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How to write a loading circle animation in .NET?

, 15 Feb 2007 CPOL 421.1K 23.9K 445
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A new kind of progress bar for .NET 2.0.

Sample Image - mrg_loadingcircle.jpg

Introduction

When it's time to wait, we are used to seeing the classic blue progress bar. It is everywhere in Windows and many other applications. However, animations are getting more and more popular.

For example, when Firefox loads a page, a small spinning circle appears and shows you that the page is loading. Moreover, Microsoft also uses this kind of animation in the Windows Media Center, Encarta 2006, SQL Server Management Studio Express, etc.

So, why don't we use this concept to show to our users that our application is working and/or loading? Let's begin by the presentation of the component I developed.

Points of interest

Rotation speed

The LoadingCircle uses a timer, and it has two responsibilities: to determine the color of the next spoke, and to redraw the circle at a specified number of milliseconds. When you use the property RotationSpeed, you modify the timer's property named Interval. Higher the value is, slower will be the rotation. The default rotation speed is 80, so at every 80 milliseconds, the circle will be redrawn.

How to draw a spoke?

First of all, we need coordinates for each spoke. We use the function DrawLine of GDI+, which needs two points, the beginning and the end of the line.

So, let's review some simple math notions. In order to draw a perfect circle, you have to know the following trigonometry concept: the cosines of an angle in degrees give us the X and the sine gives us the Y.

The method GetCoordinate computes, for a specified radius and angle, the coordinates of a point.

private PointF GetCoordinate(PointF _objCircleCenter, 
               int _intRadius, double _dblAngle)
{
      PointF objPoint = new PointF();
      double dblAngle = Math.PI * _dblAngle / NUMBER_OF_DEGREES_HALF_CIRCLE;
      objPoint.X = _objCircleCenter.X + _intRadius * (float)Math.Cos(dblAngle);
      objPoint.Y = _objCircleCenter.Y + _intRadius * (float)Math.Sin(dblAngle);
      return objPoint;
}

The method DrawLine uses the coordinates computed by GetCoordinate, and draws a line with the two specified points and a color. Of course, we have to pass to this method the Graphics object of GDI+. As you can see, each line is rounded with the properties StartCap and EndCap of the Pen object.

private void DrawLine(Graphics _objGraphics, PointF _objPointOne, 
                      PointF _objPointTwo, 
                      Color _objColor, int _intLineThickness)
{
      using(Pen objPen = new Pen(new SolidBrush(_objColor), _intLineThickness))
      {
            objPen.StartCap = LineCap.Round;
            objPen.EndCap = LineCap.Round;
            _objGraphics.DrawLine(objPen, _objPointOne, _objPointTwo);
      }
}

How to use this component?

This component is quite easy to use. Once added to your toolbox, drag it to your form, and you are in business! Now, all you have to do is to play with the properties which change the look of the circle. Those are under the category "LoadingCircle" in the Properties panel. Also, you can change the Active property to true or false to see the animation running or not.

The component has the following properties.

  • Color - The color of an inactive spoke.
  • OuterCircleRadius - This property is the radius of the outer circle. The value of this property is supposed to be higher than the InnerCircleRadius value.
  • InnerCircleRadius - This property is the radius of the inner circle.
  • NumberSpoke - This property is the number of spokes.
  • Active - Defines if the component is animated or not. So, if tour treatment is in progress, this property should be set to true, otherwise false.
  • SpokeThickness - Thickness of the line in pixel.
  • RotationSpeed - Animation speed. Lower is the value, faster is the animation.

Conclusion

Finally, I wish you will find this component useful. I had fun writing it, and wish you will use it. Thanks for reading this article.

Revision history

  • June 17, 2006 : Initial release.
  • February 05, 2007 : Better color management (alpha blending)
  • February 10, 2007 : Presets defined in the control (MacOS X, Internet Explorer 7 and FireFox). A new control has been added: LoadingCircleToolStripMenuItem. This control is compatible with the StatusStrip! Supports transparency. Some minors bug corrections.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Martin Gagne
Web Developer
Canada Canada
No Biography provided

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Comments and Discussions

 
GeneralPLZ Pin
Member 117372329-Jun-15 18:31
memberMember 117372329-Jun-15 18:31 
QuestionTransparency problem Pin
gorgicze8-Mar-15 7:33
membergorgicze8-Mar-15 7:33 
SuggestionNuGet package? Pin
Brett Hysuik30-Jan-15 12:17
memberBrett Hysuik30-Jan-15 12:17 
GeneralMy vote of 5 Pin
nitin@codeproject27-Nov-14 22:44
membernitin@codeproject27-Nov-14 22:44 
QuestionChange it's Size Pin
Elaheh Ordoni9-Sep-14 3:09
memberElaheh Ordoni9-Sep-14 3:09 
AnswerRe: Change it's Size Pin
Elaheh Ordoni9-Sep-14 18:17
memberElaheh Ordoni9-Sep-14 18:17 
GeneralVery nice Pin
Marcel Breu29-Sep-13 4:29
memberMarcel Breu29-Sep-13 4:29 
GeneralMy vote of 4 Pin
ravithejag8-Aug-12 20:11
memberravithejag8-Aug-12 20:11 
QuestionVery nice control + a question Pin
alex__b11-Jul-12 9:26
memberalex__b11-Jul-12 9:26 
QuestionWindowsFormsHost Pin
flobadob19754-Jul-12 4:44
memberflobadob19754-Jul-12 4:44 
QuestionError "Cannot embed interop types from assembly" Pin
NewOrdered130-May-12 2:04
memberNewOrdered130-May-12 2:04 
GeneralMy vote of 5 Pin
pcs041425-Apr-12 3:26
memberpcs041425-Apr-12 3:26 
AnswerAngles of spokes are shifted anticlockwise - any ideas? Solved! Pin
GuyThiebaut25-Mar-12 9:17
memberGuyThiebaut25-Mar-12 9:17 
GeneralMy vote of 5 Pin
GuyThiebaut25-Mar-12 6:17
memberGuyThiebaut25-Mar-12 6:17 
GeneralMy vote of 5 Pin
manoj kumar choubey18-Feb-12 3:08
membermanoj kumar choubey18-Feb-12 3:08 
QuestionDoes not support threading Pin
elhenawyk20062-Feb-12 6:08
memberelhenawyk20062-Feb-12 6:08 
AnswerRe: Does not support threading Pin
Martin Gagne18-Feb-12 11:23
memberMartin Gagne18-Feb-12 11:23 
Questionreally cool... Pin
Avrajit24-Nov-11 4:08
memberAvrajit24-Nov-11 4:08 
QuestionCompact Framework Pin
stijn.vandenbroucke9-Oct-11 3:36
memberstijn.vandenbroucke9-Oct-11 3:36 
QuestionLike !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Pin
raananv31-Aug-11 12:51
memberraananv31-Aug-11 12:51 
GeneralMy vote of 5 Pin
v# guy2-Sep-10 3:37
memberv# guy2-Sep-10 3:37 
GeneralVery Nice Pin
Khaniya7-Mar-10 21:48
memberKhaniya7-Mar-10 21:48 
Generaljust an observation Pin
binarydude200131-Jan-10 15:59
memberbinarydude200131-Jan-10 15:59 
Generalwell done Pin
prolingua.geo8-Nov-09 23:02
memberprolingua.geo8-Nov-09 23:02 
GeneralNice Work !!! Pin
RicardoPDV13-Aug-09 12:14
memberRicardoPDV13-Aug-09 12:14 

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