Creating an Output¶

Export settings
Export as Image
Export as SVG
Export as PDF
Generate an Atlas

The figure below shows an example of print layout including each type of layout items described in the previous section.

../../../_images/print_composer_complete.png

Print Layout with map view, legend, image, scale bar, coordinates, text and HTML frame added¶

From the Layout menu or toolbar, you can output the print layout to different file formats, and it is possible to modify the resolution (print quality) and paper size:

The ^Print icon allows you to print the layout to a connected printer or a PostScript file, depending on installed printer drivers.
The ^{Export as image} icon exports the print layout in several image formats such as PNG, BMP, TIF, JPG, and many others…
The ^{Export as SVG} icon saves the print layout as an SVG (Scalable Vector Graphic).
The ^{Export as PDF} icon saves the defined print layout directly as a PDF.

Export settings ¶

Whenever you export a print layout, there are a selection of export settings QGIS needs to check in order to return the most appropriate output. These configurations are:

the Export settings of the Layout panel, such as Export resolution, Print as raster, Always export as vectors or Save world file;
the Exclude page from exports in the page item properties panel;
the Exclude item from exports in the item properties panel.

Clicking the ^{Export as image} icon will ask you to select the image format and enter the filename to use to export the print layout: in the case of multi-page composition, each page will be exported to a file with the given name appended with the page number.

In the next Image Export Options dialog, you can optionally override the print layout resolution and the exported page dimensions (set in Layout panel).

By checking Crop to content option, the image output by the layout will include the minimal area enclosing all the items (map, legend, scale bar, shapes, label, image…) of each page of the composition:

If the composition includes a single page, then the output is resized to include EVERYTHING on the composition. The page can then be reduced or extended to all items depending on their position (on, above, below, left or right of the page).
In case of a multi-page layout, each page will be resized to include items in its area (left and right sides for all pages, plus top for the first page and bottom for the last page). Each resized page is exported to a separate file.

The Crop to content dialog also allows to add some margins around the cropped bounds.

../../../_images/image_export_options.png

Image Export Options, output is resized to items extent¶

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Use image formats that support transparency when items extend beyond the paper extent

Since layout items may be placed outside the paper extent, using the Crop to content option while exporting can result in an image that extends beyond the paper extent. Since the background outside of the paper extent will be transparent, for image formats that do not support transparency (eg, .BMP, .JPG) it will be rendered as full black, “corrupting” the image.

Use transparency-compatible formats like .TIFF or .PNG in such a case.

If you need to export your layout as a georeferenced image (e.g., to share with other projects), check the Generate world file option and a world file named like the page on which the map reference set in Layout panel is placed will be created along the export(s). This option can also be checked by default in the layout panel.

When needed, images rendering can also be improved with the Enable antialiasing option.

Export as SVG ¶

With ^{Export as SVG}, you also need to fill the filename (used as a basename for all files in case of multi-page composition) and then can apply Crop to content option.

The SVG export options dialog also allows to override the layout default export and offers other settings:

Export map layers as SVG groups: may affect label placement.
Render map labels as outlines: unchecking this will allow you to edit labels as texts in vector illustration software.
Always export as vectors: some rendering options require items to be rasterized for a better rendering. Check this option to keep the objects as vectors with the risk that the appearance of the output file may not match the print layout preview (for more details, see Export settings).
Export RDF metadata.

SVG Export Options¶

Not

Currently, the SVG output is very basic. This is not a QGIS problem, but a problem with the underlying Qt library. This will hopefully be sorted out in future versions.

Export as PDF ¶

The ^{Export as PDF} tool exports all the composition pages into a single PDF file you’d need to provide path and name. Unlike the other formats, exporting to .PDF does not provide means to override the layout export settings. So check these settings to ensure they are compatible with your needs.

PDF Export Options¶

Not

Exporting a print layout to formats like .PDF or .TIFF creates a georeferenced output (no world file needed) by default.

