Layout structure for responsive

Use the LAYOUT structure to define forms that adapt to screen sizes.

Understanding the layout structure for responsive

To achieve best responsive layout, a form should be defined with a combination of small, individual, stretchable containers, that are organized in a tree of HBOX/VBOX elements:
VBOX
|-- HBOX
|   |-- TABLE 
|   +-- GRID
+-- GRID

In GRID containers, define fields as stretchable, to allow fields to resize depending on the screen size. Containers such as TABLE are by essence stretchable.

HBOX/VBOX and leaf containers can be defined with HIDDEN@screen-size and/or ORIENTATION@screen-size attributes, to describe how these should behave depending on the size of the screen.

GRID as stretchable leaf container

In a responsive layout form, define GRID containers with basic form items such as labels and fields, without using container layout tags such as <GROUP g1 >.

Inside the GRID containers, elements can be organized by position. Right-most elements can be made horizontally stretchable, to occupy all the screen width.

Figure: Responsive form with labels and fields in grid

Diagram of a responsive form using grids

Screen-size dependant attributes

Responsive layout introduces a new syntax to indicate for what screen or window width an attribute must take effect.

For example, the HIDDEN attribute can get the @screen-size specifier:
HIDDEN@screen-size

The @screen-size specifier can be one of @SMALL, @MEDIUM, @LARGE.

The interpretation of these abtract size qualifiers is done by the front-end, depending on the device type and display area size/width.

The exact screen size/width corresponding to SMALL/MEDIUM/LARGE can be configured in the front-end, but it is not recommended to change the defaults. The predefined sizes correspond typically to a given device type: SMALL and MEDIUM for smartphones and tablets, LARGE for desktop computer screens. This abstract size can also reflect the screen orientation on any device type.

For the complete syntax, see HIDDEN attribute.

Responsive form layout definition example

In the next example:
LAYOUT
VBOX vb1
  HBOX hb1 ( ORIENTATION@SMALL = VERTICAL )
    TABLE tb1
       ...
    END
    GRID gd1 ( HIDDEN@SMALL )
       ...
    END
  END
  GRID gd2 ( HIDDEN@SMALL, HIDDEN@MEDIUM )
     ...
  END
END
END
  1. vb1 organizes hb1 and gd2 vertically, no matter the screen size or orientation.
  2. hb1 organizes tb1 and gd1 horizontally by default, but vertically on small screens.
  3. gd1 will be hidden on small screens.
  4. gd2 will be hidden on small and medium screens.