Asp Forum - Wrapping a structure as a new class...

trebor777

6/8/2007 1:46:00 AM

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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3 Answers

trebor777

6/10/2007 7:29:00 PM

Arf^^... nobody answered, but it's ok, I've solved my problem...
It's just because, i didnt' defined the initialize method as a singleton
method (other tutorials never told me to..., and it has always worked so...)
Anyway, it works now! Raaaah it was so simple xD

trebor777 wrote:
>
> 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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Nobuyoshi Nakada

6/11/2007 3:11:00 AM

Hi,

At Mon, 11 Jun 2007 04:28:33 +0900,
trebor777 wrote in [ruby-talk:255046]:
> Arf^^... nobody answered, but it's ok, I've solved my problem...

We had a development camp and RubyKaigi2007 last week.

> It's just because, i didnt' defined the initialize method as a singleton
> method (other tutorials never told me to..., and it has always worked so...)
> Anyway, it works now! Raaaah it was so simple xD

The initialize method must be an instance method. Rather
you'll need the allocator function. You should not override
Class.new unless you have special reasons.

static VALUE
bitmap_s_alloc(VALUE klass)
{
return Data_Wrap_Struct(klass, 0, SDL_FreeSurface, 0);
}

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

switch (argc) {
case 1:
new_bitmap = IMG_Load(StringValueCStr(argv[0]));
break;
case 2: {
unsigned int x = NUM2UINT(argv[0]), y = NUM2UINT(argv[1]);
new_bitmap = SDL_CreateRGBSurface(SDL_HWSURFACE, x, y, 32, 0, 0, 0, 0);
break;
default:
rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 or 2)",
argc);
}
DATA_PTR(self) = new_bitmap;
return self;
}

void
Init_bitmap(void)
{
VALUE cBitmap = rb_define_class("Bitmap", rb_cData);

rb_define_alloc_func(cBitmap, bitmap_s_alloc);
rb_define_method(cBitmap, "initialize", bitmap_init, -1);
}

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

The default allocator function would be used.

--
Nobu Nakada

trebor777

6/11/2007 3:12:00 PM

Ahh ^_^ Domo arigato! :p
You've even rewritten my code! That's great! really Thank you!

Sorry for the "nobody answered" i didn't know about that camp... ^^"

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comp.lang.ruby

Wrapping a structure as a new class...

trebor777

trebor777

Nobuyoshi Nakada

trebor777

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