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Use Reflection To Generate Complete Color Chart

In GDI+, for drawing any item we need to pick up a color for either creating a brush or a pen. .NET framework has provided System.Drawing.Color structure which contains 141 colors. That makes life pretty easy. But there are some developers like me who have hard time corelating the color names with what actually they look like.

To solve this probelm, we decided to come up with a chart that will display all the colors along with the names used in Color structure. The crude approach could have been that we use a huge switch statement with each case representing the colors defined in the structure.

But there is a very nice approach that we took. .NET framework procides a very powerful feature called Reflection. All the colors in System.Drawing.Color structure are declared as public static properties. So the idea is pretty simple.

  • Get Type of System.Drawing.Color strcuture.
  • Call GetProperties method on Type instance. Make sure that you use the appropriate BindingFlags attribute to get only the properties that are of interest. In our case we are only interested in public static properties. Therefore we will use BindingFlags.Public, BindingFlags.Static and BindingFlags.DeclaredOnly ORed together. The purpose of specifying BindingFlags.DeclaredOnly attribute is to get only the static properties that are declared only in this class only. We are not interested in properties of any parent class or structure.
  • Iterate through each item in PropertyInfo array value returned by GetProperties method. Call Name property on PropertyInfo object to get the name of each color. And call GetValue method to get the actual value of Color.
  • Rest is just implementation detail and book keeping on how to arrange all the colors on the bitmap and display it as a chart.

The complete code is attached with the article. Take a look at it for details.

Color testColor = Color.AliceBlue;
Type colorType = testColor.GetType();
if (null != colorType)
{
	PropertyInfo[] propInfoList =
	 colorType.GetProperties(BindingFlags.Static|BindingFlags.DeclaredOnly|BindingFlags.Public);
	int nNumProps = propInfoList.Length;
	for (int i = 0; i < nNumRows; i++)
	{
		PropertyInfo propInfo = (PropertyInfo)propInfoList[nIdx];
		Color color = (Color)propInfo.GetValue(null, null);
		string strColorName = propInfo.Name;
	}
}							
									

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