- article
Markup extensions are an XAML technique for receiving values that are not primitives or specific XAML types. To use attributes, markup extensions use the well-known curly opening order{in a marker expansion range and a closing curly brace}I Stop. When using .NET XAML Services, you can use some predefined XAML formatting extensions in the System.Xaml layout. You can also download frommarker extensionclass, defined in System.Xaml and define your own markup extensions. If you already reference a particular context, you can also use the markup extensions defined by that context.
XAML Object Writer can provide services for custom objects when opened using the markup extensionmarker extensionService connection point classMarkupExtension.ProvideValuecover. These services can be used to get context about usage, specific object writer capabilities, XAML schema context, and more.
Markup extensions defined by XAML
.NET XAML Services implements several markup extensions for XAML language support. These markup extensions correspond to parts of the XAML language specification. These are usually available atX:Prefixes in syntax as seen in common use. All implementations of .NET XAML services for these XAML language components come frommarker extensionbase class.
notes
ItX:The prefix is used in a standard XAML namespace mapping for XAML language namespaces, in the root element of an XAML product. For example, several Visual Studio projects and context-specific page templates use this XAML bootstrap fileX:Card. You can choose a different prefix tag in the XAML namespace mapping, but this document uses the defaultX:Mapping is a way of identifying those entities that are a specified part of the XAML language's XAML namespace, as opposed to a given framework's default XAML namespace or any other arbitrary CLR or XML namespace.
X: typen
X: typenLeveringtypeAn object of the named type. This function is typically used to use underlying CLR types and type generation as a deferral mechanism for grouping aliases or identifiers. WPF styles and templates and their usestarget typeproperty, is a specific example. For more information, seex:type tag-extensie.
x: static
x: staticStatic values are created from code entities of the value type that are not directly the value type of the property, but can be evaluated to that type. This is useful for specifying values that already exist as known constants in the type definition. For more information, seex: static markup extension.
x: muscle
x: muscledetermineinvalidIf the value of an XAML member. According to a specific type of design or a broader concept,invalidNot always the default value for an attribute or the implicit value for an empty string attribute. For more information, seex: Nulmarkeringsverlenging.
x: matrix
x: matrixGeneric table creation is supported in XAML syntax, intentionally without using the collection support provided by primitives and operating model. For more information, seex: array formatting extensionSpecifically, in XAML 2009, arrays are approached as language primitives rather than extensions. For more information, seeXML 2009 Language Features.
x: reference
x: referencePart of XAML 2009, an extension to the original set of languages (2006).x: referenceRepresents a reference to another existing object in the object graph. The object is identified by thex: name.For more information, seex: reference signal extension.
else x: build
ButX:There are structures that support XAML language features, but they are not implemented as markup extensions. For more information, seeXAML language attributes namespace (x:)..
MarkupExtension base class
To define custom markup extensions that can interact with the standard XAML reader and XAML writer implementations in System.Xaml, you can derive a class from the summarymarker extensionclass. The class has one method to override, vizthey provide value. You may also need to define additional constructors to support parameters to use markup extension and configurable attribute mapping.
passagethey provide value, custom markup extensions can access the service context, which refers to the context in which the XAML editor called the markup extension. In the cargo path, this is usually oneXamlObjectWriter.In the save path, it is usually oneXamlXmlWriterEach refers to the service context as an internal XAML service provider context class that implements the service provider pattern. For more information about the available services and what they represent, seeType converters and markup extensions for XAML.
Markup extension classes must use the public access layer; XAML editors must always be able to create the markup extension's supporting classes in order to use the services.
Defines support types for custom markup extensions
When using .NET XAML Services or a .NET XAML Services based framework, you have two options for naming support types for markup extensions. Type names refer to how authors of XAML objects try to access and invoke types supported by format extensions when they encounter the use of format extensions in XAML. Use one of the following naming strategies:
- Give the type name a name that exactly matches the XAML markup usage tag. For example, to support a
{correctly...}Extensive use, rated support typescorrectly. - Name the type name as the usage string token plus the suffix
to expandFor example, to support a{correctly...}Extensive use, rated support typesOrganization of extensions.
The search order is searchto expand- the class name with the suffix, then search for the class name without the suffixto expandconclusion.
