snapshot transition - how to obtain pointer to the snapshot object upon transition onComplete

Solar2D Advanced Graphics
#1

I’ve looked through the G2 docs and can’t find a way to determine the snapshot object when a transition on the snapshot.path fires the onComplete event.  Do I have to resort to this sort of unsatisfying stuff:  ???

local function SnapDone(snap) &nbsp;&nbsp;&nbsp; local maxlimit = 90 &nbsp;&nbsp;&nbsp; local minlimit = 20 &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; local y3 = -minlimit &nbsp;&nbsp;&nbsp; local y4 = minlimit &nbsp;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; if snap.y4 \< minlimit+1 then y4 = maxlimit; y3 = -maxlimit end &nbsp;&nbsp;&nbsp; transition.to( snap, { y3=y3, y4=y4, &nbsp;&nbsp;&nbsp; time=2500, delay=1, transition=easing.outExpo, onComplete = SnapDone} ) end local snapshot = display.newSnapshot(200,200) local circle = display.newCircle( 0, 0, 55 ) circle:setStrokeColor(0, 0, 0, 1) circle.strokeWidth = 3 circle:setFillColor(.5, .5, .5, .05) snapshot.group:insert(circle) snapshot.x = 512 snapshot.y = 200 local maxlimit = 90 snapshot.path.y3 = -maxlimit snapshot.path.y4 = maxlimit transition.to( snapshot.path, { y3=-maxlimit, y4=maxlimit, time=2500, delay=2000, transition=easing.outExpo, onComplete = SnapDone} )

I get a ‘userdata’ table in SnapDone when the onComplete fires…  how do I get back to the snapshot object?

#2

I’m running the code you provided above and it works fine without throwing an error.

#3

OK, I re-read your question and from what I can see it’s not possible to get at the underlying snapshot.

The reason being that transition.to will return the object passed to it and since ‘path’ is a userdata attribute of the snapshot that’s what will get sent to onComplete.

#4

Hmmmm… really reduces the utility of snapshots for my purposes. My application of snapshot was to reduce an object containing 30 children into a single snapshot ‘image’, since I never need the children after the parent is created. And I have a hundred or more of these parents in transitions at the same time. I thought that the use case for snapshots was a good fit… actually a perfect fit. I suppose I can put the snapshot into a container to achieve what I want! (?) Thanks for your input, inqemar.

#5

I think putting it into a group or container and then transitioning that will probably be your best bet.

Rob

#6

Never tried it, but would the following syntax work?

[lua]

transition.to( snapshot, { path.y3=-maxlimit, path.y4=maxlimit, time=2500, delay=2000, transition=easing.outExpo, onComplete = SnapDone} )

[/lua]

I’d suppose it working depends on how the lua compiler interprets the transition params.

#7

Thanks, Rob… I will try that out.  SNAPSHOT will still save a ton of children hanging around, with nothing to do!

And I tried your suggestion, mpappas… compiler chokes on it.  I tried a few variations… no go.  Thanks for the idea!

#8

Hey Rob,

I tried out the container idea, where basically the container holds the snapshot and I tried to transition the container instead of the snapshot.  Of course, the container does not have the x1, x2, etc path ability, which is what I wanted to transition in the snapshot, so I am stuck again.

I am wondering if there is a way to get the handle of a transition when the onComplete event is fired for the transition(?)  If so, I could store some info in the transition object which would allow me to track which snapshot it is associated with?  Stupid idea?

#9

I’m running the code you provided above and it works fine without throwing an error.

#10

OK, I re-read your question and from what I can see it’s not possible to get at the underlying snapshot.

The reason being that transition.to will return the object passed to it and since ‘path’ is a userdata attribute of the snapshot that’s what will get sent to onComplete.

#11

Hmmmm… really reduces the utility of snapshots for my purposes. My application of snapshot was to reduce an object containing 30 children into a single snapshot ‘image’, since I never need the children after the parent is created. And I have a hundred or more of these parents in transitions at the same time. I thought that the use case for snapshots was a good fit… actually a perfect fit. I suppose I can put the snapshot into a container to achieve what I want! (?) Thanks for your input, inqemar.

#12

I think putting it into a group or container and then transitioning that will probably be your best bet.

Rob

#13

Never tried it, but would the following syntax work?

[lua]

transition.to( snapshot, { path.y3=-maxlimit, path.y4=maxlimit, time=2500, delay=2000, transition=easing.outExpo, onComplete = SnapDone} )

[/lua]

I’d suppose it working depends on how the lua compiler interprets the transition params.

#14

Thanks, Rob… I will try that out.  SNAPSHOT will still save a ton of children hanging around, with nothing to do!

And I tried your suggestion, mpappas… compiler chokes on it.  I tried a few variations… no go.  Thanks for the idea!

#15

Hey Rob,

I tried out the container idea, where basically the container holds the snapshot and I tried to transition the container instead of the snapshot.  Of course, the container does not have the x1, x2, etc path ability, which is what I wanted to transition in the snapshot, so I am stuck again.

I am wondering if there is a way to get the handle of a transition when the onComplete event is fired for the transition(?)  If so, I could store some info in the transition object which would allow me to track which snapshot it is associated with?  Stupid idea?