原文:與眾不同 windows phone (22) - Device（設備）之攝像頭（硬件快門, 自動對焦, 實時修改捕獲視頻）

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與眾不同 windows phone (22) - Device（設備）之攝像頭（硬件快門, 自動對焦, 實時修改捕獲視頻）

作者：webabcd


介紹
與眾不同 windows phone 7.5 (sdk 7.1) 之設備

• 硬件快門
• 自動對焦、自動對焦到指定的點
• 實時修改捕獲到的視頻幀

示例
1、演示如何響應硬件快門
HardwareShutter.xaml

<phone:PhoneApplicationPage x:Class="Demo.Device.Camera.HardwareShutter"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"FontFamily="{StaticResource PhoneFontFamilyNormal}"FontSize="{StaticResource PhoneFontSizeNormal}"Foreground="{StaticResource PhoneForegroundBrush}"SupportedOrientations="Portrait" Orientation="Portrait"mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"shell:SystemTray.IsVisible="True"><Grid x:Name="LayoutRoot" Background="Transparent"><StackPanel Orientation="Vertical"><Canvas Width="480" Height="320"><Canvas.Background><VideoBrush x:Name="videoBrush"><VideoBrush.RelativeTransform><!--把捕獲到的圖像正過來--><RotateTransform CenterX="0.5" CenterY="0.5" Angle="90" /></VideoBrush.RelativeTransform></VideoBrush></Canvas.Background></Canvas><TextBlock Name="lblMsg" Text="通過按硬件快門來查看演示效果（半按壓、全按壓、釋放）" TextWrapping="Wrap" /></StackPanel></Grid></phone:PhoneApplicationPage>

HardwareShutter.xaml.cs

/** 演示如何捕獲相機的硬件快門的相關事件* * CameraButtons.ShutterKeyHalfPressed - 硬件快門半按壓時所觸發的事件* CameraButtons.ShutterKeyPressed - 硬件快門全按壓時所觸發的事件* CameraButtons.ShutterKeyReleased - 硬件快門被釋放時所觸發的事件* * * 注：無論是拍照模式還是攝像模式，只有在攝像頭工作起來的時候，系統才能響應硬件快門的相關事件*/using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using Microsoft.Phone.Controls;using Microsoft.Devices; using System.Windows.Navigation;namespace Demo.Device.Camera {public partial class HardwareShutter : PhoneApplicationPage{private PhotoCamera _camera;public HardwareShutter(){InitializeComponent();}protected override void OnNavigatedTo(NavigationEventArgs e){if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary)){_camera = new PhotoCamera(CameraType.Primary);// 注冊硬件快門的相關事件CameraButtons.ShutterKeyHalfPressed += CameraButtons_ShutterKeyHalfPressed;CameraButtons.ShutterKeyPressed += CameraButtons_ShutterKeyPressed;CameraButtons.ShutterKeyReleased += CameraButtons_ShutterKeyReleased;// 相機模式下，必須將捕獲到的信息輸出到 UI 上，系統才能響應硬件快門的事件（同理，攝像模式下，必須調用了 CaptureSource.Start() 之后系統才能響應硬件快門的事件） videoBrush.SetSource(_camera);}}protected override void OnNavigatingFrom(NavigatingCancelEventArgs e){// 清理相關資源CameraButtons.ShutterKeyHalfPressed -= CameraButtons_ShutterKeyHalfPressed;CameraButtons.ShutterKeyPressed -= CameraButtons_ShutterKeyPressed;CameraButtons.ShutterKeyReleased -= CameraButtons_ShutterKeyReleased;}void CameraButtons_ShutterKeyHalfPressed(object sender, EventArgs e){lblMsg.Text = "快門半按壓";}void CameraButtons_ShutterKeyPressed(object sender, EventArgs e){lblMsg.Text = "快門全按壓";}void CameraButtons_ShutterKeyReleased(object sender, EventArgs e){lblMsg.Text = "快門被釋放";}} }

