Re: How to store Gdk::Pixbuf pixels into std::string objects

[Markus Kolb <markus kolb+gtkmm tower-net de>]

Am 2015-02-23 21:40, schrieb Glus Xof:
> Hi guys,
>
> Before anything, I admit that probably my question is not an 
> specifically
> Gtkmm question... but nevertheless I think you may know how Gdk::Pixbuf 
> is
> done...
>
> Having the following,
>
> Glib::RefPtr<Gdk::Pixbuf> ref_orig = Gdk::Pixbuf::create_from_file
> ("./file.png");
>
> I'm trying to temporary store (because I need so) the image data into a
> std::string object. It seems that get_pixels() could solve the problem,
> getting a pointer of type guint8.

Seems that gdkmm is not up-to-date here.
gdk uses a guchar*. But this shouldn't be a problem.

> So, I wrote as follows,
>
> std::string image_pixels (reinterpret_cast<const char
> *>(ref_orig->get_pixels()), ref_orig->get_rowstride());

I think this does not what you expect.

https://developer.gnome.org/gdk-pixbuf/stable/gdk-pixbuf-The-GdkPixbuf-Structure.html#gdk-pixbuf-get-rowstride

See also the part below the description headline.

Maybe you should use gsize Gdk::Pixbuf::get_byte_length()
because 
https://developer.gnome.org/gdk-pixbuf/stable/gdk-pixbuf-The-GdkPixbuf-Structure.html#gdk-pixbuf-get-pixels-with-length 
is missing.

I hope it will help you.

But think about the std::string. Big ? ;-)