DragEvent
open class DragEvent : Parcelable
| kotlin.Any | |
| ↳ | android.view.DragEvent |
Represents an event that is sent out by the system at various times during a drag and drop operation. It is a data structure that contains several important pieces of data about the operation and the underlying data.
View objects that receive a DragEvent call getAction(), which returns an action type that indicates the state of the drag and drop operation. This allows a View object to react to a change in state by changing its appearance or performing other actions. For example, a View can react to the ACTION_DRAG_ENTERED action type by by changing one or more colors in its displayed image.
During a drag and drop operation, the system displays an image that the user drags. This image is called a drag shadow. Several action types reflect the position of the drag shadow relative to the View receiving the event.
Most methods return valid data only for certain event actions. This is summarized in the following table. Each possible getAction() value is listed in the first column. The other columns indicate which method or methods return valid data for that getAction() value:
| getAction() Value | getClipDescription() | getLocalState() | getX() | getY() | getClipData() | getResult() |
|---|---|---|---|---|---|---|
| ACTION_DRAG_STARTED | X | X | X | X | ||
| ACTION_DRAG_ENTERED | X | X | ||||
| ACTION_DRAG_LOCATION | X | X | X | X | ||
| ACTION_DRAG_EXITED | X | X | ||||
| ACTION_DROP | X | X | X | X | X | |
| ACTION_DRAG_ENDED | X | X |
The android.view.DragEvent#getAction(), android.view.DragEvent#getLocalState() android.view.DragEvent#describeContents(), android.view.DragEvent#writeToParcel(Parcel,int), and android.view.DragEvent#toString() methods always return valid data.
Summary
| Constants | |
|---|---|
| static Int |
Action constant returned by |
| static Int |
Action constant returned by |
| static Int |
Action constant returned by |
| static Int |
Action constant returned by |
| static Int |
Action constant returned by |
| static Int |
Action constant returned by |
| Inherited constants | |
|---|---|
| Public methods | |
|---|---|
| open Int |
Returns information about the |
| open Int |
Inspect the action value of this event. |
| open ClipData! |
Returns the |
| open ClipDescription! |
Returns the |
| open Any! |
Returns the local state object sent to the system as part of the call to |
| open Boolean |
Returns an indication of the result of the drag and drop operation. |
| open Float |
getX()Gets the X coordinate of the drag point. |
| open Float |
getY()Gets the Y coordinate of the drag point. |
| open String |
toString()Returns a string containing a concise, human-readable representation of this DragEvent object. |
| open Unit |
writeToParcel(dest: Parcel, flags: Int)Creates a |
| Properties | |
|---|---|
| static Parcelable.Creator<DragEvent!> |
A container for creating a DragEvent from a Parcel. |
Constants
ACTION_DRAG_ENDED
static val ACTION_DRAG_ENDED: Int
Action constant returned by getAction(): Signals to a View that the drag and drop operation has concluded. A View that changed its appearance during the operation should return to its usual drawing state in response to this event.
All views with listeners that returned boolean true for the ACTION_DRAG_STARTED event will receive the ACTION_DRAG_ENDED event even if they are not currently visible when the drag ends. Views removed during the drag operation won't receive the ACTION_DRAG_ENDED event.
The View object can call getResult() to see the result of the operation. If a View returned true in response to ACTION_DROP, then getResult() returns true, otherwise it returns false.
Value: 4
See Also
ACTION_DRAG_ENTERED
static val ACTION_DRAG_ENTERED: Int
Action constant returned by getAction(): Signals to a View that the drag point has entered the bounding box of the View.
If the View can accept a drop, it can react to ACTION_DRAG_ENTERED by changing its appearance in a way that tells the user that the View is the current drop target.
The system stops sending ACTION_DRAG_LOCATION events to a View once the user moves the drag shadow out of the View object's bounding box or into a descendant view that can accept the data. If the user moves the drag shadow back into the View object's bounding box or out of a descendant view that can accept the data, the View receives an ACTION_DRAG_ENTERED again before receiving any more ACTION_DRAG_LOCATION events.Value: 5
ACTION_DRAG_EXITED
static val ACTION_DRAG_EXITED: Int
Action constant returned by getAction(): Signals that the user has moved the drag shadow out of the bounding box of the View or into a descendant view that can accept the data. The View can react by changing its appearance in a way that tells the user that View is no longer the immediate drop target.
After the system sends an ACTION_DRAG_EXITED event to the View, the View receives no more ACTION_DRAG_LOCATION events until the user drags the drag shadow back over the View.
Value: 6
ACTION_DRAG_LOCATION
static val ACTION_DRAG_LOCATION: Int
Action constant returned by getAction(): Sent to a View after ACTION_DRAG_ENTERED while the drag shadow is still within the View object's bounding box, but not within a descendant view that can accept the data. The getX() and getY() methods supply the X and Y position of the drag point within the View object's bounding box.
A View receives an ACTION_DRAG_ENTERED event before receiving any ACTION_DRAG_LOCATION events.
The system stops sending ACTION_DRAG_LOCATION events to a View once the user moves the drag shadow out of the View object's bounding box or into a descendant view that can accept the data. If the user moves the drag shadow back into the View object's bounding box or out of a descendant view that can accept the data, the View receives an ACTION_DRAG_ENTERED again before receiving any more ACTION_DRAG_LOCATION events.
