重新想象 Windows 8 Store Apps (56) - 系统 UI: Scale, Snap, Orientation, High Contrast 等

时间:2024-01-04 08:10:32

[源码下载]

重新想象 Windows 8 Store Apps (56) - 系统 UI: Scale, Snap, Orientation, High Contrast 等

作者:webabcd

介绍
重新想象 Windows 8 Store Apps 之 系统 UI

  • 获取系统的 UI 相关的设置信息
  • 屏幕方向
  • Snap
  • 为 snap 操作和屏幕方向的改变增加动画效果
  • 缩放至不同屏幕
  • 高对比度

示例
1、演示如何获取系统的 UI 相关的设置信息
UI/UISettingsInfo.xaml.cs

/*
* 演示如何获取系统的 UI 相关的设置信息
*/ using System;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation; namespace XamlDemo.UI
{
public sealed partial class UISettingsInfo : Page
{
public UISettingsInfo()
{
this.InitializeComponent();
} protected override void OnNavigatedTo(NavigationEventArgs e)
{
UISettings uiSettings = new UISettings(); lblMsg.Text = "AnimationsEnabled: " + uiSettings.AnimationsEnabled; // 是否启用动画
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "CaretBlinkRate: " + uiSettings.CaretBlinkRate; // 输入光标的闪烁速率
lblMsg.Text += Environment.NewLine; /*
* 光标浏览模式(Caret Browsing) - 在页面中会出现一个类似于记事本中的输入光标,用户可以使用键盘(按 Shift 键 + 方向键)来精确地进行页面文字的选择
* IE8 以上可以通过“F7”来打开/关闭光标浏览模式
*/
lblMsg.Text += "CaretBrowsingEnabled: " + uiSettings.CaretBrowsingEnabled; // 当前输入光标是否可用于光标浏览模式
lblMsg.Text += Environment.NewLine; lblMsg.Text += "CaretWidth: " + uiSettings.CaretWidth; // 输入光标的宽度
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "CursorSize: " + uiSettings.CursorSize; // 指针的尺寸
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "DoubleClickTime: " + uiSettings.DoubleClickTime; // 捕获双击时,两次单击间的最长时间
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "HandPreference: " + uiSettings.HandPreference; // 用户界面的方向(LeftHanded 或 RightHanded)
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "MessageDuration: " + uiSettings.MessageDuration; // 消息显示的持续时间,单位:秒
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "MouseHoverTime: " + uiSettings.MouseHoverTime; // hover 事件触发之前,指针可以 hover 的时间
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ScrollBarArrowSize: " + uiSettings.ScrollBarArrowSize; // 当前窗口滚动条的箭头的大小
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ScrollBarSize: " + uiSettings.ScrollBarSize; // 当前窗口滚动条的大小
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ScrollBarThumbBoxSize: " + uiSettings.ScrollBarThumbBoxSize; // 当前窗口滚动条 thumb 的大小
lblMsg.Text += Environment.NewLine; // 获取当前系统的相关颜色
lblMsg.Text += "ActiveCaption: " + uiSettings.UIElementColor(UIElementType.ActiveCaption);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "Background: " + uiSettings.UIElementColor(UIElementType.Background);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ButtonFace: " + uiSettings.UIElementColor(UIElementType.ButtonFace);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ButtonText: " + uiSettings.UIElementColor(UIElementType.ButtonText);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "CaptionText: " + uiSettings.UIElementColor(UIElementType.CaptionText);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "GrayText: " + uiSettings.UIElementColor(UIElementType.GrayText);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "Highlight: " + uiSettings.UIElementColor(UIElementType.Highlight);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "HighlightText: " + uiSettings.UIElementColor(UIElementType.HighlightText);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "Hotlight: " + uiSettings.UIElementColor(UIElementType.Hotlight);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "InactiveCaption: " + uiSettings.UIElementColor(UIElementType.InactiveCaption);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "InactiveCaptionText: " + uiSettings.UIElementColor(UIElementType.InactiveCaptionText);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "Window: " + uiSettings.UIElementColor(UIElementType.Window);
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "WindowText: " + uiSettings.UIElementColor(UIElementType.WindowText);
lblMsg.Text += Environment.NewLine; AccessibilitySettings accessibilitySettings = new AccessibilitySettings();
lblMsg.Text += "是否启用了高对比度模式: " + accessibilitySettings.HighContrast; // 是否启用了高对比度模式
}
}
}

