Re: pixmap and png..background

[AKILA M <akila crlbel ernet in>]

 hello,

   Thank u Michael...... And yes the your modified png file you have sent
IS TRANSPARENT

   And one more question., i tried to convert my other png files as you
have said by adding alpha channel to the image in GIMP. But i am unable to
do so. Can you please let me know how to do it. what i did was

        1. i loaded the corresponding png file in GIMP
        2.Right clicked on image
        3.clicked  "Layers"
        4.clicked "Add Alpha Channel"

   i saved and used it for display. the background was same(white).
   i am sure that i am missing something very vital, i tried some other
options also, but couldn't
   please let me know whats to be done exactly.

And thanks a lot 
akila

On 26 Jul 2002, Michael Torrie wrote:

> On Fri, 2002-07-26 at 23:04, AKILA M wrote:
> > hello,
> >     i create a pixmap from a png file using the following API
> >
> >     pixbuf = gdk_pixbuf_new_from_file("filename.png");
> >         gdk_pixbuf_render_pixmap_and_mask(pixbuf, &pixmap, &mask, 127);
> >         image = gtk_pixmap_new(pixmap, mask);
> >
> >     i put the image in an event box and display it in a fixed
> > container. My problem is that i get a white backgroud in the image. i have
>                                         ^^^^^^^^^^^^^^^^
>
> Umm, you're getting a white background because that's what's in the png
> file (ie there's no transparency in the png)!  Evolution shows
> transparent pngs properly, and this one shows up as a blue circle on a
> white background.  I loaded the png into the gimp and added an alpha
> channel and changed the white into transparent.  The new png is
> attached.  Try it and see if it doesn't show up as transparent.
>
> By the way, you might want to use a GtkDrawingArea widget instead of
> just an event box.  Then you can render the GdkPixbuf to it with fill
> alpha blending, instead of just a threshold transparency level.
>
> Michael
>
>
> > read the previous discussions on this problem(one posted 2 days earlier).
> > i can't use
> >
> >     gtk_image_from_new_file (GTK2.0)
> >
> > since i use gtk1.2.8. i create the png image file using XPaint. i
> > alternatively use gimp also. but the background is the same white. i have
> > tried converting png to xpm file. i also found out this(background in
> > white) doesnot happen with xpm files stored in buffers...and can be used
> > in API
> >
> >      pixmap = gdk_pixmap_create_from_xpm_d(fcontainer->window,
> >                                                 &mask,
> >                                                 &style->bg[GTK_STATE_NORMAL],
> >                                                 buffer_xpm);
> >
> > But i want to know how i can get transparent background in png
> > files.(using GTK1.2.8)
> >
> > Any help would be very useful....
> >
> > i have attached a sample png file with this.."dot_circle.png"
> >
> > Thankx a lot
> > akila
> >
> >
> >
> >
> > ******************************************************************************
> > M. Akila,
> > Central Research Laboratory,
> > Bharat Electronics,
> > Jalahalli,
> > Bangalore.
> >
> > Ph.No (off): 91-080-8381125
> > E-Mail Id  : akila crlbel ernet in
> >             
> >                              HAVE A NICE DAY
> > ******************************************************************************
> -- 
> Public key available from http://students.cs.byu.edu/~torriem