在WP OS7.1中，允许我们通过编程的方式访问设备相机，可以通过访问部分API通过相机获取图像
1、把相机获取图像显示在屏幕上
新建一个画布，用于显示相机获取到的图像数据
<Canvas x:Name="cameraViewCanvas" Width="400" Margin="28,4,28,284"> <Canvas.Background> <VideoBrush x:Name="cameraVideoBrush" /> </Canvas.Background> </Canvas>
2、新建一个 相机设备 的实例，通过该实例访问相机设备，新建一个MediaLibrary 用于访问系统的媒体资源
首先需要包含命名空间（解析MediaLibrary时要先引用Microsoft.Xna.Framework命名空间）
using using Microsoft.Devices; using Microsoft.Xna.Framework.Media;
PhotoCamera cam;
MediaLibrary library = new MediaLibrary();
3、初始化相机设备（后置摄像头）和画布画刷，一般放在页面的初始化或 OnNavigatedTo 函数里
if (PhotoCamera.IsCameraTypeSupported(CameraType.Primary)) { 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); cameraVideoBrush.SetSource(cam); }
CameraType.FrontFacing表示前置摄像头（使用前判断是否支持）
注意：应该在页面退出时释放掉相机设备资源，注销事件，一般放在 OnNavigatedFrom 函数里面
if (cam != null) { cam.Dispose(); cam.Initialized -= cam_Initialized; cam.CaptureCompleted -= cam_CaptureCompleted; cam.CaptureImageAvailable -= cam_CaptureImageAvailable; cam.CaptureThumbnailAvailable -= cam_CaptureThumbnailAvailable; }
4、接下来是事件函数
cam_Initialized 相机初始化完成后执行
cam_CaptureImageAvailable 当有图像可用时发生
cam_CaptureThumbnailAvailable 当有缩略图图像可用时发生
cam_CaptureCompleted 拍摄完成时发生
View Code void cam_Initialized(object sender, CameraOperationCompletedEventArgs e) { } void cam_CaptureThumbnailAvailable(object sender, ContentReadyEventArgs e) { } void cam_CaptureImageAvailable(object sender, ContentReadyEventArgs e) { string fileName = "image.jpg"; //保存图像到CameraRoll里 library.SavePictureToCameraRoll(fileName, e.ImageStream); //保存图像到独立存储空间 using (IsolatedStorageFile isStore = IsolatedStorageFile.GetUserStoreForApplication()) { using (IsolatedStorageFileStream targetStream = isStore.OpenFile(fileName, FileMode.Create, FileAccess.Write)) { byte[] readBuffer = new byte[4096]; int bytesRead = -1; while ((bytesRead = e.ImageStream.Read(readBuffer, 0, readBuffer.Length)) > 0) { targetStream.Write(readBuffer, 0, bytesRead); } } } //关闭流 e.ImageStream.Close(); } void cam_CaptureCompleted(object sender, CameraOperationCompletedEventArgs e) { }
到这里，相机设备初始化完成了，接下来是对相机资源的操作
1、拍摄图片：
cam.CaptureImage();
2、闪光灯设置
cam.FlashMode = FlashMode.On;
3、缩略图分辨率设置（分辨率大小必须是相机设备支持的分辨率）
//获取设备支持的分辨率 IEnumerable<Size> resList = cam.AvailableResolutions; int resCount = resList.Count<Size>(); Size res; if(resCount >= 1) { //根据需要选择不同的分辨率，这里选择第一个 res = resList.ElementAt<Size>(0); } //设置分辨率 cam.Resolution = res;
4、对焦
if (cam.IsFocusSupported)
{
cam.Focus();
//cam.FocusAtPoint(0.5, 0.5);
}
5、访问快门按钮
快门按钮的访问是通过 CameraButtons 类中的一系列事件管理的
CameraButtons 类的三个事件
ShutterKeyHalfPressed 半按快门且持续800ms以上
ShutterKeyPressed 全按快门
ShutterKeyReleased 松开快门
在相机设备初始化时注册这三个事件，不用生存CameraButtons类的实例，它是一个static类
CameraButtons.ShutterKeyHalfPressed += new EventHandler(CameraButtons_ShutterKeyHalfPressed); CameraButtons.ShutterKeyPressed += new EventHandler(CameraButtons_ShutterKeyPressed); CameraButtons.ShutterKeyReleased += new EventHandler(CameraButtons_ShutterKeyReleased);
同样的，在离开页面的时候，注销这三个事件
CameraButtons.ShutterKeyHalfPressed -= CameraButtons_ShutterKeyHalfPressed; CameraButtons.ShutterKeyPressed -= CameraButtons_ShutterKeyPressed; CameraButtons.ShutterKeyReleased -= CameraButtons_ShutterKeyReleased;
实现三个事件函数
View Code void CameraButtons_ShutterKeyReleased(object sender, EventArgs e) { if (cam != null) { cam.CancelFocus(); } } void CameraButtons_ShutterKeyPressed(object sender, EventArgs e) { if (cam != null) { cam.CaptureImage(); } } void CameraButtons_ShutterKeyHalfPressed(object sender, EventArgs e) { if (cam != null) { cam.Focus(); } }