fxruby-users

[Fxruby-users] hard time using images

[Andre' W. <an...@sy...>]

Hello folks,

I think I'm failing to understand how do I manipulate a image widget
in my application. I putted the FXImage in my app - and it appears ok
- but if I try to setPixel in it then I get a segfault.

I peeked into the examples, and I see they use a FXDCWindow and a
FXCanvas, but I can't understand it very well. I looked into the
tutorial and the docs but I haven't found anything that cleared my
mind.

Is there a image tutorial for FXRuby or something like that on the
net? Or might someone give me a few pointers here?

Thank you in advance,

Andr=E9

--=20
=A9 Andre' Wagner - 2004 - All rights reserved

Re: [Fxruby-users] hard time using images

[rich l. <fx...@gm...>]

Are you wanting to draw an image (graph, chart) or import and
manipulate an image (bmp, jpg)?

-Rich


On Wed, 7 Jul 2004 11:08:50 -0300, Andre' Wagner <an...@sy...> wr=
ote:
> Hello folks,
>=20
> I think I'm failing to understand how do I manipulate a image widget
> in my application. I putted the FXImage in my app - and it appears ok
> - but if I try to setPixel in it then I get a segfault.
>=20
> I peeked into the examples, and I see they use a FXDCWindow and a
> FXCanvas, but I can't understand it very well. I looked into the
> tutorial and the docs but I haven't found anything that cleared my
> mind.
>=20
> Is there a image tutorial for FXRuby or something like that on the
> net? Or might someone give me a few pointers here?
>=20
> Thank you in advance,
>=20
> Andr=E9
>=20
> --
> =A9 Andre' Wagner - 2004 - All rights reserved
>=20
> -------------------------------------------------------
> This SF.Net email sponsored by Black Hat Briefings & Training.
> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
> digital self defense, top technical experts, no vendor pitches,
> unmatched networking opportunities. Visit www.blackhat.com
> _______________________________________________
> Fxruby-users mailing list
> Fxr...@li...
> https://lists.sourceforge.net/lists/listinfo/fxruby-users
>

Re: [Fxruby-users] hard time using images

[Andre' W. <an...@sy...>]

I'm writing a emulator, so basicly what I'm gonna do is draw single
pixels in a image. (as fast as possible)

Andr=E9

In Wednesday, July 7, 2004 you wrote:

> Are you wanting to draw an image (graph, chart) or import and
> manipulate an image (bmp, jpg)?

> -Rich


> On Wed, 7 Jul 2004 11:08:50 -0300, Andre' Wagner <an...@sy...=
> wrote:
>> Hello folks,
>>=20
>> I think I'm failing to understand how do I manipulate a image widget
>> in my application. I putted the FXImage in my app - and it appears ok
>> - but if I try to setPixel in it then I get a segfault.
>>=20
>> I peeked into the examples, and I see they use a FXDCWindow and a
>> FXCanvas, but I can't understand it very well. I looked into the
>> tutorial and the docs but I haven't found anything that cleared my
>> mind.
>>=20
>> Is there a image tutorial for FXRuby or something like that on the
>> net? Or might someone give me a few pointers here?
>>=20
>> Thank you in advance,
>>=20
>> Andr=E9
>>=20
>> --
>> =A9 Andre' Wagner - 2004 - All rights reserved
>>=20
>> -------------------------------------------------------
>> This SF.Net email sponsored by Black Hat Briefings & Training.
>> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
>> digital self defense, top technical experts, no vendor pitches,
>> unmatched networking opportunities. Visit www.blackhat.com
>> _______________________________________________
>> Fxruby-users mailing list
>> Fxr...@li...
>> https://lists.sourceforge.net/lists/listinfo/fxruby-users
>>


> -------------------------------------------------------
> This SF.Net email sponsored by Black Hat Briefings & Training.
> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -=20
> digital self defense, top technical experts, no vendor pitches,=20
> unmatched networking opportunities. Visit www.blackhat.com
> _______________________________________________
> Fxruby-users mailing list
> Fxr...@li...
> https://lists.sourceforge.net/lists/listinfo/fxruby-users



--=20
=A9 Andre' Wagner - 2004 - All rights reserved

Re: [Fxruby-users] hard time using images

[rich l. <fx...@gm...>]

I'd use FXGLCanvas - but I really don't have experience with anything
else. I've used FXGLViewer I think... and that wasn't that bad...

