UserControl and Inheritance

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Good Day,

Please your help in

I have a UserControl which have a class as shown below. This Class a method Called DrawHistogram

C#

namespace Prog1
{
	/// <summary>
	/// Summary description for HistogramaDesenat.
	/// </summary>
	public class HistogramControlClass : System.Windows.Forms.UserControl
	{ ......// Codes 

        }
        public void DrawHistogram(long[] Values)
         {
            //Doing calculation 
         }
		
}

In other hand, I have a Form with the following

C#

namespace Prog1.ImageHistogram
{
    class HistogramEqualization:PNM, HistogramControlClass
    {
//I need to call DrawHistogram here where I used using and multi base class but 
// Still unable to call it

     }
}

Simply, I need to call DrawHistogram from the Form, using "using" and Multibase class but still unable to call it.
Any help is appreciated

Posted 9-Feb-14 5:07am

Stevea2000

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Thomas Daniels · Answer 1 · 2014-02-09T05:21:00

Two things:

First, you put a method inside a namespace:

C#

namespace Prog1
{
	/// <summary>
	/// Summary description for HistogramaDesenat.
	/// </summary>
	public class HistogramControlClass : System.Windows.Forms.UserControl
	{ ......// Codes 

        }
        public void DrawHistogram(long[] Values)
         {
            //Doing calculation 
         }		
}

You can't put a method inside a namespace, you always have to put it inside a class.

Second, HistogramEqualization derives from two classes:

C#

class HistogramEqualization:PNM, HistogramControlClass

This is impossible, because C# does only support multiple inheritance for interfaces. If PNM is an interface, then multiple inheritance is possible in this case. If PNM is a class, then it is not possible.

Solution

First, put the DrawHistogram method inside the HistogramControlClass:

C#

namespace Prog1
{
	/// <summary>
	/// Summary description for HistogramaDesenat.
	/// </summary>
	public class HistogramControlClass : System.Windows.Forms.UserControl
	{ ......// Codes 
             public void DrawHistogram(long[] Values)
             {
                //Doing calculation 
             }
        }		
}

Then, solve the multiple inheritance problem. This is only necessary if PNM is not an interface. A possible solution is to move the properties/fields/methods of PNM to HistogramControlClass.

After solving these problems, you'll be able to call DrawHistogram in HistogramEqualization.

OriginalGriff · Answer 2 · 2014-02-09T05:24:00

Your code fragment shows the DrawHistogram method as not a part of the HistogramControlClass - it is outside the class definition. So if your HistogramControlClass is nested in a different class, then DrawHistogram is a method of that class, not HistogramControlClass.

A quick check says this all works:

C#

public partial class Form1 : Form
    {
    ...
    private void MyMethod()
        {
        HistogramControlClass hcc = new HistogramControlClass();
        hcc.DrawHistogram(new long[10]);
        }
    }
public class HistogramControlClass : UserControl
    {
    public void DrawHistogram(long[] values)
        {
        }
    }
public class HistogramEqualization : HistogramControlClass
    {
    public void MyMethod()
        {
        DrawHistogram(new long[100]);
        }
    }

UserControl and Inheritance

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