From the point of view of using marking, includingto expandSuffixes apply as part of usage. However, this behaves liketo expandis actually part of the class name if the supporting class doesn'tto expandconclusion.
parameterless constructor
All supported markup extension types require you to list a public constructor with no arguments. In any case, a parameterless constructor is required when an XAML object writer creates a markup extension using an object element. Supporting the use of object elements is a reasonable expectation for markup extensions, especially for serialization. However, if you only want to support the use of format extension features, you can implement format extensions without a public constructor.
If the use of the markup extension has no parameters, you need a parameterless constructor to support the use.
Construction scheme and position parameters for custom markup extensions
For a markup extension to have expected parameter usage, the public constructor must conform to the expected usage schema. In other words, if your markup extension is designed to require a positional parameter as valid usage, you must support a public constructor with a single input parameter that accepts a positional parameter.
For example, supposecorrectlyMarkup extensions are designed to support only one function, with a positional parameter specifying the function specified asOrganization functionList of constants. In this case there should be a form constructor:
public collation(CollationMode collationMode) {...}At a basic level, the parameters passed to a markup extension are a string, as they are passed by the value of the label attribute. You can create strings of all parameters and handle inputs at this level. However, you can access some processing that takes place before you pass the markup extension parameters to the support class.
Conceptually, the processing works as if the markup extension is an object that is instantiated and then the member values are set. Any named property to be set is evaluated in the same way as member names are set on objects created during XAML parsing. There are two main differences:
- As mentioned earlier, types supported by a markup extension do not require a parameterless constructor to be created in XAML. The construction of the object is delayed until the possible arguments in the text grammar are qualified and evaluated as positional or named arguments and the appropriate constructor is called.
- Using markup extensions can be nested. The inner markup extension is evaluated first. So you can assume such usage and declare one of the constructor parameters as a type that requires a value conversion (such as a markup extension) to be instantiated.
The dependence on such processing was shown in the previous examples. By default, the .NET XAML Services XAML Object Composer handles enumeration constant names as enumeration values.
Literal grammars that handle positional parameters for markup extensions can also rely on type converters associated with types in construction parameters.
These parameters are called positional parameters because the order in which the tokens are encountered during use matches the positional order of the constructor parameters they are assigned to. For example, consider the following constructor signature:
public Collate (CollationMode collationMode, object collateThis) {...}The XAML editor expects two positional parameters for this markup extension. If it is used{AlphaUp,{x:Reference circularFile}}, Thisalpha upThe token is sent in the first parameter and is evaluated asOrganization functionAn enumeration of named constants. The results of internal testsx: referenceis passed to the second argument and is evaluated as an object.
In the markup extension syntax and processing rules defined by XAML, a comma is the separator between parameters, whether they are positions or named.
Number of iterations for positional arguments
It is not necessarily an error if the XAML Object Writer encounters a use of markup extension with positional parameters and more than one constructor parameter using that number of parameters (double numbering). The behavior depends on the customizable setting of the XAML schema environment,SupportMarkupExtensionsWithDuplicateArity.ifSupportMarkupExtensionsWithDuplicateArityAndReal, the XAML object writer should not throw an exception just for two reasons. Behavior beyond this point is not strictly defined. The underlying design assumption is that the pattern framework has type information available for a given argument, and that explicit transformations can be attempted to match iterated candidates to see which signature is the best match. An exception can still be thrown if there is no signature that passes the tests enforced by the specific framework running in XAML Object Composer.
standard,SupportMarkupExtensionsWithDuplicateArityAndInaccurateCLR basedXamlSchemaContext.NET XAML services. Hence the standardXamlObjectWriterAn exception is thrown if the use of a double enumeration markup extension is encountered in a backing type constructor.
Named parameters for custom markup extensions
XAML-defined markup extensions can also use the named parameter form. At the first level of tokenization, the text grammar is divided into parameters. The presence of an equality (=) in a parameter identifies the parameter as a nominal parameter. Such parameters are also marked as name/value pairs. In this case, the named markup extension supports a public set property of type. If you plan to support the use of named parameters, you must specify these properties for public settings. These properties can be inherited as long as they remain public.
Access the service provider environment from a markup extension deployment
The available services are the same for each value converter. The difference lies in how each value converter receives the service context. Accessible services and available services are documented in topicsType converters and markup extensions for XAML.
