Package com.vaadin.client.extensions

Class DropTargetExtensionConnector

java.lang.Object

com.vaadin.client.ui.AbstractConnector

com.vaadin.client.extensions.AbstractExtensionConnector

com.vaadin.client.extensions.DropTargetExtensionConnector

All Implemented Interfaces:

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

Direct Known Subclasses:

FileDropTargetConnector, GridDropTargetConnector

public class DropTargetExtensionConnector
extends AbstractExtensionConnector

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

Since:

8.1

Author:

Vaadin Ltd

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected static String	STYLE_SUFFIX_DRAG_BOTTOM	Style name suffix for dragging data over the bottom part of the drop target.
protected static String	STYLE_SUFFIX_DRAG_CENTER	Style name suffix for dragging data over the center of the drop target.
protected static String	STYLE_SUFFIX_DRAG_TOP	Style name suffix for dragging data over the top part of the drop target.
protected static String	STYLE_SUFFIX_DROPTARGET	Style name suffix for indicating that the element is drop target.

Constructor Summary

Constructors

Constructor	Description
DropTargetExtensionConnector()

Method Summary

Modifier and Type	Method	Description
protected void	addDragOverStyle(com.google.gwt.dom.client.NativeEvent event)	Add class that indicates that the component is a target while data is being dragged over it.
protected void	addDropTargetStyle()	Add class name for the drop target element indicating that data can be dropped onto it.
protected void	extend(ServerConnector target)	Called when the extension is attached to its parent.
protected com.google.gwt.dom.client.Element	getDropTargetElement()	Finds the drop target element within the widget.
DropTargetState	getState()	Returns the shared state object for this connector.
protected boolean	isDropAllowedByCriteriaScript(com.google.gwt.dom.client.NativeEvent event)	Checks if a criteria script exists and, if yes, executes it.
protected void	onDragEnter(elemental.events.Event event)	Event handler for the dragenter event.
protected void	onDragLeave(elemental.events.Event event)	Event handler for the dragleave event.
protected void	onDragOver(elemental.events.Event event)	Event handler for the dragover event.
protected void	onDrop(elemental.events.Event event)	Event handler for the drop event.
void	onUnregister()	Event called when connector has been unregistered.
protected void	removeDragOverStyle(com.google.gwt.dom.client.NativeEvent event)	Remove the drag over indicator class name from the target element.
protected void	removeDropTargetStyle()	Remove class name from the drop target element indication that data can be dropped onto it.
protected void	sendDropEventToServer(List<String> types, Map<String,String> data, String dropEffect, com.google.gwt.dom.client.NativeEvent dropEvent)	Initiates a server RPC for the drop event.

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_DRAG_CENTER

protected static final String STYLE_SUFFIX_DRAG_CENTER

Style name suffix for dragging data over the center of the drop target.

See Also:

Constant Field Values

STYLE_SUFFIX_DRAG_TOP

protected static final String STYLE_SUFFIX_DRAG_TOP

Style name suffix for dragging data over the top part of the drop target.

See Also:

Constant Field Values

STYLE_SUFFIX_DRAG_BOTTOM

protected static final String STYLE_SUFFIX_DRAG_BOTTOM

Style name suffix for dragging data over the bottom part of the drop target.

See Also:

Constant Field Values

STYLE_SUFFIX_DROPTARGET

protected static final String STYLE_SUFFIX_DROPTARGET

Style name suffix for indicating that the element is drop target.

See Also:

Constant Field Values

Constructor Detail

DropTargetExtensionConnector

public DropTargetExtensionConnector()

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

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

getDropTargetElement

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

Finds the drop target element within the widget. By default, returns the topmost element.

Returns:

the drop target element in the parent widget.

onDragEnter

protected void onDragEnter(elemental.events.Event event)

Event handler for the dragenter event.

Override this method in case custom handling for the dragstart event is required. If the drop is allowed, the event should prevent default.

Parameters:

event - browser event to be handled

onDragOver

protected void onDragOver(elemental.events.Event event)

Event handler for the dragover event.

Override this method in case custom handling for the dragover event is required. If the drop is allowed, the event should prevent default.

Parameters:

event - browser event to be handled

onDragLeave

protected void onDragLeave(elemental.events.Event event)

Event handler for the dragleave event.

Override this method in case custom handling for the dragleave event is required.

Parameters:

event - browser event to be handled

onDrop

protected void onDrop(elemental.events.Event event)

Event handler for the drop event.

Override this method in case custom handling for the drop event is required. If the drop is allowed, the event should prevent default.

Parameters:

event - browser event to be handled

isDropAllowedByCriteriaScript

protected boolean isDropAllowedByCriteriaScript(com.google.gwt.dom.client.NativeEvent event)

Checks if a criteria script exists and, if yes, executes it. This method is protected, so subclasses as e.g. GridDropTargetConnector can override it to add additional script parameters.

Parameters:

event - browser event (dragEnter, dragOver, drop) that should be evaluated by the criteria script

Returns:

true if no script was given or if the script returned true, false otherwise.

sendDropEventToServer

protected void sendDropEventToServer(List<String> types,
                                     Map<String,String> data,
                                     String dropEffect,
                                     com.google.gwt.dom.client.NativeEvent dropEvent)

Initiates a server RPC for the drop event.

Parameters:

types - List of data types from DataTransfer.types object.

data - Map containing all types and corresponding data from the DataTransfer object.

dropEffect - The desired drop effect.

addDropTargetStyle

protected void addDropTargetStyle()

Add class name for the drop target element indicating that data can be dropped onto it. The class name has the following format:

     [primaryStyleName]-droptarget
 

The added class name is update automatically by the framework when the primary style name changes.

removeDropTargetStyle

protected void removeDropTargetStyle()

Remove class name from the drop target element indication that data can be dropped onto it.

addDragOverStyle

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

Add class that indicates that the component is a target while data is being dragged over it.

This is triggered on dragenter and dragover events pending if the drop is possible. The drop is possible if the drop effect for the target and source do match and the drop criteria script evaluates to true or is not set.

Parameters:

event - the dragenter or dragover event that triggered the indication.

removeDragOverStyle

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

Remove the drag over indicator class name from the target element.

This is triggered on drop, dragleave and dragover events pending on whether the drop has happened or if it is not possible. The drop is not possible if the drop effect for the source and target don't match or if there is a drop criteria script that evaluates to false.

Parameters:

event - the event that triggered the removal of the indicator

getState

public DropTargetState 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)