.NET/Java PDF, Tiff, Barcode SDK Library

For the really simple lists, Qt offers the QStringListModel. Because lists of items are often kept in QStringList objects in Qt applications, it s nice to have a model that takes a string list and works with all views. Listing 5-8 shows how the QStringList object list is created and populated. A QStringListModel is created, and the list is set with setStringList(const QStringList&). Finally, the list is used in the list view. Listing 5-8. Using the QStringListModel to populate a QListView QListView list; QStringListModel model; QStringList strings; strings << "Huey" << "Dewey" << "Louie"; model.setStringList( strings ); list.setModel( &model );

barcode generator excel 2007 free, barcode font for microsoft excel 2007, excel 2007 barcode formula, barcode add in excel 2007, create barcodes in excel 2010 free, activebarcode excel 2010, microsoft excel barcode generator free, active barcode excel 2007 download, excel barcode inventory, barcode add in for excel free,

private void myButton_Click(object sender, RoutedEventArgs e) { messageText.Text = "Hello, world!"; }

Because the Xaml refers to this handler method in the Button element s Click attribute, the method will run anytime the button is clicked. The one line of code we added here refers to the TextBlock element. If you look at the Xaml, you ll see that the element s x:Name attribute has a value of messageText, and this lets us use this name in the code behind to refer to that element. Example 20-2 sets the Text property, which, as you ve no doubt guessed, causes the TextBlock to show the specified text when the button is clicked.

In this example, you will continue looking at binding information between controls but will look a little further into the data transformation by using a custom transformation. In this page there is a text box, a selection list, and a label. When you type something into the text box and tab out of it, the label will display the text you typed using the color specified in the selection list. You can achieve this, as you would expect, through a binding between the label and

Just to be clear, this is happening on the client side. The Silverlight plugin downloads your application and then renders the UI as defined by your Xaml. It hosts your code behind (and any other code in your Silverlight project) inside the web browser process, and calls the specified event handlers without needing to communicate any further with the web server. Silverlight applications can communicate back with the web server after being loaded, but this click-handling interaction does not involve the server at all, unlike clicking a button on a normal web form.

Being able to show models through existing views can be useful, but sometimes you need to be able to customize the views to your own needs. There are two approaches to this: either build a delegate from the QAbstractItemDelegate class or create a completely custom view from the QAbstractItemView class. Creating a delegate is the easiest approach, so start there. The views shipped with Qt all use delegates to draw and edit its items. By creating a delegate for drawing a row or a column or all items in a view you can usually get the look and feel that you need.

The Xaml in Example 20-1 and the C# in Example 20-2 both set the Text of the TextBlock. The Xaml does this using standard XML s attribute syntax, while the C# code does it using normal C# property syntax. This highlights an important feature of Xaml: elements typically correspond to objects, and attributes correspond either to properties or to events.

Although Xaml is the usual mechanism for defining the user interface of WPF and Silverlight applications, it s not strictly necessary. You could remove the bold code in Example 20-1 that adds the Button and TextBlock to the Xaml, and instead modify the class definition and constructor in the code behind, as Example 20-3 shows.

public partial class MainPage : UserControl { private Button myButton; private TextBlock messageText; public MainPage() { InitializeComponent(); myButton = new Button { HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Top, FontSize = 20, Content = "Click me!" }; myButton.Click += myButton_Click; messageText = new TextBlock { Text = "Message will appear here", TextWrapping = TextWrapping.Wrap, TextAlignment = TextAlignment.Center, FontSize = 30, FontWeight = FontWeights.Bold, HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center }; LayoutRoot.Children.Add(myButton); LayoutRoot.Children.Add(messageText);

}

Start by creating a delegate to show integer values as a bar. The delegate can be seen in action in the table view shown in Figure 5-5. The bars range from 0 100, where 0 is just a thin line in blue, and 100 is a full green bar. If the value exceeds 100, the bar turns red to indicate that it is out of range.

Each element that had an x:Name attribute has been replaced here with a field in the class, and we initialize that field in the constructor This example uses the C# object initializer syntax to set the property values to emphasize the structural similarity between this code and the Xaml it replaces, but normal property setter syntax works too, of course XML attribute values are just text, whereas in C# we have to provide values of the correct type enumeration entries, numbers, or strings as appropriate The Xaml compiler works out how to turn text into something of the appropriate type (It uses the NET Framework class library s TypeConverter system to do this.