OpenEuphoria

RE: Display Picture.

• Posted by Chris Bensler <bensler at mail.com> Apr 09, 2002
• 393 views

Sam wrote:
> Hi ...
> 
>    Appreciate the answers I've gotten from you guys. Hope you can come 
> up with one more. I can't seem to get Euphoria to display a picture.
> 
>   include image.e
>   sequence Pic1
>   Pic1 = read_bitmap ("C:\\Euphoria\\MyPic.Bmp")
> 
>   Got message "type_check failure, MyPic is 1" 
> 
>    Tried a different picture. This time, for variety, I got, "type_check 
> failure, DiffPic is 3."
> 
>    Wasn't going to give up that easily though. Changed the program 
> slightly.
> 
>    include image.e
>    object Pic1
>    Pic1 = read_bitmap ("C:\\Euphoria\\MyPic.Bmp")
> 
>    Hey! No error msg. this time!
> 
>    So I added a line:
> 
>    display_image ({100, 20}, Pic1 [2])
> 
>    This time I got, "attempt to subscript an atom
>                      (reading from it)"
> 
>    So then I tried to run the `Bitmap.ex' program in the demo\dos32 
> directory. Tried three different pictures. One showed up on screen, but 
> only the bottom 20 percent. The other two get msg, `unsupported format.' 
> 
> 
>    Any idea??
> 
>    Thanks,
> 
>    Sam 
> 

read_bitmap() returns a a 2-element sequence where the first element is 
a sequence that contains the bitmap palette, and the second is a 
sequence containing the bitmap data.

Bitmaps of 2, 4, 16 or 256 colors are supported. If the file is not in a 
good format, an error code (atom) is returned instead: 
 
     global constant BMP_OPEN_FAILED = 1,
                 BMP_UNEXPECTED_EOF = 2,
             BMP_UNSUPPORTED_FORMAT = 3


Your first attempt failed to open the specified bitmap. Your second 
attempt tried to open an unsupported bitmap. The third attempt also 
failed to read_bitmap(), but you didn't check to see if Pic1 was 
successful and passed an atom to display_image(), when it accepts a 
sequence.

This is what you should have, to be safe.
(untested code)

object Pic1
Pic1 = read_bitmap("C:\\Euphoria\\MyPic.Bmp")
if atom(Pic1) then
   puts(2,sprintf("read_bitmap() failed. Error code: %d\n",Pic1))
   abort(1)
end if

display_image({100,20},Pic1[2])


I can't explain why you would get unexpected images displayed, except 
that the bitmaps you are trying to use probably aren't supported.


Chris