2、演示如何自動對焦，以及如何自動對焦到指定的點
Focus.xaml

<phone:PhoneApplicationPage x:Class="Demo.Device.Camera.Focus"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"FontFamily="{StaticResource PhoneFontFamilyNormal}"FontSize="{StaticResource PhoneFontSizeNormal}"Foreground="{StaticResource PhoneForegroundBrush}"SupportedOrientations="Portrait" Orientation="Portrait"mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"shell:SystemTray.IsVisible="True"><Grid x:Name="LayoutRoot" Background="Transparent"><StackPanel Orientation="Vertical"><Canvas Name="canvas" Width="480" Height="320" Tap="canvas_Tap"><Canvas.Background><VideoBrush x:Name="videoBrush"><VideoBrush.RelativeTransform><!--把捕獲到的圖像正過來--><RotateTransform CenterX="0.5" CenterY="0.5" Angle="90" /></VideoBrush.RelativeTransform></VideoBrush></Canvas.Background></Canvas><Button Name="btnFocus" Content="自動對焦" Click="btnFocus_Click" /><TextBlock Name="lblMsg" /></StackPanel></Grid></phone:PhoneApplicationPage>

Focus.xaml.cs

/** 演示如何自動對焦，以及如何自動對焦到指定的點* * PhotoCamera - 用于提供相機功能* Focus() - 讓相機自動對焦* FocusAtPoint(double x, double y) - 自動對焦到取景器上指定的點* x, y - 取景器上需要對焦的點的坐標，取景器左上角坐標為 0,0，取景器右下角坐標為 1,1* AutoFocusCompleted - 自動對焦完成后所觸發的事件（事件參數為 CameraOperationCompletedEventArgs 類型）* * * CameraOperationCompletedEventArgs* Succeeded - 操作是否成功* Exception - 異常信息*/using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using Microsoft.Phone.Controls;using Microsoft.Devices; using System.Windows.Navigation;namespace Demo.Device.Camera {public partial class Focus : PhoneApplicationPage{private PhotoCamera _camera;public Focus(){InitializeComponent();}protected override void OnNavigatedTo(NavigationEventArgs e){if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary)){// 實例化 PhotoCamera，注冊相關事件_camera = new PhotoCamera(CameraType.Primary);_camera.AutoFocusCompleted += _camera_AutoFocusCompleted;// 在 VideoBrush 上顯示攝像頭捕獲到的實時信息 videoBrush.SetSource(_camera);}}protected override void OnNavigatingFrom(NavigatingCancelEventArgs e){// 清理相關資源_camera.AutoFocusCompleted -= _camera_AutoFocusCompleted;}void _camera_AutoFocusCompleted(object sender, CameraOperationCompletedEventArgs e){if (e.Succeeded){Deployment.Current.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "自動對焦完成";});}else{Deployment.Current.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "自動對焦失敗";});}}private void btnFocus_Click(object sender, RoutedEventArgs e){if (_camera.IsFocusSupported == true){try{// 開始自動對焦 _camera.Focus();lblMsg.Text = "開始自動對焦";}catch (Exception ex){this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "自動對焦失敗：" + ex.ToString();});}}else{this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "相機不支持自動對焦";});}}private void canvas_Tap(object sender, System.Windows.Input.GestureEventArgs e){if (_camera != null){if (_camera.IsFocusAtPointSupported == true){try{// 獲取用戶觸摸的點相對于 canvas 的坐標Point tapLocation = e.GetPosition(canvas);// 計算觸摸點映射于取景器上的坐標（取景器左上角為0,0，右下角為1,1）double focusXPercent = tapLocation.X / canvas.Width;double focusYPercent = tapLocation.Y / canvas.Height;// 自動對焦到指定的點 _camera.FocusAtPoint(focusXPercent, focusYPercent);this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = String.Format("自動對焦到指定的點{0}X：{1:N2}{2}Y：{3:N2}", System.Environment.NewLine, focusXPercent, System.Environment.NewLine, focusYPercent);});}catch (Exception ex){this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "自動對焦到指定的點失敗：" + ex.ToString();});}}else{this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "相機不支持自動對焦到指定的點";});}}}} }

3、演示如何實時修改捕獲到的視頻幀
LiveAlter.xaml

<phone:PhoneApplicationPage x:Class="Demo.Device.Camera.LiveAlter"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"FontFamily="{StaticResource PhoneFontFamilyNormal}"FontSize="{StaticResource PhoneFontSizeNormal}"Foreground="{StaticResource PhoneForegroundBrush}"SupportedOrientations="Landscape" Orientation="Landscape"mc:Ignorable="d" d:DesignHeight="480" d:DesignWidth="728"shell:SystemTray.IsVisible="True"><Grid x:Name="LayoutRoot" Background="Transparent"><StackPanel Orientation="Vertical"><Grid Width="480" Height="320" HorizontalAlignment="Left"><Canvas Visibility="Collapsed"><Canvas.Background><VideoBrush x:Name="videoBrush" /></Canvas.Background></Canvas><!--用于顯示經過處理后的實時畫面--><Image x:Name="imgEffect" HorizontalAlignment="Left" /></Grid><TextBlock Name="lblMsg" /></StackPanel></Grid></phone:PhoneApplicationPage>

