com.vaadin.flow.component.dnd.internal

Class DndUtil

java.lang.Object

com.vaadin.flow.component.dnd.internal.DndUtil

public class DndUtil
extends Object

Internal class for drag and drop related utility methods. This class is not meant for external usage and can be removed at any point.

Since:

2.0

Author:

Vaadin Ltd

Field Summary

Fields

Modifier and Type	Field and Description
static String	DND_CONNECTOR Resource path for importing dnd connector.
static String	DND_CONNECTOR_COMPATIBILITY Resource path for importing dnd connector for compatibility mode.
static String	DRAG_SOURCE_DATA_KEY Key for storing server side drag data for a DragSource.
static String	DROP_EFFECT_ELEMENT_PROPERTY Property name for storing the DropEffect on element level.
static String	DROP_TARGET_ACTIVE_PROPERTY Property name for storing drop target activity data for an element.
static String	EFFECT_ALLOWED_ELEMENT_PROPERTY Property name for storing the EffectAllowed on element level.
static String	END_LISTENER_REGISTRATION_KEY Key for storing an internal drag end listener registration for a DragSource.
static String	START_LISTENER_REGISTRATION_KEY Key for storing an internal drag start listener registration for a DragSource.

Method Summary

Modifier and Type	Method and Description
static void	addDndConnectorWhenComponentAttached(Component component) Includes the dnd connector when the component is attached to a UI.
static void	addMobileDndPolyfillIfNeeded(Component component) Adds the mobile dnd polyfills when a iOS device is used.
static void	reportUsage() Reports DnD feature usage from mixin interfaces.
static <T extends Component> void	updateDragSourceActivation(DragSource<T> dragSource) Triggers drag source activation method in JS connector once when the component has been attached.
static <T extends Component> void	updateDropTargetActivation(DropTarget<T> dropTarget) Triggers drop target activation method in JS connector once when the component has been attached.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DND_CONNECTOR_COMPATIBILITY

public static final String DND_CONNECTOR_COMPATIBILITY

Resource path for importing dnd connector for compatibility mode.

See Also:

Constant Field Values

DND_CONNECTOR

public static final String DND_CONNECTOR

Resource path for importing dnd connector.

See Also:

Constant Field Values

EFFECT_ALLOWED_ELEMENT_PROPERTY

public static final String EFFECT_ALLOWED_ELEMENT_PROPERTY

Property name for storing the EffectAllowed on element level.

See Also:

Constant Field Values

DRAG_SOURCE_DATA_KEY

public static final String DRAG_SOURCE_DATA_KEY

Key for storing server side drag data for a DragSource.

See Also:

Constant Field Values

START_LISTENER_REGISTRATION_KEY

public static final String START_LISTENER_REGISTRATION_KEY

Key for storing an internal drag start listener registration for a DragSource.

See Also:

Constant Field Values

END_LISTENER_REGISTRATION_KEY

public static final String END_LISTENER_REGISTRATION_KEY

Key for storing an internal drag end listener registration for a DragSource.

See Also:

Constant Field Values

DROP_TARGET_ACTIVE_PROPERTY

public static final String DROP_TARGET_ACTIVE_PROPERTY

Property name for storing drop target activity data for an element.

See Also:

Constant Field Values

DROP_EFFECT_ELEMENT_PROPERTY

public static final String DROP_EFFECT_ELEMENT_PROPERTY

Property name for storing the DropEffect on element level.

See Also:

Constant Field Values

Method Detail

addDndConnectorWhenComponentAttached

public static void addDndConnectorWhenComponentAttached(Component component)

Includes the dnd connector when the component is attached to a UI.

This is only for the case when the project is in compatibility mode and the static methods in DragSource and DropTarget are used, because otherwise the connector is not loaded.

Parameters:

component - the component that should be attached and uses dnd connector

addMobileDndPolyfillIfNeeded

public static void addMobileDndPolyfillIfNeeded(Component component)

Adds the mobile dnd polyfills when a iOS device is used. Calling this is NOOP for non-iOS devices. The polyfills are only loaded once per page.

Parameters:

component - the component using dnd

updateDragSourceActivation

public static <T extends Component> void updateDragSourceActivation(DragSource<T> dragSource)

Triggers drag source activation method in JS connector once when the component has been attached.

Type Parameters:

T - the type of the drag source component

Parameters:

dragSource - the drag source to update active status on

updateDropTargetActivation

public static <T extends Component> void updateDropTargetActivation(DropTarget<T> dropTarget)

Triggers drop target activation method in JS connector once when the component has been attached. Will make sure the activation in JS is done again when the component is detached and attached again, because otherwise the element will not be a drop target again.

Type Parameters:

T - the type of the drop target component

Parameters:

dropTarget - the drop target to update active status on

reportUsage

public static void reportUsage()

Reports DnD feature usage from mixin interfaces.