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我有一项功能，允许用户在设备上的FrontFacing和主摄像头之间切换。在切换过程中，我想向用户显示一个ProgressBar和TextBlock。出于某种原因，我不能让这些在视图中显示，并且在切换过程中，显示的唯一的事情就是nonrotated的VideoBrush的冻结图像如何在VideoBrush上显示ProgressBar
MainPage.xaml中
<Grid.RowDefinitions>
<RowDefinition Height="72"/>
<RowDefinition Height="*"/>
<RowDefinition Height="68"/>
<RowDefinition Height="72"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="72"/>
<ColumnDefinition Width=".33*"/>
<ColumnDefinition Width=".33*"/>
<ColumnDefinition Width=".33*"/>
<ColumnDefinition Width="72"/>
</Grid.ColumnDefinitions>
<!-- Center this on the screen -->
<Canvas x:Name="VideoCanvas" Grid.Row="0" Grid.RowSpan="4" Grid.ColumnSpan="5"
VerticalAlignment="Center" HorizontalAlignment="Center">
<Canvas.Background>
<VideoBrush x:Name="videoBrush">
<VideoBrush.RelativeTransform>
<CompositeTransform x:Name="videoBrushTransform"
CenterX="0.5" CenterY="0.5"/>
</VideoBrush.RelativeTransform>
</VideoBrush>
</Canvas.Background>
</Canvas>
...
<StackPanel Grid.Row="1" Grid.ColumnSpan="5" VerticalAlignment="Center">
<ProgressBar x:Name="progressIndicator" IsIndeterminate="False" Background="Transparent"/>
<TextBlock x:Name="modeChangeTextBlock" Margin="12"
VerticalAlignment="Top" HorizontalAlignment="Center" FontSize="28"
Foreground="{StaticResource PhoneSubtleBrush}"/>
</StackPanel>
MainPage.xaml中的.cs
void sensor_Click(object sender, EventArgs e)
{
CameraType type = camera.CameraType;
//Switch to other camera, if available
if(type == CameraType.Primary)
{
if(PhotoCamera.IsCameraTypeSupported(CameraType.FrontFacing) == true)
{
ShowProgress("Switching cameras");
UninitializeCamera();
InitializeCamera(CameraType.FrontFacing);
HideProgress();
}
}
else
{
if(PhotoCamera.IsCameraTypeSupported(CameraType.Primary) == true)
{
ShowProgress("Switching cameras");
UninitializeCamera();
InitializeCamera(CameraType.Primary);
HideProgress();
}
}
}
...
private void ShowProgress(String msg)
{
progressIndicator.IsIndeterminate = true;
modeChangeTextBlock.Text = msg;
//progressIndicator.Visibility = Visibility.Visible;
}
private void HideProgress()
{
progressIndicator.IsIndeterminate = false;
modeChangeTextBlock.Text = "";
//progressIndicator.Visibility = Visibility.Collapsed;
}
编辑*加入下面现有XAML代码用于测试
<Rectangle x:Name="cameraSwitchingFill" Visibility="Visible"
Fill="{StaticResource SelfiePageBackgroundColorBrush}"
Grid.Row="0" Grid.Column="0" Grid.RowSpan="4" Grid.ColumnSpan="5"/>
<StackPanel Grid.Row="1" Grid.ColumnSpan="5" VerticalAlignment="Center">
<ProgressBar x:Name="progressIndicator" IsIndeterminate="True" Background="Transparent"/>
<TextBlock x:Name="modeChangeTextBlock" Margin="12"
VerticalAlignment="Top" HorizontalAlignment="Center" FontSize="28"
Foreground="{StaticResource PhoneSubtleBrush}" Text="test"/>
</StackPanel>
添加的编辑尝试了解在摄像头切换过程中未显示进度条的原因。设置屏幕上显示的所有内容，当第一次导航到这个页面时，我所看到的只有cameraSwitchingFill矩形，没有ProgressBar或TextBlock（尽管在设计器中我可以看到这些）。在切换摄像头时（如预期的那样），我看到矩形但没有ProgressBar或TextBlock。
我然后回到未示出的编辑和修改
空隙sensor_Click（对象发件人，EventArgs的） { //切换到其他相机（如果可用） CameraType类型= camera.CameraType;
if(type == CameraType.Primary)
{
if(PhotoCamera.IsCameraTypeSupported(CameraType.FrontFacing) == true)
{
ShowProgress(AppResources.CapturePage_SwitchingCameras);
cameraSwitchingFill.Visibility = Visibility.Visible;
UninitializeCamera();
InitializeCamera(CameraType.FrontFacing);
cameraSwitchingFill.Visibility = Visibility.Collapsed;
HideProgress();
}
}
else
{
if(PhotoCamera.IsCameraTypeSupported(CameraType.Primary) == true)
{
ShowProgress(AppResources.CapturePage_SwitchingCameras);
cameraSwitchingFill.Visibility = Visibility.Visible;
UninitializeCamera();
InitializeCamera(CameraType.Primary);
cameraSwitchingFill.Visibility = Visibility.Collapsed;
HideProgress();
}
}
}
所以结果是，当我永久使屏幕上的矩形和进度显示，只显示矩形，直到第一台相机开关点击事件发生，之后无论是矩形或进度条会显示。此外，即使矩阵和进度条在xaml中的videobrush实现下声明，在此期间被设置为可见，但切换期间冻结的图像仍保留在屏幕上。
这只是一个想法 - 你可以使用覆盖 –