Use attribute element for markup extensions
Scenarios for using markup extensions are often designed around using markup extensions when using functions. However, it is also possible to define supporting classes to support the use of attribute elements.
To support the use of markup extension attribute elements, define a public constructor with no parameters. This must be an instance constructor, not a static constructor. This is necessary because the XAML editor generally needs to call the no-argument constructor on every object element that the markup processes, and this also applies to markup extension classes that are object elements. For advanced scenarios, you can set non-default class build paths. (For more information, seex: FactoryMethod directive.) However, you should not use these patterns to extend markers, as this makes it more difficult to discover usage patterns, both for the designer and the user of the original markers.
Assigned to the custom markup extension
To support both the authoring environment and some XAML object registration scenarios, you must use different CLR properties to represent the markup extension support type. These properties report the expected usage of markup extensions.
Markup extension return type attribuutRapporttypeinformation about the object typethey provide valueYIELD. With his clear signaturethey provide valueYIELDGoal. But different consumers may need more precise information about the return type. This includes:
- Designers and IDEs, which may provide type-aware support for using markup extensions.
- advanced application of
set the markup extensionOperators in target classes, which can rely on reflection to determine a markup extension's return type, rather than branching to a particular well-known branchmarker extensionNominally implemented.
Serialize to use markup extension
When the XAML Object Writer handles the use of the markup extension and callsthey provide value, the context previously used as a formatting extension is still present in the XAML node stream, but not in the object graph. In an object graph, only the values are preserved. If you have a design or other reason to preserve the original use of the markup extension in the serial output, you must design your own infrastructure to track the use of the markup extension by the XAML load path node stream. You can implement behaviors to recreate the node stream elements from the load path and reproduce them in the XAML writer for serialization in the storage path, replacing the values in the appropriate places in the node stream.
Markup extensions for XAML nodeflow
If you use an XAML node stream in the load path, the use of the markup extension will appear as an object in the node stream.
If the use of the markup extension has a positional parameter, it will be represented as a starting object with an initial value. As a rough textual representation, a node stream looks like this:
start object(Typ Xamlis the definition type of the markup extension, not the return type)
start subscription(nameLid XamlAnd_Initialization text)
value(values are positional arguments as strings, including intervening separators)
end member
last object
Using markup extensions with named parameters is represented as objects with associated name members, each set with a string value.
really callthey provide valueImplementing markup extensions requires an XAML schema framework, as it requires mapping types and creating instances of types supported by markup extensions. This is one of the reasons why markup extension usage is preserved in this way in the standard .NET XAML service node stream - the read portion of the load path often does not have the necessary XAML schema framework available.
If you use the XAML node stream in the storage path, there is usually nothing in the object graph view to tell you that the object being enqueued was originally created using a markup extension andthey provide valueresult. Scripts that need to preserve round trip markup usage while also logging other changes to the object graph must devise their own techniques to preserve knowledge of markup usage from the original XAML input. For example, to restore use of the markup extension, you may need to restore use of the markup extension using the node stream in the save path, or do some sort of merge between the original XAML and the returned XAML. Some XAML implementation frameworks, such as WPF, use intermediate types (expressions) to represent situations where using a markup extension returns a value.
Also see
- marker extension
- Type converters and markup extensions for XAML
- Markup extensions and WPF XAML
FAQs
Overview of markup extensions for XAML - XAML? ›
Markup extensions are a XAML technique for obtaining a value that's not a primitive or a specific XAML type. For attribute usage, markup extensions use the known character sequence of an opening curly brace { to enter the markup extension scope, and a closing curly brace } to exit.
What are the markup extensions in WPF? ›The most common markup extensions used in WPF programming are those that support resource references ( StaticResource and DynamicResource ), and those that support data binding ( Binding ). StaticResource provides a value for a property by substituting the value of an already defined resource.
What is the advantage of using XAML markup extensions? ›XAML markup extensions help extend the power and flexibility of XAML by allowing element attributes to be set from sources other than literal text strings. In either case, the text string set to the Color attribute is converted to a Color value by the ColorTypeConverter class.
Which mark up extension allows you to set a XAML property to a static value that's defined in a code behind class? ›The x:Static Markup Extension.
