How To Dynamically Create Excel 5.0 Charts in OLE 2.0 Control

MORE INFORMATION

The Visual Basic OLE container control can be used to embed new OLE objects at run-time. One of the objects that you can embed is an Excel chart. It is basically a four-step process:

1. To embed a new chart into the OLE control, set the Class property to Excel.Chart or Excel.Chart.5. Both classes (Excel.Chart and Excel.Chart.5) are for Excel charts. But Excel.Chart.5 is version dependent; it specifies an Excel version 5.0 chart object.
2. Create the object by setting the Action property to OLE_CREATE_EMBED. This embeds a default chart (Chart1) from Excel into the OLE control. The chart (Chart1) is part of a default workbook (Book1) that also contains a default worksheet (Sheet1) to provide data for the chart.
3. Set object variables to reference the Excel objects you need to manipulate the chart through OLE Automation. This will make your code smaller and easier to understand.
4. Call the ChartWizard Method to format the chart.

Setting Object Variables to Reference Excel Objects

The OLE control provides the Object property to allow you to refer to the object you created. For example, the following code creates and embeds a chart into the OLE control and then sets the title:

   Const OLE_CREATE_EMBED = 0
   Ole1.Class = "Excel.Chart.5"
   Ole1.Action = OLE_CREATE_EMBED
   Ole1.Object.HasTitle = 1
   Ole1.Object.ChartTitle.Caption = "Expenses"
				

You could navigate from the Object property all the time, but it would be cumbersome. To make it easier, you can set object variables to reference the objects you want. Here is a modified version of the previous example with object variables:

   Const OLE_CREATE_EMBED = 0
   Dim objChart as Object
   Dim objChartTitle as Object
   Ole1.Class = "Excel.Chart.5"
   Ole1.Action = OLE_CREATE_EMBED
   Set objChart = Ole1.Object
   Set objChartTitle = Ole1.Object.ChartTitle
   objChart.HasTitle = 1
   objChartTitle.Caption = "Expenses"
				

The example shown at the end of this article uses three object variables:

• One referring to the chart.
• One referring to the worksheet.
• One referring to the application object.

Calling the ChartWizard Method to Format a Chart

To format a chart quickly, Excel provides the ChartWizard method. With one call to the ChartWizard method, you can create a chart in one of many predefined formats. The example uses this method, but you could also use direct object manipulation of the chart.

Before you can call the ChartWizard method, the worksheet needs to be filled with the proper data. The example creates random data. Most of the time you will be using more meaningful data that you can manipulate with Excel. In the example, the xlRows orientation is used with 1 row for category labels and one column for series labels. Here is a diagram showing how the data is put into the worksheet:

-----------------------------------------------------------
|                | Category 1 Label | Category 2 Label |
-----------------------------------------------------------
| Series 1 Label | Data Value       | Data Value       |
-----------------------------------------------------------
| Series 2 Label | Data Value       | Data Value       |
 -----------------------------------------------------------
|                |                  |                  |
				

Once the data (including labels) has been added to the worksheet, you pass the entire range to the ChartWizard method along with the other formatting parameters.

ChartWizard Syntax, Parameters, and Descriptions

SYNTAX:

Object.ChartWizard(Source, Gallery, Format, PlotBy, CategoryLabels, SeriesLabels, HasLegend, Title, CategoryTitle, ValueTitle, ExtraTitle)

Parameter       Description
--------------  -------------------------------------------------
Object          The Chart object.
Source          Specifies range that contains source data for the chart.
Gallery         Specifies chart type (see constants in example.)
Format          Specifies built-in autoformat.
PlotBy          Specifies orientation of the data (xlRows or xlColumns.)
CategoryLabels  The number of rows or columns containing category labels.
SeriesLabels    The number of rows or columns containing series labels.
HasLegend       Specifies if chart has a legend.
Title           The title text of the chart.
CategoryTitle   Category axis title text.
ValueTitle      Value axis title text.
ExtraTitle      Additional axis title text for some charts.
				

