.. index:: Layout; Label item .. _layout_label_item: The Label Item =============== .. only:: html .. contents:: :local: The :guilabel:`Label` item is a tool that helps decorate your map with texts that would help to understand it; it can be the title, author, data sources or any other information... You can add a label with the |label| :guilabel:`Add Label` tool following :ref:`items creation instructions ` and manipulate it the same way as exposed in :ref:`interact_layout_item`. By default, the label item provides a default text that you can customize using its :guilabel:`Item Properties` panel. Other than the :ref:`items common properties `, this feature has the following functionalities (see :numref:`figure_layout_label`): .. _figure_layout_label: .. figure:: img/label_mainproperties.png :align: center Label Item Properties Panel Main properties ---------------- The :guilabel:`Main properties` group is the place to provide the text (it can be in HTML) or the expression to build the label. Expressions need to be surrounded by ``[%`` and ``%]`` in order to be interpreted as such. * Labels can be interpreted as HTML code: check |checkbox| :guilabel:`Render as HTML`. You can now insert a URL, a clickable image that links to a web page or something more complex. * You can also use :ref:`expressions `: click on :guilabel:`Insert or Edit an expression...` button, write your formula as usual and when the dialog is applied, QGIS automatically adds the surrounding characters. .. note:: Clicking the :guilabel:`Insert or Edit an Expression...` button when no selection is made in the textbox will append the new expression to the existing text. If you want to update an existing text, you need to select it the part of interest beforehand. You can combine HTML rendering with expressions, leading to advanced labeling. The following code will output :numref:`figure_layout_label_html`: .. code-block:: css Feature Information
  • Feature Id: [% ID %]
  • Airport: [% NAME %]
  • Main use: [% USE %]
Last check: [% concat( format_date( "control_date", 'yyyy-MM-dd'), ' by ', @user_full_name, '' ) %]

QGIS icon .. _figure_layout_label_html: .. figure:: img/label_htmlexpression.png :align: center Leveraging a label with HTML styling Appearance ---------- * Define :guilabel:`Font` by clicking on the :guilabel:`Font...` button or a :guilabel:`Font color` by pushing the :ref:`color widget `. * You can specify different horizontal and vertical margins in ``mm``. This is the margin from the edge of the layout item. The label can be positioned outside the bounds of the label e.g. to align label items with other items. In this case you have to use negative values for the margin. * Using the text alignment is another way to position your label. It can be: * :guilabel:`Left`, :guilabel:`Center`, :guilabel:`Right` or :guilabel:`Justify` for :guilabel:`Horizontal alignment` * and :guilabel:`Top`, :guilabel:`Middle`, :guilabel:`Bottom` for :guilabel:`Vertical alignment`. .. _layout_label_expressions: Exploring expressions in a label item ------------------------------------- Below some examples of expressions you can use to populate the label item with interesting information - remember that the code, or at least the calculated part, should be surrounded by ``[%`` and ``%]`` in the :guilabel:`Main properties` frame: * Display a title with the current atlas feature value in "field1": :: 'This is the map for ' || "field1" or, written in the :guilabel:`Main properties` section: :: This is the map for [% "field1" %] * Add a pagination for processed atlas features (eg, ``Page 1/10``): :: concat( 'Page ', @atlas_featurenumber, '/', @atlas_totalfeatures ) * Return the name of the airports of the current atlas region feature, based on their common attributes: :: aggregate( layer := 'airports', aggregate := 'concatenate', expression := "NAME", filter := fk_regionId = attribute( @atlas_feature, 'ID' ), concatenator := ', ' ) Or, if an :ref:`attributes relation ` is set: :: relation_aggregate( relation := 'airports_in_region_relation', aggregate := 'concatenate', expression := "NAME", concatenator := ', ' ) * Return the name of the airports contained in the current atlas region feature, based on their spatial relationship: :: aggregate( layer := 'airports', aggregate := 'concatenate', expression := "NAME", filter := contains( geometry( @parent ), $geometry ), concatenator := ', ' ) OR:: array_to_string( array:= overlay_contains( layer := 'airports', expression := "NAME" ), delimiter:= ', ' ) * Return the lower X coordinate of the ``Map 1`` item's extent: :: x_min( map_get( item_variables( 'Map 1' ), 'map_extent' ) ) * Retrieve the name of the layers in the current layout ``Map 1`` item, and formats in one name by line: :: array_to_string( array_foreach( map_get( item_variables( 'Map 1' ), 'map_layers' ), -- retrieve the layers list layer_property( @element, 'name' ) -- retrieve each layer name ), '\n' -- converts the list to string separated by breaklines ) .. Substitutions definitions - AVOID EDITING PAST THIS LINE This will be automatically updated by the find_set_subst.py script. If you need to create a new substitution manually, please add it also to the substitutions.txt file in the source folder. .. |checkbox| image:: /static/common/checkbox.png :width: 1.3em .. |label| image:: /static/common/mActionLabel.png :width: 1.5em