2、演示与“屏幕方向”相关的知识点
UI/ScreenOrientation.xaml

<Page
x:Class="XamlDemo.UI.ScreenOrientation"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.UI"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Grid Background="Transparent">
<StackPanel Margin="120 0 0 0"> <ToggleButton Name="btnLock" Content="锁定当前方向" IsChecked="False" Checked="btnLock_Checked_1" Unchecked="btnLock_Unchecked_1" /> <TextBlock Name="lblMsg" FontSize="14.667" Margin="0 10 0 0" /> </StackPanel> </Grid>
</Page>

UI/ScreenOrientation.xaml.cs

/*
* 演示与“屏幕方向”相关的知识点
*/ using System;
using Windows.Graphics.Display;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation; namespace XamlDemo.UI
{
public sealed partial class ScreenOrientation : Page
{
public ScreenOrientation()
{
this.InitializeComponent();
} protected override void OnNavigatedTo(NavigationEventArgs e)
{
// 平板上的“windows”键相对于平板本身的方向
lblMsg.Text = "NativeOrientation: " + DisplayProperties.NativeOrientation.ToString();
lblMsg.Text += Environment.NewLine; // 平板的方向(Windows.Graphics.Display.DisplayOrientations 枚举:None, Landscape, Portrait, LandscapeFlipped, PortraitFlipped)
// 注:Landscape 顺时针转是 Portrait
lblMsg.Text += "CurrentOrientation: " + DisplayProperties.CurrentOrientation.ToString(); // DisplayProperties.CurrentOrientation 发生变化时触发的事件
DisplayProperties.OrientationChanged += DisplayProperties_OrientationChanged;
} protected override void OnNavigatedFrom(NavigationEventArgs e)
{
DisplayProperties.OrientationChanged -= DisplayProperties_OrientationChanged;
} void DisplayProperties_OrientationChanged(object sender)
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "CurrentOrientation: " + DisplayProperties.CurrentOrientation.ToString();
} private void btnLock_Checked_1(object sender, RoutedEventArgs e)
{
// DisplayProperties.AutoRotationPreferences - 指定当前 app 所支持的方向,即仅允许设备支持指定的方向(模拟器中无效)
// 注:可在 Package.appxmanifest 中指定
DisplayProperties.AutoRotationPreferences = DisplayProperties.CurrentOrientation;
btnLock.Content = "解除方向锁定";
} private void btnLock_Unchecked_1(object sender, RoutedEventArgs e)
{
DisplayProperties.AutoRotationPreferences = DisplayOrientations.None;
btnLock.Content = "锁定当前方向";
}
}
}

3、演示与“snap”相关的知识点
UI/Snap.xaml

<Page
x:Class="XamlDemo.UI.Snap"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.UI"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Grid Background="Transparent">
<StackPanel Margin="120 0 0 0"> <Button Name="btnUnsnap" Content="unsnap" Click="btnUnsnap_Click_1" /> <TextBlock Name="lblMsg" FontSize="14.667" Margin="0 10 0 0">
<Run>snap 可以通过手势操作,也可以通过快捷键:win + .</Run>
</TextBlock> </StackPanel>
</Grid>
</Page>