If you're looking for a tutorial, I might be able to write one for you
on FXGLCanvas...

At:
http://fox-toolkit.net/cgi-bin/wiki.pl?Documentation
there is a link:
[Developing GUIs with FOX and Ruby]
That has a bit of a tutorial on FXGLCanvas I think...

-Rich

On Wed, 7 Jul 2004 11:45:35 -0300, Andre' Wagner <an...@sy...> wr=
ote:
> I'm writing a emulator, so basicly what I'm gonna do is draw single
> pixels in a image. (as fast as possible)
>=20
> Andr=E9
>=20
>=20
>=20
> In Wednesday, July 7, 2004 you wrote:
>=20
> > Are you wanting to draw an image (graph, chart) or import and
> > manipulate an image (bmp, jpg)?
>=20
> > -Rich
>=20
> > On Wed, 7 Jul 2004 11:08:50 -0300, Andre' Wagner <an...@sy...=
> wrote:
> >> Hello folks,
> >>
> >> I think I'm failing to understand how do I manipulate a image widget
> >> in my application. I putted the FXImage in my app - and it appears ok
> >> - but if I try to setPixel in it then I get a segfault.
> >>
> >> I peeked into the examples, and I see they use a FXDCWindow and a
> >> FXCanvas, but I can't understand it very well. I looked into the
> >> tutorial and the docs but I haven't found anything that cleared my
> >> mind.
> >>
> >> Is there a image tutorial for FXRuby or something like that on the
> >> net? Or might someone give me a few pointers here?
> >>
> >> Thank you in advance,
> >>
> >> Andr=E9
> >>
> >> --
> >> =A9 Andre' Wagner - 2004 - All rights reserved
> >>
> >> -------------------------------------------------------
> >> This SF.Net email sponsored by Black Hat Briefings & Training.
> >> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
> >> digital self defense, top technical experts, no vendor pitches,
> >> unmatched networking opportunities. Visit www.blackhat.com
> >> _______________________________________________
> >> Fxruby-users mailing list
> >> Fxr...@li...
> >> https://lists.sourceforge.net/lists/listinfo/fxruby-users
> >>
>=20
> > -------------------------------------------------------
> > This SF.Net email sponsored by Black Hat Briefings & Training.
> > Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
> > digital self defense, top technical experts, no vendor pitches,
> > unmatched networking opportunities. Visit www.blackhat.com
> > _______________________________________________
> > Fxruby-users mailing list
> > Fxr...@li...
> > https://lists.sourceforge.net/lists/listinfo/fxruby-users
>=20
> --
> =A9 Andre' Wagner - 2004 - All rights reserved
>=20
> -------------------------------------------------------
> This SF.Net email sponsored by Black Hat Briefings & Training.
> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
> digital self defense, top technical experts, no vendor pitches,
> unmatched networking opportunities. Visit www.blackhat.com
> _______________________________________________
> Fxruby-users mailing list
> Fxr...@li...
> https://lists.sourceforge.net/lists/listinfo/fxruby-users
>

Re: [Fxruby-users] hard time using images

[Jeroen v. d. Z. <je...@fo...>]

On Wednesday 07 July 2004 10:08 am, Andre' Wagner wrote:
> Hello folks,
>
> I think I'm failing to understand how do I manipulate a image widget
> in my application. I putted the FXImage in my app - and it appears ok
> - but if I try to setPixel in it then I get a segfault.
>
> I peeked into the examples, and I see they use a FXDCWindow and a
> FXCanvas, but I can't understand it very well. I looked into the
> tutorial and the docs but I haven't found anything that cleared my
> mind.
>
> Is there a image tutorial for FXRuby or something like that on the
> net? Or might someone give me a few pointers here?
>
> Thank you in advance,
>
> Andr=E9

The think to keep in mind is that there's two sides to FXImage: the
array of pixels which is kept in your program and the device-specific
bitmap which is kept in the display server.

