
#include "jm_gui/jm_gui.bi"
Dim Shared gQuit as integer = False
Function PopUp_BoxProc (ByVal box As UI_BOX_PTR, ByVal msgid As Integer, ByVal msgdata As UI_MSG_DATA_T Ptr) As Integer 
 function = 1 '' Default not processed
 Select Case msgid
 Case UI_MSG_MOUSE_CLICK
 Select Case UI_GetBoxID(box)
 Case 1 '' Caption
 UI_SetCaption box, "Hello Again!"
 Case 2 '' Close
 gQuit = True
 function = 0
 End select
 End Select
End Function
Function PopUp_Create(byval owner As UI_BOX_PTR) As UI_BOX_PTR
 Dim As UI_BOX_PTR frm, btn, cap
frm = UI_CreateFrame(owner, 0, 640 \ 2 - 228 \ 2, 50, 228, 48, @PopUp_BoxProc, UI_BOX_FLAG_NORMAL or UI_BOX_FLAG_DRAG) cap = UI_CreateCaption(frm, 1, 228 \ 2 - 64 \ 2, 4, 64, 16, @PopUp_BoxProc, UI_BOX_FLAG_NORMAL, "Hello World!") btn = UI_CreateButton(frm, 2, 228 \ 2 - 64 \ 2, 24, 64, 16, @PopUp_BoxProc, UI_BOX_FLAG_NORMAL, "Close") 
 Function = frm
End Function
Dim as UI_BOX_PTR gPopup
Dim as integer mx,my,mw,mb,ret
Dim Shared fnt As JM_FONT_PTR = 0
ScreenRes 640,480,16,2
UI_UpdateScreenInfo(640,480,16)
UI_SetSysColor UI_SYSCLR_FRAME_FACE, RGB(63,191,127)
UI_SetSysColor UI_SYSCLR_TEXT , RGB(0,255,255)
ScreenSet 1,0
fnt = FONT_CreateFromBmp(6,8,"../data/6x8.bmp")
FONT_Set fnt
gPopup = PopUp_Create(NULL)
While gQuit = False
 GetMouse mx,my,mw,mb
 ret = UI_UpdateMouseInfo(NULL, mx, my, mw, mb)
 cls
 ret = UI_Draw(NULL, 0)
 flip
 sleep 1
Wend
FONT_Delete fnt
----
Basically, what I want to do is wrap all the UI_ functions so that they can be used in a lua script in almost exactly the same way as in FreeBasic. This is what I've been able to come up with for the function wrappers so far. I only started programming a few months ago so there's probably a better way than what I've been able to do 
(this is FreeBasic, not C, but the lua api functions are the same)
----
' lua wrappers for jm_gui
#macro UserdataStubs(HANDLE, DATATYPE)
Function To##HANDLE (Byval L As lua_State Ptr, Byval index As Integer) As DATATYPE Ptr 
 var h = cptr(DATATYPE Ptr, lua_touserdata(L, index))
 If h = NULL Then luaL_typerror(L, index, #HANDLE)
 Return h
 End Function
 Function push##HANDLE (Byval L As lua_State Ptr) As DATATYPE Ptr
var newvalue = cptr(DATATYPE Ptr, lua_newuserdata(L, sizeof(DATATYPE))) 
 luaL_getmetatable(L, #HANDLE)
 lua_pushvalue(L, -1)
 lua_setmetatable(L, -3)
 lua_pushstring(L, "__index")
 lua_pushstring(L, #HANDLE)
 lua_gettable(L, LUA_GLOBALSINDEX)
 lua_settable(L, -3)
 lua_pop(L, 1)
 Return newvalue
 End Function
#endmacro
#macro UserdataRegister(HANDLE, METHODS, METAMETHODS)
 Function HANDLE##_register(Byval L As lua_State Ptr) As Integer
luaL_newmetatable(L, #HANDLE) ' create New metatable For file handles 
 lua_pushliteral(L, "__index")
lua_pushvalue(L, -2) ' push metatable lua_rawset(L, -3) ' metatable.__index = metatable luaL_openlib(L, 0, METAMETHODS, 0) 
 luaL_openlib(L, #HANDLE, METHODS, 0)
lua_pushstring(L, #HANDLE) 
 lua_gettable(L, LUA_GLOBALSINDEX)
 luaL_getmetatable(L, #HANDLE)
 lua_setmetatable(L, -2)
Return 1 End Function 
#endmacro
#include once "jm_gui/jm_gui.bi"
UserdataStubs(Font, JM_FONT_PTR Ptr)
function load_jm_font Cdecl(Byval L As lua_State Ptr) As Integer
if (lua_gettop(L) < 1) or (lua_gettop(L) > 3) then return Lual_error(L, "[UI.FontLoad] takes 3 arguments") 
 dim as string error_msg ', f_file
 'dim as integer f_w, f_h
 dim new_font as JM_FONT_PTR
 dim as string f_file = *lual_checkstring(L,1)
 dim as integer _
 f_w = lual_checkinteger(L,2),_
 f_h = lual_checkinteger(L,3)
if not FileExists(f_file) then return luaL_argerror(L, 3, "[UI.FontLoad] cannot find "&f_file) select case ucase(right(f_file, 3)) 
 case "BMP"
