NavigationDrawerItem_Stylesheet.yaml

One destination in a navigation drawer: an icon and a label, highlighted when selected.

The look of NavigationDrawerItem (in Navigation drawer). How component stylesheets work.

The stylesheet

# NavigationDrawerItem: the look of each part of the component, by the part's id.
# A value in {{ }} is one of the component's parameters.
styles:
  - id: root
    style:
      width: "{{ width }}"
      height: 56
      corner_radius: 28
      background:
        if: "{{ selected }}"
        then: secondary_container
        else: transparent
      flex_direction: horizontal
      align_content: left
      gap: 12
      padding:
        left: 16
        right: 24
        top: 0
        bottom: 0
  - id: icon
    style:
      width: 24
      height: 24
      foreground:
        if: "{{ selected }}"
        then: on_secondary_container
        else: on_surface_variant
  - id: label
    style:
      foreground:
        if: "{{ selected }}"
        then: on_secondary_container
        else: on_surface_variant
      flex: expand_horizontal
      min_width: 0

How it is tied to the component

NavigationDrawerItem_Component.yaml holds the structure: the parts, each with an id. This file holds the look: each rule's id names a part, and its style is what that part looks like. When a view uses component: NavigationDrawerItem, Tesserae fills in the parameters (a value like "{{ width }}" becomes the width the view passed), picks a branch of any if:, and puts each rule under the style the part already has, so a part's own style: always wins.

The parts

root (Rect)

Field	Value	What it does
width	the width parameter	Pixels, auto (its content's size, or stretched), or a percentage of the parent such as 50%.
height	56	Pixels, auto (its content's size, or stretched), or a percentage of the parent such as 50%.
corner_radius	28	Pixels, or a shape token (none to extra_large, or full for a pill or circle). Per corner: a list [top_left, top_right, bottom_right, bottom_left], or a mapping of corners and edges (top, right, bottom, left) with the rest square.
background	secondary_container if selected, else transparent	Its fill: a theme role such as surface, #RRGGBB, any CSS colour, or a gradient such as linear-gradient(90deg, primary, tertiary).
flex_direction	horizontal	How its children are laid out: horizontal (the default) or vertical.
align_content	left	Where its children sit: top_left, top, top_right, left, center, right, bottom_left, bottom or bottom_right. Not set, they fill the space across the layout.
gap	12	Space between its children.
padding	left 16, right 24, top 0, bottom 0	Space inside it: one number, or {left, right, top, bottom}.

icon (Icon)

Field	Value	What it does
width	24	Pixels, auto (its content's size, or stretched), or a percentage of the parent such as 50%.
height	24	Pixels, auto (its content's size, or stretched), or a percentage of the parent such as 50%.
foreground	on_secondary_container if selected, else on_surface_variant	Its text or glyph colour: a theme role, #RRGGBB, any CSS colour, or a gradient.

label (Text)

Field	Value	What it does
foreground	on_secondary_container if selected, else on_surface_variant	Its text or glyph colour: a theme role, #RRGGBB, any CSS colour, or a gradient.
flex	expand_horizontal	How it takes room in its parent: none (the default) is as big as its content and never squeezed, expand_horizontal and expand_vertical take the room left over in that direction, fill both.
min_width	0	The least width it can take.

What it makes

With label: Go, icon: home, width: 120, selected: False, each part's style is:

root:
  width: 120
  height: 56
  corner_radius: 28
  background: transparent
  flex_direction: horizontal
  align_content: left
  gap: 12
  padding: {left: 16, right: 24, top: 0, bottom: 0}
icon: {width: 24, height: 24, foreground: on_surface_variant}
label: {foreground: on_surface_variant, flex: expand_horizontal, min_width: 0}

Changing it

Put a NavigationDrawerItem_Stylesheet.yaml next to your views. Its rules go over this file's, field by field:

styles:
  - id: root
    style: {background: tertiary}