【注意】この文書にはより新しいバージョンが存在します: WCAG 2.1 達成方法集
この達成方法 (参考) の使用法と、この達成方法が WCAG 2.0 達成基準 (規定) とどのように関係するのかに関する重要な情報については、WCAG 達成基準の達成方法を理解するを参照のこと。適用 (対象) のセクションは、その達成方法の範囲について説明しており、特定の技術に関する達成方法の存在は、その技術があらゆる状況で WCAG 2.0 を満たすコンテンツを作成するために使用できることを意味するものではない。
Microsoft Silverlight, versions 3 and greater
Silverlight managed programming model and Silverlight XAML
訳注: Silverlight は、2021 年 11 月にサポートを終了する計画が Microsoft 社より公表されている (Microsoft サポート - Silverlight のライフサイクルポリシー)。
WAIC では、Silverlight に関する達成方法の翻訳を行っていないが、将来もその予定がないことに留意されたい。
これは、次の達成基準に関連する達成方法である:
SL16 に関するユーザエージェントサポートノートを参照のこと。Silverlight Technology Notesも参照。
The objective of this technique is to use text captioning that is
embedded in the stream with media displayed in a Silverlight MediaElement,
and present that text captioning in a separate Silverlight control
or text element.
This particular technique uses scripting files with a TimelineMarkers collection
that are embedded directly within the media file. When text captioning
is embedded directly in the streams, synchonization of the scripting
stream versus the video content stream is done automatically by the MediaElement component.
Each time the MarkerReached event fires, that is an
indication that a synch point in the video that corresponds to a script
marker entry has been reached. Silverlight application authors can
obtain the text from the relevant timeline marker entry through their
event handler implementations, and can display captions in the user
interface area where the text captions are displayed. Typical Silverlight
controls that can be used for displaying text captions include TextBlock (nonfocusable), TextBox,
or RichTextBox. A typical interface design would place
the caption-display control in close proximity to the MediaElement control
that is being captioned, for example might place the captions directly
underneath the MediaElement "screen".
Script-embedded captions are captions that are stored directly in the media file as metadata, rather than as a separate file. For information about techniques for captions in separate files, see SL28: Using Separate Text-Format Text Captions for MediaElement Content.
Producing the media file with TimelineMarkers captions
directly in embedded scripting can be accomplished using the Microsoft
Expression Encoder tool. Online help for the procedure of encoding
scripting with text captions in the stream are available in the offline
Help file that installs with the Microsoft Expression 4 Encoder products.
For more information, see Expression
Encoder Pro Overview.
There is a public
API for introducing Markers into a WMV file, as part of the Windows
Media Format SDK. Using Expression Encoder is the way that the task
of directly embedding TimelineMarkers is presented
and taught in Microsoft's available instructional material on Silverlight.
However, because the mechanism is public, it is possible that other
tools exist or will exist that can also produce media with script-encoded TimelineMarkers.
This example has a UI definition in XAML and interaction logic in
C#. The following is the basic UI in XAML. This example is deliberately
simple and does not include AutomationProperties for
identification or user instructions. The most relevant part of this
example is that the Silverlight author declares a handler for the event MarkerReached.
This event fires potentially hundreds of times, once for each caption
in the stream. Each time the event fires, the event handler runs and
adds the text to the dedicated TextBox in the user
interface.
<UserControl x:Class="MediaTimelineMarkers.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
>
<StackPanel x:Name="LayoutRoot" Background="White">
<MediaElement MarkerReached="OnMarkerReached"
HorizontalAlignment="Left"
Source="/spacetime.wmv"
Width="300" Height="200" />
<ScrollViewer>
<TextBox Name="captionText" Height="40"
IsReadOnly="true" AcceptsReturn="true"/>
</ScrollViewer>
</StackPanel>
</UserControl>
private void OnMarkerReached(object sender, TimelineMarkerRoutedEventArgs e)
{
captionText.Focus();
captionText.SelectedText = e.Marker.Text.ToString() + "\n";
}
This example is shown in operation in the working example of Media Timeline Markers.
この参考リソースは、あくまでも情報提供のみが目的であり、推薦などを意味するものではない。
Accessible Media Project - a reference implementation MediaPlayer control from the Silverlight product team that includes several accessibility features including captioning; note that the codebase might not be updated to Silverlight version 4
Using a browser that supports Silverlight, open an HTML page that references a Silverlight application through an object tag. The application plays media that is expected to have text captioning.
Check that a text area in the user interface shows captions for the media.
# 2 is true.
この達成方法が「十分な達成方法」の一つである場合、この手順や期待される結果を満たしていなければ、それはこの達成方法が正しく用いられていないことを意味するが、必ずしも達成基準を満たしていないことにはならない。場合によっては、別の達成方法によってその達成基準が満たされていることもありうる。