Constraints questions about spacer

[Brian Parma]

I'm having some trouble getting the result I want from spacer.  I am trying to replicate something created in Qt Desginer.  It's essentially a grid container that takes up a fixed width, and to center that container in the window a horizontal spacer is placed on the left and right side of it.

In designer, both the spacers have equal "weight", so they take up the same amount of space, but I can't figure out how to do this in enaml.  If I just try:

```

hbox(spacer, grid(...), spacer)

```

Then the first spacer takes up all the space.  Is there a way to tell them to take up equal space (equal weights)?  Since they are created in-place, I don't have ids to add an additional constraint with.  Or is there a way to say "center grid"?

[Matthieu Dartiailh]

Hi Brian,

Spacer themselves are not constrainable so you cannot impose the equality constraint directly on the spacer. One way around this is to define constraints with respect to the container edges and some elements in the grid. I illustrates this possibility below.

Another option would be to wrap the grid into a container but I guess that you are trying to avoid that.

Best

Matthieu

from enaml.layout.api import grid, hbox, spacer

from enaml.widgets.api import Window, Container, Label, PushButton

enamldef Main(Window):

Container:

constraints = [

hbox(spacer,

grid((lbl_a, lbl_b, lbl_c),

(lbl_d, lbl_e, lbl_f),

(lbl_g, lbl_g, lbl_g),

(btn_1, btn_2, btn_3)),

spacer),

lbl_a.left - contents_left == contents_right - lbl_c.right

]

Label: lbl_a:

text = "Label A"

Label: lbl_b:

text = "Label B"

Label: lbl_c:

text = "Label C"

Label: lbl_d:

text = "Label D"

Label: lbl_e:

text = "Label E"

Label: lbl_f:

text = "Label F"

Label: lbl_g:

text = "Label G"

PushButton: btn_1:

text = "Button 1"

PushButton: btn_2:

text = "Button 2"

PushButton: btn_3:

text = "Button 3"

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[Matthieu Dartiailh]

Actually you can also do that. I forgot that the helpers are actually also constrainable.

from enaml.layout.api import grid, hbox, spacer, align

from enaml.widgets.api import Window, Container, Label, PushButton

enamldef Main(Window):

Container:

layout_constraints => ():

g = grid((lbl_a, lbl_b, lbl_c),

(lbl_d, lbl_e, lbl_f),

(lbl_g, lbl_g, lbl_g),

(btn_1, btn_2, btn_3))

constraints = [hbox(spacer,g, spacer) ,

align('h_center', g, contents_h_center)

]

return constraints

Label: lbl_a:

text = "Label A"

Label: lbl_b:

text = "Label B"

Label: lbl_c:

text = "Label C"

Label: lbl_d:

text = "Label D"

Label: lbl_e:

text = "Label E"

Label: lbl_f:

text = "Label F"

Label: lbl_g:

text = "Label G"

PushButton: btn_1:

text = "Button 1"

PushButton: btn_2:

text = "Button 2"

PushButton: btn_3:

text = "Button 3"

[Brian Parma]

Ah thanks, didn't know about `content_h_center`.