Generate an Atlas ¶

Atlas functions allow you to create map books in an automated way. Atlas uses the features of a vector or table layer called coverage layer and creates an output for each atlas feature. The most common usage is to zoom a map item to the current atlas feature. Further use cases include:

a map item showing, for another layer, only features that share the same attribute as the atlas feature or are within its geometry;
a label or html item whose text is replaced as features are iterated over;
a table item showing attributes of associated parent or children features of the current atlas feature…

For each feature, an output is processed for all pages and items according to their exports settings.

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Use variables for more flexibility

QGIS provides a large panel of functions and variables, including atlas related ones, that you can use to manipulate the layout items but also the layers symbology according to atlas status. Combining these features gives you a lot of flexibility and helps you easily produce advanced mappings.

To enable the generation of an atlas and access atlas parameters, refer to the Atlas panel. This panel contains the following functionalities (see figure_layout_atlas):

Atlas Panel¶

Generate an atlas, which enables or disables the atlas generation;
A Coverage layer combo box that allows you to choose the table or vector layer containing the features to iterate over;
An optional Hidden coverage layer that, if checked, will hide the coverage layer (but not the other layers) during the generation;
An optional Page name combo box to give a more explicit name to each feature page(s) when previewing atlas. You can select a field of the coverage layer or set an expression. If this option is empty, QGIS will use an internal ID, according to the filter and/or the sort order applied to the layer;
An optional Filter with text area that allows you to specify an expression for filtering features from the coverage layer. If the expression is not empty, only features that evaluate to True will be processed;
An optional Sort by that allows you to sort features of the coverage layer, using a field of the coverage layer or an expression. The sort order (either ascending or descending) is set by the two-state Sort direction button that displays an up or a down arrow.

You also have options to set the output of the atlas:

An Output filename expression textbox that is used to generate a filename for each geometry if needed. It is based on expressions. This field is meaningful only for rendering to multiple files;
A Single file export when possible that allows you to force the generation of a single file if this is possible with the chosen output format (PDF, for instance). If this field is checked, the value of the Output filename expression field is meaningless;
An Image export format drop-down list to select the output format when using the ^{Export atlas as Images…} button.

Control map by atlas ¶

The most common usage of atlas is with the map item, zooming to the current atlas feature, as iteration goes over the coverage layer. This behavior is set in the Controlled by atlas group properties of the map item. See Controlled by atlas for different settings you can apply on map item.

Customize labels with expression ¶

In order to adapt labels to the feature the atlas iterates over, you can include expressions. What you should take care of is to place expression part (including functions, fields or variables) between [% and %] (see The Label Item for more details).

For example, for a city layer with fields CITY_NAME and ZIPCODE, you could insert this:

The area of [% concat( upper(CITY_NAME), ',', ZIPCODE, ' is ',
format_number($area/1000000, 2) ) %] km2

or, another combination:

The area of [% upper(CITY_NAME)%],[%ZIPCODE%] is
[%format_number($area/1000000,2) %] km2

The information [% concat( upper(CITY_NAME), ',', ZIPCODE, ' is ', format_number($area/1000000, 2) ) %] is an expression used inside the label. Both expressions would result in the generated atlas as:

The area of PARIS,75001 is 1.94 km2

Explore Data-defined override buttons with atlas ¶

There are several places where you can use a ^{Data defined
override} button to override the selected setting. These options are particularly useful with atlas generation. See Data defined override setup for more details on this widget.

For the following examples the Regions layer of the QGIS sample dataset is used and selected as coverage layer for the atlas generation. We also assume it’s a single page layout containing a map and a label items.

When the height (north-south) of the extents of a region is greater than its width (east-west), you rather want to use Portrait instead of Landscape orientation to optimize the use of paper. With a ^{Data Defined Override} button you can dynamically set the paper orientation.

