World: r4wp

If 'load-image returns a pointer, how do I know when I have reached 
the end of the image?

Better yet, assuming 'load-image returns a pointer, how do I access 
the first memory location referenced by the pointer?

See the function spec in GDK.reds. It returns a pointer to an image! 
struct, so if you want to access the image internally, you have to 
go by that struct definition

As you can see in the same file, I haven't finished the definition 
of that struct, because I don't have to look inside the image

What is your goal?

Doc, could you bring lex-scope up to date with master? Then I can 
start testing it

Done.

Thanks! Been anxiously awaiting those fixes

I'm working on fixing #405 too in the lex-scope branch. Once that 
done, I will merge it in master if there is no regression.

I figured so

I might add #374 too the list too as it is related to scoping.

I hoped so :-)

No build regressions in a full build run

Oddly, there's a build regression in a GTK program just for Syllable, 
which is not even a valid combination

I can't replicate it

I want to be able to compare two images pixel-by-pixel.

Ah, that's relatively easy, because you don't have to know the image 
format. At least not if you can compare byte values instead of strict 
pixels

So you only have to look in the GDK/GLib headers to finish the image! 
struct definition enough to know the data length

Have to run

Do you only want two know if two images are the same? Then why not 
just read the files and compare them?

Actually, I want to know which pixels are different between the two 
images. Thanks for the tips!

You'd have to know GDK's internal image format, then

Perhaps there are more suitable functions in Oldes' ImageMagick binding

I'll take a look.

Looks like ImageMagick will do the trick, if I can just figure how 
to translate the tutorials from C to Red/System.

Kaj: are we good with the fixes in lex-scope branch? If all is fine, 
I will merge it tonight.

Yep, it's starting to look good. I'll build the examples once more

Great, I'll add a few binding tests from the tickets, then I'll do 
the merge.

No build problems

I'm happy to report that literal arguments work now. For example:

cycle: func ["Cycle a series through its index."
	'series [word!]
	/local s
][
	either tail? s: get series [
		set series  next head s
		first head s
	][
		set series  next s
		s/1
	]
]

Nice one!

Branch `lex-scope` merged in master.

It seems that the optional attributes and function description are 
swapped in Red/System compared to REBOL. Is that intentional?

http://www.rebol.com/r3/docs/concepts/funcs-defining.html#section-1

Yes, it makes it easier and faster to find optional attributes this 
way.

We could change it though, it's no significant impact on the compiler.

I believe REBOL allows either order, so it's just the docs that say 
it has to be that way.

I like the REBOL order better in the formatting of the program

I can see arguments both ways. Attrs are short, and having them first 
makes them easier to see, because they will be used far less than 
doc strings. OTOH, being used less makes them feel "more optional" 
than doc strings, hence could come after the doc string.

This would be a great question for Carl, as to why he did it the 
way he did it in REBOL. That is, allowing either order.

I like to put the function description on the same line as the function 
name, so it's easy to scan through a program text for them. Having 
the attributes in front of it makes the line too long and hides the 
atrributes in the text

So when there are attributes, I have to move the description in line 
with the arguments, where it becomes hidden because it's not lined 
up with the other function descriptions

Kaj: I've pushed a change in attributes handling for Red/System functions, 
you can now specify attributes or function's description doc-string 
in any order. I've replaced direct spec block access for attributes 
by a function call in deep compiler's code parts, so watch out for 
regressions especially in callbacks!

Fast response, thanks!

Pekr mentioned on 7-Jun-2012 in this group that an OpenCV binding 
was coming, but I can't find it anywhere.  Does anyone know if it 
exists?

Good question. I have no idea where Petr pulled that from

OpenCV binding is done by François Jouen, it's a work in progress. 
There's a Red/System version that you could find from this page (in 
french):


http://www.digicamsoft.com/cgi-bin/rebelBB.cgi?thread=%3C25May2012200150764026200%3E


There's a Red version that François sent me privately a few days 
ago for testing, but I haven't had the time yet to review it.

François showed me a few nice demos done with that binding a couple 
of weeks ago when I visited him in Paris. He had some camera-controlling 
and image recognition demos done from Red(/System).

Any chance he'd be willing to share his Red/System code?  I want 
to do something similar, and it would be great if I could see working 
examples!