mx.collections

# IViewCursor - AS3 Flex

Package | mx.collections
Interface | public interface IViewCursor extends IEventDispatcher

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Defines the interface for enumerating a collection view bi-directionally. This cursor provides find, seek, and bookmarking capabilities along with the modification methods insert and remove. When a cursor is first retrieved from a view, (typically by the ICollectionView `createCursor()` method) the value of the `current` property should be the first item in the view, unless the view is empty.

Public Properties

| Property | Defined By
--- | --- | ---
|  | afterLast : Boolean [read-only] If the cursor is located after the last item in the view, this property is true . | IViewCursor
|  | beforeFirst : Boolean [read-only] If the cursor is located before the first item in the view, this property is true. | IViewCursor
|  | bookmark : CursorBookmark [read-only] Provides access to a bookmark that corresponds to the item returned by the current property. | IViewCursor
|  | current : Object [read-only] Provides access the object at the location in the source collection referenced by this cursor. | IViewCursor
|  | view : ICollectionView [read-only] A reference to the ICollectionView with which this cursor is associated. | IViewCursor

Public Methods
Hide Inherited Public Methods
Show Inherited Public Methods

| Method | Defined By
--- | --- | ---
|  | addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. | IEventDispatcher
|  | dispatchEvent(event:Event):Boolean Dispatches an event into the event flow. | IEventDispatcher
|  | findAny(values:Object):Boolean Finds an item with the specified properties within the collection and positions the cursor to that item. | IViewCursor
|  | findFirst(values:Object):Boolean Finds the first item with the specified properties within the collection and positions the cursor to that item. | IViewCursor
|  | findLast(values:Object):Boolean Finds the last item with the specified properties within the collection and positions the cursor on that item. | IViewCursor
|  | hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event. | IEventDispatcher
|  | insert(item:Object):void Inserts the specified item before the cursor's current position. | IViewCursor
|  | moveNext():Boolean Moves the cursor to the next item within the collection. | IViewCursor
|  | movePrevious():Boolean Moves the cursor to the previous item within the collection. | IViewCursor
|  | remove():Object Removes the current item and returns it. | IViewCursor
|  | removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object. | IEventDispatcher
|  | seek(bookmark:CursorBookmark, offset:int = 0, prefetch:int = 0):void Moves the cursor to a location at an offset from the specified bookmark. | IViewCursor
|  | willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. | IEventDispatcher

Events
Click for more information on events

| Event | Summary | Defined By
--- | --- | --- | ---
|  | cursorUpdate | Dispatched whenever the cursor position is updated. | IViewCursor

Property Detail

### afterLast

property

`afterLast:Boolean` [read-only]

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

If the cursor is located after the last item in the view, this property is `true` . If the ICollectionView is empty (length == 0), this property is `true`.

This property can be used as the source for data binding. When this property is modified, it dispatches the `cursorUpdate` event.

Implementation
`public function get afterLast():Boolean`

### beforeFirst

property

`beforeFirst:Boolean` [read-only]

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

If the cursor is located before the first item in the view, this property is `true`. If the ICollectionView is empty (length == 0), this property is `true`.

This property can be used as the source for data binding. When this property is modified, it dispatches the `cursorUpdate` event.

Implementation
`public function get beforeFirst():Boolean`

### bookmark

property

`bookmark:CursorBookmark` [read-only]

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Provides access to a bookmark that corresponds to the item returned by the `current` property. The bookmark can be used to move the cursor to a previously visited item, or to a position relative to that item. (See the `seek()` method for more information.)

This property can be used as the source for data binding. When this property is modified, it dispatches the `cursorUpdate` event.

Implementation
`public function get bookmark():CursorBookmark`

Related API Elements

current
seek()

### current

property

`current:Object` [read-only]

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Provides access the object at the location in the source collection referenced by this cursor. If the cursor is beyond the ends of the collection (`beforeFirst`, `afterLast`) this will return `null`.

This property can be used as the source for data binding. When this property is modified, it dispatches the `cursorUpdate` event.

Implementation
`public function get current():Object`

Related API Elements

moveNext()
movePrevious()
seek()
beforeFirst
afterLast

### view

property

`view:ICollectionView` [read-only]

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

A reference to the ICollectionView with which this cursor is associated.

