Handling user input

You can set how and which elements in your application react to user input. In Kanzi, to handle user input you can:

../../_images/input.gif

For these Kanzi nodes you do not have to create input manipulators manually, because they handle input by default:

Use triggers and actions to create interactions based on user input.

See Using triggers.

Using input manipulators

Kanzi provides low and high-level access to input:

  • The high-level system provides input in terms of gestures, such as click, pan, pinch, and so on. It is recommended to use the high-level system to bind gestures to the UI components or application functionality.

  • The low-level input system reports raw touch events as they happen in nodes.

Kanzi provides input manipulators to enable gesture recognition for nodes in your Kanzi application. You can create and configure the manipulators:

  • In Kanzi Studio using the Input Manipulators node components and input manipulator triggers

  • Through the Kanzi Engine API

Kanzi provides these input manipulators:

In Kanzi Studio when you select a node and in the Node Components > Input Manipulators create an input manipulator node component, Kanzi installs to that node the corresponding input manipulator. Kanzi Studio provides these input manipulator components for enabling gesture recognition:

  • Click Manipulator

  • Key Manipulator

  • Long-Press Manipulator

  • Multi-Click Manipulator

  • Navigation Manipulator

  • Pan Manipulator

../../_images/input-manipulator-components.png

In the Kanzi Engine API InputManipulator is the base class for input manipulators, and functions, such as ClickManipulator::create and PanManipulator::create create input manipulators responsible for the corresponding gesture recognition.

When you create an input manipulator, to recognize a gesture, attach it to the node with Node::addInputManipulator. This function attaches all the children of that node, too.

The attached input manipulator generates messages in response to user actions. Each manipulator uses messages to report different events during gesture recognition, such as PanManipulator::StartedMessage, PanManipulator::MovedMessage, PanManipulator::FinishedMessage for the pan manipulator, and so on.

Controlling how a node reacts to input

Use the Input > Enabled property to control how a node reacts to input.

Tip

The Button, List Box, Scroll View, Slider, and Text Box nodes handle input by default and do not react to input when they are disabled.

When you disable the Enabled property of a node, you effectively disable that node and its descendant nodes in the same popup-type focus scope.

Kanzi delivers input also to effectively disabled nodes. This enables you to control the behavior of a disabled node.

When you effectively disable a node:

  • When the node is focused, it receives keyboard input until the focus moves to another node.

  • When the node is not focused, it is not part of the focus chain and does not receive keyboard input.

To observe whether a node is effectively enabled, use the Input > Effectively Enabled property in a state manager or a binding. For example, to visually indicate to the user whether a node is in use, create a state manager and use the Effectively Enabled property as its controller property.

To learn more about focus, see Focus.

To learn more about the Kanzi state manager, see State manager.

To control how a node reacts to input:

  1. In the Node Tree or Prefabs select the node, in the State Tools create a state group, and name it.

    For example, name the state group Enabled.

    ../../_images/select-button2.png ../../_images/button-in-preview1.png ../../_images/create-state-group.png ../../_images/enabled-state-group.png

  2. In the State Tools create two states, one that defines the appearance and behavior of the node when it is in use, and another that defines the node when it is not in use.

    For example, name the states Enabled and Disabled.

    ../../_images/enabled-disabled-states.png

  3. For each state, define the appearance and behavior of the node in that state.

    For example, to set how the node looks when it is not in use, in the Disabled state set the Opacity property to 0.3.

    ../../_images/opacity-0.3.png ../../_images/set-to-disabled-state.png ../../_images/opacity-set-disabled-state.png

  4. In the State Tools set the Controller Property to Input > Effectively Enabled.

    The Effectively Enabled property indicates whether a node and its ancestor nodes are enabled.

    ../../_images/set-effectively-enabled-controller-property.png

  5. In the State Tools set the value of the Effectively Enabled controller property in the Disabled state to False.

    This way you set your application to use:

    • The Disabled state when the node is not in use and does not react to input.

    • The Enabled state when the node is in use and reacts to input.

    ../../_images/set-effectively-enabled-false.png

  6. In the State Tools click Edit State Manager to deactivate the State Tools.

    ../../_images/exit-state-tools1.png

When you change the value of the Input > Enabled property, the appearance of the node changes. When you disable the Enabled property and try to interact with the node in the Preview, the node does not react.

../../_images/node-enabled-disabled1.gif

Defining which node receives input

When creating a user interface, pay attention to how your application handles input, because only one node can receive input at a time. For example, define whether a click is handled by the node in the front or by the one behind it.

Kanzi uses hit testing to determine the nodes that receive input. In practice, hit testing projects a ray from the camera towards the 3D scene based on the screen coordinates of the input event.

By default hit testing is enabled for the Button, List Box Item Container, Scroll View, Slider, and Text Box nodes.

To enable hit testing for a node of any other node type, add and enable the Input > Hit Testable property to that node.

The first node from the Camera node whose bounding box is intersected and has the Hit Testable property enabled, receives the input, consumes the event, and generates set actions, such as sending a click message.

For example, if you place two Box nodes so that the BoxFront node is in front of the BoxRear node and occludes it:

  • The BoxFront node receives the input when the Hit Testable property of the BoxFront node is enabled.

  • The BoxRear node receives the input even though it is occluded by the BoxFront node when:

    • Hit Testable property of the BoxFront node is disabled

    • Hit Testable property of the BoxRear node is enabled

../../_images/hit-testable.gif

Setting the size of the input area of 3D nodes

When you want to change the area within which a 3D node receives input, use the Input > Hit Testable Container property. In Kanzi hit testing for all nodes is by default based on the layout size of each node. Use the Hit Testable Container property to include in the input area the layout size of the 3D node that has the property and the layout size of any of its child nodes, rather than just the bounding volume of the node.

By default the Hit Testable Container property is enabled for the Button 3D, List Box Item Container 3D, Scroll View 3D, and Slider 3D nodes. To set the size of the input area for a 3D node of any other node type, add and enable the Hit Testable Container and Hit Testable properties.

For example, a Stack Layout 3D node which contains a Box node receives click input:

  • When the Hit Testable Container property of the Stack Layout 3D node is disabled, from the area defined by the Width, Height, and Depth properties of the Box node

  • When the Hit Testable Container property of the Stack Layout 3D node is enabled, from the area defined by the Layout Width, Layout Height, and Layout Depth properties of either the Stack Layout 3D or the Box node

../../_images/hit-testable-container.gif