UI/Snap.xaml.cs

/*
* 演示与“snap”相关的知识点
*
* 注:
* snap 视图的宽度是固定的:320 像素
* 支持 snap 的最小分辨率为 1366 * 768
*/ using System;
using Windows.UI.Core;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls; namespace XamlDemo.UI
{
public sealed partial class Snap : Page
{
public Snap()
{
this.InitializeComponent(); Window.Current.SizeChanged += Current_SizeChanged; ShowCurrentApplicationViewState();
} void Current_SizeChanged(object sender, WindowSizeChangedEventArgs e)
{
ShowCurrentApplicationViewState();
} void ShowCurrentApplicationViewState()
{
/*
* ApplicationView.Value - 获取当前的视图状态(Windows.UI.ViewManagement.ApplicationViewState 枚举)
* Snapped - snap 后的小视图
* Filled - snap 后的大视图
* FullScreenLandscape - 全屏水平视图
* FullScreenPortrait - 全屏垂直视图
*/
ApplicationViewState currentState = ApplicationView.Value; if (currentState == ApplicationViewState.Snapped)
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "This app is snapped";
}
else if (currentState == ApplicationViewState.Filled)
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "This app is in the fill state";
}
else if (currentState == ApplicationViewState.FullScreenLandscape)
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "This app is full-screen landscape";
}
else if (currentState == ApplicationViewState.FullScreenPortrait)
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "This app is full-screen portrait";
}
} private void btnUnsnap_Click_1(object sender, RoutedEventArgs e)
{
/*
* ApplicationView.TryUnsnap() - 尝试解除 snap,尝试之后返回当前是否是 unsnapped 状态
*/
bool unsnapped = ((ApplicationView.Value != ApplicationViewState.Snapped) || ApplicationView.TryUnsnap()); lblMsg.Text += Environment.NewLine;
lblMsg.Text += "unsnapped: " + unsnapped;
}
}
}

4、演示如何为 ApplicationViewState 的变化增加动画效果
UI/ApplicationViewStateAnimation.xaml

<Page
x:Class="XamlDemo.UI.ApplicationViewStateAnimation"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.UI"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Grid Background="Transparent"> <StackPanel Margin="120 0 0 0"> <TextBlock Name="lblMsg" FontSize="48" TextWrapping="Wrap" Text="为 snap 操作和屏幕方向的改变增加动画效果" Foreground="White" Margin="0 0 20 0" /> </StackPanel> <!--
自定义 ApplicationViewState 变化时的动画效果,由 code-behind 中的 VisualStateManager 控制
关于 VisualState 请参见 XamlDemo/Controls/UI/VisualStateDemo.xaml
-->
<VisualStateManager.VisualStateGroups>
<VisualStateGroup>
<VisualState x:Name="Landscape">
<Storyboard>
<ColorAnimation Storyboard.TargetName="lblMsg" Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)"
To="White" />
</Storyboard>
</VisualState>
<VisualState x:Name="Portrait">
<Storyboard>
<ColorAnimation Storyboard.TargetName="lblMsg" Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)"
To="Blue" />
</Storyboard>
</VisualState>
<VisualState x:Name="Snapped">
<Storyboard>
<ColorAnimation Storyboard.TargetName="lblMsg" Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)"
To="Red" />
</Storyboard>
</VisualState>
<VisualState x:Name="Filled">
<Storyboard>
<ColorAnimation Storyboard.TargetName="lblMsg" Storyboard.TargetProperty="(TextBlock.Foreground).(SolidColorBrush.Color)"
To="Orange" />
</Storyboard>
</VisualState>
<VisualStateGroup.Transitions>
<VisualTransition To="Landscape" GeneratedDuration="0:0:1">
<VisualTransition.GeneratedEasingFunction>
<ElasticEase EasingMode="EaseInOut" />
</VisualTransition.GeneratedEasingFunction>
</VisualTransition>
<VisualTransition To="Portrait" GeneratedDuration="0:0:1">
<VisualTransition.GeneratedEasingFunction>
<ElasticEase EasingMode="EaseInOut" />
</VisualTransition.GeneratedEasingFunction>
</VisualTransition>
<VisualTransition To="Snapped" GeneratedDuration="0:0:1">
<VisualTransition.GeneratedEasingFunction>
<ElasticEase EasingMode="EaseInOut" />
</VisualTransition.GeneratedEasingFunction>
</VisualTransition>
<VisualTransition To="Filled" GeneratedDuration="0:0:1">
<VisualTransition.GeneratedEasingFunction>
<ElasticEase EasingMode="EaseInOut" />
</VisualTransition.GeneratedEasingFunction>
</VisualTransition>
</VisualStateGroup.Transitions>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups> </Grid>
</Page>

