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vb 2008 drawline not working in Vista

Posted on 2009-04-12
Medium Priority
Last Modified: 2013-11-08
What am I missing here?

I am using Visual Basic Express 2008.

I have a working pilot logbook and flight planning application, which was written, compiled, and functions well in Windows XP on my old PC.

The application  uses e.graphics.drawline, e.graphics.drawcircle, e.graphics.drawarc, e.graphics.drawellipse and e.graphics.drawrectangle to draw a simple flight plan chart.

When I compile the code and run it on my new laptop (Sony Vaio VGN-NS15G) none of the lines, arcs, circles or rectangles appear. There are no runtime errors.

The rest of the programme runs fine on the laptop. It is just the graphics functions that are ignored so I am assuming it is a result of some setting or switch that I have missed  to make the graphics visible on the Vista laptop.

What am I overlooking?

Question by:bantamb20
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LVL 15

Accepted Solution

oobayly earned 2000 total points
ID: 24129260
I'm guessing from you example that the lines etc. are being drawn in the OnPaint event. What type of control are you painting onto? Also, have you added a breakpoint in the OnPaint event to verify that it's being executed?

A workaround could be to create a bitmap on which you draw your flight plan, and then set the bitmap as the Image for a PictureBox control. The bonus with doing this is that you only have to draw the image once, not ever time the control gets redrawn, and also you'll be able to save the image (if you're so inclined)

Author Comment

ID: 24132731

I am painting to the form  using the form_paint subroutine, not OnPaint.
This process works fine in the XP environment.

First the DrawAll sub is executed, which contains the various subs to draw each portion of the flight plan. This enabled me to debug the earlier version easily, and allows users to choose various overlays, add text for latitude and longitude, names of places and so on.
All this worked fine in  XP.

I have checked with breakpoints, and yes it is executing all the code.

I have attached the form_paint code, the DrawAll sub, and the simplest of the  other subs it calls, the DrawBorder sub.

Your suggestions of using OnPaint and drawing to a bitmap are good ones. I will investigate and see what's involved to change the present method of drawing the plan.

I am going flying today so won't be able to complete the task now, but will get on to it asap.


    ' ==================================================================
    '  paint this form and draw the flight track and other little bits
    ' ------------------------------------------------------------------
    Private Sub frmShowMap_Paint(ByVal sender As Object, ByVal e As  _
    System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
            If bGo Then
                Cursor = Cursors.WaitCursor
            End If
        Catch ex As Exception
            Cursor = Cursors.Default
        End Try
        Cursor = Cursors.Default
    End Sub
    ' ==================================================================
    '  draw background map, aircraft tracks, zone, area boundaries,text 
    ' ------------------------------------------------------------------
    Private Sub DrawAll(ByVal e As PaintEventArgs)
            If bGo = True Then
                bGo = False
                ' draw debugging grid
                ' draw border around map area
                ' draw nz background map
                DrawNZMap(e, bShowMap)
                ' draw latitude and longitude grid
                DrawGrid(e, bShowGrid)
                ' draw airport control zones CTR. if files exist and zones in area, draw them
                If CTZFindFiles() And CTZonesInArea() Then CTZonesDraw(e, bShowCTZones)
                ' draw danger areas 
                ' draw temporary airspace restrictions
                ' draw tracks and aerodromes and waypoints
                DrawTracks(e, bShowTrack)
                ' write mag heading or distance and leg time text along track line 
                DrawText(e, bShowText)
            End If
        Catch ex As Exception
            MsgBox(ex.Message & " drawmap error")
        End Try
    End Sub
    ' ==========================================================
    '  draw border around map
    ' ----------------------------------------------------------
    Private Sub DrawBorder(ByVal e As PaintEventArgs)
            e.Graphics.DrawRectangle(Pens.Black, 2, 2, MEWIDTHH, MEHEIGHT)
        Catch ex As Exception
            MsgBox(ex.Message & " --- drawborder")
        End Try
    End Sub

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LVL 15

Expert Comment

ID: 24132776
Now that's a hobby/job I wouldn't mind having.

If the Paint event doesn't do the job, I very much doubt that the OnPaint override would do the job. I can only imagine it's an effect of the Aero interface. Not that I've seen any mention of there being issues with drawing on a form's graphics object in Vista.

Author Comment

ID: 24142166

I have re-written the map display section to draw to a bitmap and display it on  a picture box.  It works well thanks

[The flying (microlights) and the coding are both hobbies . . .  one more expensive than the other]

Author Closing Comment

ID: 31569395
The programme now works well in Vista as well as XP with this bitmap solution, it's a sunny day ... time to go flying and turn some petrol into noise . . . cheers

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