responsive_layout_grid

Description:

responsive layout grid

Introduction #
The [ResponsiveLayoutGrid] creates a Responsive Layout Grid as defined in the Material design guidelines

The ResponsiveLayoutGrid is made up of columns and gutters,
providing a convenient layout structure for elements within the body region.
As the width of the body region grows or shrinks,
the number of grid columns and column widths change in response.


Examples #
See the live web demo including source code

ResponsiveLayoutGrid #
The ResponsiveLayoutGrid has the following constructor parameters:

[minimumColumnWidth]
[maxNumberOfColumns]
[columnGutterWidth]
[rowGutterHeight]
[padding]
children (the cells)
layoutFactory (that determines the position of the cells)

The ResponsiveLayoutGrid has children, named cells.

Cells align with the column grid to create a logical and consistent
layout experience across screen sizes and orientations:

The ResponsiveLayoutGrid sets de width of the cells.
The cells can determine their own height, unless the RowHeight is set.


Cells are Widgets
Cells can span one or more columns
Cells are separated with gutters (separation space)

It is recommended to always directly wrap a ResponsiveLayoutGrid in a
[SingleChildScrollView] so that the user can vertically scroll trough
all cells, even when they do not all fit in the viewport.

ResponsiveLayoutCell #
You can wrap your cell Widgets
with a ResponsiveLayoutCell when you are using the [DefaultLayoutFactory],
so that you can provide the following information of the
cell Widget
(the [child]):

ColumnSpan of the cell Widget.
CellPosition of the cell Widget.


ColumnSpan #
A ColumnSpan tells the [DefaultLayoutFactory] how many columns a
ResponsiveLayoutCell may span.
There is a [min], [preferred] and [max] value. The [DefaultLayoutFactory]
will try to use these values, but may also decide to use different values
e.g.:

When the number of available columns exceed [min] or [max]
When the [RowAlignment.center] or [RowAlignment.justify] are used.
In these cases it is good practice to have some distance between the
[min], [preferred] and [max] values, so that the [DefaultLayoutFactory]
has some flexibility to optimize the layout.


CellPosition #
A ResponsiveLayoutCell has a CellPosition. There are 2 types:

nextColumn: The cell is to be positioned on the next available column.
This could be on the next row if there aren't enough empty columns
on the current row.
nextRow: The cell is to be positioned on a new row.
You can set the RowAlignment or RowHeight for every new row.


RowAlignment #
The RowAlignment can be set when a CellPosition.nextRow is used in a
ResponsiveLayoutCell. It can be one of the following values:

left: Align all cells on the left side of the row
right: Align all cells on the right side of the row
center: Try to align all cells in the middle of the row by
increasing or decreasing the ColumnSpan of one of the cells if needed.
justify: Try to fill the row from left to right by
increasing or decreasing the ColumnSpans of the cells if needed.


RowHeight #
The RowHeight is used as a parameter in
CellPosition.nextRow.
It defines the height the following row.
There are 2 types of row heights:

highestCell: The row will get the height of the highest
ResponsiveLayoutCell
expanded: The row will get the remaining available height.
If multiple rows are expanded, the available space is divided
among them according to the [minHeight], but also respecting
[maxHeight].

Both types can have a [minHeight] and a [maxHeight]
The [minHeight] of the ResponsiveLayoutCell:

null= no minimum height (ResponsiveLayoutCell can shrink to zero)
>0 = ResponsiveLayoutCell minimum size.
Note that the [RenderResponsiveLayout] children now can take up
more space than available. It is therefore recommended to wrap
the [RenderResponsiveLayout] inside a [SingleChildScrollView] or
other scroll view

The [maxHeight] of the ResponsiveLayoutCell:

null= no maximum height (ResponsiveLayoutCell can shrink to zero)
>0 = ResponsiveLayoutCell maximum size.


ResponsiveLayoutFactory #
The ResponsiveLayoutFactory is responsible for creating a [Layout].
It orders the children into a Layout with a given number of columns.
The ResponsiveLayoutGrid uses a [DefaultLayoutFactory] by default.
You could create your own ResponsiveLayoutFactory if you need to
do something outside the box. See example.