4.2. Lesson: Creating a Dynamic Print Layout¶

Now that you have learned to create a basic map layout we go a step further and create a map layout that adapts dynamically to our map extent and to the page properties, e.g. when you change the size of the page. Also, the date of creation will adapt dynamically.

4.2.1. Follow Along: Creating the dynamic map canvas¶

Load the ESRI Shapefile format datasets protected_areas.shp, places.shp, rivers.shp and water.shp into the map canvas and adapt its properties to suit your own convenience.
After everything is rendered and symbolized to your liking, click the ^{New Print Layout} icon in the toolbar or choose File ▶ New Print Layout. You will be prompted to choose a title for the new print layout.
We want to create a map layout consisting of a header and a map of the region near Swellendam, South Africa. The layout should have a margin of 7.5 mm and the header should be 36mm high.
Create a map item called main map on the canvas and go to the Layout panel. Scroll down to the Variables section and find the Layout part. Here we set some variables you can use all over the dynamic print layout. Go to the Layout panel and scroll down to the Variables section. The first variable will define the margin. Press the button and type in the name sw_layout_margin. Set the value to 7.5. Press the button again and type in the name sw_layout_height_header. Set the value to 36.
Now you are ready to create the position and the size of the map canvas automatically by means of the variables. Make sure that your map item is selected, go to the Item Properties panel, scroll down to and open the Position and Size section. Click the ^{Data defined override} for X and from the Variables entry, choose @sw_layout_margin.
Click the ^{Data defined override} for Y, choose Edit… and type in the formula:
```
to_real(@sw_layout_margin) + to_real(@sw_layout_height_header)
```
You can create the size of the map item by using the variables for Width and Height. Click the ^{Data defined override} for Width and choose Edit … again. Fill in the formula:
```
@layout_pagewidth - @sw_layout_margin * 2
```
Click the ^{Data defined override} for Height and choose Edit …. Here fill in the formula:
```
@layout_pageheight -  @sw_layout_height_header -  @sw_layout_margin * 2
```
We will also create a grid containing the coordinates of the main canvas map extent. Go to Item Properties again and choose the Grids section. Insert a grid by clicking the button. Click on Modify grid … and set the Interval for X, Y and Offset according to the map scale you chose in the QGIS main canvas. The Grid type Cross is very well suited for our purposes.

4.2.2. Follow Along: Creating the dynamic header¶

Insert a rectangle which will contain the header with the ^{Add Shape} button. In the Items panel enter the name header.
Again, go to the Item Properties and open the Position and Size section. Using ^{Data defined override}, choose the sw_layout_margin variable for X as well as for Y. Width shall be defined by the expression:
```
@layout_pagewidth - @sw_layout_margin * 2
```
and Height by the sw_layout_height_header variable.
We will insert a horizontal line and two vertical lines to divide the header into different sections using the ^{Add Node Item}. Create a horizontal line and two vertical lines and name them Horizontal line, Vertical line 1 Vertical line 2.
1. For the horizontal line:
  1. Set X to the variable sw_layout_margin
  2. Set the expression for Y to:
    @sw_layout_margin + 8
  3. Set the expression for Width to:
    @layout_pagewidth - @sw_layout_margin * 3 - 53.5
2. For the first vertical line:
  1. Set the expression for X to:
    @layout_pagewidth - @sw_layout_margin * 2 - 53.5
  2. Set Y to the variable sw_layout_margin
  3. The height must be the same as the header we created, so set Height to the variable sw_layout_height_header.
3. The second vertical line is placed to the left of the first one.
  1. Set the expression for X to:
    @layout_pagewidth - @sw_layout_margin * 2 - 83.5
  2. Set Y to the variable sw_layout_margin
  3. The height shall be the same as the other vertical line, so set Height to the variable sw_layout_height_header.
The figure below shows the structure of our dynamic layout. We will fill the areas created by the lines with some elements.

