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.

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

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

ObjectAtPointer works differently in PowerBuilder and the Web ActiveX.

DataWindowName.ObjectAtPointer ( "graphName", seriesNumber,
	dataNumber )

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

DataWindowName.ObjectAtPointer ( "graphName" )

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.

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.

int SeriesNum, DataNum

double Value

grObjectType ObjectType

string SeriesName, ValueAsString

string GraphName

GraphName = "gr_sale"

// The following method stores the series number

// clicked on in SeriesNum and stores the number

// of the data point clicked on as DataNum.

ObjectType = &

		dw_printer.ObjectAtPointer (GraphName, &

		SeriesNum, DataNum)

IF ObjectType = TypeSeries! THEN

		SeriesName = &

			dw_printer.SeriesName (GraphName, SeriesNum)

		MessageBox("Graph", &

			"You clicked on the series " + SeriesName)

ELSEIF ObjectType = TypeData! THEN

		Value = dw_printer.GetData (GraphName, &

			SeriesNum, DataNum)

		ValueAsString = String(Value)

		MessageBox("Graph", &

			dw_printer.SeriesName (GraphName, &

			SeriesNum) + " value is " + ValueAsString)

END IF

number SeriesNum, DataNum, ObjectType, Success, Value;

string SeriesName, GraphName;

GraphName = "gr_sales";

ObjectType =

		dw_sales.GrObjectAtPointer(GraphName);

if (ObjectType == 1) {

		SeriesName =

			dw_sales.GetSeriesName(GraphName, SeriesNum);

		alert("You clicked on the series " + SeriesName);

}

else {

		if (ObjectType == 2) {

			Success = dw_sales.GetDataNumber(GraphName,

				SeriesNum, DataNum, 1);

			if (Success == 1) {

				Value = GetDataNumberVariable( );

				alert(dw_sales.GetSeriesName(GraphName,

					SeriesNum) +		" value is " + Value);	

			}		}

}