Re: [perl-win32-gui-users] display images--sample code?

[Johan L. <jo...@ba...>]

At 17:40 2002-01-07 -0800, Glenn Linderman wrote:
>ImageMagick can do lots of nice conversions of whatever graphic format
>to BMP format, if that is what Win32::GUI::Bitmap needs.

Yes, that's what you want.


>How can I get from there, to a window that displays the data? Do I have
>to
>
>$errstr = $image -> Write ( 'xxx.bmp' );
>
>as it appears that the Win32::GUI::Bitmap call requires a filename?
>use Win32::GUI;
>$bitmap = new Win32::GUI::Bitmap ( 'xxx.bmp' );

That would be the first quick solution to get something working until you 
figure out how to assign the bitmap data directly to object 
Win32::GUI::Bitmap object.

Encapsulate it into a sub or method and you can easily change 
implementation afterwards.

Read up on the graphics stuff in the Win32 API docs. And read the source 
(Perl + C) for the Bitmap class, that should get you going in the right 
direction.


>And then, having somehow or another a $bitmap reference, how do I
>display it in a window?
>
>I see one possibility of
>
>$main_window -> AddLabel ( -name => bitmap, -bitmap => $bitmap );

Good approach. And, as mentioned earlier on the list, keep the $bitmap 
object from being destroyed during the entire lifespan of the label.


>Are there any pros or cons of using Labels vs Buttons vs ???  And do you

Go with the label. I don't think you can remove the "button look" anyway.


>need to specify the exact size of the bitmap as the size of the label?
>Or do you need to leave room for borders, and other stuff?

Yes. I think there are no margins to consider if you align the image 
top-left or center-middle. But like you said, experiment, possibly using 
TGL to get things done fast (save the Design before you add bitmaps and 
place the bitmap files-in-or-below the .tgl directory).


>If there are any scaling capabilities, it'd be nice to know about them,
>I didn't find any the first pass through.

There is one sample program in the distro, resizing the background of a window.


>On the other hand, I fear that none of that will allow me to add scroll
>bars to the bitmap, so that I can display a portion of a bigger than
>screen image.

Difficult. Maybe if you can add a scrollbar style to the bitmap? That 
_might_ work, possibly... (look at the CreateWindow function in the Win32 
API).


>I fear I'll have to dive into Win32::GUI::DC to do some
>of this... I've been avoiding that so far... but this seems oriented to
>line art, rather than bitmap art...

If you have to do the DC thing you definitely should take a look at the 
Win32::GUI:Control::Label control (the Paint method... but the important 
methods are inherited from Win32::GUI:Control i think, let me know if you 
can't find them), because there are some really tricky things to consider 
when painting bitmaps on a device context, like pixel offsets etc. And 
there are useful utility routines in Win32::GUI::AdHoc for that i think.


All modules I mentioned:
http://www.bahnhof.se/~johanl/perl/Loft/


/J

-------- ------ ---- --- -- --  --  -    -     -      -         -
Johan Lindström    Sourcerer @ Boss Casinos     jo...@ba...

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