Step 3 - Create a control to navigate between the Page nodes

In this step you first create a header and a footer in the RootPage node, then you create the buttons to navigate between the Page nodes you created in the previous step of this tutorial.

The content you add to a Page node is visible in all Page nodes in its tree. So when you add content to the RootPage node, that content is visible in all Page nodes of that Kanzi application.

Create the header and footer

In this section you create the application header and footer:

In the Project press Alt and right-click the RootPage node and create two Empty Node 2D nodes. You use these to set the background and structure for the header and footer in the entire application.
For example, name one Header and the other Footer.
In the Project select the Header node and in the Properties:
- Click next to the Layout Height property and set it to 60.
  The properties that are frequently used with a certain node type are marked with in the Properties. When you click , Kanzi Studio adds that property to the node selected in the Project.
- Click next to the Background Brush to add the property to the Header node:
  1. In the Background Brush property select + Color Brush.
  2. Click next to the Background Brush property and set the color you want to use as the background for the Header and Footer in your application.
In the Properties click and drag the Layout Height and Background Brush properties to the Project and drop them on the Footer node to add and apply the same properties to the Footer node.
In the Project select the Footer node, in the Properties click next to the Vertical Alignment property and set it to Bottom.
Kanzi uses the default value of a property until you set it to a different value. The default value of the Vertical Alignment property is Top. This is why both Header and Footer nodes are aligned to the top of their parent node, the RootPage node, until you set the value of the Vertical Alignment property in the Footer node to Bottom.
In the Project press Alt and right-click the Header node and select Stack Layout 2D and from the Assets drag to the Stack Layout 2D node all Icon images.
You can use layout nodes to position nodes in relation to the application screen and other nodes. Layout consists of properties alignment, margins and layout size and can be defined either specific to a node or as general rules imposed on child nodes by specific layout containers. Use a Stack Layout node to place items next to each other.
In the Project select all the Icon Image nodes in the Stack Layout 2D node, in the bottom-right corner of the Properties click to open the Add Properties window. In the left column of the Add Properties window double-click the Horizontal Margin property to add it to the nodes you selected in the Project.
In the left column of the Add Properties window that opens you can see which properties you can add to the node you selected in the Project window.
To quickly find a property, type the first few letters of a property name in the search box of the Add Properties window.
With all Icon nodes in the Project still selected set the value of the Horizontal Margin property Right property field to 10.
This way you create a 10 pixel margin on the right side of the nodes.
In the Project select the Stack Layout 2D node, in the Preview select the Node tool , and click the center square in the Align tool to align the Stack Layout 2D to the center of the Header node.
TIP
Use the Align tool to set the Horizontal Alignment and Vertical Alignment properties.

Create a prefab for the navigation button

Use prefabs (prefabricated templates) to structure your application and to create consistent interfaces. Prefabs allow you to create the building blocks of your application and make the application easier to maintain.

In this section you create a prefab for the toggle button you then use in the Footer node as a control to navigate between the Page nodes in your application.

To create a prefab for the navigation button:

In the Project press Alt and right-click Prefabs and create a Toggle Button 2D node and in the Toggle Button 2D node:
1. Create a Stack Layout 2D node.
2. Drag from the Assets to the Stack Layout 2D node the Menu image.
3. In the Stack Layout 2D node create a Text Block 2D node.
In the Project > Prefabs select the Toggle Button 2D node, in the Properties click , and add the Index in Group property.
Kanzi uses the Index in Group property to keep track of which button is selected in a Toggle Button Group node. When the value of the Index in Group property is -1 the Toggle Button Group node sets the index for that Toggle Button. Toggle buttons in a toggle button group behave like radio buttons, where only one toggle button can be active at a time.
In the Prefabs double-click the Toggle Button 2D prefab to open only that prefab in the Preview in a separate tab.
When you open a prefab in the Preview, Kanzi Studio shows it as a tab below the main menu. Open prefabs in the Preview when you want to view and adjust the prefab without the distraction of the context where you use that prefab.
In the Project select the Prefabs > Toggle Button 2D > Stack Layout 2D > Text Block 2D node and in the Properties next to the Text property click . This enables you to display a different text for each instance of the prefab.
A prefab can contain a tree of nodes, each with their own properties. When you edit the nodes in a prefab or any of its instances in a project, you change those nodes in all instances of that prefab. However, you can customize individual instances of the prefab to have individual values by overriding the values in the default prefab. For example, when you create a prefab for an address book entry you want to show a different name, number, and photo for each address book entry.
When you click Kanzi Studio creates from that property a custom property, adds it to the root of the prefab, and creates a ##Template binding to the property in the prefab root. That way you can set in the root of the prefab instance the text you want the Text Block 2D node to show.
With the Text Block 2D selected, in the Preview use the Node tool , and click the center square in the Align tool to align the Text Block 2D to the center of the Stack Layout 2D node.
Click the Screen tab under the main menu to show the entire application in the Preview.
In the Project select the Footer node:
1. Create a Toggle Button Group 2D node.
  Use the Toggle Button Group nodes to allow users to select only one option from a set of options that are mutually exclusive. Toggle buttons in a toggle button group behave like radio buttons, where only one toggle button can be active at a time.
2. In the Toggle Button Group 2D node create a Stack Layout 2D node.
3. From the Prefabs drag three Toggle Button 2D prefabs to the Footer > Toggle Button Group 2D > Stack Layout 2D node.
  When you drag a prefab from the Project > Prefabs to any node in the scene graph Kanzi Studio creates an instance of that prefab in the scene graph where you drop the prefab.
4. Select each Toggle Button 2D prefab instance, press F2, and name them Navigation, Car, and Media.
5. Select each Toggle Button 2D prefab instance and in the Properties add and set the value of the FirstApplication.ToggleButton2D.Text property to Navigation, Car, and Media.
In the Project for each Toggle Button 2D prefab instance in the Footer > Toggle Button Group 2D > Stack Layout 2D node in the Node Components window:
1. Click next to the Toggle Button: Toggled On trigger to add that trigger.
  Use triggers and actions to create interactions. Use triggers to set off actions, such as setting a property to a certain value or setting the state of an application.
2. In the Toggle Button: Toggled On trigger click the Add dropdown menu and select the Navigate to Page action.
3. In the Navigate to Page action settings set the Item property to the Page node to which you want this button to navigate your application.
  For example, set the action in the Navigation toggle button to go to the Navigation Page node.
4. Click Save.
5. In the Preview click to enter the Interact mode.
  In the Interact mode you can interact with your application in the Preview window as you would on a device.
When you click each button in the Footer node the trigger in the button sets off an action that transitions to the Page node you set in each button.