Difference between revisions of "WxHaskell/Layout"

Latest revision as of 20:47, 15 January 2012

Layout

Most useful resource: the wxHaskell layout documentation

Layout setting by gridding

In general, we can create layout by setting the layout argument in a frame or a panel, for example,

gui = do f <- frame [ text := "Layout" ]
         p <- panel f []
         b <- button p [ text := "button" ]
         set f [ layout := margin 2 $ container p $ floatCenter $
                              widget b
               , clientSize := sz 100 100
               ]

I will call this Layout setting by gridding.

Gridding means using the layout function, such as grid, row, column etc, to set the layout.

Layout setting by positioning

Also, we could set the layout by another way, Layout setting by positioning

gui = do f <- frame [ text := "Layout"
                    , clientSize := sz 100 100 ]
         p <- panel f [ clientSize := sz 98 98,
                      , position := pt 2 2 ]
         b <- button p [ text := "button"
                       , position := pt 45 45 ]

The result of both examples are about the same, only the button position has a bit different. (Please measure the exact position by yourself). By this way, we can have more flexible layout rather than limited the layout by grids.

EYK: it seems like layout by positioning allows for more precise control, but it does not seem like it would respond nicely to window resizing, no?

Layout reconfiguration

We can also re-configure the layout by just simply re-assign a new layout value to the layout. But remember, do not assign the same tab to the layout twice, it will append the same tab to the notebook. To prevent this, assign an empty list to the notebook

f <- frame [ text := "Layout" ]
nb <- notebook f []
set f [ layout := tabs nb [] ]

Transformers

fill = stretch . expand

NB: these are tentative explanations, could be wrong

Two dimensions are important here

shape (expansion)

the widget's shape: how does a widget use the space around it? Your options are

rigid (default): fixed shape
shaped expands but retains proportions
expand just expands without caring about proportions

stretch

the widget's dynamic behaviour: OK so your widget is laid out and has expanded however much it wants to. Now what happens when you give it even more space by resizing the parent window? Your options are

static (default): no stretching!
stretch, hstretch, vstretch: stretches perhaps along one dimension only
minsize (not sure how this behaves)

TODO: screenshots

dynamic

??? how does this relate to expand/stretch?

margin, boxed

Questions

Where can you define layouts? The API says frames, panels, and dialogues, but is it seems like defining sub-layouts in panels is a bit problematic
Wait, you mean I have to put all my layout in the frame? That's not very modular!
Why do I need to expand in addition to stretching to fill resized space?

Troubleshooting

Not in right place

Checklist
- Did you use layout? Declaring the widget is not enough. You have to tell wxHaskell where it fits in wrt other widgets in the window
- Did you put the layout in the right parent? (elaborate)
- Do you need to use one of hfloatRight and hfloatLeft?
- Are you using glue to push things to the side as needed?

Too small

Really tiny frame when my app launches
Solution: set clientSize

Widgets too small, lots of space around them though!
Solution: have you tried expanding them to use that space?

Widgets do not resize when window is resized
Checklist
- Make sure you are using the stretch combinators.
- Remember that columns (h)stretch only if all their members (h)stretch, and similarly for rows and vstretch.

Still too small!
Suggestion: are your transformers cancelling each other out? hstretch will make the vertical dimension rigid and vice-versa, so hstretch . vstretch will probably not do what you want!

Sash too small on splits
Workaround: put margins on both sides of the split

Too big

Absurdly huge widget
Possible solution make sure the widget is placed in the correct parent.

Disappearing widgets

Widgets that vanish when you resize the window
Workaround Set a minsize on the layout for the affected widgets

@@ Line 1: / Line 1: @@
 == Layout ==
-All details are based on using [[wxHaskell]] on Microsoft Windows XP.
+Most useful resource: the wxHaskell [http://hackage.haskell.org/packages/archive/wxcore/latest/doc/html/Graphics-UI-WXCore-Layout.html layout documentation]
 === Layout setting by gridding ===
 In general, we can create layout by setting the layout argument in a frame or a panel, for example,
@@ Line 38: / Line 40: @@
  nb <- notebook f []
  set f [ layout := tabs nb [] ]
 == Transformers ==
@@ Line 90: / Line 91: @@
 * Widgets too small, lots of space around them though!<br/>'''Solution''': have you tried <code>expand</code>ing them to use that space?
-* Widgets do not resize when window is resized<br/>'''Solution''': make sure you are using the <code>stretch</code> combinators.  Remember that columns only (h)stretch if all their members (h)stretch, and similarly for rows and vstretch.
+* Widgets do not resize when window is resized<br/>'''Checklist'''
+** Make sure you are using the <code>stretch</code> combinators.
+** Remember that columns (h)stretch '''only''' if all their members (h)stretch, and similarly for rows and vstretch.
+* Still too small!<br/>'''Suggestion''': are your transformers cancelling each other out?  <code>hstretch</code> will make the vertical dimension rigid and vice-versa, so <code>hstretch . vstretch</code> will probably not do what you want!
+* Sash too small on splits<br/>'''Workaround''': put margins on both sides of the split
 === Too big ===
 * Absurdly huge widget<br/>'''Possible solution''' make sure the widget is placed in the correct parent.
+=== Disappearing widgets ===
+* Widgets that vanish when you resize the window<br/>'''Workaround''' Set a minsize on the layout for the affected widgets
 == See also ==
 * [[WxHaskell/Button sizing problem | Button sizing]] - It has problems to set the size of button
+[[Category:wxHaskell]]