What is markup extension in Xamarin forms? ›On the programmatic level, a XAML markup extension is a class that implements the IMarkupExtension or IMarkupExtension<T> interface. You can explore the source code of the standard markup extensions described below in the MarkupExtensions directory of the Xamarin. Forms GitHub repository.
What markup language is used in WPF? ›XAML is used extensively in Windows Presentation Foundation (WPF), Silverlight, Workflow Foundation (WF), Windows UI Library (WinUI) and Universal Windows Platform (UWP).
Is XAML a markup language? ›XAML is a declarative markup language.
What is the difference between auto and * in XAML? ›Auto means that a column is given as much width as the elements within it require. The width of * sized columns is calculated by allocating space for the Auto , and fixed width columns, and then dividing up the remaining space.
What is the difference between user control and custom control in XAML? ›User controls are better suited for developing reusable UI components that can be used across different applications, whereas custom controls are better for creating UI components particular to a single application.
What does Xmlns mean in XAML? ›The xmlns attribute specifically indicates the default XAML namespace. Within the default XAML namespace, object elements in the markup can be specified without a prefix. The xmlns:x attribute indicates an additional XAML namespace, which maps the XAML language namespace http://schemas.microsoft.com/winfx/2006/xaml.
What are margin values in XAML? ›
XAML Values
Margin="20,50" will be interpreted to mean a Thickness with Left and Right set to 20, and Top and Bottom set to 50. The default unit for a Thickness measure is device-independent unit (1/96th inch). You can also specify other units by appending the unit type strings cm , in , or pt to any measure.
Content property is the content property set by the ContentPropertyAttribute. If a Button is instantiated in XAML, the Content of the Button will be set to the element that is between the start and end button tags.
What is static resource in XAML? ›Static Resource - Static resources are the resources which you cannot manipulate at runtime. The static resources are evaluated only once by the element which refers them during the loading of XAML.
What is the difference between padding and margin Xamarin forms? ›Margin values can be specified on layout and view classes. The Padding property represents the distance between an element and its child elements, and is used to separate the control from its own content. Padding values can be specified on layout classes.
What is the extension name for hypertext markup language? ›A FlyoutPage contains Flyout and Detail properties that are both of type Page , which are used to get and set the flyout and detail pages respectively.
Which is the most commonly used markup language? ›The most widely used markup languages are SGML (Standard Generalized Markup Language), HTML (Hypertext Markup Language), and XML (Extensible Markup Language).
What is the difference between XAML and XML? ›What is difference between XML and XAML? XAML stands for Extensible Application Markup Language XML stands for Extensible Markup Language XAML is based on XML, so it uses XML for its markup. If you look at a XAML document, it is also a valid XML document. But any XML document is not XAML.
What are the types of XAML? ›- x:Object. For CLR backing, the x:Object primitive corresponds to Object. ...
- x:Boolean. For CLR backing, the x:Boolean primitive corresponds to Boolean. ...
- x:Char. ...
- x:String. ...
- x:Decimal. ...
- x:Single. ...
- x:Double. ...
- x:Int16.
WPF uses XAML, which is a language based on XML, to declare the user interface elements. In a simple WPF app, the . xaml file describes the GUI and the code-behind file describes the logic. DirectX is used to draw whatever is described in the .
What language does XAML use? ›
Overview of XAML
Extensible Application Markup Language (XAML) is a declarative language that's based on XML. XAML is used extensively in the following types of applications to build user interfaces: Windows Presentation Foundation (WPF) apps. Universal Windows Platform (UWP) apps.
In a Xamarin. Forms application, XAML is mostly used to define the visual contents of a page and works together with a C# code-behind file. The code-behind file provides code support for the markup. Together, these two files contribute to a new class definition that includes child views and property initialization.
How does XAML data binding work? ›Data binding is a mechanism in XAML applications that provides a simple and easy way for Windows Runtime Apps using partial classes to display and interact with data. The management of data is entirely separated from the way the data is displayed in this mechanism.
What is dynamic resource in XAML? ›Dynamic Resource
The concept is the same as data binding in WPF if the value of the bound property is changed. So is the value on UI. Change XAML as follows: added a new button. <Window x:Class="A.MainWindow"
The XAML User Interface framework offers an extensive library of controls that supports UI development for Windows. Some of them have a visual representation such Button, Textbox, TextBlock, etc.; while other controls are used as containers for other controls or content, for example, images.
