First, the resources system has predictable behavior for where it will check for the existence of a resource based on scope. If a resource isn't found in the initial scope, the scope expands. The lookup behavior continues on throughout the locations and scopes that a XAML resource could possibly be defined by an app or by the system.
If all possible resource lookup attempts fail, an error often results. It's usually possible to eliminate these errors during the development process. The lookup behavior for XAML resource references starts with the object where the actual usage is applied and its own Resources property. If a ResourceDictionary exists there, that ResourceDictionary is checked for an item that has the requested key. This first level of lookup is rarely relevant because you usually do not define and then reference a resource on the same object.
In fact, a Resources property often doesn't exist here. The lookup sequence then checks the next parent object in the runtime object tree of the app. If a FrameworkElement. Resources exists and holds a ResourceDictionary , the dictionary item with the specified key string is requested.
If the resource is found, the lookup sequence stops and the object is provided to the location where the reference was made. Otherwise, the lookup behavior advances to the next parent level towards the object tree root. The search continues recursively upwards until the root element of the XAML is reached, exhausting the search of all possible immediate resource locations. Note It is a common practice to define all the immediate resources at the root level of a page, both to take advantage of this resource-lookup behavior and also as a convention of XAML markup style.
If the requested resource is not found in the immediate resources, the next lookup step is to check the Application. Resources property. Resources is the best place to put any app-specific resources that are referenced by multiple pages in your app's navigation structure.
Control templates have another possible location in the reference lookup: theme dictionaries. The theme dictionary might be a merged dictionary from Application.
The theme dictionary might also be the control-specific theme dictionary for a templated custom control. Finally, there is a resource lookup against platform resources. Platform resources include the control templates that are defined for each of the system UI themes, and which define the default appearance of all the controls that you use for UI in a Windows Runtime app.
Platform resources also include a set of named resources that relate to system-wide appearance and themes. These resources are technically a MergedDictionaries item, and thus are available for lookup from XAML or code once the app has loaded. For example, the system theme resources include a resource named "SystemColorWindowTextColor" that provides a Color definition to match app text color to a system window's text color that comes from the operating system and user preferences.
Other XAML styles for your app can refer to this style, or your code can get a resource lookup value and cast it to Color in the example case. Because of the tiered lookup behavior for resource dictionaries, you can deliberately define multiple resource items that each have the same string value as the key, as long as each resource is defined at a different level.
In other words, although keys must be unique within any given ResourceDictionary , the uniqueness requirement does not extend to the lookup behavior sequence as a whole. During lookup, only the first such object that's successfully retrieved is used for the XAML resource reference, and then the lookup stops.
You could use this behavior to request the same XAML resource by key at various positions within your app's XAML but get different resources back, depending on the scope from which the XAML resource reference was made and how that particular lookup behaves.
XAML resource references within a particular resource dictionary must reference a resource that has already been defined with a key, and that resource must appear lexically before the resource reference. Forward references cannot be resolved by a XAML resource reference. For this reason, if you use XAML resource references from within another resource, you must design your resource dictionary structure so that the resources that are used by other resources are defined first in a resource dictionary.
Resources defined at the app level cannot make references to immediate resources. This is equivalent to attempting a forward reference, because the app resources are actually processed first when the app first starts, and before any navigation-page content is loaded.
However, any immediate resource can make a reference to an app resource, and this can be a useful technique for avoiding forward-reference situations. For an object to exist in a ResourceDictionary , that object must be shareable. Being shareable is required because, when the object tree of an app is constructed and used at run time, objects cannot exist at multiple locations in the tree. Internally, the resource system creates copies of resource values to use in the object graph of your app when each XAML resource is requested.
You can also use custom types as a shareable resource if you follow the necessary implementation patterns. You define such classes in your backing code or in runtime components that you include and then instantiate those classes in XAML as a resource. Examples are object data sources and IValueConverter implementations for data binding.
Custom types must have a default constructor, because that's what a XAML parser uses to instantiate a class. Custom types used as resources can't have the UIElement class in their inheritance, because a UIElement can never be shareable it's always intended to represent exactly one UI element that exists at one position in the object graph of your runtime app. A UserControl element has a special situation for resource-lookup behavior because it has the inherent concepts of a definition scope and a usage scope.
A UserControl that makes a XAML resource reference from its definition scope must be able to support the lookup of that resource within its own definition-scope lookup sequence—that is, it cannot access app resources. From a UserControl usage scope, a resource reference is treated as being within the lookup sequence towards its usage page root just like any other resource reference made from an object in a loaded object tree and can access app resources.
Load method. The FileInfo. If you would like to suggest any additions or updates to this page, please let us know. DIC File Extension. DIC File Extension 3 file types use the. Dictionary File 2. Windows 10 Custom Spelling Dictionary.
Apache OpenOffice. IBM Lotus Notes. JGsoft EditPad Pro. Microsoft Windows. Kingsoft Writer. You can use spreadsheets to measure and track a variety of information, such as numbers and contact information. The TXT file supports simple text documents. You may use a TXT to write notes, instructions or plain text. This file can work on different computers and processing software programs.
If you want to create advanced formats or use different fonts, you may consider choosing a different file type. You may use video files for your company's website, marketing campaigns or presentations. Here are some of the most common video file types you might work with:. The MP4 file format is a popular video format. Most computers and mobile devices can open and play MP4 videos, making it a common choice for professionals and companies sharing video content.
You can use this file to send, upload and receive videos for your company's website or social media platforms. This file saves visual and audio information accurately, but it has a lower resolution than other video format types.
This video file format, created by Microsoft, is another popular format you may encounter in the workplace. It is a large file type, which means it can take up a lot of space on your computer or cloud system. It maintains quality throughout multiple saves and changes. You may use this file format to share videos on social platforms or through your company's website. This file works well for movies and longer videos, although the files can be large. You can edit these files in different sections, which may be helpful for longer projects.
Depending on your industry, you may use this file to create training videos or promotional films. The FLV file format works well on streaming services and websites.
It's a popular type of file that's small and easy to share, but it may not work with all mobile phones. If you're sharing content with clients on their phones, you may choose another file type.
If you're uploading a video to a streaming website, this file may work well. Professional videographers may use this file format. It maintains high-quality images for short and long projects. If you're creating a professional video, for real estate, marketing or entertainment purposes, you may work with this file format. Depending on your position, you may use presentation files to prepare for a meeting or training. Here are some of the most common presentation file types:. This file type, created by Microsoft, is a popular way to share and upload presentations and slideshows.
If your company using PowerPoint software, you may use the file type to save your slideshows. This file type helps you create and share visual presentations with your team members or clients. For example, you may share a PPT file with your team members after a meeting so they can refer to the slides and notes. If your organization uses this software program, you may share a presentation in this file format.
You can create and share slideshows with text, graphics and animations. The KEY file format works with Apple's Keynote program, where professionals can create and share visual presentations.
You may add text slides, images, sounds and transition elements in this file format. You may choose to use this file type if your company, team members or clients use this software, or if you're sharing a presentation directly from your computer and you have this program installed.
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