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im trying to figure out how to make a pie chart to visualize statistics in my program. however ive never done anything in the graphics department for VB. i cant find to much on google on the subject and what i can i dont get or it doesnt work. can anybody show me a simplistic way to draw a pie chart please?
Using simple VB methods, a crude pie chart can be created rather easily. The example below shows that.
Some notes
1) VB draws arcs counter-clockwise.
2) VB uses radians not angles, therefore, a conversion is needed
3) In the example below, I used 10 percentages which total to 100%, 10 pies. If you will be using the pie chart for similar purposes, you must ensure the total is never > 100%
Add a command button and picturebox. Make the picturebox the size of the circle/pie you desire
Then paste this code. I commented the code a bunch. Hopefully you can follow it easily
Code:Private Sub Command1_Click()
Dim midPt As Long, endPt As Double
Dim angle As Double, startPt As Double
Dim totalPct As Double, Radius As Long
Dim x As Long
Dim RadianRatio As Double
Dim lGrayScaleColor As Long
Dim samplePcts(9) As Double
samplePcts(0) = 5: samplePcts(1) = 15
samplePcts(2) = 20: samplePcts(3) = 15
samplePcts(4) = 5: samplePcts(5) = 9
samplePcts(6) = 10: samplePcts(7) = 12
samplePcts(8) = 3: samplePcts(9) = 6
' to color the pies
Picture1.FillStyle = vbSolid
' VB's arc draws counter-clockwise from W > N > E > S > W
' 90
'
' 180 0/360
'
' 270
' VB uses radians not degrees. Following multiplied against angle = radians
RadianRatio = (Atn(1) * 4) / 180
' set midpoint where circle will be centered around
If Picture1.ScaleWidth > Picture1.ScaleHeight Then
midPt = Picture1.ScaleHeight \ 2
Else
midPt = Picture1.ScaleWidth \ 2
End If
' radius of the circle/arc
Radius = midPt
' start on the 0 degree mark. Note we want -values and you can't get -0 but can get -360
startPt = 360 * RadianRatio
For x = 0 To 9 ' process the percentages which total to 100
totalPct = totalPct + samplePcts(x)
angle = (360 * totalPct) / 100
endPt = angle * RadianRatio
' set the pie color (grayscale)
lGrayScaleColor = x * 20
Picture1.FillColor = RGB(lGrayScaleColor, lGrayScaleColor, lGrayScaleColor)
' vbWhite below is the outline color
' negative startpt & endpt values closes the arc vs opened arc
Picture1.Circle (midPt, midPt), Radius, vbWhite, -startPt, -endPt
startPt = endPt ' set next pie start pos to last pie's end pos
Next
End Sub
thank you for your response. your code doesnt seem to work on my version of VB (visual basic 2008 express). i altered the code to draw on the form itself. however its buggy and i cant figure out why. it skips all but 2 of the slices. i imagine i buggered something up rewriting your code. here is my code and an attached pic of the pie
Code:Private Sub Form3_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
Dim dblIncome, dblMonth, dblTransit, dblSelf, dblDaily, dblSum As Double
dblMonth = CDbl(Form1.lblTotalMonth.Text)
dblTransit = CDbl(Form1.lblTotalCar.Text)
dblSelf = CDbl(Form1.lblTotalSelf.Text)
dblDaily = CDbl(Form1.lblTotalOther.Text)
dblIncome = CDbl(Form1.lblTotal.Text)
If dblIncome < 0 Then
dblIncome = 0
End If
dblSum = dblMonth + dblTransit + dblSelf + dblDaily + dblIncome
dblIncome = (dblIncome / dblSum)
dblMonth = (dblMonth / dblSum)
dblTransit = (dblTransit / dblSum)
dblSelf = (dblSelf / dblSum)
dblDaily = (dblDaily / dblSum)
Dim startPt, endPt, angle, totalPct As Double
Dim intx, Radius As Integer
Dim RadianRatio As Double
Dim Percents(4) As Double
Percents(0) = dblIncome
Percents(1) = dblMonth
Percents(2) = dblTransit
Percents(3) = dblSelf
Percents(4) = dblDaily
Dim Colors(4) As Color
Colors(0) = Color.Green
Colors(1) = Color.Blue
Colors(2) = Color.Cyan
Colors(3) = Color.Gray
Colors(4) = Color.Aqua
RadianRatio = (3.14159265 / 180)
startPt = 0
Radius = 200
For intx = 0 To 4
Dim BrushColor As New Drawing.SolidBrush(Colors(intx))
totalPct = totalPct + Percents(intx)
angle = (360 * totalPct)
endPt = angle * RadianRatio
e.Graphics.FillPie(BrushColor, 185, 40, Radius, Radius, CInt(-startPt), CInt(-endPt))
startPt = endPt
Next
lblIncomeStat.Text = FormatPercent(dblIncome)
lblMonthlyStat.Text = FormatPercent(dblMonth)
lblTransitStat.Text = FormatPercent(dblTransit)
lblSelfStat.Text = FormatPercent(dblSelf)
lblDailyStat.Text = FormatPercent(dblDaily)
End Sub
Sorry, I gotta bug out, not a .Net user.
I don't know how FillPie works. Though it looks very similar to VB6's Circle method.
I see you are using negative values though. And if you set startPt at zero, it can't be negative (no such thing as -0). Could that be the problem? Try starting startPt out as 360*RadianRatio
i changed startpt back to 360 * radianratio but it still has the same prob. what i dont understand is i set the first color to be green but it starts at blue. is it a problem in the design of the for loop?
I can't really help that much as I'm not a .Net guy. But I don't think it is the loop necessarily. I just think the first pie isn't drawing. You may want to verify startPt and endPt. Also, are you sure CInt() should be used for the start/end points? I would think that would round/up down the decimal values? Again, I'm not familiar with the FillPie function
i didnt initially convert it to integer but option stict was having a problem with doubles in the fillpie method
Try singles, not doubles, per this MSDN linkQuote:
Originally Posted by Aest
Edited: Also ensure .Net's FillPie requires radians, just maybe, it requires degrees? Check your help files or search forum/google for FillPie
you know what, i got so involved with the graphics that thought didnt even occur to me. im getting a full cyan circle now but at least its a full circle. ill just fiddle around with this but hopefully this is in the right direction. thanks for all your help
yup i got it working now. now that i knew how to word it correctly i found out what i need on google. turns out the method is (brush, x coordinate, y coordinate, length, height, start angle, sweep angle). so the endpt was actually just 360 * percents(intx) and the startpt was startpt = startpt + angle. and of course what opened my eyes in the first place was the angle was in degrees. thanks so much for your help
Glad you got it figured out. One of these days, soon maybe, I'll start to play with .Net and you'll be able to answer my questions :)
Don't forget to mark this resolved, if it is now resolved. Use the Thread Tools menu near the top of your first post above.