From: trebor777 <mrobert@...777.net>
Date: 2007-06-08T10:46:11+09:00
Subject: Wrapping a structure as a new class...


well i don't know if my title is exactly what i mean...
anyway

I'm writing a C extension,  which can create a Bitmap class.(I'm using SDL)

So far, it's working.. for the initialization:

//========================================
VALUE cBitmap;

void sdl_freeSurface(SDL_Surface* surface)
{
    SDL_FreeSurface(surface);
}

VALUE bitmap_init(int argc, VALUE *argv, VALUE self)
{
SDL_Surface *new_bitmap;

if (argc == 1)
	{
	Check_Type(argv[0],T_STRING);
	new_bitmap=IMG_Load(STR2CSTR(argv[0]));
	}
else
	{
	Check_Type(argv[0],T_FIXNUM);
	Check_Type(argv[1],T_FIXNUM);

new_bitmap=SDL_CreateRGBSurface(SDL_HWSURFACE,FIX2UINT(argv[0]),FIX2UINT(argv[1]),32,0,0,0,0);
	}
return Data_Wrap_Struct(cBitmap,0,sdl_freeSurface,new_bitmap);
}
//=========================================================

when i do a=Bitmap.new(23,32)
i got a bitmap object.
but here comes the problem:

I got an argument type error on the class methods...(a.width for example):
"wrong argument type Bitmap <expected Data>"

I've understand that the wrapped structure is a T_DATA object.... but all I
want is to access this structure.
a class method example using which try to access the struct:
//===============================
VALUE bitmap_width(VALUE obj)
{
SDL_Surface *surface;
Data_Get_Struct(obj,SDL_Surface,surface);
return INT2FIX(surface->w);
}
//===============================

If i use the 'self' argument in the Data_wrap instead of cBitmap, I can't
create the object and got the same error:  '........ type Bitmap <expected
Class>'

So if someone can explain me :p how to get back my structure...please. ^^
would be great!




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