Feature Style

Extension Title

Feature Style

Introduction

This extension defines styles and icons for feature geometries. Feature tables may assigned default styles and features may be individually styled. Styles may be assigned as geometry type specific.

This extension depends on the OGC GeoPackage Related Tables Extension.

This extension depends on the NGA Contents Id Extension for default style configurations.

Extension Author

National Geospatial-Intelligence Agency, author_name nga

Extension Name or Template

nga_feature_style

Extension Type

New Requirement

Applicability

This extension applies to the table names of feature user tables (2.1.6).

Scope

Read-write

Requirements

GeoPackage

Extension Table Entries

The Feature Style extension is registered into the gpkg_extensions table once per feature table. Each user-defined mapping table between a feature or table and a style or icon is registered per the Related Tables Extension.

<feature_table_name> = name of a feature table

`gpkg_extensions entries`
table_name	column_name	extension_name	definition	scope
`<feature_table_name>`	null	`nga_feature_style`	URL to this extension description	read-write
`nga_style_<feature_table_name>`	null	`related_tables`	http://www.geopackage.org/18-000.html	read-write
`nga_icon_<feature_table_name>`	null	`related_tables`	http://www.geopackage.org/18-000.html	read-write
`nga_style_default_<feature_table_name>`	null	`related_tables`	http://www.geopackage.org/18-000.html	read-write
`nga_icon_default_<feature_table_name>`	null	`related_tables`	http://www.geopackage.org/18-000.html	read-write

Contents Entries

The Feature Style extension nga_style and nga_icon tables are listed as attribute contents tables alongside feature tables.

`gpkg_contents entries`
table_name	data_type	identifier	description	last_change	min_x	min_y	max_x	max_y	srs_id
`<feature_table_name>`	features	any	any	any	any	any	any	any	any
`nga_style`	attributes	any	any	any	null	null	null	null	null
`nga_icon`	attributes	any	any	any	null	null	null	null	null

Style Table

The Style Table defines a geometry style and is an Attributes Table.

`nga_style`
Column Name	Type	Description	Null	Key
`id`	INTEGER	Autoincrement primary key	no	PK
`name`	TEXT	Feature Style name	yes
`description`	TEXT	Feature Style description	yes
`color`	TEXT	Geometry color in hex format `#RRGGBB` or `#RGB`, when null assume #000000	yes
`opacity`	REAL	Geometry color opacity inclusively between 0.0 and 1.0, when null assume 1.0	yes
`width`	REAL	Geometry line stroke or point width >= 0.0, when null assume 1.0	yes
`fill_color`	TEXT	Closed geometry fill color in hex format `#RRGGBB` or `#RGB, no fill when null`	yes
`fill_opacity`	REAL	Closed geometry fill color opacity inclusively between 0.0 and 1.0, when null assume 1.0	yes


CREATE TABLE nga_style (
  id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
  name TEXT,
  description TEXT,
  color TEXT,
  opacity REAL,
  width REAL,
  fill_color TEXT,
  fill_opacity REAL
);

Icon Table

The Icon Table defines a geometry icon or marker and is a Related Tables Extension Media Table.

`nga_icon`
Column Name	Type	Description	Null	Key
`id`	INTEGER	Autoincrement primary key	no	PK
`data`	BLOB	Feature Icon content	no
`content_type`	TEXT	Mime-type of the feature icon	no
`name`	TEXT	Feature Icon name	yes
`description`	TEXT	Feature Icon description	yes
`width`	REAL	Icon display width. When null and height has value, maintain aspect ratio. When null and height is null, use data icon width.	yes
`height`	REAL	Icon display height. When null and width has value, maintain aspect ratio. When null and width is null, use data icon height.	yes
`anchor_u`	REAL	UV Mapping horizontal anchor distance inclusively between 0.0 and 1.0 from the left edge, when null assume 0.5 (middle of icon)	yes
`anchor_v`	REAL	UV Mapping vertical anchor distance inclusively between 0.0 and 1.0 from the top edge, when null assume 1.0 (bottom of icon)	yes


CREATE TABLE nga_icon (
  id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
  data BLOB NOT NULL,
  content_type TEXT NOT NULL,
  name TEXT,
  description TEXT,
  width REAL,
  height REAL,
  anchor_u REAL,
  anchor_v REAL
);

Contents Id

The Contents Id Extension is used to relate default styles to a feature table by an INTEGER primary key, as required by the Related Tables Extension User-Defined Mapping Tables.

`nga_contents_id entries`
id	table_name
any	`<feature_table_name>`

Mapping Tables

Related Tables Extension Mapping Tables are used to relate:

Feature Tables to Default Styles - nga_style_default_<feature_table_name>
Feature Tables to Default Icons - nga_icon_default_<feature_table_name>
Features to Styles - nga_style_<feature_table_name>
Features to Icons - nga_icon_<feature_table_name>

The Mapping Tables are defined in the Related Tables Extension Relations Table:

`gpkgext_relations entries`
id	base_table_name	base_primary_column	related_table_name	related_primary_column	relation_name	mapping_table_name
any	`nga_contents_id`	`id`	`nga_style`	`id`	attributes	`nga_style_default_<feature_table_name>`
any	`nga_contents_id`	`id`	`nga_icon`	`id`	media	`nga_icon_default_<feature_table_name>`
any	`<feature_table_name>`	`id`	`nga_style`	`id`	attributes	`nga_style_<feature_table_name>`
any	`<feature_table_name>`	`id`	`nga_icon`	`id`	media	`nga_icon_<feature_table_name>`

Style and Icon Mapping Tables contain the id mapping columns and a nullable geometry_type_name.

`nga_style_default_<feature_table_name>, nga_icon_default_<feature_table_name>, nga_style_<feature_table_name>, nga_icon_<feature_table_name>`
Column Name	Type	Description	Null
`base_id`	INTEGER	The primary key value of the base data table (`nga_contents_id` or `<feature_table_name>`)	no
`related_id`	INTEGER	The primary key value of the related data table (`nga_style` or `nga_icon`)	no
`geometry_type_name`	TEXT	Name from Geometry Type Codes (Core) or Geometry Type Codes (Extension) in Geometry Types (Normative) A null value configures a top level or default geometry style or icon. A defined geometry type maps the style or icon for geometries of that and inherited geometry types. The lowest configured feature matching geometry type takes priority. User-Defined Mapping Table unique constraints are discouraged, but duplicate `base_id`, `related_id`, and `geometry_type_name` triplets are discouraged as conflicting styling may be unpredictable.	yes


CREATE TABLE nga_[style_default|icon_default|style|icon]_<feature_table_name> (
  base_id INTEGER NOT NULL,
  related_id INTEGER NOT NULL,
  geometry_type_name TEXT
);

GeoPackage SQLite Configuration

None

GeoPackage SQLite Extension

None

Examples

The rivers GeoPackage has a default style for the rivers feature table.

The example GeoPackage has styles and icons for the geometry1 and geometry2 feature tables.