Namespaces in VB.NET

Painting QR Code in VB.NET Namespaces

Namespaces
Denso QR Bar Code Creator In Visual Basic .NET
Using Barcode generator for VS .NET Control to generate, create Denso QR Bar Code image in VS .NET applications.
www.OnBarcode.com
QR Code 2d Barcode Reader In VB.NET
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
We ll now elaborate on the XAML file structure. Two important namespaces, similar for regular WPF application XAML files, appear in the root element of each Silverlight application XAML files. (Expression Blend adds a couple of others, but we ll look at the two most important here.) The first is the default namespace, specified by xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation". This namespace contains the various elements that correspond to objects in Silverlight, such as UserControl, Canvas, and Grid. If you remove this declaration from a XAML file in Visual Studio, blue squiggly lines will show just how much is defined in this namespace. The other namespace declaration contains XAML XML namespace extensions. Elements in this namespace are assigned to the x scope. Table 2-1 describes the most important aspects of the XAML (x:) namespace.
Matrix Barcode Creator In VB.NET
Using Barcode generation for .NET framework Control to generate, create Matrix Barcode image in VS .NET applications.
www.OnBarcode.com
Create Barcode In VB.NET
Using Barcode creator for Visual Studio .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
SILVERLIGHT CONCEPTS
ANSI/AIM Code 39 Drawer In Visual Basic .NET
Using Barcode generator for .NET framework Control to generate, create Code 39 Extended image in Visual Studio .NET applications.
www.OnBarcode.com
Paint Barcode In Visual Basic .NET
Using Barcode creator for Visual Studio .NET Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
Table 2-1. Key Features of the XAML (x:) Namespace
Making Code 128B In Visual Basic .NET
Using Barcode printer for Visual Studio .NET Control to generate, create Code 128C image in VS .NET applications.
www.OnBarcode.com
Encode UPC - E0 In VB.NET
Using Barcode generator for .NET Control to generate, create UPC - E1 image in VS .NET applications.
www.OnBarcode.com
Feature
QR Code JIS X 0510 Generator In Java
Using Barcode encoder for Java Control to generate, create QR Code JIS X 0510 image in Java applications.
www.OnBarcode.com
Print QR Code JIS X 0510 In None
Using Barcode creator for Online Control to generate, create QR-Code image in Online applications.
www.OnBarcode.com
x:Class
Print Code 39 In Java
Using Barcode drawer for Java Control to generate, create USS Code 39 image in Java applications.
www.OnBarcode.com
Painting PDF-417 2d Barcode In None
Using Barcode encoder for Microsoft Excel Control to generate, create PDF-417 2d barcode image in Microsoft Excel applications.
www.OnBarcode.com
Description
Code 3/9 Scanner In Visual Basic .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
Code 39 Scanner In C#.NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Joins different pieces of a partial class together. Valid syntax for this is x:Class="namespace.classname" and x:Class="namespace.classname;assembly=assemblyname". The XAML page generates code to a piece of the class that combines with the code-behind. Provides a unique identifier to resources defined in XAML, vital for referencing resources via a markup extension. Identifiers must begin with a letter or an underscore and can contain only letters, digits, and the underscore. Provides a way to give an identifier to an object element in XAML for accessing via the codebehind. This is not appropriate for use with resources (instead use x:Key). Many elements have a Name property, and while Name and x:Name can be used interchangeably, only one should be set. Identifiers must begin with a letter or an underscore and can contain only letters, digits, and the underscore. Corresponds to null in C# (or Nothing in VB .NET). Can be used via a markup extension ({x:Null}) or through a property element (<x:Null/>).
Painting QR In Objective-C
Using Barcode maker for iPhone Control to generate, create Quick Response Code image in iPhone applications.
www.OnBarcode.com
Data Matrix 2d Barcode Printer In Java
Using Barcode creator for Eclipse BIRT Control to generate, create DataMatrix image in BIRT applications.
www.OnBarcode.com
x:Key
Barcode Maker In Objective-C
Using Barcode drawer for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Code-128 Encoder In None
Using Barcode creation for Online Control to generate, create ANSI/AIM Code 128 image in Online applications.
www.OnBarcode.com
x:Name
Read Code 128 Code Set A In None
Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Decode USS Code 128 In Visual Basic .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
x:Null
Dependency Property System
The dependency property system is a significant aspect of Silverlight. It provides a way for multiple discrete sources, such as animation and data binding, to gain access to object properties. You can see the top classes in this hierarchy in Figure 2-4. Notice that the top of the hierarchy is DependencyObject. This root object provides much of the infrastructure needed to support the dependency property system, though it has only a few public methods. Let s look more closely at what dependency properties are and then highlight a few aspects of DependencyObject that will make more sense in light of dependency properties.
SILVERLIGHT CONCEPTS
Figure 2-4. Top portion of object hierarchy relating to visual elements
Dependency Properties
A dependency property is a special type of property that backs a .NET property. The importance of dependency properties lies in the fact that the value depends on multiple sources (which is why it s called dependency property), and therefore, a standard .NET property is not enough. The value of a dependency property might come from data binding, animation, template resources specified in the XAML, styles, or local values. Figure 2-5 shows the precedence of these sources.
SILVERLIGHT CONCEPTS
Figure 2-5. Precedence for sources of dependency property values Animation has the highest precedence. Property values influenced by animation must be the values that take effect, or the user will never see the animation, since a different source will trump the animation values. Local values are those set via an attribute or property element. Local values can also be set via data binding or a static resource, so these are effectively local values thus, at equal precedence (i.e., if you have set the local value using any approach, later, if you set the local value using another approach, it will replace the previous value entirely). Next lowest are values from a data template or a control template, which take effect if a local value does not override them. Styles defined in the page/application are next lowest, and if absolutely nothing is set, the dependency property takes on its default value.
Caution The base value for a property is not the same as its default value. A property s base value is determined by applying the sources in the preceding precedence chart but stopping before getting to animation. A property s default value is its value when no other sources provide a value (e.g., a layout container s constructor may establish a default value for a size property, and if this is not modified anywhere else, its value remains untouched).
Let s examine an actual dependency property, one that you have already used. The Width property, defined in the FrameworkElement class, is first defined as a dependency property and then wrapped by a .NET property. This provides all the capability of a dependency property while providing a traditional approach to getting and setting its value. Let s examine how this particular dependency property is defined:
Copyright © OnBarcode.com . All rights reserved.