 new_font = FONT_CreateFromBMP(f_w, f_h, f_file)
 case else
 luaL_argerror(L, 1, "[UI.FontLoad] font format not recognized")
 end select
dim as JM_FONT_PTR ptr fnt = PushFont(L) 
 *fnt = new_font
return 1 
end function
function fnt_del Cdecl(Byval L As lua_State Ptr) As Integer
 var fnt = toFont(L,1)
 if *fnt then
 FONT_Delete *fnt
 *fnt = 0
 return 1
 else
if *fnt = 0 then return luaL_error(L, "[font.delete] font expected got nil") 
 endif
end function
Static Shared As luaL_reg font_methods(2) = {_
 (@"load", @load_jm_font),_
 (0,0)}
Static Shared As luaL_reg font_meta(1) = {(@"__gc", @fnt_del), (0,0)}
UserdataRegister(Font, @font_methods(0), @font_meta(0))
Font_Register(L)
function ui_scd Cdecl(Byval L As lua_State Ptr) As Integer
if lua_gettop(L) <> 1 then return lual_error(L, "[UI.SetColorDepth] takes one argument") 
 dim as integer col_d = lual_checknumber(L,1)
 UI_SetColorDepth(col_d)
end function
function setfnt Cdecl(Byval L As lua_State Ptr) As Integer
if lua_gettop(L) <> 1 then return lual_error(L, "[UI.FontSet] takes one argument") 
 if lua_type(L, 1) <> LUA_TUSERDATA then
var error_msg = "[UI.SetFont] font expected, got "& *lua_typename(L, lua_type(L,3)) 
 return lual_argerror(L, 1, error_msg)
 endif
Dim As JM_FONT_PTR Ptr pfnt = toFont(L,1) 
 dim As JM_FONT_PTR fnt = *pfnt
 var a = FONT_set(fnt)
end function
function fnt_print Cdecl(Byval L As lua_State Ptr) As Integer
if (lua_gettop(L) < 5) or (lua_gettop(L) > 6) then return luaL_error(L, "[UI.FontPrint] takes either 5 or 6 args") 
 dim as integer x = lual_checknumber(L,1), y = lual_checknumber(L,2)
dim as uinteger fc = lual_checknumber(L,4), bc = lual_checknumber(L,5), trans = 1 
 dim as string text = *lual_checkstring(L,3)
 if lua_gettop(L) = 6 then trans = lual_checknumber(L,6)
 FONT_DrawString x, y, text, fc, bc, trans
end function
function f_GTW Cdecl(Byval L As lua_State Ptr) As Integer
 var text = *lual_checkstring(L,1)
 lua_pushnumber(L, FONT_GetTextWidth(text))
 return 1
end function
function f_GTH Cdecl(Byval L As lua_State Ptr) As Integer
 var text = *lual_checkstring(L,1)
 lua_pushnumber(L, FONT_GetTextHeight(text))
 return 1
end function
function ui_ssc Cdecl(Byval L As lua_State Ptr) As Integer
if lua_gettop(L) <> 2 then return luaL_error(L, "[UI.SetSysColor] takes 2 args") 
 dim as uinteger _
 flag = lual_checknumber(L,1),_
 col = lual_checknumber(L,2)
 UI_SetSysColor flag, col
end function
function ui_cf Cdecl(Byval L As lua_State Ptr) As Integer
if lua_gettop(L) <> 8 then return lual_error(L, "[UI.CreateFrame] takes 8 args") 
 dim ownerbox as UI_BOX_PTR = 0
 dim As integer _
 id = lual_checknumber(L, 2), _
 x = lual_checknumber(L, 3), _
 y = lual_checknumber(L, 4), _
 w = lual_checknumber(L, 5), _
 h = lual_checknumber(L, 6), _
 flags = lual_checknumber(L, 8)
 dim as string func_string = *lual_checkstring(L,7)
var ret = UI_CreateFrame(ownerbox, id, x, y, w, h, @callback_function , flags) end function 
Static Shared As luaL_reg ui_functions(7) = {_
 (@"SetColorDepth", @ui_scd),_
 (@"FontSet", @setfnt),_
 (@"FontPrint", @fnt_print),_
 (@"FontGetTextWidth", @f_GTW),_
 (@"FontGetTextHeight", @f_GTH),_
 (@"SetSysColor", @ui_ssc),_
 (@"CreateFrame", @ui_cf),_
 (0,0)}
luaL_openlib(L, @"UI", @ui_functions(0),0)
----
In this line of the ui_cf function: var ret = UI_CreateFrame(ownerbox, id, x, y, w, h, @callback_function , flags) the argument '@callback_function' is the function that I need to create that will link to a lua function, but I don't really know where to begin 
You can get the library I'm using from this page:
http://www.execulink.com/~coder/freebasic/jmgui.html

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