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IN THIS ARTICLE

Step 2: Add a ComponentModeDelegate

Step 2: Add a ComponentModeDelegate

To add this feature to the Point Light component, you must update the component so that it can detect the intent to begin editing a component and manage the creation of a Component Mode. To do so, add a new type called a ComponentModeDelegate to your existing component.

To add a ComponentModeDelegate

  1. Navigate to the EditorPointLightComponent.h file and open the file in a text editor.

  2. Add the ComponentModeDelegate.
    Example EditorPointLightComponent.h

[ Before ] 

#pragma once
  
#include "EditorLightComponent.h"
  
namespace LmbrCentral
{
    /*!
     * In-editor Point Light component.
     * Handles previewing and activating lights in the editor.
     */
    class EditorPointLightComponent
        : public EditorLightComponent
    {
    public:
        AZ_COMPONENT(EditorPointLightComponent, "{00818135-138D-42AD-8657-FF3FD38D9E7A}", AzToolsFramework::Components::EditorComponentBase);
  
        static void Reflect(AZ::ReflectContext* context);
  
        void Init() override;
  
    protected:
        const char* GetLightTypeText() const override
        {
            return "Point Light";
        }
    };
} // namespace LmbrCentral

[ After ]

See the following code changes.

#pragma once
  
#include "EditorLightComponent.h"
  
// BEGIN ADD
#include <AzToolsFramework/ComponentMode/ComponentModeDelegate.h>
// END ADD
  
namespace LmbrCentral
{
    /**
     * In-editor Point Light component.
     * Handles previewing and activating lights in the editor.
     */
    class EditorPointLightComponent
        : public EditorLightComponent
    {
    public:
        AZ_COMPONENT(EditorPointLightComponent, "{00818135-138D-42AD-8657-FF3FD38D9E7A}", AzToolsFramework::Components::EditorComponentBase);
  
        static void Reflect(AZ::ReflectContext* context);
  
        void Init() override;
        // BEGIN ADD
        void Activate() override;
        void Deactivate() override;
        // END ADD
  
    protected:
        const char* GetLightTypeText() const override
        {
            return "Point Light";
        }
  
        // BEGIN ADD
        using ComponentModeDelegate = AzToolsFramework::ComponentModeFramework::ComponentModeDelegate;            
        ComponentModeDelegate m_componentModeDelegate; ///< Responsible for detecting ComponentMode activation
                                                       ///< and creating a concrete ComponentMode(s).
        /// END ADD
    };
} // namespace LmbrCentral

In this example, there’s an #include for ComponentModeDelegate.h, which is where you add the file as a member. The using declaration reduces the length of the m_componentDelegate definition. The updated file also provides Activate and Deactivate member functions for the component.

  1. Save the file.

Now that you’ve updated the EditorPointLightComponent.h file, you must make changes to the EditorPointLightComponent.cpp implementation file.

To update the EditorPointLightComponent.cpp

  1. In a text editor, open the EditorPointLightComponent.cpp file.

  2. Add an #include for the unwritten Component Mode and comment out the change. This becomes the EditorPointLightComponentMode.h file.

    // #include "EditorPointLightComponentMode.h"

  3. Serialize the m_componentModeDelegate member to expose it to the EditContext.

    ->Field("ComponentMode", &EditorPointLightComponent::m_componentModeDelegate)

  4. Enter the following changes so that the ComponentModeDelegate appears in the Entity Inspector. This change adds the Edit button to the Point Light component.

    ->DataElement(AZ::Edit::UIHandlers::Default, &EditorPointLightComponent::m_componentModeDelegate, "Component Mode", "Point Light Component Mode")
    ->Attribute(AZ::Edit::Attributes::Visibility, AZ::Edit::PropertyVisibility::ShowChildrenOnly)

Tip
The Attribute ensures that the Edit button appears inline without being nested inside the ComponentModeDelegate class/struct.

  1. Inside the Activate call, add the following code.

    m_componentModeDelegate.ConnectWithSingleComponentMode <
    EditorPointLightComponent, /*EditorPointLightComponentMode*/>(
        AZ::EntityComponentIdPair(GetEntityId(), GetId()), nullptr);

    1. The helper function ConnectWithSingleComponentMode handles the most common case of adding a Component Mode. This call wraps a more complex API where multiple Component Modes can be activated at the same time.

      For example, see the EditorTubeShapeComponent.h file.

    2. Specify the component type and Component Mode itself. Note
      The template parameters generalize connecting and instantiating Component Modes. For more information, see the CreateComponentModeBuilder.h and its AddComponentModes function.

    3. Specify the EntityId that the component is attached to and the ComponentId. Note
      It’s possible (although not often used) to address an EBus not only by the EntityId but by the EntityId and ComponentId pair. A ComponentId isn’t guaranteed to be unique on its own, but when it’s combined with an EntityId, you can target a specific component attached to an entity. This is useful when you have multiple components of the same type attached to a single entity.

    4. The final argument is a nullptr, which is an EditorComponentSelectionRequestBus::Handler. To use this handler, the EditorComponent must implement the EditorComponentSelectionRequestsBus. If the EBus was implemented, you can pass 'this' here, but as you haven’t implemented it yet, enter nullptr for now.

      These changes enable you to double-click in the viewport to select a component. You implement the EditorComponentSelectionRequestBus in Step 5: Handle Selection in the Viewport.

      For examples, see the EditorBaseShapeComponent.h and EditorSplineComponent.h files.

  2. Enter the following code to disconnect the ComponentModeDelegate when the EditorComponent is deactivated.

    m_componentModeDelegate.Disconnect();

    This change ensures that the ComponentModeDelegate disconnects from the various EBuses that are connected to in the Activate function.