What is the difference between user control and DataTemplate? ›A user control helps in organizing chunks of XAML that you want to re-use throughout your application that has behaviors and functionality tied to it. This is more than what a DataTempate will do. A DataTemplate is tied to one DataType and display a visual for that type.
What is the difference between user control and Window? ›A window is managed by the OS and is placed on the desktop. A UserControl is managed by wpf and is placed in a Window or in another UserControl. Applcations could be created by have a single Window and displaying lots of UserControls in that Window. Save this answer.
What is the difference between control template and user control? ›A UserControl is a self-contained composite control, with parts individually editable in the designer, and is best used if you need to see your components and manage them in the designer. A ControlTemplate, on the other hand, will not expose its components for manipulation in the designer (although it will be visible).
What is the difference between namespace and xmlns? ›How xmlns attribute is different from targetNamespace attribute? The target namespace is used for the internal referencing in the xml document to make sure it is valid as declared from the schema. The xmlns attribute actually declares the namespace of a particular element or group of elements.
What is StackPanel in XAML? ›StackPanel is a layout panel that arranges child elements into a single line that can be oriented horizontally or vertically. By default, StackPanel stacks items vertically from top to bottom in the order they are declared. You can set the Orientation property to Horizontal to stack items from left to right.
What is TextBlock in XAML? ›
A TextBlock provides a lightweight control for displaying small amounts of read-only text.
What are the 4 margin values? ›If the margin property has four values:
top margin is 10px. right margin is 5px. bottom margin is 15px. left margin is 20px.
The main difference between padding and margin is that padding is the space between the element's content and its border, while margin is the space between the element's border and the next element. Padding is used to create space within an element, while margin is used to create space between elements.
What is margin as a function of markup? ›The key difference between Margin and Markup is that margin refers to the amount derived by subtracting the cost of the goods sold by the company during an accounting period from its total sales. In contrast, markup refers to the amount or percentage of profits derived by the company over the product's cost price.
What are the XAML layout elements? ›The built-in XAML layout panels include RelativePanel, StackPanel, Grid, VariableSizedWrapGrid, and Canvas.
What is the purpose of the content property? ›The content property in CSS is used to create the generated content. We will write the content which is not included in the HTML document. If we want to insert the generated content, we have to use the content property with the ::before and ::after pseudo-elements.
What is the use of content property? ›The content CSS property replaces an element with a generated value. Objects inserted using the content property are anonymous replaced elements.
What is the difference between static and dynamic resources in XAML? ›A StaticResource is a onetime lookup, whereas a DynamicResource works more like a data binding. It remembers that a property is associated with a particular resource key. If the object associated with that key changes, dynamic resource will update the target property.
What are the two types of resources available in WPF? ›A resource is an object that can be reused in different places in your application. WPF supports different types of resources. These resources are primarily two types of resources: XAML resources and resource data files.
What makes a file static? ›Static files are files that don't change when your application is running. These files do a lot to improve your application, but they aren't dynamically generated by your Python web server like a usual HTML response.
What is the difference between flex margin and padding? ›
The margin clears an area around an element (outside the border), but the padding clears an area around the content (inside the border) of an element. it means that your element does not know about its outside margins, so if you are developing dynamic web controls, I recommend that to use padding vs margin if you can.
Why use margin and padding? ›In web development and design, the margin of an element represents the outside space of the element itself, while the padding represents the inner space surrounding the element. It's important to understand how different components, such as padding and margins, come together to separate text and graphics.
What do you understand by margin? ›In the business world, margin is the difference between the price at which a product is sold and the costs associated with making or selling the product (or cost of goods sold). Broadly speaking, a company's margin is its ratio of profit to revenue.
What is the difference between hypertext markup language and extensible markup language? ›The basic difference between XML and HTML is that HTML displays data and represent the structure of a webpage, while the XML stores and transfers the given data. XML is a standard language that defines other computer languages, whereas the HTML is a predefined language that has its own implications.
What is the difference between Xhtml and XML? ›XML is a markup language where all documents must be marked up correctly (be "well-formed"). XHTML was developed to make HTML more extensible and flexible to work with other data formats (such as XML).
