Re: image resizing

["James M. Cape" <jcape ignore-your tv>]

On Fri, 2003-07-11 at 22:13, ritwik kumar wrote:
> hey,
>     how do i scale images to my desired size and then
> display using GtkImage widget? othetwise on part of
> the image shows when window is smaller than the image.
> Please help.
> 
> 
> ritwik

You must create/scale a pixbuf yourself:

GtkWidget *
get_image_from_file_at_size (const gchar *filename,
                             gint dest_width,
                             gint dest_height)
{
    GtkWidget *img;
    GdkPixbuf *raw, *display;
    GError *err = NULL;

    raw = gdk_pixbuf_new_from_file (filename, &err);
    /* The pixbuf could not be loaded */
    if (err != NULL)
    {
        g_warning ("Could not load file '%s': %s",
                   "/path/to/whatever.png", err->message);
        g_error_free (err);
        return NULL;
    }

    if (gdk_pixbuf_get_width (raw) > dest_width ||
        gdk_pixbuf_get_height (raw) > dest_height)
    {
        gdouble scale_x, scale_y;
        gdouble offset_x, offset_y;

        scale_x = gdk_pixbuf_get_width (raw) / (gdouble) dest_width;
        scale_y = gdk_pixbuf_get_height (raw) / (gdouble) dest_height;

        if (scale_y > scale_x)
            scale_y = scale_x;
        else if (scale_x > scale_y)
            scale_x = scale_y;

        offset_x = (scale_x * gdk_pixbuf_get_width (raw)) / 2.0;
        offset_y = (scale_y * gdk_pixbuf_get_height (raw)) / 2.0;

        display = gdk_pixbuf_new (GDK_COLORSPACE_RGB,
                                  gdk_pixbuf_get_has_alpha (raw),
                                  8, dest_width, dest_height);

        gdk_pixbuf_scale (raw, display, 0, 0, dest_width, dest_height,
                          offset_x, offset_y, scale_x, scale_y,
                          GDK_INTERP_HYPER);

        g_object_unref (raw);
    }
    else
    {
        display = raw;
    }

    img = gtk_image_new_from_pixbuf (display);
    g_object_unref (display);

    return img;
}

Notes:
1.) This function will only scale an image down, not up.
2.) I'm not sure if this function will compile, not segv, and work
properly, but it looks like it should [i.e. I did no testing on this at
all, it's off the top of my head].
3.) The API docs for GdkPixbuf are at:
http://developer.gnome.org/doc/API/2.0/gdk-pixbuf/index.html

4.) Perhaps the GtkImage widget needs a "scaled" property -- to handle
automatically scaling the pixbuf to the widget size...? Anyone?
Developers? Bueller? :-)

-- 
Peace,

    Jim Cape
    http://ignore-your.tv

    "It is literally true that, like Christianity, Socialism
     has conquered the world by defeating itself."
        -- Alexander Berkman, ABC of Anarchism

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