Example EditorPointLightComponent.cpp
Your code should look like the following.

#include "LmbrCentral_precompiled.h"
#include "EditorPointLightComponent.h"
 
#include <AzCore/Serialization/SerializeContext.h>
#include <AzCore/Serialization/EditContext.h>
#include <AzCore/RTTI/BehaviorContext.h>
 
namespace LmbrCentral
{
    void EditorPointLightComponent::Reflect(AZ::ReflectContext* context)
    {
        if (auto serializeContext = azrtti_cast<AZ::SerializeContext*>(context))
        {
            serializeContext->Class<EditorPointLightComponent, EditorLightComponent>()
                ->Version(1)
                ;
 
            if (AZ::EditContext* editContext = serializeContext->GetEditContext())
            {
                editContext->Class<EditorPointLightComponent>(
                    "Point Light", "The Point Light component allows an entity to create a point of light")
                    ->ClassElement(AZ::Edit::ClassElements::EditorData, "")
                        ->Attribute(AZ::Edit::Attributes::Category, "Rendering")
                        ->Attribute(AZ::Edit::Attributes::Icon, "Editor/Icons/Components/PointLight.png")
                        ->Attribute(AZ::Edit::Attributes::ViewportIcon, "Editor/Icons/Components/Viewport/PointLight.png")
                        ->Attribute(AZ::Edit::Attributes::AppearsInAddComponentMenu, AZ_CRC("Game", 0x232b318c))
                        ->Attribute(AZ::Edit::Attributes::AutoExpand, true)
                        ->Attribute(AZ::Edit::Attributes::Visibility, AZ::Edit::PropertyVisibility::ShowChildrenOnly)
                        ->Attribute(AZ::Edit::Attributes::HelpPageURL, "https://docs.aws.amazon.com/lumberyard/latest/userguide/component-point-light.html")
                        ;
            }
        }
        
        if (auto behaviorContext = azrtti_cast<AZ::BehaviorContext*>(context))
        {
            behaviorContext->Class<EditorPointLightComponent>()->RequestBus("EditorPointLightComponentBus");
        }
    }
 
    void EditorPointLightComponent::Init()
    {
        SetLightType(EditorLightConfiguration::LightType::Point);
        EditorLightComponent::Init();
    }
} // namespace LmbrCentral

#include "LmbrCentral_precompiled.h"
#include "EditorPointLightComponent.h"
// BEGIN ADD
// #include "EditorPointLightComponentMode.h"
// END ADD
 
#include <AzCore/Serialization/SerializeContext.h>
#include <AzCore/Serialization/EditContext.h>
#include <AzCore/RTTI/BehaviorContext.h>
 
namespace LmbrCentral
{
    void EditorPointLightComponent::Reflect(AZ::ReflectContext* context)
    {
        if (auto serializeContext = azrtti_cast<AZ::SerializeContext*>(context))
        {
            serializeContext->Class<EditorPointLightComponent, EditorLightComponent>()
                ->Version(1)
                // BEGIN ADD
                ->Field("ComponentMode", &EditorPointLightComponent::m_componentModeDelegate)
                // END ADD
                ;
 
            if (AZ::EditContext* editContext = serializeContext->GetEditContext())
            {
                editContext->Class<EditorPointLightComponent>(
                    "Point Light", "The Point Light component allows an entity to create a point of light")
                    ->ClassElement(AZ::Edit::ClassElements::EditorData, "")
                        ->Attribute(AZ::Edit::Attributes::Category, "Rendering")
                        ->Attribute(AZ::Edit::Attributes::Icon, "Editor/Icons/Components/PointLight.png")
                        ->Attribute(AZ::Edit::Attributes::ViewportIcon, "Editor/Icons/Components/Viewport/PointLight.png")
                        ->Attribute(AZ::Edit::Attributes::AppearsInAddComponentMenu, AZ_CRC("Game", 0x232b318c))
                        ->Attribute(AZ::Edit::Attributes::AutoExpand, true)
                        ->Attribute(AZ::Edit::Attributes::Visibility, AZ::Edit::PropertyVisibility::ShowChildrenOnly)
                        ->Attribute(AZ::Edit::Attributes::HelpPageURL, "https://docs.aws.amazon.com/lumberyard/latest/userguide/component-point-light.html")
                    // BEGIN ADD
                    ->DataElement(AZ::Edit::UIHandlers::Default, &EditorPointLightComponent::m_componentModeDelegate, "Component Mode", "Point Light Component Mode")
                        ->Attribute(AZ::Edit::Attributes::Visibility, AZ::Edit::PropertyVisibility::ShowChildrenOnly)
                    // END ADD
                        ;
            }
        }
        
        if (auto behaviorContext = azrtti_cast<AZ::BehaviorContext*>(context))
        {
            behaviorContext->Class<EditorPointLightComponent>()->RequestBus("EditorPointLightComponentBus");
        }
    }
 
    void EditorPointLightComponent::Init()
    {
        SetLightType(EditorLightConfiguration::LightType::Point);
        EditorLightComponent::Init();
    }
 
    // BEGIN ADD
    void EditorPointLightComponent::Activate()
    {
        EditorLightComponent::Activate();
        // m_componentModeDelegate.ConnectWithSingleComponentMode <
        //    EditorPointLightComponent, EditorPointLightComponentMode>(
        //        AZ::EntityComponentIdPair(GetEntityId(), GetId()), nullptr);
    }

    void EditorPointLightComponent::Deactivate()
    {
        // m_componentModeDelegate.Disconnect();
        EditorLightComponent::Deactivate();
    }
    // END ADD
} // namespace LmbrCentral