Implementation
`public function get view():ICollectionView`
Method Detail

### findAny

()
method

`public function findAny(values:Object):Boolean`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Finds an item with the specified properties within the collection and positions the cursor to that item. If the item can not be found, the cursor location does not change.

The `findAny()` method can only be called on sorted views; if the view isn't sorted, a `CursorError` is thrown.

If the associated collection is remote, and not all of the items have been cached locally, this method begins an asynchronous fetch from the remote collection. If one is already in progress, this method waits for it to complete before making another fetch request.

If multiple items can match the search criteria then the item found is non-deterministic. If it is important to find the first or last occurrence of an item in a non-unique index, use the `findFirst()` or `findLast()` method.

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown.

Parameters

| `values:Object` — The search criteria. The values in the Object must be configured as name-value pairs, as in an associative array (or be the actual object to search for). The values of the names specified must match properties specified in the sort. For example, if properties `x`, `y`, and `z` are in the current sort, the values specified should be `{x: x-value, y: y-value, z: z-value}`.

Returns

| `Boolean` — When all of the data is local this method returns `true` if the item can be found and `false` otherwise.

Related API Elements

findFirst()
findLast()
mx.collections.errors.ItemPendingError

### findFirst

()
method

`public function findFirst(values:Object):Boolean`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Finds the first item with the specified properties within the collection and positions the cursor to that item. If the item can not be found, no cursor location does not change.

The `findFirst()` method can only be called on sorted views; if the view isn't sorted, a `CursorError` is thrown.

If the associated collection is remote, and not all of the items have been cached locally, this method begins an asynchronous fetch from the remote collection. If one is already in progress, this method waits for it to complete before making another fetch request.

If it is not important to find the first occurrence of an item in a non-unique index, use `findAny()`, which may be a little faster than the `findFirst() method`.

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown.

Parameters

| `values:Object` — The search criteria. The values in the Object must be configured as name-value pairs, as in an associative array (or be the actual object to search for). The values of the names specified must match properties specified in the sort. For example, if properties `x`, `y`, and `z` are in the current sort, the values specified should be `{x: x-value, y: y-value, z: z-value}`.

Returns

| `Boolean` — When all of the data is local this method returns `true` if the item can be found and `false` otherwise.

Related API Elements

findAny()
findLast()
mx.collections.errors.ItemPendingError

### findLast

()
method

`public function findLast(values:Object):Boolean`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Finds the last item with the specified properties within the collection and positions the cursor on that item. If the item can not be found, the cursor location does not chanage.

The `findLast()` method can only be called on sorted views; if the view isn't sorted, a `CursorError` is thrown.

If the associated collection is remote, and not all of the items have been cached locally, this method begins an asynchronous fetch from the remote collection. If one is already in progress, this method waits for it to complete before making another fetch request.

If it is not important to find the last occurrence of an item in a non-unique index, use the `findAny()` method, which may be a little faster.

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown.

Parameters

| `values:Object` — The search criteria. The values in the Object must be configured as name-value pairs, as in an associative array (or be the actual object to search for). The values of the names specified must match properties specified in the sort. For example, if properties `x`, `y`, and `z` are in the current sort, the values specified should be `{x: x-value, y: y-value, z: z-value}`.

Returns

| `Boolean` — When all of the data is local this method returns `true` if the item can be found and `false` otherwise.

Related API Elements

findAny()
findFirst()
mx.collections.errors.ItemPendingError

### insert

()
method

`public function insert(item:Object):void`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Inserts the specified item before the cursor's current position. If the cursor is `afterLast`, the insertion occurs at the end of the view. If the cursor is `beforeFirst` on a non-empty view, an error is thrown.

Parameters

| `item:Object` — The item to insert before the cursor's current position.

### moveNext

()
method

`public function moveNext():Boolean`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Moves the cursor to the next item within the collection. On success the `current` property is updated to reference the object at this new location. Returns `true` if the resulting `current` property is valid, or `false` if not (the property value is `afterLast`).

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown. See the ItemPendingError documentation and the collections documentation for more information on using the ItemPendingError.

Returns

| `Boolean` — `true` if still in the list, `false` if the `current` value initially was or now is `afterLast`.