UI/ApplicationViewStateAnimation.xaml.cs

/*
* 演示如何为 ApplicationViewState 的变化增加动画效果
*/ using Windows.UI.Core;
using Windows.UI.ViewManagement;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls; namespace XamlDemo.UI
{
public sealed partial class ApplicationViewStateAnimation : Page
{
public ApplicationViewStateAnimation()
{
this.InitializeComponent(); Window.Current.SizeChanged += Current_SizeChanged; ChangeViewSate();
} void Current_SizeChanged(object sender, WindowSizeChangedEventArgs e)
{
ChangeViewSate();
} void ChangeViewSate()
{
// 根据 ApplicationViewState 的变化触发相应的动画
switch (ApplicationView.Value)
{
case ApplicationViewState.FullScreenLandscape:
VisualStateManager.GoToState(this, "Landscape", true);
break;
case ApplicationViewState.FullScreenPortrait:
VisualStateManager.GoToState(this, "Portrait", true);
break;
case ApplicationViewState.Snapped:
VisualStateManager.GoToState(this, "Snapped", true);
break;
case ApplicationViewState.Filled:
VisualStateManager.GoToState(this, "Filled", true);
break;
default:
break;
}
}
}
}

5、演示 WinRT 中关于“缩放至不同屏幕”的概念
UI/Scale.xaml

<Page
x:Class="XamlDemo.UI.Scale"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.UI"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Grid Background="Transparent">
<StackPanel Margin="120 0 0 0" HorizontalAlignment="Left"> <TextBlock FontSize="14.667" LineHeight="20" TextWrapping="Wrap">
<Run>1、区分屏幕的指标:尺寸,分辨率,密度</Run>
<LineBreak />
<Run>2、最小分辨率为 1024 * 768(无 snap),支持 snap 的最小分辨率为 1366 * 768</Run>
<LineBreak />
<Run>3、系统会根据屏幕密度自动进行缩放,也就是说在开发 app 的时候只要考虑分辨率的适应问题即可</Run>
<LineBreak />
<Run>4、系统有 3 种缩放倍数:100%, 140%, 180%</Run>
<LineBreak />
<Run>5、比如 10.6 寸屏幕:1366*768 会缩放至 100%,1920*1080 会缩放至 140%,2560*1440 会缩放至 180%</Run>
<LineBreak />
<Run>6、通过 Window.Current.Bounds 获取到的宽度和高度不是屏幕分辨率,而是屏幕分辨率与缩放相结合之后的值</Run>
<LineBreak />
<Run>7、px 是像素,dpi 是密度(每英寸的点数),pt 是 1/72 英寸,px = pt * dpi / 72,WinRT 中与尺寸相关的单位通常是 px</Run>
<LineBreak />
<Run>8、Package.appxmanifest 中引用的图片也支持 scale</Run>
</TextBlock> <TextBlock Name="lblMsg" FontSize="14.667" Margin="0 10 0 0" /> <!--
在 /Assets/ 目录内放 3 个目录 scale-100, scale-140, scale-180, 每个目录内均放一个 MyImage.png 文件
它们分别对应 100% 缩放, 140% 缩放, 180% 缩放
通过 /Assets/MyImage.png 引用图片,系统会自动找到并使用对应缩放比的图片
-->
<Image Source="/Assets/MyImage.png" Width="100" Height="100" Margin="0 10 0 0" HorizontalAlignment="Left" VerticalAlignment="Top" /> <!--
在 /Assets/scale/ 目录内放 3 个文件 MyImage.scale-100.png, MyImage.scale-140.png, MyImage.scale-180.png
它们分别对应 100% 缩放, 140% 缩放, 180% 缩放
通过 /Assets/scale/MyImage.png 引用图片,系统会自动找到并使用对应缩放比的图片
-->
<Image Source="/Assets/scale/MyImage.png" Width="100" Height="100" Margin="0 10 0 0" HorizontalAlignment="Left" VerticalAlignment="Top" /> </StackPanel>
</Grid>
</Page>

