C# 4 and .NET 4

1128 ❘ ChaPTer 39 windOws fOrms
If the values in the list are wide, you can change the width of the drop-down portion of the control with
the DropDownWidth property. The MaxDropDownItems property sets the number of items to show when the
drop-down portion of the list is displayed.
The FindString and FindStringExact methods are two other useful methods of the list
controls. FindString finds the first string in the list that starts with the passed-in string. FindString
Exact finds the first string that matches the passed-in string. Both return the index of the value that
is found or -1 if the value is not found. They can also take an integer that is the starting index to search
from.
Lastly, the CheckedListBox control is similar to the ListBox; however, the DisplayMember and
ValueMember properties do not show up in IntelliSense, nor do they display in the property grid.
They are available on the actual control, but an attribute has been added to them to indicate that they
are not used. This is not the case — you can use DisplayMember to determine what will show up on the
user interface, or as an alternative, you can simply override the ToString() method on the objects
you are adding into this list to display whatever you like onscreen.
The datagridView Control
The DataGrid control that has been available from the initial release of .NET was functional, but it had
many aspects that made it unsuitable for use in a commercial application — such as an inability to display
images, drop-down controls, or lock columns, to name but a few. The control always felt half-completed,
so many control vendors provided custom grid controls that overcame these deficiencies and also provided
much more functionality.
.NET 2.0 introduced an additional Grid control — the DataGridView. This addressed many of the
deficiencies of the original control, and added significant functionality that previously was available only
with add-on products.
The DataGridView control has binding capabilities similar to the old DataGrid, so it can bind to an Array,
DataTable, DataView, or DataSet class, or a component that implements either the IListSource or IList
interface. It gives you a variety of views of the same data. In its simplest guise, data can be displayed (as in
a DataSet class) by setting the DataSource and DataMember properties — note that this control is not a
plugin replacement for the DataGrid, so the programmatic interface to it is entirely different from that of
the DataGrid. This control also provides more complex capabilities, which are discussed in the course
of this chapter.
In this section we use the Northwind sample database. If you don’t already have it installed, please
download the installer from the Web and create a database called Northwind in your SQL Server or SQL
Express instance. You can find the installation scripts for Northwind at http://msdn.microsoft.com/
enus/library/ms143221.aspx.
Displaying Tabular Data
Chapter 20, “Threads, Tasks, and Synchronization,” introduced numerous ways of selecting data and
reading it into a data table, although the data was displayed in a very basic fashion using Console
.WriteLine().
The following example demonstrates how to retrieve some data and display it in a DataGridView
control. For this purpose, you will build a new application, DisplayTabularData, shown
in Figure 39-2.
www.it-ebooks.info