../../../_images/dynamic_layout_structure.png

4.2.3. Follow Along: Creating labels for the dynamic header¶

The title of your QGIS project can be included automatically. The title is set in the Project Properties. Insert a label with the ^{Add Label} button and enter the name project title (variable). In the Main Properties of the Items Properties Panel enter the expression:
```
[%@project title%]
```
Set the position of the label.
1. For X, use the expression:
```
@sw_layout_margin + 3
```
2. For Y, use the expression:
```
@sw_layout_margin + 0.25
```
3. For Width, use the expression:
```
@layout_pagewidth - @sw_layout_margin *2 - 90
```
4. Enter 11.25 for Height
Under Appearance set the Font size to 16 pt.
The second label will include a description of the map you created. Again, insert a label and name it map description. In the Main Properties enter the text map description. In the Main Properties we will also include:
```
printed on: [%format_date(now(),'dd.MM.yyyy')%]
```
Here we used two Date and Time functions (now and format_date).

Set the position of the label.
1. For X, use the expression:
```
@sw_layout_margin + 3
```
2. For Y, use the expression:
```
@sw_layout_margin + 11.5
```
The third label will include information about your organisation. First we will create some variables in the Variables menu of the Item Properties. Go to the Layout menu, click the button each time and enter the names o_department, o_name , o_adress and o_postcode. In the second row enter the information about your organisation. We will use these variables in the Main Properties section.

In Main Properties enter:
```
[% @o_name %]
[% @o_department %]
[% @o_adress %]
[% @o_postcode %]
```
Set the position of the label.
1. For X, use the expression:
```
@layout_pagewidth - @sw_layout_margin - 49.5
```
2. For Y, use the expression:
```
@sw_layout_margin + 15.5
```
3. For Width, use 49.00
4. For Height, use the expression:
```
@sw_layout_height_header - 15.5
```

../../../_images/dynamic_layout_organisation.png

4.2.4. Follow Along: Adding pictures to the dynamic header¶

Use the ^{Add Picture} button to place a picture above your label organisation information. After entering the name organisation logo define the position and size of the logo:
1. For X, use the expression:
```
@layout_pagewidth - @sw_layout_margin * 2 - 78
```
2. For Y, use the expression:
```
@sw_layout_margin + 3.5
```
3. For Width, use 39.292
4. For Height, use 9.583
To include a logo of your organisation you have to save your logo under your home directory and enter the path under Main Properties ▶ Image Source.
Our layout still needs a north arrow. This will also be inserted by using ^{Add North Arrow}. We will use the default north arrow. Define the position:
1. For X, use the expression:
```
@layout_pagewidth - @sw_layout_margin * 2 - 78
```
2. For Y, use the expression:
```
@sw_layout_margin + 9
```
3. For Width, use 21.027
4. For Height, use 21.157

4.2.5. Follow Along: Creating the scalebar of the dynamic header¶

To insert a scalebar in the header click on ^{Add Scale Bar} and place it in the rectangle above the north arrow. In Map under the Main Properties choose your main map(Map 1). This means that the scale changes automatically according to the extent you choose in the QGIS main canvas. Choose the Style Numeric. This means that we insert a simple scale without a scalebar. The scale still needs a position and size.
1. For X, use the expression:
```
@layout_pagewidth - @sw_layout_margin * 2 - 78
```
2. For Y, use the expression:
```
@sw_layout_margin + 1
```
3. For Width, use 25
4. For Height, use 8
5. Place the Reference point in the center.

Congratulations! You have created your first dynamic map layout. Take a look at the layout and check if everything looks the way you want it! The dynamic map layout reacts automatically when you change the page properties. For example, if you change the page size from DIN A4 to DIN A3, click the ^{Refresh view} button and the page design is adapted.

4.2.6. What’s Next?¶

On the next page, you will be given an assignment to complete. This will allow you to practice the techniques you have learned so far.