UI/Scale.xaml.cs

/*
* 演示 WinRT 中关于“缩放至不同屏幕”的概念
*/ using System;
using Windows.ApplicationModel.Resources.Core;
using Windows.Graphics.Display;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls; namespace XamlDemo.UI
{
public sealed partial class Scale : Page
{
public Scale()
{
this.InitializeComponent(); Window.Current.SizeChanged += Current_SizeChanged; ShowInfo();
} void Current_SizeChanged(object sender, Windows.UI.Core.WindowSizeChangedEventArgs e)
{
ShowInfo();
} private void ShowInfo()
{
// 通过 Window.Current.Bounds 获取到的宽度和高度不是屏幕分辨率,而是屏幕分辨率与缩放相结合之后的值
lblMsg.Text = string.Format("Window.Current.Bounds: {0} * {1}", Window.Current.Bounds.Width, Window.Current.Bounds.Height);
lblMsg.Text += Environment.NewLine; // 获取屏幕的 dpi(dots per inch)
lblMsg.Text += "LogicalDpi: " + DisplayProperties.LogicalDpi.ToString();
lblMsg.Text += Environment.NewLine; // 获取当前的缩放比例(Windows.Graphics.Display.ResolutionScale 枚举:Invalid, Scale100Percent, Scale140Percent, Scale180Percent)
lblMsg.Text += "ResolutionScale: " + DisplayProperties.ResolutionScale.ToString();
lblMsg.Text += Environment.NewLine; // 另一个获取当前的缩放比例的方法
string scale;
ResourceManager.Current.DefaultContext.QualifierValues.TryGetValue("Scale", out scale);
lblMsg.Text += "Scale: " + scale;
lblMsg.Text += Environment.NewLine;
}
}
}

6、演示 WinRT 中关于“对比度”的概念
UI/HighContrast.xaml

<Page
x:Class="XamlDemo.UI.HighContrast"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.UI"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Grid Background="Transparent">
<StackPanel Margin="120 0 0 0"> <TextBlock Name="lblMsg" FontSize="14.667" /> <!--
注:Package.appxmanifest 中引用的图片也支持 high contrast 有 3 种模式,分别是
1、标准模式
2、黑色主题的高对比度模式
3、白色主题的高对比度模式 系统资源包含了对全部 3 种模式的支持
-->
<Button Content="默认的 Button 样式,启用高对比度模式(电脑设置 -> 轻松使用 -> 高对比度)可查看效果" Margin="0 10 0 0" /> <!--
具体图片文件请查看 /Assets/highContrast/ 目录
1、xxx.contrast-standard.png 对应 标准模式
2、xxx.contrast-black.png 对应 黑色主题的高对比度模式
3、xxx.contrast-white.png 对应 白色主题的高对比度模式
4、xxx.scale-100_contrast-standard.png 或 xxx.contrast-standard_scale-100.png 对应 scale 与 HighContrast 相结合的方式
-->
<Image Source="/Assets/highContrast/TheImage.png" Width="200" Height="100" Margin="0 10 0 0" HorizontalAlignment="Left" /> <!--
通过 ResourceDictionary.ThemeDictionaries 来指定 3 种模式下的不同资源
Default 代表 标准模式
HighContrastBlack 代表 黑色主题的高对比度模式
HighContrastWhite 代表 白色主题的高对比度模式
-->
<StackPanel Margin="0 10 0 0">
<StackPanel.Resources>
<ResourceDictionary>
<ResourceDictionary.ThemeDictionaries>
<ResourceDictionary x:Key="Default">
<SolidColorBrush x:Key="TargetForeground" Color="Red"/>
</ResourceDictionary>
<ResourceDictionary x:Key="HighContrastBlack">
<SolidColorBrush x:Key="TargetForeground" Color="White"/>
</ResourceDictionary>
<ResourceDictionary x:Key="HighContrastWhite">
<SolidColorBrush x:Key="TargetForeground" Color="Black"/>
</ResourceDictionary>
</ResourceDictionary.ThemeDictionaries>
</ResourceDictionary>
</StackPanel.Resources> <TextBlock Text="启用高对比度模式可查看效果" FontSize="14.667" Foreground="{StaticResource TargetForeground}" />
</StackPanel> </StackPanel>
</Grid>
</Page>

UI/HighContrast.xaml.cs

/*
* 演示 WinRT 中关于“对比度”的概念
*/ using Windows.ApplicationModel.Resources.Core;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation; namespace XamlDemo.UI
{
public sealed partial class HighContrast : Page
{
public HighContrast()
{
this.InitializeComponent();
} protected override void OnNavigatedTo(NavigationEventArgs e)
{
string contrast;
// 获取当前的对比度模式
ResourceManager.Current.DefaultContext.QualifierValues.TryGetValue("Contrast", out contrast);
lblMsg.Text = "current contrast: " + contrast;
}
}
}

OK
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