Data Source 

 First, let’s generate some data to display via the chart.   We will create it at design time  to allow us to get on with the core Graphics Class parts of the project.  If you prefer to have the data input by the user at run time then you can adapt the techniques covered in Part 3.

Create Data

  Shown below is what has become  our standard code  to create initial variables and to generate  and store some data.   I won’t trundle through the details as they are fully covered in earlier articles:

Option Strict On

Imports System.Drawing.Drawing2D
Imports System.Collections

Structure GraphData
        Dim Country As String
        Dim Sales As Integer
        Dim BarColor As Color
        Sub New(ByVal country As String, ByVal sales As Short, ByVal barcol As Color)
            Me.Country = country
            Me.Sales = sales
            Me.BarColor = barcol
        End Sub
    End Structure

'  Create Variables

‘ # of pixels vertical Axis is inset from PictureBox Left
    Dim LeftMargin As Integer = 35
    '  # of Pixels left unused at right side of PictureBox
    Dim RightMargin As Integer = 15
    '  The number of pixels above bottom of baseline
    Dim BaseMargin As Integer = 35
    '  Margin at Top
    Dim TopMargin As Integer = 10
    '   Set size of gap between each bar
    Dim BarGap As Integer = 12

    Dim SalesData As New ArrayList 
    Dim HighSale As Double  ' Maximum sales figure
    Dim VertScale As Double  ' Scaling used for bar heights

  '   Minor changes for this version:
  '   Declare a variable to hold a Graphics object
        Dim g As Graphics
  '  Variable for Bitmap to be displayed in (PictureBox) control
    Dim bmap As Bitmap
  '  Length of vertical axis
    Dim VertLineLength As Integer
Dim BarWidth As Integer  ' width of bars
Dim BaseLineLength As Integer  ' X Axis length

Private Sub GetData()
        SalesData.Clear() ' Avoid data duplication
        '  Generate some data and store it in the arraylist
        SalesData.Add(New GraphData("Belgium", 934, Color.Blue))
        SalesData.Add(New GraphData("Greece", 385, Color.DarkOrange))
        SalesData.Add(New GraphData("Portugal", 1029, Color.Green))
        SalesData.Add(New GraphData("Spain", 729, Color.IndianRed))
        SalesData.Add(New GraphData("Turkey", 1472, Color.Tomato))
        SalesData.Add(New GraphData("UK", 1142, Color.Aquamarine))
End Sub

Controls

   Add a PictureBox named PBBarChart and a Button named btnDraw to the Form. 

  Place the button somewhere down in the bottom corner of the Form.

   Stretch the PictureBox so that it is close to the top, right and left edges of the form.   Set its Anchor property so that it is anchored to all four sides.  Doing this will allow the user to click the button for a resized version of the chart to be displayed whenever the form size is altered .   (As we will see in later articles, there are more dynamic ways of achieving this, but we’ll stick with this method for now.)