The parameters that are most important to the ChartWizard method are:

• PlotBy
• CategoryLabels
• SeriesLabels

These parameters either determine how your data is going to be set up, or they are initialized to fit the data you have.

To determine the Gallery and Format parameters, you may want to modify the example. Also, you could record the use of the ChartWizard in Excel and see what parameters are used.

All that is left after calling the ChartWizard method is closing the application and object references.

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.
2. Add an OLE 2.0 control to Form1, and choose the Cancel button on the Insert Object dialog.
3. Add a CommandButton (Command1) to Form1.
4. Put the following code in the CommandButton click event.

          Private Sub cmdPrint_Click()
             Me.PrintForm
         End Sub
   
            Private Sub cmdQ147803_Click()
   
               ' Excel chart constants (ODK 1.0 XLCONST.BAS or MsgBox
               ' in Excel):
               Const xlArea = 1
               Const xlBar = 2
               Const xlColumn = 3
               Const xlLine = 4
               Const xlPie = 5
               Const xlRadar = -4151
               Const xlXYScatter = -4169
               Const xlCombination = -4111
               Const xl3DArea = -4098
               Const xl3DBar = -4099
               Const xl3DColumn = -4100
               Const xl3DLine = -4101
               Const xl3DPie = -4102
               Const xl3DSurface = -4103
               Const xlDoughnut = -4120
   
               ' Excel orientation constants:
               Const xlRows = 1
               Const xlColumns = 2
   
               Dim objChart As Object           'Object reference to Excel
                                                'Chart
               Dim objXL As Object              'Object reference for Excel
                                                 App
               Dim objSheet As Object           'Object reference to Excel
                                                'Worksheet
               Dim iRow As Integer              'Index variable for the
                                                'current Row
               Dim iCol As Integer              'Index variable for the
                                                'current Row
               Dim cRows As Integer             'Number of rows
               Dim cCols As Integer             'Number of Columns
               Dim cwSource As String           'Named Range
               Static cwGallery(15) As Integer  'Array for Chart types
               Static iGallery As Integer       'Index for Chart type array
               Dim cwFormat As Integer          'Format of Chart type
               Dim cwPlotBy As Integer          'How data is taken from
                                                'Worksheet
               Dim cwCategoryLabels As Integer  'Rows/Cols with Catagory
                                                'labels
               Dim cwSeriesLabels As Integer    'Rows/Cols with Catagory
                                                'Labels
               Dim cwHasLegend As Integer       'Display Legend
               Dim cwTitle As String            'Chart Title
               Dim cwCategoryTitle As String    'Category Title
               Dim cwValueTitle As String       'Value Title
               Dim cwExtraTitle As String       'Extra Title for some Charts
                                                'disable this button
               cmdQ147803.Enabled = False
               ' Fill in array with possible Chart types:
               cwGallery(1) = xlArea
               cwGallery(2) = xlBar
               cwGallery(3) = xlColumn
               cwGallery(4) = xlLine
               cwGallery(5) = xlPie
               cwGallery(6) = xlRadar
               cwGallery(7) = xlXYScatter
               cwGallery(8) = xlCombination
               cwGallery(9) = xl3DArea
               cwGallery(10) = xl3DBar
               cwGallery(11) = xl3DColumn
               cwGallery(12) = xl3DLine
               cwGallery(13) = xl3DPie
               cwGallery(14) = xl3DSurface
               cwGallery(15) = xlDoughnut
   