Now, to keep memory down, by default FXImage ditches the pixel array
in the program, since USING the image in drawing operations normally
requires only the bitmap in the display server.  Of course, sometimes
you need the local pixel array, and there's a way to hang on to that,
by passing the IMAGE_KEEP option.  Also, there is a way to regenerate
the server-side bitmap from the local pixel array, which you can do
by calling render().  Finally, since you can use drawing commands
to draw things into the bitmap that is kept in the server, you can
read back the bitmap into the local image pixel array by calling
restore().

The API setPixel() works on the local image pixel array, and you
must make sure that the pixel array is kept around for that to
work properly.

Note also that the local pixel array is only deleted after the
server-side bitmap has been populated, which means basically
that prior to create() you still have full access to the local
pixel array.


Hope this helps,

	- Jeroen

Re: [Fxruby-users] hard time using images

[Andre' W. <an...@sy...>]

Thank you so much for the very complete info! However, I still can't
draw :-( So let us speak ruby. I wrote this small class:

require 'fox'
include Fox

class Test

        def initialize
                app =3D FXApp.new
                main_window =3D FXMainWindow.new(app, "test", nil, nil, D=
ECOR_ALL, 500, 330,
540, 370)

                # Image
                image =3D FXImage.new(app, nil, 0, 30, 30)
                imageview =3D FXImageView.new(main_window, image)

                # Set a pixel
                image.setPixel(10, 10, FXRGB(255, 255, 255))
               =20
                app.create
                main_window.show
                app.run
        end

end
t =3D Test.new

When the code gets into the setPixel, I get a segfault. What am I
missing?

Thank you in advance,

Andr=E9

--=20
=A9 Andre' Wagner - 2004 - All rights reserved

RE: [Fxruby-users] hard time using images

[Oliver S. <ol...@mo...>]

Hi, I'll give this a shot...

I think what you want is the canvas/dc paradigm.  An FXImageView is usually
for displaying static image files such as .bmp or .jpg.  Since you want to
create an image from scratch, the right way to do it is to replace your
FXImageView with an FXCanvas and forget about the FXImage for now.  It's
kind of complicated to explain briefly, but think of an FXDCWindow (which
contains an FXDC) as an artist.  You give the artist a brush and some paint
and a canvas and tell him to draw lines and pixels.  So something like this
untested code:

@canvas = FXCanvas.new(...)

@canvas.connect(SEL_PAINT) {
	FXDCWindow.new(@canvas) { |dc|
		dc.foreground = "white"
		dc.fillRectangle(0, 0, @canvas.width, @canvas.height)
		dc.foreground = "black"
		dc.drawPoint(20, 20) # draw a pixel
	}
}

But it gets more complicated.  Note that you should paint on the canvas
during the SEL_PAINT handler.  This ensures that FOX knows to display the
changes on the screen.  You can tell FOX to send a new SEL_PAINT message by
calling @canvas.update when you need it.

Now, while that method works, the problem with drawing on an FXCanvas is
that the user can see you draw.  So during slow operations the user will see
flicker as you update the painting.  That's where the FXImage comes in.  The
FXImage is an off-screen buffer that you can paint on just like an FXCanvas.
Look at the bounce.rbw example - it uses the FXCanvas to display the scene
to the user, but all actual drawing is done on the FXImage "behind the
scenes".  When the FXImage has been changed, the program calls
@canvas.update.  Then, when SEL_PAINT arrives, it uses dc.drawImage to throw
the entire FXImage onto the canvas at once.  Thus, less chance of flicker.
This technique is called 'double buffering'.

Actually, bounce.rbw is a great place to start.  You can see how it creates
the FXImage - first by calling the constructor, but then in SEL_CONFIGURE
(sent when the window is created or resized) the buffer is actually created
(i.e. memory for it is allocated) and given a size.  Drawing to the buffer
before it's created may be the source of your crash, although I'm not sure.

