.. index:: Legend item, Map legend .. _layout_legend_item: The Legend Item ================ .. only:: html .. contents:: :local: The :guilabel:`Legend` item is a box or a table that explains the meanings of the symbols used on the map. A legend is then bound to a map item. You can add a legend item with the |addLegend| :guilabel:`Add Legend` tool following :ref:`items creation instructions ` and manipulate it the same way as exposed in :ref:`interact_layout_item`. By default, the legend item displays all available layers and can be refined using its :guilabel:`Item Properties` panel. Other than the :ref:`items common properties `, this feature has the following functionalities (see :numref:`figure_layout_legend`): .. showing all layers is a bug (https://issues.qgis.org/issues/13575) but given that it's the behavior for a long moment now, let's document it... .. _figure_layout_legend: .. figure:: img/legend_properties.png :align: center Legend Item Properties Panel Main properties --------------- The :guilabel:`Main properties` group of the legend :guilabel:`Item Properties` panel provides the following functionalities (see :numref:`figure_layout_legend_ppt`): .. _figure_layout_legend_ppt: .. figure:: img/legend_mainproperties.png :align: center Legend Main properties group In Main properties you can: * Change the :guilabel:`Title` of the legend. It can be made dynamic using the :ref:`data-defined override ` setting, useful for example when generating an atlas; * Choose which :guilabel:`Map` item the current legend will refer to. By default, the map over which the legend item is drawn is picked. If none, then it falls back to the :ref:`reference map `. .. note:: :ref:`Variables ` of the linked map item (@map_id, @map_scale, @map_extent...) are also accessible from data-defined properties of the legend. * Wrap the text of the legend on a given character: each time the character appears, it's replaced with a line break; * Set the symbols and text placement in the legend: the :guilabel:`Arrangement` can be :guilabel:`Symbols on left` or :guilabel:`Symbols on right`. The default value depends on the locale in use (right-to-left based or not). * Use |checkbox| :guilabel:`Resize to fit contents` to control whether or not a legend should be automatically resized to fit its contents. If unchecked, then the legend will never resize and instead just stick to whatever size the user has set. Any content which doesn't fit the size is cropped out. Legend items ------------ The :guilabel:`Legend items` group of the legend :guilabel:`Item Properties` panel provides the following functionalities (see :numref:`figure_layout_legend_items`): .. _figure_layout_legend_items: .. figure:: img/legend_items.png :align: center Legend Items group * The legend will be updated automatically if |checkbox| :guilabel:`Auto update` is checked. When :guilabel:`Auto update` is unchecked this will give you more control over the legend items. All the icons below the legend items list will be activated. * The legend items window lists all legend items and allows you to change item order, group layers, remove and restore items in the list, edit layer names and add a filter. * The item order can be changed using the |arrowUp| and |arrowDown| buttons or with 'drag-and-drop' functionality. The order can not be changed for WMS legend graphics. * Use the |addGroup| button to add a legend group. * Use the |signPlus| button to add layers and |signMinus| button to remove groups, layers or symbol classes. * The |symbologyEdit| button is used to edit the layer, group name or title. First you need to select the legend item. Double-clicking the item also opens the text box to rename it. * The |expression| button uses expressions to customize each symbol label of the selected layer (see :ref:`legend_items_data_defined`) * The |sum| button adds a feature count for each class of vector layer. * The |expressionFilter| :sup:`Filter legend by expression` helps you filter which of the legend items of a layer will be displayed, i.e. using a layer that has different legend items (e.g., from a rule-based or categorized symbology), you can specify a boolean expression to remove from the legend tree, styles that have no feature satisfying a condition. Note that the features are nevertheless kept and shown in the layout map item. While the default behavior of the legend item is to mimic the :guilabel:`Layers` panel tree, displaying the same groups, layers and classes of symbology, right-click any item offers you options to hide layer's name or raise it as a group or subgroup. In case you have made some changes to a layer, you can revert them by choosing :guilabel:`Reset to defaults` from the contextual menu of the legend entry. After changing the symbology in the QGIS main window, you can click on :guilabel:`Update All` to adapt the changes in the legend element of the print layout. * With the |checkbox| :guilabel:`Only show items inside linked map`, only the legend items visible in the linked map will be listed in the legend. This tool remains