Value: 2
See Also
ACTION_DRAG_STARTED
static val ACTION_DRAG_STARTED: Int
Action constant returned by getAction(): Signals the start of a drag and drop operation. The View should return true from its onDragEvent() handler method or OnDragListener.onDrag() listener if it can accept a drop. The onDragEvent() or onDrag() methods usually inspect the metadata from getClipDescription() to determine if they can accept the data contained in this drag. For an operation that doesn't represent data transfer, these methods may perform other actions to determine whether or not the View should accept the data. If the View wants to indicate that it is a valid drop target, it can also react by changing its appearance.
Views added or becoming visible for the first time during a drag operation receive this event when they are added or becoming visible.
A View only receives further drag events for the drag operation if it returns true in response to ACTION_DRAG_STARTED.
Value: 1
See Also
ACTION_DROP
static val ACTION_DROP: Int
Action constant returned by getAction(): Signals to a View that the user has released the drag shadow, and the drag point is within the bounding box of the View and not within a descendant view that can accept the data. The View should retrieve the data from the DragEvent by calling getClipData(). The methods getX() and getY() return the X and Y position of the drop point within the View object's bounding box.
The View should return true from its View#onDragEvent(DragEvent) handler or OnDragListener.onDrag() listener if it accepted the drop, and false if it ignored the drop.
The View can also react to this action by changing its appearance.
Value: 3
See Also
Public methods
describeContents
open fun describeContents(): Int
Returns information about the android.os.Parcel representation of this DragEvent object.
| Return | |
|---|---|
Int |
Information about the android.os.Parcel representation. |
getAction
open fun getAction(): Int
Inspect the action value of this event.
| Return | |
|---|---|
Int |
One of the following action constants, in the order in which they usually occur during a drag and drop operation: |
getClipData
open fun getClipData(): ClipData!
Returns the android.content.ClipData object sent to the system as part of the call to startDragAndDrop(). This method only returns valid data if the event action is ACTION_DROP.
| Return | |
|---|---|
ClipData! |
The ClipData sent to the system by startDragAndDrop(). |
getClipDescription
open fun getClipDescription(): ClipDescription!
Returns the android.content.ClipDescription object contained in the android.content.ClipData object sent to the system as part of the call to startDragAndDrop(). The drag handler or listener for a View can use the metadata in this object to decide if the View can accept the dragged View object's data.
This method returns valid data for all event actions except for ACTION_DRAG_ENDED.
| Return | |
|---|---|
ClipDescription! |
The ClipDescription that was part of the ClipData sent to the system by startDragAndDrop(). |
getLocalState
open fun getLocalState(): Any!
Returns the local state object sent to the system as part of the call to startDragAndDrop(). The object is intended to provide local information about the drag and drop operation. For example, it can indicate whether the drag and drop operation is a copy or a move.
The local state is available only to views in the activity which has started the drag operation. In all other activities this method will return null
This method returns valid data for all event actions.
| Return | |
|---|---|
Any! |
The local state object sent to the system by startDragAndDrop(). |
getResult
open fun getResult(): Boolean
Returns an indication of the result of the drag and drop operation. This method only returns valid data if the action type is ACTION_DRAG_ENDED. The return value depends on what happens after the user releases the drag shadow.
If the user releases the drag shadow on a View that can accept a drop, the system sends an ACTION_DROP event to the View object's drag event listener. If the listener returns true, then getResult() will return true. If the listener returns false, then getResult() returns false.
Notice that getResult() also returns false if no ACTION_DROP is sent. This happens, for example, when the user releases the drag shadow over an area outside of the application. In this case, the system sends out ACTION_DRAG_ENDED for the current operation, but never sends out ACTION_DROP.
| Return | |
|---|---|
Boolean |
true if a drag event listener returned true in response to ACTION_DROP. If the system did not send ACTION_DROP before ACTION_DRAG_ENDED, or if the listener returned false in response to ACTION_DROP, then false is returned. |
getX
open fun getX(): Float
Gets the X coordinate of the drag point. The value is only valid if the event action is ACTION_DRAG_STARTED, ACTION_DRAG_LOCATION or ACTION_DROP.
| Return | |
|---|---|
Float |
The current drag point's X coordinate |
getY
open fun getY(): Float
Gets the Y coordinate of the drag point. The value is only valid if the event action is ACTION_DRAG_STARTED, ACTION_DRAG_LOCATION or ACTION_DROP.
| Return | |
|---|---|
Float |
The current drag point's Y coordinate |
toString
open fun toString(): String
Returns a string containing a concise, human-readable representation of this DragEvent object.
| Return | |
|---|---|
String |
A string representation of the DragEvent object. |
writeToParcel
open fun writeToParcel(
dest: Parcel,
flags: Int
): Unit
Creates a android.os.Parcel object from this DragEvent object.
| Parameters | |
|---|---|
dest |
Parcel: A android.os.Parcel object in which to put the DragEvent object. |
flags |
Int: Flags to store in the Parcel. |
Properties
CREATOR
static val CREATOR: Parcelable.Creator<DragEvent!>
A container for creating a DragEvent from a Parcel.