Trying to undeerstand Morphic subclasses and step/stepAt:

Hi,

I want to build a morphic application (for algorithm animation) so I need to do something in the step method.

I wanted to make it a subclass of SystemWindow (I'd actually prefer StandardWindow in Pharo but there doesn't appear to be an equivalent in Squeak).  But when I do, the step method doesn't get called.  (Nor does stepAt:) (And StandardWindow behaves the same.).

But if I move it to MorphicModel step/stepAt: gets called, but I don't get any of that SystemWindow goodness.

I've looked at the dispatch in Morph, and I don't see anything different in Worldstate>>runLocalStepMethodIn: but this stuff is very difficult to debug, because there's asynchronous stuff running behind the scenes.  In particular,
                lastStepMessage value: now.
          lastStepMessage ifNotNil: [...
is a little weird!

Any pointers appreciated.

Thanks  ../Dave

Hi.

You need to call #startStepping if you want #step to get called frequently according to #stepTime.

Nevertheless, you may want to take a closer look at this project:
https://www.hpi.uni-potsdam.de/hirschfeld/trac/SqueakCommunityProjects/wiki/animations

Marcel

Hi Marcel,

On 2012-Feb-5, at 2:04 , Marcel Taeumel wrote:

> You need to call #startStepping if you want #step to get called frequently
> according to #stepTime.

Actually you don't with Squeak 4.2 and Pharo 1.3 (don't know about earlier versions), because Morph>>initialize does that. But just for completeness, I did that, and it made no difference.  My class is just:

MorphExp>>initialize
        super initialize.
        self startStepping.
        self color: Color red lighter
MorphExp>>step
        self halt
MorphExp>>stepAt: t
        self halt

and it doesn't halt if it is a subclass of SystemWindow, but does if it's any higher up the hierarchy.

> Nevertheless, you may want to take a closer look at this project:
> https://www.hpi.uni-potsdam.de/hirschfeld/trac/SqueakCommunityProjects/wiki/animations

Thanks, but I don't want the issue about unloading, and I'm not worried about it being super-smooth animation.

Also thanks for the link, because it looks like interesting things are happening at HPI!

../Dave

Look at the methods #wantsSteps.

Cheers,
Bob

On 2/5/12 7:29 AM, Dave Mason wrote:

Hi Marcel,

On 2012-Feb-5, at 2:04 , Marcel Taeumel wrote:

You need to call #startStepping if you want #step to get called frequently
according to #stepTime.

Actually you don't with Squeak 4.2 and Pharo 1.3 (don't know about earlier versions), because Morph>>initialize does that. But just for completeness, I did that, and it made no difference.  My class is just:

MorphExp>>initialize
	super initialize.
	self startStepping.
	self color: Color red lighter
MorphExp>>step
	self halt
MorphExp>>stepAt: t
	self halt

and it doesn't halt if it is a subclass of SystemWindow, but does if it's any higher up the hierarchy.

Nevertheless, you may want to take a closer look at this project:
https://www.hpi.uni-potsdam.de/hirschfeld/trac/SqueakCommunityProjects/wiki/animations

Thanks, but I don't want the issue about unloading, and I'm not worried about it being super-smooth animation.

Also thanks for the link, because it looks like interesting things are happening at HPI!

../Dave

On 2012-Feb-5, at 7:40 , Bob Arning wrote:

> Look at the methods #wantsSteps.

Bingo!  I assumed it was something stupid I was missing.

On 2012-Feb-4, at 14:23 , Sean P. DeNigris wrote:

> I don't know if it's any better, but when I create my own morph-in-a-window,
> I usually don't subclass SystemWindow, but add my morph to a window using
> openInWindowLabelled: or addMorph:fullFrame:. I feel like I have a little
> more flexibility if I later want to use it not-in-a-window.

After defining wantsSteos, I see that color: seems to work a bit strangely too in SystemWindow, so I'm going to try this.

Thanks, Bob and Sean.

One thing to consider is whether you really want to subclass SystemWindow or if it might be better to instantiate a vanilla SystemWindow and install your specialized morph inside it.

Cheers,
Bob

On 2/5/12 9:57 AM, Dave Mason wrote:

On 2012-Feb-5, at 7:40 , Bob Arning wrote:

Look at the methods #wantsSteps.

Bingo!  I assumed it was something stupid I was missing.

On 2012-Feb-4, at 14:23 , Sean P. DeNigris wrote:

I don't know if it's any better, but when I create my own morph-in-a-window,
I usually don't subclass SystemWindow, but add my morph to a window using
openInWindowLabelled: or addMorph:fullFrame:. I feel like I have a little
more flexibility if I later want to use it not-in-a-window.

After defining wantsSteos, I see that color: seems to work a bit strangely too in SystemWindow, so I'm going to try this.

Thanks, Bob and Sean.

On 2012-Feb-5, at 10:11 , Bob Arning wrote:

> One thing to consider is whether you really want to subclass SystemWindow or if it might be better to instantiate a vanilla SystemWindow and install your specialized morph inside it.

What are the considerations for one approach over the other?  (In broad terms - not asking for a tutorial here! :-)

Thanks  ../Dave

Fundamentally, the question is whether you are trying to create a new kind of windowing behavior (if so, subclassing may be the right approach) or if you just want your new widget inside a window for ease of moving, collapsing, expanding, etc (if so, adding your morph to a plain SystemWindow is probably better).

Also ask yourself if you could ever want more than one of your widgets inside a single window. Or if you could ever want your widget naked in the World or inside some other graphical structure. Yes to any of these is a further indication to move away from subclassing and toward assembling components into larger components.

Cheers,
Bob

On 2/5/12 10:16 AM, Dave Mason wrote:

On 2012-Feb-5, at 10:11 , Bob Arning wrote:

One thing to consider is whether you really want to subclass SystemWindow or if it might be better to instantiate a vanilla SystemWindow and install your specialized morph inside it.

What are the considerations for one approach over the other?  (In broad terms - not asking for a tutorial here! :-)

Thanks  ../Dave