Spinning a Picture Without Flickering

[Klogg]

In my program, I rotate the image in a PictureBox 180 degrees, showing it every .05 degrees. My problem is that the image flickers because I clear it before it redraws the image at the next angle. However, when I don't clear it, it leaves a mess behind. Does anyone know how to fix this problem? Here is my code:

 

Dim g As Graphics = Graphics.FromHwnd(Handle)
Dim decAngle As Decimal

Me.PictureBox.Visible = False

For decAngle = 180 To 360 Step 0.05
     g.RotateTransform(decAngle)
     g.TranslateTransform(Me.PictureBox.Location.X + Me.PictureBox.Image.Width \ 2, Me.PictureBox.Location.Y + Me.PictureBox.Image.Height \ 2, Drawing2D.MatrixOrder.Append)
     g.DrawImage(Me.PictureBox.Image, Me.PictureBox.Image.Width \ 2, Me.PictureBox.Image.Height \ 2, -Me.PictureBox.Image.Width, -Me.PictureBox.Image.Height)
     g.ResetTransform()
     g.Clear(System.Drawing.SystemColors.Control)
Next decAngle

g.Dispose()

Me.PictureBox.Image.RotateFlip(RotateFlipType.Rotate180FlipNone)
Me.PictureBox.Visible = True

[aewarnick]

Make you own picturebox inheriting from UserControl and

call SetStyle in the contructor to set up DoubleBuffing. Look up DoubleBuffer in search and you will find many posts about this.

[Klogg]

I tried doing what you suggested, but the instructions that I found aren't quite specific enough for a beginner like me. In the PictureBox part of the "Windows Form Designer generated code," I put:

 

Me.SetStyle(ControlStyles.DoubleBuffer, True)
Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)

The rest of my code now looks like this:

 

Private Sub PictureBox_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles PictureBox.Click
       Me.PictureBox.Visible = False

       Me.Invalidate()

       Me.PictureBox.Image.RotateFlip(RotateFlipType.Rotate180FlipNone)
       Me.PictureBox.Visible = True
   End Sub

Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
       Dim g As Graphics = Graphics.FromHwnd(Handle)
       Dim decAngle As Decimal

       For decAngle = 180 To 360 Step 0.05
           g.RotateTransform(decAngle)
           g.TranslateTransform(Me.PictureBox.Location.X + Me.PictureBox.Image.Width \ 2, _
               Me.PictureBox.Location.Y + Me.PictureBox.Image.Height \ 2, Drawing2D.MatrixOrder.Append)
           g.DrawImage(Me.PictureBox.Image, Me.PictureBox.Image.Width \ 2, Me.PictureBox.Image.Height \ 2, _
               -Me.PictureBox.Image.Width, -Me.PictureBox.Image.Height)
           g.ResetTransform()
           g.Clear(System.Drawing.SystemColors.Control)
       Next decAngle

       g.Dispose()
   End Sub

The picture still flickers when it's spinning, and now the Me.PictureBox.Visible = False statement appears to have no effect. Could you please tell me what I did wrong (or didn't do)?

[PlausiblyDamp]

try putting the

Me.SetStyle(ControlStyles.DoubleBuffer, True)
Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)

 

in the form_load event

[Klogg]

Still flickers.

[aewarnick]

You need to paint with the Graphics from OnPaint, not FromHandle. e.Graphics.

 

You don't need that code in Load, just leave it in the constructor.

Also include:

Me.SetStyle(ControlStyles.UserPaint, True)

[aewarnick]

Also, why are you using

g.Clear(System.Drawing.SystemColors.Control)?

 

When you paint in OnPaint, the only thing that will remain on the control is what you paint in each OnPaint event, everything else is reset, or erased.

[Klogg]

I did what you said above, but after I changed the Dim statement to Dim g As Graphics = e.Graphics, it gave me an error when I ran the program. The error was, "An unhandled exception of type 'System.ArgumentException' occurred in system.drawing.dll."

 

Also, I have g.Clear in my code because when I didn't have it, it left behind the picture for every angle it painted it at. I had a square image, and by the time it was done spinning, it was a circle because none of the images were erased.

[Hamburger1984]

...see attachment... !

 

Hope this helps!

 

Andreas

rotate.zip

[Klogg]

Ok, I've got everything figured out except for one thing (I think). I took the For loop out of my OnPaint sub procedure, and that stopped my last problem. I added a timer to control it instead. Now, however, when I put in the Me.SetStyle stuff in, it causes a problem. It's fine until I load an image, then it comes up with the same error that I mentioned in my last post. I don't know why it's doing this or how to stop it.

[aewarnick]

Are you going to post the code?

[Hamburger1984]

uhm in the code you posted above you did a "g.Dispose()"... do you still have this line in your code? because if so this might cause the Error!

 

Andreas

[Klogg]

Yep, it was the g.Dispose(). It works now. Thanks for all of your help for and putting up with my ignorance of GDI+. I learned quite a bit about it from this problem.

[Camaro Z28]

I would create a bitmap in memory and do your graphics stuff to it then apply to your picture box. Nice, Fast, and No flicker at all.

 

 

 

Jason