Windows Phone 7-相机Flash应用程序无法正常工作

Question

在尝试遵循这里的说明- http://msdn.microsoft.com/en-us/library/hh202949.aspx，我已经编写了一个非常简单的WP7应用程序来打开相机闪光灯。一切似乎都正常，except....the闪存不能激活。

我的手机是三星SGH-I917 (最新的操作系统更新)，我正在使用WP7 SDK7.1，我已经检查了我相机的闪光灯是否真的可以工作。我还进行了检查，以确保以下内容在WMAppManifest.xml文件中。

<Capability Name="ID_CAP_ISV_CAMERA" />

你在下面的代码中看到的MessageBox用法，表明相机对象已经正确初始化，支持闪光模式，并且已经设置了FlashMode.On。Yet...no闪光灯实际上会打开。我遗漏了什么？

代码如下：

public partial class MainPage : PhoneApplicationPage
{
    PhotoCamera cam;        

    public MainPage()
    {
        InitializeComponent();  
    }

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        cam = new PhotoCamera(CameraType.Primary);
        cam.Initialized += new EventHandler<CameraOperationCompletedEventArgs>(cam_Initialized);
        cam.CaptureCompleted += new EventHandler<CameraOperationCompletedEventArgs>(cam_CaptureCompleted);
        cam.CaptureImageAvailable += new EventHandler<ContentReadyEventArgs>(cam_CaptureImageAvailable);
        cam.CaptureThumbnailAvailable += new EventHandler<ContentReadyEventArgs>(cam_CaptureThumbnailAvailable);
        viewfinderBrush.SetSource(cam);
    }

    void cam_CaptureThumbnailAvailable(object sender, ContentReadyEventArgs e)
    {
        return;
    }

    void cam_CaptureImageAvailable(object sender, ContentReadyEventArgs e)
    {
        return;
    }

    void cam_CaptureCompleted(object sender, CameraOperationCompletedEventArgs e)
    {
        return;
    }

    protected override void OnNavigatingFrom(System.Windows.Navigation.NavigatingCancelEventArgs e)
    {
        if (cam != null)
        {
            cam.Dispose();
            cam.Initialized -= cam_Initialized;
            cam.CaptureCompleted -= cam_CaptureCompleted;
            cam.CaptureImageAvailable -= cam_CaptureImageAvailable;
            cam.CaptureThumbnailAvailable -= cam_CaptureThumbnailAvailable;
        }
    }

    void cam_Initialized(object sender, CameraOperationCompletedEventArgs e)
    {
        this.Dispatcher.BeginInvoke(delegate()
        {
            MessageBox.Show("Cam Init, FlashMode.On Supported?: " + cam.IsFlashModeSupported(FlashMode.On).ToString());
        });

        return;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        if(cam.FlashMode == FlashMode.On)
            cam.FlashMode = FlashMode.Off;
        else
            cam.FlashMode = FlashMode.On;

        this.Dispatcher.BeginInvoke(delegate()
        {
            MessageBox.Show(cam.FlashMode.ToString());
        });
    }
}

下面是XAML：

<phone:PhoneApplicationPage 
x:Class="PhoneApp1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True">
<Grid x:Name="LayoutRoot" Background="Transparent">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
        <TextBlock x:Name="ApplicationTitle" Text="" Style="{StaticResource PhoneTextNormalStyle}"/>
        <TextBlock x:Name="PageTitle" Text="FlashLite" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
    </StackPanel>
    <Canvas x:Name="viewfinderCanvas" HorizontalAlignment="Center" >
        <Canvas.Background>
            <VideoBrush x:Name="viewfinderBrush" />
        </Canvas.Background>
    </Canvas>
    <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
        <Button Width="200" Height="100" Content="Flash" Click="Button_Click" />
    </Grid>
</Grid>

​

Answer 1

cam.FlashMode = FlashMode.On;

仅表示在采集图像时会激活闪光灯。

这是通过这样做来实现的

cam.CaptureImage();

编辑:如果你只想触发闪存，你可以直接调用cam.Focus();