[Proposal] Grid: Add layout definition for view framework independent control

Currently the combined use of type section and fieldset with css properties defines the layout for the bootstrap decorator and the material decorator is adding a grid system, but a generalised layout model is needed for a standard that can be implemented by any library.

The key elements will always be: horizontal grouping, vertical grouping, width & height with additional support for passing alignment and more view specific details if needed.

ASF Bootstrap is very bootstrap centric

{
  "type": "section",
  "htmlClass": "row",
  "items": [
    {
      "type": "section",
      "htmlClass": "col-xs-6",
      "items": [ "name" ]
    },
    {
      "type": "section",
      "htmlClass": "col-xs-6",
      "items": [ "email" ]
    }
  ]
}

ASF Material is currently a little flex centric

{
  "type": "section",
  "grid": { "layout": "column" },
  "items": [
    {
      "type": "section",
      "grid": { "layout": "row", "flex": 50 },
      "items": [
        {
          "key": "firstname",
          "grid": { "flex": 50 }
        },
        {
          "key": "lastname",
          "grid": { "flex": "" }
        }
      ]
    }
  ]
}

Proposed

{
  "type": "section",
  "grid": { "layout": "column" },
  "items": [
    {
      "type": "section",
      "grid": { "layout": "row", "span": 50 },
      "items": [
        {
          "key": "firstname",
          "grid": { "span": 50 }
        },
        {
          "key": "lastname",
          "grid": { "span": "auto" }
        }
      ]
    }
  ]
}

The grid attribute is short and to the point although I was also partial to structure early on. Grid being a parent object for anything layout related can help separate structure and make it easier to find and operate on or set defaults for.

json-schema-form / json-ui-schema

[Proposal] Grid: Add layout definition for view framework independent control #2