What does XHTML stand for? ›HTML stands for Hypertext Markup Language. XHTML stands for Extensible Hypertext Markup Language. Both of these are used to develop web-based and android-based applications.
Is Xamarin forms being deprecated? ›Microsoft will continue to support Xamarin. Forms until May 1, 2024. After that time, apps built with Xamarin. Forms will continue to work and be maintainable, but there will be no new releases of the platform or official support from Microsoft.
What is MVVM in Xamarin forms? ›The Model-View-ViewModel (MVVM) pattern helps to cleanly separate the business and presentation logic of an application from its user interface (UI).
How to cache data in Xamarin forms? ›- Step 1: Create a file new Xamarin App. In a separate or new visual studio, create a file new Xamarin App name this ClientSideCachingApp and use the blank template to keep it simple. ...
- Step 2: Create a Model folder. ...
- Step 3: Implement your UI. ...
- Step 4: Implement the code-behind.
HTML (Hypertext Markup Language) is defined as a standard markup language, which is used to create the webpages and the webpage front layer. The two most used extensions of HTML documents are . html and . htm.
What is padding vs Margin in WPF? ›
Margin property represents the distance between an element and its adjacent elements, is used to control the element's rendering position and the rendering position of its neighbors, while the Padding property represents the distance between an element and its child elements, and is used to separate the control from ...
What is the difference between Margin and padding in WPF? ›In web development and design, the margin of an element represents the outside space of the element itself, while the padding represents the inner space surrounding the element.
What are the list of panels in WPF? ›There are six panel classes available in UI scenarios: Canvas, DockPanel, Grid, StackPanel, VirtualizingStackPanel, and WrapPanel. These panel elements are easy to use, versatile, and extensible enough for most applications.
What does XML extension markup language mean? ›Extensible Markup Language (XML) is a markup language that provides rules to define any data. Unlike other programming languages, XML cannot perform computing operations by itself. Instead, any programming language or software can be implemented for structured data management.
What is a .htm file extension? ›HTM or HTML is short for Hypertext Markup Language. It's a file format used for containing HTML language which constructs a web page. This file format is based on markup codes intended to be used in Web Browsers. HTM contains formatted text, images, and other elements in a way that can be translated with web browsers.
What is the extension of XML text file? ›An XML file contains XML code and ends with the file extension ".xml". It contains tags that define not only how the document should be structured but also how it should be stored and transported over the internet.
What is the difference between * and auto in WPF? ›Auto means that a column is given as much width as the elements within it require. The width of * sized columns is calculated by allocating space for the Auto , and fixed width columns, and then dividing up the remaining space.
What is margin in XAML? ›XAML Values
Margin="20,50" will be interpreted to mean a Thickness with Left and Right set to 20, and Top and Bottom set to 50.
In general, use margins when you're adjusting the spacing of an element in relation to another element (i.e a div in relation to another div on the page), and padding when you're adjusting the look of an individual element (i.e the amount of pixels between the edge of a div and the text within it).
What is the difference between margin padding and border? ›Padding - The inner space between the content and the border of your box. Border - The perimeter of the box. Borders can be invisible or they could be a thick colored line like the green one pictured above. Margin - The outer space (or lack of space) surrounding the box.
What is the difference between padding and margin XML? ›
With padding though, the text is away from the edge of the screen just like margin but, in padding the text is away and all the space between the text and the edge of the screen is filled in with the color or any text preference you chose to be. This is the difference between android margin and android padding.
Is padding the same as layout margin? ›Difference between Margin and Padding in Android
Padding is used to create extra space around the content of a view. Margin affects layout outside the border of a view. Padding affects the layout inside the border of a view. Margin is not affected by the background color of a view.
The only difference between StackPanel and WrapPanel is that it doesn't stack all the child elements in a single line; it wraps the remaining elements to another line if there is no space left.
What are the different types of grids in WPF? ›- Nested grid inside a row or column.
- Nested grid layout of row and column.
- Multiple nested grid inside a covered range with its rows using row layout.
- Multiple nested grid inside a covered range with its columns using column layout.
- Nested grid inside a covered with its rows and columns independent of parent grid.
Grids are used when you want to define particular cell and don't want your element to be in a sequence. Grid will overlap controls but StackPanel will stack them. Both have their own usage and you can make choice according to your needs.