LiveAlter.xaml.cs

/** 演示如何實時處理攝像頭捕獲到的圖像* * PhotoCamera - 用于提供相機功能* PreviewResolution - 捕獲到的圖像的當前的分辨率（返回 System.Windows.Size 類型的結構體，其包含 Width 和 Height 字段）* GetPreviewBufferArgb32(int[] pixelData) - 將當前捕獲到的圖像的 ARGB 數據復制到指定的緩沖區中* * * 注：* Resolution 指的是相機設置的分辨率* PreviewResolution 指的是系統針對顯示設備縮放后的真實分辨率* 因為通常相機能夠拍攝大于設備顯示器的分辨率的圖像，所以實時顯示攝像頭捕獲到的圖像時，系統會對其分辨率進行優化，PreviewResolution 就是優化后的數據*/using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using Microsoft.Phone.Controls;using Microsoft.Devices; using System.Threading; using System.Windows.Media.Imaging; using System.Windows.Navigation;namespace Demo.Device.Camera {public partial class LiveAlter : PhoneApplicationPage{private PhotoCamera _camera = new PhotoCamera();// 用于顯示處理后的圖像private WriteableBitmap _writeableBitmap;// 有信號private static ManualResetEvent _manualReset = new ManualResetEvent(true);public LiveAlter(){InitializeComponent();}protected override void OnNavigatedTo(NavigationEventArgs e){if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary)){// 實例化 PhotoCamera，并注冊相關事件_camera = new PhotoCamera(CameraType.Primary);_camera.Initialized += _camera_Initialized;videoBrush.SetSource(_camera);}else{this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "設備不支持主攝像頭";});}}protected override void OnNavigatingFrom(NavigatingCancelEventArgs e){// 清理資源if (_camera != null){_camera.Dispose();_camera.Initialized -= _camera_Initialized;}}void _camera_Initialized(object sender, CameraOperationCompletedEventArgs e){// 新開線程去執行實時處理圖片的任務Thread thread = new Thread(CameraToGray);thread.Start();this.Dispatcher.BeginInvoke(delegate(){// 讓 Image 顯示 WriteableBitmap 中的內容_writeableBitmap = new WriteableBitmap((int)_camera.PreviewResolution.Width, (int)_camera.PreviewResolution.Height);imgEffect.Source = _writeableBitmap;});}private void CameraToGray(){// 初始化緩沖區大小：圖像寬和高的乘積int[] buffer = new int[(int)_camera.PreviewResolution.Width * (int)_camera.PreviewResolution.Height];try{while (true){// 實例化 ManualResetEvent 的時候，指定了其是有信號的_manualReset.WaitOne(); // 有信號則不阻塞，無信號則阻塞// 將當前捕獲到的圖像以 ARGB 的方式寫入到緩沖區 _camera.GetPreviewBufferArgb32(buffer);// 將緩沖區中的每一個像素的顏色都轉換為灰色系for (int i = 0; i < buffer.Length; i++){buffer[i] = ColorToGray(buffer[i]);}_manualReset.Reset(); // 設置為無信號 Deployment.Current.Dispatcher.BeginInvoke(delegate(){// 將處理后的圖像數據保存到 WriteableBitmap 對象buffer.CopyTo(_writeableBitmap.Pixels, 0);// 重新繪制整個 WriteableBitmap 對象 _writeableBitmap.Invalidate();lblMsg.Text = "圖像實時處理中";_manualReset.Set(); // 設置為有信號 });}}catch (Exception ex){this.Dispatcher.BeginInvoke(delegate(){lblMsg.Text = "圖像處理失敗：" + ex.ToString();});}}// 將指定的顏色轉換成灰色系的顏色private int ColorToGray(int color){int gray = 0;int a = color >> 24;int r = (color & 0x00ff0000) >> 16;int g = (color & 0x0000ff00) >> 8;int b = (color & 0x000000ff);if ((r == g) && (g == b)){gray = color;}else{int i = (7 * r + 38 * g + 19 * b + 32) >> 6;gray = ((a & 0xFF) << 24) | ((i & 0xFF) << 16) | ((i & 0xFF) << 8) | (i & 0xFF);}return gray;}} }

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