Re: [ruby-gnome2-devel-en] cannot set pixbuf pixels - how to modify an image?

[Michal S. <hra...@ce...>]

2009/8/2 Kouhei Sutou <ko...@co...>:
> Hi,
>
> In <a5d...@ma...>
>  "Re: [ruby-gnome2-devel-en] cannot set pixbuf pixels - how to modify an image?" on Sun, 2 Aug 2009 08:37:15 +0200,
>  Michal Suchanek <hra...@ce...> wrote:
>
>>>> Which I resolved by patching the pixbuf bindings.
>>>
>>> set_pixels:
>>>
>>>  * We should use RSTRING_PTR() instead of RSTRING()->ptr
>>>    and RSTRING_LEN() instead of RSTRING()->len.
>>>  * We should return self for setter method:
>>>    http://ruby-gnome2.sourceforge.jp/hiki.cgi?Naming+and+Conversion+Rules#Accessors+%28Setter%2FGetter+methods%29
>>
>> OK, these are easy to change, I just used whatever worked (and
>> whatever was described in README.EXT)
>
> Please.
>
>>>  * Why memmove()? Should we use memcpy()?
>>
>> memmove is the safer variant. If the user got to the original pointer
>> somehow the copied regions might overlap. While it's unlikely  one
>> more check should not impact performance and should avoid some
>> interesting bugs.
>
> It seems that the user can't get the original pointer.
> If the user can get the original pointer, the user doesn't
> need to set pixels. The user can only change the original
> pointer.
>
> So I think that we can use memcpy().
>
>>>  * Should we require "pixbuf.pixels.size == new_pixels.size"?
>>
>> I guess it's OK to set only part of the pixels. I am not sure
>> returning error is appropriate if the sizes do not match.
>
> If we provide an 'offset' argument, it will be reasonable.
> But set_pixels doesn't provide it.
>
> So I think that the sizes should be matched.

Perhaps a [] interface would be better than pixels and pixels= then?

Thanks

Michal