IFocusDelegate

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Interface IFocusDelegate

interface IFocusDelegate

Extends com.amazon.apmf.IStandard Interface handles APIs for searching Views that can take focus and manages requesting and clearing focus of a View. Each function of this delegate provides an additional parameter which holds a pointer to the default implementation of this delegate. This enables the user to call the base implementation of the function as per the use-case (similar to calling the parent class function from the overriden function in child class).

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Methods

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findNextFocusableView()

IView? findNextFocusableView(IView* currentView, FocusDirection direction, IFocusDelegate* defaultDelegate)

Searches for the next focusable View in the specified direction. This function searches for the next focusable View in the specified direction from the given View. If no focusable View is found in the specified direction, the function returns nullptr.

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Parameters

currentView

IView* — Required IView The current View from which to start the search.

direction

FocusDirection — Required IView The FocusDirection in which to search for the next focusable View.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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Returns

IView? The return value is optional and might be absent. A pointer to the next focusable View, or nullptr if no focusable View is found in the specified direction.

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addFocusables()

void addFocusables(IView* requesterView, inout IView*[]* outFocusables, FocusDirection direction, bool onlyTouchFocusableViews, IFocusDelegate* defaultDelegate)

Adds Views that can take focus to the specified list. This function is called to populate a list of Views that can take focus based on the given parameters.

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Parameters

requesterView

IView* — Required IView The View requesting to add focusables.

outFocusables (inout)

IView*[]* — Required IView[] An array to which focusable Views will be added.

direction

FocusDirection — Required FocusDirection The direction of the focus operation.

onlyTouchFocusableViews

bool — Required bool If true, only add Views focusable in touch mode, if false, add all focusable Views.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate. Note: The outFocusables array will be populated with Views that can take focus in the specified direction and mode.

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clearFocus()

void clearFocus(IView* view, IFocusDelegate* defaultDelegate)

Clears the focus from this view. This method is called when this view wants to give up focus. If focus is cleared, the onFocusChanged listener will be invoked. The framework will try to give focus to the first focusable View from the top of the View hierarchy after focus is cleared. If this view is the first focusable View from the top, then all callbacks related to clearing focus will be invoked, after which the framework will give focus to this view. After clearing focus, no focusable item is immediately focused. The first focusable item in the View hierarchy will become focused and visible only when the user interacts with the D-pad or keyboard.

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Parameters

view

IView* — Required IView The View for which to clear focus.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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requestFocus()

bool requestFocus(IView* view, FocusDirection? direction, com.amazon.kepler.uitoolkit.graphics.Rect? previouslyFocusedRect, IFocusDelegate* defaultDelegate)

Call this to try to give focus to a specific View or to one of its descendants and give it a hint about what direction focus is heading. A View will not actually take focus if it is not focusable, or if it is focusable and it is not focusable in touch mode while the device is in touch mode. A View will not take focus if it is not visible. A View will not take focus if one of its parents has getDescendantFocusability() equal to FOCUS_BLOCK_DESCENDANTS. The default implementation of this function will prioritize self view for getting focus, then will call IFocusDelegate::searchChildrenForFocus if the descendant focusability is set to FOCUS_BEFORE_DESCENDANTS, and vice-versa for FOCUS_AFTER_DESCENDANTS. See also- IFocusState::setDescendantFocusability.

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Parameters

view

IView* — Required IView The View for which to request focus.

direction

FocusDirection? — Optional FocusDirection One of FocusDirection enum value.

previouslyFocusedRect

com.amazon.kepler.uitoolkit.graphics.Rect? — Optional Rect The rectangle (in this View’s coordinate system) to give a finer-grained hint about where focus is coming from. May be null if there is no hint.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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Returns

bool Whether this View or one of its descendants actually took focus.

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requestChildFocus()

void requestChildFocus(IView* parent, IView* child, IView* focused, IFocusDelegate* defaultDelegate)

Called when a child of this parent wants focus.

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Parameters

parent

IView* — Required IView The parent View that is handling the focus request.

child

IView* — Required IView The child of this ViewParent that wants focus. This View will contain the focused View. It is not necessarily the View that actually has focus.

focused

IView* — Required IView The View that is a descendant of child that actually has focus.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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clearChildFocus()

void clearChildFocus(IView* parent, IView* child, IFocusDelegate* defaultDelegate)

Called when a child of this parent is giving up focus. This method will traverse up the view hierarchy and recursively call this function for the parent of this view.

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Parameters

parent

IView* — Required IView The parent View that is handling the focus request.

child

IView* — Required IView The View that is giving up focus.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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unFocus()

void unFocus(IView* view, IFocusDelegate* defaultDelegate)

Method to clear focus on requested view. It will recursively traverse down to the leaf view and will set the focus child to null. Once the focussed child has been cleared, it will internally call onFocusChanged.

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Parameters

view

IView* — Required IView The View that is giving up focus.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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searchChildrenForFocus()

bool searchChildrenForFocus(IView* view, FocusDirection direction, com.amazon.kepler.uitoolkit.graphics.Rect? previousFocusArea, IFocusDelegate* defaultDelegate)

This function is called from by the default implementation of IFocusDelegate::requestFocus internally depending on the value set by IFocusState::setDescendantFocusability. The default implementation of this function searches through the children of current view to determine which child should get next focus.

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Parameters

view

IView* — Required IView The parent view for which next child to be focussed is to be determined.

direction

FocusDirection — Required FocusDirection The direction of focus movement.

previousFocusArea

com.amazon.kepler.uitoolkit.graphics.Rect? — Optional Rect Represents the area which was previously having focus.

defaultDelegate

IFocusDelegate* — Required IFocusDelegate Pointer to the default implementation of IFocusDelegate.

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Returns

bool bool True if any child has taken focus, else false.

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