So, to summarize, you can draw to an FXImage anytime after it's created and
sized, but when you're done call @canvas.update and wait for the SEL_PAINT
to flip the image onto the FXCanvas the user will see.  Or, just draw to the
FXCanvas directly from SEL_PAINT if you don't care about flicker or only
need to draw once.  Read the help for FXDC for a list of drawing methods and
operations.  Drawing an entire screen of individual pixels is going to be
pretty slow, by the way... :|  Hope some of this is helpful,

Oliver

> -----Original Message-----
> From: fxr...@li...
> [mailto:fxr...@li...]On Behalf Of Andre'
> Wagner
> Sent: Wednesday, July 07, 2004 10:10 AM
> To: fxr...@li...
> Subject: Re: [Fxruby-users] hard time using images
>
>
> Thank you so much for the very complete info! However, I still can't
> draw :-( So let us speak ruby. I wrote this small class:
>
> require 'fox'
> include Fox
>
> class Test
>
>         def initialize
>                 app = FXApp.new
>                 main_window = FXMainWindow.new(app, "test", nil,
> nil, DECOR_ALL, 500, 330,
> 540, 370)
>
>                 # Image
>                 image = FXImage.new(app, nil, 0, 30, 30)
>                 imageview = FXImageView.new(main_window, image)
>
>                 # Set a pixel
>                 image.setPixel(10, 10, FXRGB(255, 255, 255))
>
>                 app.create
>                 main_window.show
>                 app.run
>         end
>
> end
> t = Test.new
>
> When the code gets into the setPixel, I get a segfault. What am I
> missing?
>
> Thank you in advance,
>
> André
>
> --
> © Andre' Wagner - 2004 - All rights reserved
>
>
>
> -------------------------------------------------------
> This SF.Net email sponsored by Black Hat Briefings & Training.
> Attend Black Hat Briefings & Training, Las Vegas July 24-29 -
> digital self defense, top technical experts, no vendor pitches,
> unmatched networking opportunities. Visit www.blackhat.com
> _______________________________________________
> Fxruby-users mailing list
> Fxr...@li...
> https://lists.sourceforge.net/lists/listinfo/fxruby-users

Re: [Fxruby-users] hard time using images (thank you)

[Andre' W. <an...@sy...>]

Thank you so much for everyone's help, I couldn't do without you!
Someday someone has to write a tutorial on that. (maybe I will, if
ever got some experience)

So here is my final code. Any hints on optimization would be
appreciated.

require 'fox'
include Fox

class Test

        def initialize
                app =3D FXApp.new
                main_window =3D FXMainWindow.new(app, "test", nil, nil, D=
ECOR_ALL, 500, 330, 540, 370)

                # Canvas & image
                canvas =3D FXCanvas.new(main_window, nil, 0, LAYOUT_FIX_W=
IDTH|LAYOUT_FIX_HEIGHT, 0, 0, 30, 30)
                @buffer =3D FXImage.new(app, nil, IMAGE_KEEP)
                @buffer.create
                canvas.connect(SEL_PAINT) { |sender, sel, evt|=20
                        FXDCWindow.new(sender, evt) { |dc|
                                dc.drawImage(@buffer, 0, 0)
                        }
                }
                canvas.connect(SEL_CONFIGURE) { |sender, sel, evt|
                        @buffer.create unless @buffer.created?
                        @buffer.resize(sender.width, sender.height)
                        draw
                }

                app.create
                main_window.show

                # sets the pixel
                setPixel(10, 10, FXRGB(0,0,0))
               =20
                app.run
               =20
        end

        def draw
                FXDCWindow.new(@buffer) { |dc|
                        dc.setForeground(FXRGB(255, 255, 255))
                        dc.fillRectangle(0, 0, @buffer.width, @buffer.hei=
ght)
                }
        end

        def setPixel(x, y, color)
                FXDCWindow.new(@buffer) { |dc|
                        dc.foreground =3D color
                        dc.drawPoint(x, y)
                }
        end

end
t =3D Test.new


Regards to all,

Andr=E9

--=20
=A9 Andre' Wagner - 2004 - All rights reserved