[jira] [Commented] (FLEX-34741) Spark DataGrid Drag and Drop non functioning

["Jan Weber (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLEX-34741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17495445#comment-17495445 ] 

Jan Weber commented on FLEX-34741:
----------------------------------

If anyone encounters the same problem, the solution worked fine with the attached DataGrid AS Class _but_ you need to also override the function "{*}destroyDropIndicator{*}".

As stated above:
"{_}All the drag handlers in DataGrid need to call showDropIndicator(), hideDropIndicator(), and destroyDropIndicator() on the GridViewLayout, not the GridLayout.{_}"

 

Since the attached class does not contain an _override_ to the *destroyDropIndicator* function, it will cause a null-pointer in the base class when it tries to access "{*}_gridViewLayout.dropIndicator{*}".

 

{{The override looks like:}}
{{        override public function destroyDropIndicator():DisplayObject}}
{{        {}}
{{            var gridViewLayout : GridViewLayout = GridViewLayout(GridLayout(grid.layout).centerGridView.layout);}}
{{            var dropIndicatorInstance:DisplayObject = gridViewLayout.dropIndicator;}}{{            if (!dropIndicatorInstance)}}
{{                return null;}}{{            // Release the reference from the layout}}
{{            gridViewLayout.dropIndicator = null;}}{{            // Release it if it's a dynamic skin part}}
{{            var count:int = numDynamicParts("dropIndicator");}}{{            for (var i:int = 0; i < count; i++)}}
{{            {}}
{{                if (dropIndicatorInstance == getDynamicPartAt("dropIndicator", i))}}
{{                {}}
{{                    // This was a dynamic part, remove it now:}}
{{                    removeDynamicPartInstance("dropIndicator", dropIndicatorInstance);}}
{{                    break;}}
{{                }}}
{{            }}}{{            return dropIndicatorInstance;}}
{{        }}}

> Spark DataGrid Drag and Drop non functioning
> --------------------------------------------
>
>                 Key: FLEX-34741
>                 URL: https://issues.apache.org/jira/browse/FLEX-34741
>             Project: Apache Flex
>          Issue Type: Bug
>          Components: Spark: DataGrid
>    Affects Versions: Apache Flex 4.14.0
>            Reporter: Devin
>            Assignee: Mark Kessler
>            Priority: Major
>              Labels: drag&drop
>             Fix For: Apache Flex 4.15.0
>
>         Attachments: DragDropGrid.as
>
>
> Description
> Dropping a dragged item onto the grid does not work. When calculating the DropLocation (in dragEnter, dragOver, dragDrop handlers) it falls through to LayoutBase.calculateDropIndex which simply executes "return target.numElements;" That's clearly not how the dropIndex should be calculated on the grid. The GridLayout class should be overriding this method and calculating it correctly.
> Furthermore, upon trying to fix this issue (which is more complicated than it should be because DataGrid.calculateDropPosition() is marked as private) the DataGrid.calculateDropPosition() does not perform a null check on the DropLocation (which is valid value).
> Steps to Reproduce
> 1. Create a DataGrid with dragEnabled, dragMoveEnabled, and dropEnabled all set to true.
> 2. Try dragging rows around and dropping them.
> Environment
> Windows 8, Apache Flex 4.14
> Expected Behavior
> Seeing the drop indicator.
> The expected behavior of dragging a row and dropping it in another location.
> Actual Behavior
> No drop indicator. Dropping a row does nothing.



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