The Map Item¶

Main properties¶

The Main properties dialog of the map Item Properties panel provides the following functionalities (see figure_composer_map):

Map Item Properties Panel

• The Preview drop-down menu allows you to select one of the preview modes ‘Rectangle’, ‘Cache’ and ‘Render’, as described above. If you change the view on the QGIS map canvas by changing vector or raster properties, you can update the Print Composer view by selecting the map element and clicking the [Update preview] button.
• The field Scale manually sets the map item scale.
• The field Map rotation allows you to rotate the map element content clockwise in degrees. The rotation of the map canvas can be imitated here.
• Draw map canvas items lets you show annotations that may be placed on the map canvas in the main QGIS window.

Layers¶

The Layers dialog of the map item panel provides the following functionality (see figure_composer_map_layers):

Map Layers Dialog

• If you want to keep the map item constantly updated with a visibility preset, use the Follow visibility preset and set the preset you want. Any changes applied to the preset in QGIS’s main window (using the replace preset) will also show in the map item. In this case, the Lock styles for layers option will be disabled because Follow visibility preset also updates the style (symbology, label, diagram) of the visibility preset layers.

• To lock the layers shown on a map item to the current map canvas check Lock layers. After this option is enabled, any changes on the layers visibility in the QGIS’s main window won’t affect the Composer’s map item. Nevertheless, style and labels of locked layers are still refreshed according to QGIS’s main window. You can prevent this by using Lock styles for layers.

  Using the button, you can lock the map item’s layers to one of the visibility presets you have prepared in QGIS (see Painel das Camadas to find out how to create visibility presets). Clicking the button will show the list of all the preset views. Select the preset you want to display. The map canvas will lock the preset layers automatically by enabling the Lock layers. You can release the preset by unchecking the Lock layers and press the button in the map composer’s Navigation toolbar.

  Note that, unlike the Follow visibility preset, using the Lock layers option enabled and set to a preset, the map item layers won’t be updated if the preset is changed (using the replace preset option) in QGIS’s main window.

  Locked layers in the map can also be data-defined, using the icon beside the option. When used, this overrides the selection set in the drop-down list. You need to pass a list of layers separated by | character. The following example locks the map item to use only layers layer 1 and layer 2:

  concat ('layer 1', '|', 'layer 2')
  

Extents¶

The Extents dialog of the map item panel provides the following functionalities (see figure_composer_map_extents):

Map Extents Dialog

The Map extents area allows you to specify the map extent using X and Y min/max values and by clicking the [Set to map canvas extent] button. This button sets the map extent of the composer map item to the extent of the current map view in the main QGIS application. The button [View extent in map canvas] does exactly the opposite; it updates the extent of the map view in the QGIS application to the extent of the composer map item.

If you change the view on the QGIS map canvas by changing vector or raster properties, you can update the Print Composer view by selecting the map element in the Print Composer and clicking the [Update preview] button in the map Item Properties panel (see figure_composer_map).

Grids¶

The Grids dialog of the map Item Properties panel provides the possibility to add several grids to a map item.

• With the and buttons you can add or remove a selected grid.
• With the and buttons you can move a grid in the list and set the drawing priority.

When you double-click the added grid you can give it another name.

Map Grids Dialog

After you have added a grid, you can activate the checkbox Draw grid to overlay a grid onto the map element. Expand this option to provide a lot of configuration options, see Figure_composer_map_grid_draw.

Draw Grid Dialog

As grid type, you can specify to use a ‘Solid’, ‘Cross’, ‘Markers’ or ‘Frame and annotations only’. ‘Frame and annotations only’ is especially useful when working with rotated maps or reprojected grids. In the divisions section of the Grid Frame Dialog mentioned below you then have a corresponding setting. Symbology of the grid and its rendering mode can be chosen. See Rendering mode. Furthermore, you can define an interval in the X and Y directions, an X and Y offset, and the width used for the cross or line grid type.

Grid Frame Dialog

• There are different options to style the frame that holds the map. Following options are available: No Frame, Zebra, Interior ticks, Exterior ticks, Interior and Exterior ticks and Lineborder.
• With ‘Latitude/Y only’ and ‘Longitude/X only’ setting in the divisions section you have the possibility to prevent a mix of latitude/y and longitude/x coordinates showing on a side when working with rotated maps or reprojected grids.
• Advanced rendering mode is also available for grids.
• The Draw coordinates checkbox allows you to add coordinates to the map frame. You can choose the annotation numeric format, the options range from decimal to degrees, minute and seconds, with or without suffix, aligned or not and a custom format using the expression dialog. You can choose which annotation to show. The options are: show all, latitude only, longitude only, or disable(none). This is useful when the map is rotated. The annotation can be drawn inside or outside the map frame. The annotation direction can be defined as horizontal, vertical ascending or vertical descending. Finally, you can define the annotation font, the annotation font color, the annotation distance from the map frame and the precision of the drawn coordinates.

Grid Draw Coordinates dialog

Overviews¶

The Overviews dialog of the map Item Properties panel provides the following functionalities:

Map Overviews Dialog

You can choose to create an overview map, which shows the extents of the other map(s) that are available in the composer. First you need to create the map(s) you want to include in the overview map and the map you want to use as the overview map, just like a normal map.

Then expand Overviews option and press the green plus icon-button to add an overview. Initially this overview is named ‘Overview 1’ (see Figure_composer_map_overview). You can change the name when you double-click on the overview item in the list named ‘Overview 1’ and change it to another name.

• With the plus and minus button you can add or remove an overview.
• With the up and down button you can move an overview in the list and set the drawing priority.

When you select the overview item in the list you can customize it.

• The Draw “<name_overview>” overview needs to be activated to draw the extent of selected map frame.
• The Map frame combo list can be used to select the map item whose extents will be drawn on the present map item.
• The Frame Style allows you to change the style of the overview frame.
• The Blending mode allows you to set different transparency blend modes.
• The Invert overview creates a mask around the extents when activated: the referenced map extents are shown clearly, whereas everything else is blended with the frame color.
• The Center on overview puts the extent of the overview frame in the center of the overview map. You can only activate one overview item to center, when you have added several overviews.