available when |checkbox| :guilabel:`Auto-update` is active * While generating an atlas with polygon features, you can filter out legend items that lie outside the current atlas feature. To do that, check the |checkbox| :guilabel:`Only show items inside current atlas feature` option. .. _legend_items_data_defined: Data-define the legend labels ............................. |expression| allows you to add :ref:`expressions ` to each symbol label of a given layer. New variables (``@symbol_label``, ``@symbol_id`` and ``@symbol_count``) help you interact with the legend entry. For example, given a ``regions`` layer categorized by its ``type`` field, you can append to each class in the legend their number of features and total area, e.g. ``Borough (3) - 850ha``: #. Select the layer entry in the legend tree #. Press the |expression| button, opening the :guilabel:`Expression String Builder` dialog #. Enter the following expression (*assuming symbol labels have not been edited*):: concat( @symbol_label, ' (', @symbol_count, ') - ', round( aggregate(@layer, 'sum', $area, filter:= "type"=@symbol_label)/10000 ), 'ha' ) #. Press :guilabel:`OK` Fonts ----- The :guilabel:`Fonts` group of the legend :guilabel:`Item Properties` panel provides the following functionalities: .. _figure_layout_legend_fonts: .. figure:: img/legend_fonts.png :align: center Legend Fonts properties * You can change the font of the legend title, group, subgroup and item (feature) in the legend item using the :ref:`font selector ` widget * For each of these levels you can set the text :guilabel:`Alignment`: it can be :guilabel:`Left` (default for left-to-right based locales), :guilabel:`Center` or :guilabel:`Right` (default for right-to-left based locales). * You set the :guilabel:`Color` of the labels using the :ref:`color selector ` widget. The selected color will apply to all the font items in the legend. Columns ------- Under the :guilabel:`Columns` group of the legend :guilabel:`Item Properties` panel, legend items can be arranged over several columns: * Set the number of columns in the :guilabel:`Count` |selectNumber| field. This value can be made dynamic e.g., following atlas features, legend contents, the frame size... * |checkbox| :guilabel:`Equal column widths` sets how legend columns should be adjusted. * The |checkbox| :guilabel:`Split layers` option allows a categorized or a graduated layer legend to be divided between columns. .. _figure_layout_legend_columns: .. figure:: img/legend_columns.png :align: center Legend Columns settings Symbol ------ The :guilabel:`Symbol` group of the legend :guilabel:`Item Properties` panel configures the size of symbols displayed next to the legend labels. You can: * Set the :guilabel:`Symbol width` and :guilabel:`Symbol height` * Set the markers' :guilabel:`Min symbol size` and :guilabel:`Max symbol size`: ``0.00mm`` means there is no value set. * |checkbox| :guilabel:`Draw stroke for raster symbols`: this adds an outline to the symbol representing the band color of the raster layer; you can set both the :guilabel:`Stroke color` and :guilabel:`Tickness`. .. _figure_layout_legend_symbol: .. figure:: img/legend_symbol.png :align: center Legend Symbol configuration WMS LegendGraphic and Spacing ------------------------------ The :guilabel:`WMS LegendGraphic` and :guilabel:`Spacing` groups of the legend :guilabel:`Item Properties` panel provide the following functionalities (see :numref:`figure_layout_legend_wms`): .. _figure_layout_legend_wms: .. figure:: img/legend_wms.png :align: center WMS LegendGraphic and Spacing groups When you have added a WMS layer and you insert a legend item, a request will be sent to the WMS server to provide a WMS legend. This Legend will only be shown if the WMS server provides the GetLegendGraphic capability. The WMS legend content will be provided as a raster image. :guilabel:`WMS LegendGraphic` is used to be able to adjust the :guilabel:`Legend width` and the :guilabel:`Legend height` of the WMS legend raster image. :guilabel:`Spacing` around title, groups, subgroups, symbols, labels, boxes, columns and lines can be customized through this dialog. .. 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. .. |addGroup| image:: /static/common/mActionAddGroup.png :width: 1.5em .. |addLegend| image:: /static/common/mActionAddLegend.png :width: 1.5em .. |arrowDown| image:: /static/common/mActionArrowDown.png :width: 1.5em .. |arrowUp| image:: /static/common/mActionArrowUp.png :width: 1.5em .. |checkbox| image:: /static/common/checkbox.png :width: 1.3em .. |expression| image:: /static/common/mIconExpression.png :width: 1.5em .. |expressionFilter| image:: /static/common/mIconExpressionFilter.png :width: 1.5em .. |selectNumber| image:: /static/common/selectnumber.png :width: 2.8em .. |signMinus| image:: /static/common/symbologyRemove.png :width: 1.5em .. |signPlus| image:: /static/common/symbologyAdd.png :width: 1.5em .. |sum| image:: /static/common/mActionSum.png :width: 1.2em .. |symbologyEdit| image:: /static/common/symbologyEdit.png :width: 1.5em