               ' Embed a new Excel 5.0 Chart into the OLE control:
               OLE1.CreateEmbed "", "Excel.Chart.5"
               'BEGIN FIX FOR DIFFERING OBJECT MODELS BETWEEN VERSIONS 7 & 8
               ' Set object references to Chart, Worksheet, and Application
               'objects:
               If Left(OLE1.object.Application.Version, 1) = "7" Then
               'Excel 95's object model is different from Excel 97's
                 Set objChart = OLE1.object ' Chart1 default chart
               Else  'assume all future excel object models are going to be
                     'the same
               Set objChart = OLE1.object.ActiveChart 'ole1.object is in
                                                      'Excel 97 the workbook
               End If
               Set objSheet = objChart.Parent.Worksheets(1) ' Sheet1 default
                                                            ' data
   
               Set objXL = objChart.Application
               'END FIX
               ' Set the number of columns and rows used for data:
               cCols = 10
               cRows = 3
   
               ' Create Series Labels on Worksheet:
               For iRow = 1 To cRows
                  objSheet.Cells(iRow + 1, 1).Value = "SL" & iRow
               Next
   
               ' Create Category Labels on Worksheet:
               For iCol = 1 To cCols
                  objSheet.Cells(1, iCol + 1).Value = "CL" & iCol
               Next
               'exiting here leaves the default chart drawn with sample data
               ' Create random data on Worksheet:
               Randomize Timer
               For iRow = 1 To cRows
                  For iCol = 1 To cCols
                     objSheet.Cells(iRow + 1, iCol + 1).Value = _
                  Int(Rnd * 50) + 1
               Next iCol
               Next iRow
   
               ' Name the Range containing the previously added data:
               objSheet.Range(objSheet.Cells(1, 1), objSheet.Cells(cRows + _
               1, cCols + 1)).Name = "ChartDataRange"
               'objSheet.Range(objSheet.Cells(1, 1), objSheet.Cells(cRows + _
               1, cCols + 1)).Clear
               ' Set the ChartWizard parameters:
               cwSource = "ChartDataRange"       'Name of Named Range
               iGallery = iGallery Mod 15 + 1    'Iterate through 15 Chart
                                                 'types
               cwFormat = 1                      'Use default format of Chart
                                                 'Type
               cwPlotBy = xlRows                 'Rows = Series orientation
               cwCategoryLabels = 1              '1 Row contains Category
                                                 'Labels
               cwSeriesLabels = 1                '1 Column contains Series
                                                 'Labels
               cwHasLegend = 1                   'Display the Legend
               cwTitle = "Embedded Chart"        'Chart Title
               cwCategoryTitle = "Categories"    'Category Title
               cwValueTitle = "Values"           'Value Title
               cwExtraTitle = "Extras"           'Extra Title
   
               ' Use the ChartWizard method to fill in the Chart:
               objChart.ChartWizard cwSource, cwGallery(iGallery), cwFormat,
               cwPlotBy, cwCategoryLabels, cwSeriesLabels, cwHasLegend,
               cwTitle,cwCategoryTitle, cwValueTitle, cwExtraTitle
               ' Shut Down Excel and erase objects:
               Set objXL = Nothing
               Set objChart = Nothing
               Set objSheet = Nothing
               'enable this button
               cmdQ147803.Enabled = True
            End Sub
   
         Private Sub cmdXLView_Click()
               OLE1.DoVerb vbOLEOpen
         End Sub
   						

5. Save the project.
6. Run the program, and click the Command1 button. The first chart should be created.
7. Keep clicking the Command1 button to cycle through the 15 Gallery chart types of Format 1.

Notes

• To modify a chart in the OLE control, you must activate the control by first setting the Verb property to -1 (Edit) and then setting the Action property to 7 (OLE_ACTIVATE). Then the Object property will refer to an active object.
• The example uses Format 1 with the ChartWizard method. You may want to experiment with other values.
• After using the ChartWizard method, you can still use objects, methods, and properties of the Chart object to modify it.
• Users will be able to edit the chart by double-clicking the OLE control or by clicking the right mouse button and choosing Edit from the pop-up menu. You can eliminate this ability by setting the AutoActivate and AutoVerbMenu properties of the OLE control.