Right-click on the page and select Page Properties to open the panel. We want to set the orientation dynamically, using an expression depending on the region geometry so press the button of field Orientation, select Edit… to open the Expression string builder dialog and enter the following expression:

CASE WHEN bounds_width(@atlas_geometry) > bounds_height(@atlas_geometry)
THEN 'Landscape' ELSE 'Portrait' END

Now if you preview the atlas, the paper orients itself automatically but items placement may not be ideal. For each Region you need to reposition the location of the layout items as well. For the map item you can use the button of its Width property to set it dynamic using following expression:

@layout_pagewidth - 20

Likewise, use the button of the Height property to provide following expression and constrain map item size:

@layout_pageheight - 20

To ensure the map item is centered in the page, set its Reference point to the upper left radio button and enter 10 for its X and Y positions.

Let’s add a title above the map in the center of the page. Select the label item and set the horizontal alignment to Center. Next move the label to the right position, activate from Reference point any of the middle buttons, and provide the following expression for field X:

@layout_pagewidth / 2

For all other layout items you can set the position in a similar way so they are correctly positioned when the page is automatically rotated in portrait or landscape. You can also do more tweaks such as customizing the title with feature attributes (see Customize labels with expression example), updating images with atlas feature, resizing the legend columns number according to page orientation…

Information provided is an update of the excellent blog (in English and Portuguese) on the Data Defined Override options Multiple_format_map_series_using_QGIS_2.6 .

This is just one example of how you can use some advanced settings with atlas.

Preview and generate an atlas ¶

Atlas Preview toolbar¶

Once the atlas settings have been configured and layout items (map, table, image…) linked to it, you can create a preview of all the pages by clicking Atlas ‣ Preview Atlas or ^{Preview Atlas} icon. You can then use the arrows in the same toolbar to navigate through all the features:

^{First feature}
^{Previous feature}
^{Next feature}
^{Last feature}

You can also use the combo box to directly select and preview a specific feature. The combo box shows atlas features name according to the expression set in the atlas Page name option.

As for simple compositions, an atlas can be generated in different ways (see Creating an Output for more information). Instead of Layout menu, rather use tools from Atlas menu or toolbar.

This means that you can directly print your compositions with Atlas ‣ Print Atlas. You can also create a PDF using Atlas ‣ Export Atlas as PDF…: You will be asked for a directory to save all the generated PDF files, except if the Single file export when possible has been selected. In that case, you’ll be prompted to give a filename.

With Atlas ‣ Export Atlas as Images… or Atlas ‣ Export Atlas as SVG… tool, you’re also prompted to select a folder. Each page of each atlas feature composition is exported to the image file format set in Atlas panel or to SVG file.

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Print a specific atlas feature

If you want to print or export the composition of only one feature of the atlas, simply start the preview, select the desired feature in the drop-down list and click on Layout ‣ Print (or Export… to any supported file format).

Use project defined relations for atlas creation ¶

For users with HTML and Javascript knowledge it’s possible to operate on GeoJSON objects and use project defined relations from the QGIS project. The difference between this approach and using expressions directly inserted into the HTML is that it gives you a full, unstructured GeoJSON feature to work with. This means that you can use the existing Javascript libraries and functions which operate on GeoJSON feature representations.

The following code includes all related child features from the defined relation. Using the JavaScript setFeature function it allows you to make flexible HTML which represents relations in whatever format you like (lists, tables, etc). In the code sample, we create a dynamic bullet list of the related child features.

// Declare the two HTML div elements we will use for the parent feature id
// and information about the children
<div id="parent"></div>
<div id="my_children"></div>

<script type="text/javascript">
   function setFeature(feature)
   {
   // Show the parent feature's identifier (using its "ID" field)
   document.getElementById('parent').innerHTML = feature.properties.ID;
   //clear the existing relation contents
   document.getElementById('my_children').innerHTML = '';
   feature.properties.my_relation.forEach(function(child_feature) {
   // for each related child feature, create a list element
   // with the feature's name (using its "NAME" field)
      var node = document.createElement("li");
      node.appendChild(document.createTextNode(child_feature.NAME));
      document.getElementById('my_children').appendChild(node);
      });
   }
</script>

During the atlas creation there will be an iteration over the coverage layer containing the parent features. On every page, you will see a bullet list of the related child features following the parent’s identifier.