Using graph methods
You call the data-access methods after a graph has been created
and populated with data. Some graphs, such as graphs that display data
for a page or group of data, are destroyed and re-created internally as
the user pages through the data. Any changes you made to the display of
a graph, such as changing the color of a series, are lost when the graph
is re-created.
Event for graph creation
To be assured that data-access methods are called whenever a graph
has been created and populated with data, you can call the methods in
the code for an event that is triggered when a graph is created. The
event is:
-
PowerBuilder
Event ID pbm_dwngraphcreate, which you can assign to a user
event for a DataWindow control (described below)
The graph-creation event is triggered by the DataWindow control
after it has created a graph and populated it with data, but before it
has displayed the graph. By accessing the data in the graph in this
event, you are assured that you are accessing the current data and that
the data displays the way you want it.
Setting up the PowerBuilder user
event
PowerBuilder provides an event ID, pbm_dwngraphcreate, that you
can assign to a user event for a DataWindow control.
To access data properties of a graph in a DataWindow
control:
-
Place the DataWindow control in a window or user object and
associate it with the DataWindow object containing the graph.Next you create a user event for the DataWindow control that
is triggered whenever a graph in the control is created or
changed. -
Select Insert>Event from the menu bar.
The Script view displays and includes prototype fields for
adding a new event. -
Select the DataWindow control in the first drop-down list of
the prototype window.If the second drop-down list also changes to display an
existing DataWindow event prototype, scroll to the top of the list
to select New Event or select Insert>Event once again from the
menu bar.
-
Name the user event you are creating.
For example, you might call it GraphCreate.
-
Select pbm_dwngraphcreate for the event ID.
-
Click OK to save the new user event.
-
Write a script for the new GraphCreate event that accesses the
data in the graph.Calling data access methods in the GraphCreate event assures
you that the data access happens each time the graph has been
created or changed in the DataWindow.
Examples
PowerBuilder
The following statement sets to black the foreground (fill) color
of the Q1 series in the graph gr_quarter, which is in the DataWindow
control dw_report. The statement is in the GraphCreate event, which is
associated with the event ID pbm_dwngraphcreate in PowerBuilder:
|
1 2 |
dw_report.SetSeriesStyle("gr_quarter", "Q1", & foreground!, 0) |
The following statement changes the foreground (fill) color to red
of the second data point in the Stellar series in the graph gr_sale in a
window. The statement can be in a script for any event:
|
1 2 3 4 5 6 |
int SeriesNum // Get the number of the series. SeriesNum = gr_sale.FindSeries("Stellar") // Change color of second data point to red gr_sale.SetDataStyle(SeriesNum, 2, foreground!, 255) |
For more information
For complete information about the data-access graph methods, see
Methods for Graphs in the DataWindow Control in DataWindow Reference.
For more about PowerBuilder user events, see the section called “Working with User Events” in Users Guide.