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  3. USingleClickOrDragInputBehavior

USingleClickOrDragInputBehavior

[USingleClickOrDragInputBehavior](API\Runtime\InteractiveToolsFramework\BaseBehaviors\USingleClickOrDr-) is a combination of a USingleClickBehavior and UClickDragBehavior, and allows for the common UI interaction where a click-and-release does one action, but if the mouse is moved, then a drag interaction is started.

API > API/Runtime > API/Runtime/InteractiveToolsFramework > API/Runtime/InteractiveToolsFramework/BaseBehaviors

Inheritance Hierarchy

References

   
Module InteractiveToolsFramework
Header /Engine/Source/Runtime/InteractiveToolsFramework/Public/BaseBehaviors/SingleClickOrDragBehavior.h
Include #include "BaseBehaviors/SingleClickOrDragBehavior.h"

Syntax

class USingleClickOrDragInputBehavior : public UAnyButtonInputBehavior

Remarks

USingleClickOrDragInputBehavior is a combination of a USingleClickBehavior and UClickDragBehavior, and allows for the common UI interaction where a click-and-release does one action, but if the mouse is moved, then a drag interaction is started. For example click-to-select is often combined with a drag-marquee-rectangle in this way. This can be directly implemented with a UClickDragBehavior but requires the client to (eg) detect movement thresholds, etc. This class encapsulates all that state/logic.

The .ClickDistanceThreshold parameter determines how far the mouse must move (in whatever device units are in use) to switch from a click to drag interaction

The .bBeginDragIfClickTargetNotHit parameter determines if the drag interaction will be immediately initiated if the initial 'click' mouse-down does not hit a valid clickable target. Defaults to true.

The hit-test and on-clicked functions are provided by a IClickBehaviorTarget instance, while an IClickDragBehaviorTarget provides the can-click-drag/begin-drag/update-drag/end-drag functionality.

Variables

  Type Name Description
Public variable bool bBeginDragIfClickTargetNotHit If true (default), then if the click-mouse-down does not hit a valid click target (determined by IClickBehaviorTarget::IsHitByClick), then the Drag will be initiated
Protected variable bool bImmediatelyBeginDragInBeginCapture Flag used to communicate between WantsCapture and BeginCapture
Protected variable bool bInDrag Set to true if we are in an active drag capture, eg after rejecting possible click
Protected variable EInputCaptureSide CaptureSide Device capture
Public variable float ClickDistanceThreshold If the device moves more than this distance in 2D (pixel?) units, the interaction switches from click to drag
Protected variable IClickBehaviorTarget * ClickTarget Click Target object
Protected variable IClickDragBehaviorTarget * DragTarget Drag Target object
Public variable TFunction< bool(const FInputDeviceState &)> ModifierCheckFunc WantsCapture() will only return capture request if this function returns true (or is null)
Public variable FInputBehaviorModifierStates Modifiers The modifier set for this behavior
Protected variable FVector2D MouseDownPosition2D Click-down position, to determine if mouse has moved far enough to swap to drag interaction
Protected variable FRay MouseDownRay  

Functions

  Type Name Description
Public function Virtual void Set the targets for Click and Drag interactions
Protected function Virtual void Internal function that forwards click evens to DragTarget::OnClickDrag, you can customize behavior here
Protected function Virtual void

OnClickDragPressInternal ( const FInputDeviceState& Input,
EInputCaptureSide Side
)

 Internal function that forwards click evens to DragTarget::OnClickPress, you can customize behavior here
Protected function Virtual void Internal function that forwards click evens to DragTarget::OnClickRelease, you can customize behavior here
Protected function Virtual void

OnClickedInternal ( const FInputDeviceState& Input,
const FInputCaptureData& Data
)

 Internal function that forwards click evens to ClickTarget::OnClicked, you can customize behavior here
Public function Virtual void Change the Drag BehaviorTarget

Overridden from UInputBehavior

  Type Name Description
Public function Virtual FInputCaptureUpdate

BeginCapture ( const FInputDeviceState& InputState,
EInputCaptureSide eSide
)

 Called after WantsCapture() returns a capture request that was accepted
Public function Virtual void

ForceEndCapture ( const FInputCaptureData& CaptureData
)

 If this is called, the Behavior has forcibly lost capture (eg due to app losing focus for example) and needs to clean up accordingly
Public function Virtual FInputCaptureUpdate

UpdateCapture ( const FInputDeviceState& InputState,
const FInputCaptureData& CaptureData
)

 Called for each new input event during a capture sequence.
Public function Virtual FInputCaptureRequest

WantsCapture ( const FInputDeviceState& InputState
)

 Given the input state, does this Behavior want to begin capturing some input devices?

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