Using point and click

Users can click graphs during execution. The DataWindow control
provides a method called ObjectAtPointer that stores information
about what was clicked. You can use this method in a number of ways
in mouse events. For example, with the ObjectAtPointer information,
you can call other graph methods to report to the user the value
of the clicked data point. This section shows you how.

Mouse events and graphs

To cause actions when a user clicks a graph, you might:

• PowerBuilder Write a Clicked script for the DataWindow control
• Web ActiveX Write code for the MouseDown or onButtonClick event

You should call ObjectAtPointer in the first statement of
the event’s code.

Using ObjectAtPointer

ObjectAtPointer works differently in PowerBuilder and the
Web ActiveX.

PowerBuilder ObjectAtPointer has this syntax:

ObjectAtPointer does these things:

• Returns the kind of object the user clicked
  The object is identified by a grObjectType enumerated value.
  For example, if the user clicks on a data point, ObjectAtPointer
  returns TypeData!. If the user clicks on the graph’s title,
  ObjectAtPointer returns TypeTitle!.

  For a list of object values, see the chapter on constants
  in the DataWindow Reference
  . In PowerBuilder,
  you can also open the Browser and click the Enumerated tab.

• Stores the number of the series the pointer was
  over in the variable seriesNumber
  , which is
  an argument passed by reference
• Stores the number of the data point in the variable dataNumber
  ,
  also an argument passed by reference

Web ActiveX ObjectAtPointer is used with two supporting methods to get
all the information. ObjectAtPointer has this syntax:

To get the information, you:

1. Call ObjectAtPointer, which returns the kind of graph element
   the user clicked.
   The element type is identified by a number. For example, if
   the user clicks on a series, ObjectAtPointer returns 1. If the user
   clicks on a graph’s title, ObjectAtPointer returns 4.

   For a list of values for individual graph elements, see the
   chapter on constants in the DataWindow Reference
   .

2. Call ObjectAtPointerSeries, which returns the number
   of the series the pointer was over.
3. Call ObjectAtPointerDataPoint, which returns the
   number of the data point the pointer was over.

The second two methods must be called after ObjectAtPointer.

Example

Assume there is a graph named gr_sales in the DataWindow
control dw_sales. The following code for the control’s
MouseDown event displays a message box:

• If the user clicks on a series
  (that
  is, if ObjectAtPointer returns 1), the message box shows the name
  of the series clicked on. The example uses the method GetSeriesName
  to get the series name, given the series number stored by ObjectAtPointer.
• If the user clicks on a data point
  (that
  is, if ObjectAtPointer returns 2), the message box lists the name
  of the series and the value clicked on. The example uses GetDataNumber
  to get the data’s value, given the data’s series
  and data point number.

PowerBuilder This code is for the Clicked event:

Web ActiveX This code is for the MouseDown event:

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