uniform spacing of children within resizable view

[johnagrandy]

hi antun.

for the middle view of a horizontal stableborderlayout (or a horizontal resizelayout with middle view releasedtolayout), is there a simple way to cause the view's child controls (e.g. buttons) to be positioned symmetrically ? (the buttons don't resize, they just get "spaced-out" uniformly)

thanks.

[antun]

Can you show me what code you're trying to run?

I think you would have to act on the children of the view that you would want to have resize, but I'd have to see the code.

-Antun

[johnagrandy]

i do have questions about the code i'm trying to run .... but i also suspect there is a built-in lzx ability to space equal-width objects evenly over a horizontal range.

here is my code:

<view bgcolor="#bdbdbd" width="parent.width" height="this.leftButtons.refButton.height + 8">
<resizelayout axis="x" spacing="5" />
<view name="leftButtons" left="5" valign="middle">
<button name="refButton">1</button>
</view>
<view name="middleButtons" options="releasetolayout" valign="middle">
<attribute name="spacer" when="always" value="(this.width - 3 * this.refButton.width)/4" />
<simplelayout axis="x" spacing="5" />
<button name="refButton" left="parent.spacer">2</button>
<button left="${parent.spacer * 2 + this.width}">3</button>
<button left="${parent.spacer * 3 + this.width * 2}">4</button>
</view>
<view width="${parent.leftButtons.width}" />
</view>

also: while its great that tag attributes can use ${} to include javascript, i wonder about why lzx sometimes requires this and sometimes does not.

example:

<view height="parent.height">

works fine ...

so why does

<button name="refButton" left="parent.spacer">1</button>

give a "reference to undefined variable 'parent' error" ? ... but the problem is solved if ${} used ...

[antun]

You might want to check out <wrappinglayout>. There's a thread about it here:

http://www.laszlosystems.com/developers/community/forums/showthread.php?s=&threadid=282&highlight=wrappinglayout

Let me know if that works for you.


also: while its great that tag attributes can use ${} to include javascript, i wonder about why lzx sometimes requires this and sometimes does not.


This is really a legacy issue. It used to be that you could only write constraints in attributes for non-custom numeric attributes:


x="parent.with/2"


... but if you wanted to do anything like use a custom attribute, or a non-numeric value, you would have to use the <attribute> tag.

Now you can use the ${} syntax to do just about any attribute evaluation inside of an attribute, however we retained the old x="parent.with/2" syntax for backwards compatability, although that syntax is not formally deprecated at the moment.

If unsure, use the ${} syntax.

-Antun

[johnagrandy]

Antun, are you saying that because "spacer" is a custom attribute, referring to it in attribute value assignments inside tags must be done with ${} ?

... but that's not consistent with the error message = "reference to undefined variable 'parent'" ... it's not able to evaluate "parent", it doesn't even get to "parent.spacer" ...

[antun]

No, what I'm saying is that it used to be that since height and width were both numeric, you could say:

<view height="width/2">

I believe also that this was dependent on not being a custom attribute, but I'm not 100% sure there.

I would like to give you an example regarding what you said:


<button name="refButton" left="parent.spacer">1</button>


... but there isn't a "left" attribute for button. Can you tell me what you intended to write there?

-Antun

[johnagrandy]

oh, ok, "x", not "left"

i was getting bogus error messages from lde. it should have caught that "left" is not a intrinsic attribute of button.

[antun]

You're right, it should give you a practical error message. Could you post the code you were writing to get the bogus error?

When I do:


<canvas>
<view>
<button name="refButton" left="parent.spacer">1</button>
</view>
</canvas>


I get a Compliation Warning that says:


attributeerror.lzx:3:55: attribute "left" not allowed at this point; ignored


-Antun