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Customising the .NET Panel control

, 15 Sep 2004 CPOL
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An article on customising the .NET Panel control to give it a gradient fill, and round corners.

Sample Image - custompanel.png


Whenever I use a Windows Panel, the first thing that annoys me with the default .NET Panel is the inability to set the border color. This is closely followed by the lack of gradients and rounded corners. As you can see from the screen shot above, a gradient fill with rounded corners makes for a very simple imitation of an XP style command button.


Since various people have asked me for Fixed3D borderStyle support, and I have found a number of small, but annoying problems with the positioning of this panel control I have updated the code. However it was not easy. Setting the borderStyle to Fixed3D has the nasty effect off adding a 3D border to all the children of the control! Consequently this version includes a method to draw my own 3D border. When using this style the panel will always be rectangular.


The easiest way to enhance a control is by visual inheritance, although there are one or two things to watch out for.

There is a big difference between Overriding a property and Shadowing a property. If you override a property then any code in the base class which uses that property will call the code in the inherited class, whereas shadowing a property leaves the base class calling its own code and the shadowed property will only be available in the inherited class.

In C#, the override modifier is used instead of the VB Overrides modifier, and the new modifier is used instead of the VB Shadows modifier.

Some controls do not allow transparent backgrounds. Fortunately, the Windows Panel control does.

One very useful property of all controls is DesignMode. This can be used to discover if the control is in a run-time, or design-time environment.

The Solution

Some of the important parts of the solution are as follows.

We must ensure that transparent backgrounds are supported, and that we have full control of painting the control by adding the following code to the constructor:

Me.SetStyle(System.Windows.Forms.ControlStyles.DoubleBuffer, True)
Me.SetStyle(System.Windows.Forms.ControlStyles.AllPaintingInWmPaint, False)
Me.SetStyle(System.Windows.Forms.ControlStyles.ResizeRedraw, True)
Me.SetStyle(System.Windows.Forms.ControlStyles.UserPaint, True)
Me.SetStyle(System.Windows.Forms.ControlStyles.SupportsTransparentBackColor, True)
MyBase.BackColor = System.Drawing.Color.Transparent

ResizeRedraw makes sure that the control will repaint itself if you stretch it, and DoubleBuffer makes the drawing happen off-screen so as to reduce flickering.

Always remember to dispose off drawing objects as they wrap the unmanaged GDI+ API and will chew up resources if left hanging.

Using the code

As you will see, in the demo solution, it is very easy to make the panels 'Hot' by swapping the colors over on mouse enter and leave.

To use the control, make sure you have the control and the enum in your solution, build it, add the custom panel to your Toolbox, and away you go. The new or enhanced properties are:

  • BackColor - Shadows the basic BackColor property.
  • BackColor2 - The second color of the gradient background.
  • GradientMode - The direction of the gradient (defaults to none).
  • BorderStyle - Only the FixedSingle works in this sub-class.
  • BorderWidth - Controls the width of the border.
  • BorderColor - The color of the border.
  • Curvature - The radius of the curve used to draw the corners of the panel.
  • CurveMode - The style of the curves to be drawn on the control.


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


About the Author

The Man from U.N.C.L.E.
Software Developer
United Kingdom United Kingdom
Unfortunately my real name was already in use as a code project login. For those of you who are wondering I am really Napoleon Solo. Sorry, I mean, Mark Jackson. Well, I do look a bit like him I think.

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Comments and Discussions

GeneralTransparent controls Pin
jdkl5415-Jun-10 3:08
memberjdkl5415-Jun-10 3:08 
GeneralIncorrect redrawing when scrolling Pin
crypto_rsa28-May-10 2:25
membercrypto_rsa28-May-10 2:25 
GeneralRe: Incorrect redrawing when scrolling Pin
The Man from U.N.C.L.E.28-May-10 2:40
memberThe Man from U.N.C.L.E.28-May-10 2:40 
GeneralUnable to download code Pin
hswear38-Apr-10 16:33
memberhswear38-Apr-10 16:33 
GeneralRe: Unable to download code Pin
hswear38-Apr-10 16:35
memberhswear38-Apr-10 16:35 
QuestionError BC30002 - Type MyApp.CustomPanel is not defined Pin
Member 31389385-Apr-10 11:09
memberMember 31389385-Apr-10 11:09 
QuestionFlickering Issue Pin
PareshM22-Jan-09 3:31
memberPareshM22-Jan-09 3:31 
AnswerRe: Flickering Issue Pin
Yann Romefort4-Mar-09 23:10
memberYann Romefort4-Mar-09 23:10 
GeneralMine works great! Thanks for the code! Pin
234wer28-Oct-08 16:22
member234wer28-Oct-08 16:22 
GeneralC++ /CLI Pin
Xaria14-Oct-08 20:01
memberXaria14-Oct-08 20:01 
AnswerRe: C++ /CLI Pin
The Man from U.N.C.L.E.14-Oct-08 23:46
memberThe Man from U.N.C.L.E.14-Oct-08 23:46 
QuestionBlack edges Pin
laith_b29-Apr-08 11:23
memberlaith_b29-Apr-08 11:23 
QuestionProgrammatically created CustomPanel is not transparent Pin
DustinDS24-Aug-07 6:16
memberDustinDS24-Aug-07 6:16 
GeneralExcellent component! Pin
philnad13-Jul-07 8:41
memberphilnad13-Jul-07 8:41 
QuestionBackground image? Pin
sgmisguided14-Jun-07 20:25
membersgmisguided14-Jun-07 20:25 
AnswerRe: Background image? Pin
ca0v23-Oct-07 9:08
memberca0v23-Oct-07 9:08 
Generalusing and import Pin
roel_v13-Mar-07 0:40
memberroel_v13-Mar-07 0:40 
GeneralCustom Panel having a User Control Pin
srinivas_vemla22-Nov-06 12:54
membersrinivas_vemla22-Nov-06 12:54 
Question1-pixel width missing from Top and Left.. [modified] Pin
skurs25-Oct-06 8:21
memberskurs25-Oct-06 8:21 
AnswerRe: 1-pixel width missing from Top and Left.. Pin
boohooo9-Mar-09 1:58
memberboohooo9-Mar-09 1:58 
QuestionAdding the Control to the Toolbox in VB .NET Pin
skurs19-Oct-06 8:57
memberskurs19-Oct-06 8:57 
AnswerRe: Adding the Control to the Toolbox in VB .NET Pin
skurs19-Oct-06 11:47
memberskurs19-Oct-06 11:47 
AnswerRe: Adding the Control to the Toolbox in VB .NET Pin
The Man from U.N.C.L.E.20-Oct-06 0:02
memberThe Man from U.N.C.L.E.20-Oct-06 0:02 
QuestionControls not visible at runtime Pin
Hakkoos12-Oct-06 1:03
memberHakkoos12-Oct-06 1:03 
AnswerRe: Controls not visible at runtime Pin
Hakkoos23-Oct-06 6:33
memberHakkoos23-Oct-06 6:33 

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