Related API Elements

current
movePrevious()
mx.collections.errors.ItemPendingError
Example
How to use this example

          var myArrayCollection:ICollectionView = new ArrayCollection([ "Bobby", "Mark", "Trevor", "Jacey", "Tyler" ]);
          var cursor:IViewCursor = myArrayCollection.createCursor();
          while (!cursor.afterLast)
          {
              trace(cursor.current);
              cursor.moveNext();
          }

### movePrevious

()
method

`public function movePrevious():Boolean`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Moves the cursor to the previous item within the collection. On success the `current` property is updated to reference the object at this new location. Returns `true` if the resulting `current` property is valid, or `false` if not (the property value is `beforeFirst`).

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown. See the ItemPendingError documentation and the collections documentation for more information on using the ItemPendingError.

Returns

| `Boolean` — `true` if still in the list, `false` if the `current` value initially was or now is `beforeFirst`. For example:
          var myArrayCollection:ICollectionView = new ArrayCollection([ "Bobby", "Mark", "Trevor", "Jacey", "Tyler" ]);
          var cursor:IViewCursor = myArrayCollection.createCursor();
          cursor.seek(CursorBookmark.last);
          while (!cursor.beforeFirst)
          {
              trace(current);
              cursor.movePrevious();
          }

Related API Elements

current
moveNext()
mx.collections.errors.ItemPendingError

### remove

()
method

`public function remove():Object`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Removes the current item and returns it. If the cursor location is `beforeFirst` or `afterLast`, throws a CursorError. If you remove any item other than the last item, the cursor moves to the next item. If you remove the last item, the cursor is at the AFTER_LAST bookmark.

If the item after the removed item is not local and an asynchronous operation must be performed, an ItemPendingError is thrown. See the ItemPendingError documentation and the collections documentation for more information on using the ItemPendingError.

Returns

| `Object` — The item that was removed.

Related API Elements

mx.collections.errors.ItemPendingError

### seek

()
method

`public function seek(bookmark:CursorBookmark, offset:int = 0, prefetch:int = 0):void`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Moves the cursor to a location at an offset from the specified bookmark. The offset can be negative, in which case the cursor is positioned an `offset` number of items prior to the specified bookmark.

If the associated collection is remote, and not all of the items have been cached locally, this method begins an asynchronous fetch from the remote collection.

If the data is not local and an asynchronous operation must be performed, an ItemPendingError is thrown. See the ItemPendingError documentation and the collections documentation for more information on using the ItemPendingError.

Parameters

| `bookmark:CursorBookmark` — `CursorBookmark` reference to marker information that allows repositioning to a specific location. You can set this parameter to value returned from the `bookmark` property, or to one of the following constant bookmark values:

- `CursorBookmark.FIRST` - Seek from the start (first element) of the collection
- `CursorBookmark.CURRENT` - Seek from the current position in the collection
- `CursorBookmark.LAST` - Seek from the end (last element) of the collection

| `offset:int` (default = `0`)`` — Indicates how far from the specified bookmark to seek. If the specified number is negative, the cursor attempts to move prior to the specified bookmark. If the offset specified is beyond the end of the collection, the cursor is be positioned off the end, to the `beforeFirst` or `afterLast` location.
| `prefetch:int` (default = `0`)`` — Used for remote data. Indicates an intent to iterate in a specific direction once the seek operation completes. This reduces the number of required network round trips during a seek. If the iteration direction is known at the time of the request, the appropriate amount of data can be returned ahead of the request to iterate it.

Related API Elements

mx.collections.errors.ItemPendingError
Event Detail

### cursorUpdate

Event

Event Object Type: `mx.events.FlexEvent`
property FlexEvent.type = `mx.events.FlexEvent.CURSOR_UPDATE`

Language Version: | ActionScript 3.0

Product Version: | Flex 3

Runtime Versions: | Flash Player 9, AIR 1.1

Dispatched whenever the cursor position is updated.

The `FlexEvent.CURSOR_UPDATE` constant defines the value of the `type` property of the event object for a `cursorUpdate` event.

The properties of the event object have the following values:

Property | Value
--- | ---
`bubbles` | false
`cancelable` | false
`currentTarget` | The Object that defines the event listener that handles the event. For example, if you use `myButton.addEventListener()` to register an event listener, myButton is the value of the `currentTarget`.
`target` | The Object that dispatched the event; it is not always the Object listening for the event. Use the `currentTarget` property to always access the Object listening for the event.

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Mon Apr 10 2017, 12:28 PM -07:00