lock objects from being dragged out of the screen

[tomerp]

hi!
i have an app in which the user can move object around. what will be the most efficient way of preventing them from dragging the object out of the screen?

tnx
tomer

[dunbarx]

Hi.

How are you moving the objects around?

In any case, the "mouseMove" message is sent whether in edit or run mode, so you could (pseudo):

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on mouseMove
  put the target
  if the mouseLoc is beyond the borders of this card then do not allow this to happen
end mouseMove

Silly, eh? But can you take it from there? To check either the mouseLoc in relation to the edges of the card, or, if you want to get fancy (and I always recommend fancifulness) check the edges of the object in relation to the edges of the card. The "target" is your friend here.

Write back with your fancies.

Craig Newman

[jmburnod]

Hi,
You may define a rect and test if all points of your control is within this rect at mousemove
Best regards
Jean-Marc

[SparkOut]

Learning to do this yourself is the best idea, but Animation Engine includes some very nice features including constraints to location.

[tomerp]

i am moving the object with:

Code: Select all

grab me

where should i put this code that u wrote? in the card script?

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on mouseMove
  put the target
  if the mouseLoc is beyond the borders of this card then do not allow this to happen
end mouseMove

[Randy Hengst]

Try something like this in the script of the object you’re moving:

local tStartLoc

on mouseDown
put the loc of target into tStartLoc
grab me
end mouseDown

on mouseUp
if the loc of target is not within the rect of this card then
move target to tStartLoc
end if
end mouseUp

[Klaus]

Hi Tomerp,

what Randy wrote!

Important hint:

.. so you could (pseudo):

PSEUDO in this case means, this is what it should do, but is really NOT the actual script!


Best

Klaus

[richmond62]

I did it DIFFERENTLY . . . .

Stack removed as updated, improved version uploaded.

[Klaus]

You ALWAYS do it differently!

[richmond62]

This version allows one to resize the stack . . . .

What A Drag.livecode.zip

Here's the stack.

(65.36 KiB) Downloaded 287 times

[Newbie4]

...and if you want it to work for any size card, you can generalize the tests for right and bottom. (other than an 800x600 sized card in Richmond's example)

give the card a name (e.g. "main") and modify the code to check for

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... > the right of card "main"

instead of just

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... > 800

.

and the

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... > the bottom of card "main"

instead of 600.

[Newbie4]

RATS,

I tried to get there with a more universal solution before you did (Richmond). But I went back to edit it and while I was editing it, you uploaded your new stack. So your time stamp was earlier than mine.

I like your idea of using variables for the right and bottom locations. It makes the code simpler reading.

Good job, nice example

[richmond62]

It makes the code simpler reading.

That's because I really don't understand complex code.

[Newbie4]

Yes, I do too but sometimes when teaching newbies, you have to step through the process in logical steps (as you help them think thru it) Some people can not make the jump to the better code in one step.

[richmond62]

To understand what happens when the stack is resized, and so that
the TROLL doesn't "get lost" when it is resized, you need to look at
the stackScript: