com.vaadin.client.extensions

Class DragSourceExtensionConnector

java.lang.Object

com.vaadin.client.ui.AbstractConnector

com.vaadin.client.extensions.AbstractExtensionConnector

com.vaadin.client.extensions.DragSourceExtensionConnector

All Implemented Interfaces:

com.google.gwt.event.shared.EventHandler, StateChangeEvent.StateChangeHandler, ServerConnector, Connector, Serializable

Direct Known Subclasses:

GridDragSourceConnector

public class DragSourceExtensionConnector
extends AbstractExtensionConnector

Extension to add drag source functionality to a widget for using HTML5 drag and drop. Client side counterpart of DragSourceExtension.

Since:

8.1

Author:

Vaadin Ltd

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	STYLE_SUFFIX_DRAGGED Style suffix for indicating that the element is being dragged.
protected static String	STYLE_SUFFIX_DRAGSOURCE Style suffix for indicating that the element is a drag source.

Constructor Summary

Constructors

Constructor and Description
DragSourceExtensionConnector()

Method Summary

Modifier and Type	Method and Description
protected void	addDraggable(com.google.gwt.dom.client.Element element) Makes the given element draggable and adds class name.
protected void	addDraggedStyle(com.google.gwt.dom.client.NativeEvent event) Add class name to indicate that the drag source element is being dragged.
protected void	addDragListeners(com.google.gwt.dom.client.Element element) Adds dragstart and dragend event listeners to the given DOM element.
protected Map<String,String>	createDataTransferData(com.google.gwt.dom.client.NativeEvent dragStartEvent) Creates the data map to be set as the DataTransfer object's data.
protected void	extend(ServerConnector target) Called when the extension is attached to its parent.
protected void	fixDragImageOffsetsForDesktop(com.google.gwt.dom.client.NativeEvent dragStartEvent, com.google.gwt.dom.client.Element draggedElement) Fixes missing or offset drag image caused by using css transform: translate (or such) by using a cloned drag image element, for which the property has been cleared.
protected void	fixDragImageTransformForMobile(com.google.gwt.dom.client.Element draggedElement) Fix drag image offset for touch devices when the dragged image has been offset with css transform: translate/translate3d.
protected com.google.gwt.dom.client.Element	getDraggableElement() Finds the draggable element within the widget.
protected static String	getDropEffect(com.google.gwt.dom.client.DataTransfer dataTransfer) Returns the dropEffect for the given data transfer.
DragSourceState	getState() Returns the shared state object for this connector.
protected boolean	isAndoidChrome() Returns whether the current browser is Android Chrome.
protected boolean	isNativeDragEvent(com.google.gwt.dom.client.NativeEvent nativeEvent) Returns whether the given event is a native (android) drag start/end event, and not produced by the drag-drop-polyfill.
protected void	onDragEnd(elemental.events.Event event) Event handler for the dragend event.
protected void	onDragStart(elemental.events.Event event) Event handler for the dragstart event.
void	onUnregister() Event called when connector has been unregistered.
protected void	removeDraggable(com.google.gwt.dom.client.Element element) Removes draggable and class name from the given element.
protected void	removeDraggedStyle(com.google.gwt.dom.client.NativeEvent event) Remove class name that indicated that the drag source element was being dragged.
protected void	removeDragListeners(com.google.gwt.dom.client.Element element) Removes dragstart and dragend event listeners from the given DOM element.
protected void	sendDragEndEventToServer(com.google.gwt.dom.client.NativeEvent dragEndEvent, DropEffect dropEffect) Initiates a server RPC for the drag end event.
protected void	sendDragStartEventToServer(com.google.gwt.dom.client.NativeEvent dragStartEvent) Initiates a server RPC for the drag start event.
protected void	setDragImage(com.google.gwt.dom.client.NativeEvent dragStartEvent) Sets the drag image to be displayed.

Methods inherited from class com.vaadin.client.extensions.AbstractExtensionConnector

setParent

Methods inherited from class com.vaadin.client.ui.AbstractConnector

addStateChangeHandler, addStateChangeHandler, createState, doInit, ensureHandlerManager, fireEvent, forceStateChange, getChildren, getConnection, getConnectorId, getParent, getResourceUrl, getRpcImplementations, getRpcProxy, getStateType, getTag, hasEventListener, init, isEnabled, onStateChanged, registerRpc, removeStateChangeHandler, removeStateChangeHandler, setChildren, setTag, unregisterRpc, updateEnabledState

Methods inherited from class java.lang.Object

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

Field Detail

STYLE_SUFFIX_DRAGSOURCE

protected static final String STYLE_SUFFIX_DRAGSOURCE

Style suffix for indicating that the element is a drag source.

See Also:

Constant Field Values

STYLE_SUFFIX_DRAGGED

protected static final String STYLE_SUFFIX_DRAGGED

Style suffix for indicating that the element is being dragged.

See Also:

Constant Field Values

Constructor Detail

DragSourceExtensionConnector

public DragSourceExtensionConnector()

Method Detail

extend

protected void extend(ServerConnector target)

Description copied from class: AbstractExtensionConnector

Called when the extension is attached to its parent. This method is only called once as an extension cannot be moved from one parent to another.

Specified by:

extend in class AbstractExtensionConnector

Parameters:

target - The connector this extension extends

addDraggable

protected void addDraggable(com.google.gwt.dom.client.Element element)

Makes the given element draggable and adds class name.

Parameters:

element - Element to be set draggable.

removeDraggable

protected void removeDraggable(com.google.gwt.dom.client.Element element)

Removes draggable and class name from the given element.

Parameters:

element - Element to remove draggable from.

addDragListeners

protected void addDragListeners(com.google.gwt.dom.client.Element element)

Adds dragstart and dragend event listeners to the given DOM element.

Parameters:

element - DOM element to attach event listeners to.

removeDragListeners

protected void removeDragListeners(com.google.gwt.dom.client.Element element)

Removes dragstart and dragend event listeners from the given DOM element.

Parameters:

element - DOM element to remove event listeners from.

onUnregister

public void onUnregister()

Description copied from interface: ServerConnector

Event called when connector has been unregistered.

Specified by:

onUnregister in interface ServerConnector

Overrides:

onUnregister in class AbstractConnector

onDragStart

protected void onDragStart(elemental.events.Event event)

Event handler for the dragstart event. Called when dragstart event occurs.

Parameters:

event - browser event to be handled

fixDragImageOffsetsForDesktop

protected void fixDragImageOffsetsForDesktop(com.google.gwt.dom.client.NativeEvent dragStartEvent,
                                             com.google.gwt.dom.client.Element draggedElement)

Fixes missing or offset drag image caused by using css transform: translate (or such) by using a cloned drag image element, for which the property has been cleared.

This bug only occurs on Desktop with Safari (gets offset and clips the element for the parts that are not inside the element start & end coordinates) and Firefox (gets offset), and calling this method is NOOP for any other browser.

This fix is not needed if custom drag image has been used.

Parameters:

dragStartEvent - the drag start event

draggedElement - the element being dragged

fixDragImageTransformForMobile

protected void fixDragImageTransformForMobile(com.google.gwt.dom.client.Element draggedElement)

Fix drag image offset for touch devices when the dragged image has been offset with css transform: translate/translate3d.

This necessary for e.g grid rows.

This method is NOOP for non-touch browsers.

Parameters:

draggedElement - the element that forms the drag image

createDataTransferData

protected Map<String,String> createDataTransferData(com.google.gwt.dom.client.NativeEvent dragStartEvent)

Creates the data map to be set as the DataTransfer object's data.

Parameters:

dragStartEvent - The drag start event

Returns:

The map from type to data, or null for not setting any data. Returning null will cancel the drag start.

sendDragStartEventToServer

protected void sendDragStartEventToServer(com.google.gwt.dom.client.NativeEvent dragStartEvent)

Initiates a server RPC for the drag start event.

This method is called only if there is a server side drag start event handler attached.

Parameters:

dragStartEvent - Client side dragstart event.

setDragImage

protected void setDragImage(com.google.gwt.dom.client.NativeEvent dragStartEvent)

Sets the drag image to be displayed.

Override this method in case you need custom drag image setting. Called from onDragStart(Event).

Parameters:

dragStartEvent - The drag start event.

onDragEnd

protected void onDragEnd(elemental.events.Event event)

Event handler for the dragend event. Called when dragend event occurs.

Parameters:

event - browser event to be handled

sendDragEndEventToServer

protected void sendDragEndEventToServer(com.google.gwt.dom.client.NativeEvent dragEndEvent,
                                        DropEffect dropEffect)

Initiates a server RPC for the drag end event.

Parameters:

dragEndEvent - Client side dragend event.

dropEffect - Drop effect of the dragend event, extracted from DataTransfer.dropEffect parameter.

addDraggedStyle

protected void addDraggedStyle(com.google.gwt.dom.client.NativeEvent event)

Add class name to indicate that the drag source element is being dragged. This method is called during the dragstart event.

Parameters:

event - The drag start event.

removeDraggedStyle

protected void removeDraggedStyle(com.google.gwt.dom.client.NativeEvent event)

Remove class name that indicated that the drag source element was being dragged. This method is called during the dragend event.

Parameters:

event - The drag end element.

getDraggableElement

protected com.google.gwt.dom.client.Element getDraggableElement()

Finds the draggable element within the widget. By default, returns the topmost element.

Override this method to make some other than the root element draggable instead.

In case you need to make more than whan element draggable, override extend(ServerConnector) instead.

Returns:

the draggable element in the parent widget.

isNativeDragEvent

protected boolean isNativeDragEvent(com.google.gwt.dom.client.NativeEvent nativeEvent)

Returns whether the given event is a native (android) drag start/end event, and not produced by the drag-drop-polyfill.

Parameters:

nativeEvent - the event to test

Returns:

true if native event, false if not (polyfill event)

isAndoidChrome

protected boolean isAndoidChrome()

Returns whether the current browser is Android Chrome.

Returns:

true if Android Chrome, false if not

getDropEffect

protected static String getDropEffect(com.google.gwt.dom.client.DataTransfer dataTransfer)

Returns the dropEffect for the given data transfer.

Parameters:

dataTransfer - the data transfer with drop effect

Returns:

the currently set drop effect

getState

public DragSourceState getState()

Description copied from class: AbstractConnector

Returns the shared state object for this connector. Override this method to define the shared state type for your connector.

Specified by:

getState in interface ServerConnector

Overrides:

getState in class AbstractConnector

Returns:

the current shared state (never null)