Display properties

[noahgibbs]

Shoes has certain properties which are set/modified by the display side. For instance, if you say "@button.width" you get the displayed width, which is often different from the width Shoes style. Similarly, you can set the width Shoes style to "100%" and @button.width will instead give a width in pixels.

This requires sending a message to the display side and getting a value back. We don't currently have a convenient way to do that (possible, yes, convenient, no.)

Display properties will need to be able to override styles in many cases -- starting with width and height where, as stated above, the display property is a different thing than the Shoes style with the same name.

[noahgibbs]

Note: speedometer_app.rb example uses "left" display property, so it's a good test case for this.

[noahgibbs]

This is going to require taking CatsCradle (or similar Fiber-based flow control, but I assume CatsCradle) and using to run all the app code.

[noahgibbs]

CatsCradle cleanup before doing this is in #493. Still need to add CatsCradle to the app code, of course.

[noahgibbs]

Which are the display properties? Looks like at least top, left, width, height, margin (various), gutter, displace_left, displace_top, scroll_top, scroll_max. A lot of slot styles, plus anything that can be set to a percentage, seems like. Maybe also font size stuff since it can be a percent?

Could do UI like checkboxes and radio buttons that way, though I suspect we'd rather keep having JS notify Ruby and keep a "most recent" value we can return from Ruby (as we currently do.)

[noahgibbs]

Relevant manual excerpt:

### style() » styles

Gives you the full set of styles applied to this element, in the form of a
Hash.  While methods like `width` and `height` and `top` give you back specific
pixel dimensions, using `style[:width]` or `style[:top]`, you can get the
original setting (things like "100%" for width or "10px" for top.)

 Shoes.app do
   # A button which take up the whole page
   @b = button "All of it", width: 1.0, height: 1.0

   # When clicked, show the styles
   @b.click { alert(@b.style.inspect) }
 end

[noahgibbs]

Looks like Shoes3 returns 0 for the relevant display properties I've checked before first paint. So maybe I can just return 0 with no JS query when initially setting up the drawable tree, and then call the JS handler code in Fibers. That'll be much easier than changing how all of drawable-tree setup works. Probably won't even require a change in the Lacci API, which looked like it was going to be necessary to run initial setup code in a Fiber.

Though eventually we'll need it if we want to run code after the Shoes::App block -- that'll have to be in a Fiber. And if we want to do the right thing with ask/confirm/etc dialogs.

[noahgibbs]

I have a local branch with a prototype of this, but it's not working yet. This Fiber stuff is being really annoying...