拍照自动使用网络摄像头在C＃中使用WIA [英] Take a picture automatically using a webcam in C# using WIA

问题描述

我使用WIALib访问我的摄像头。我开发的代码非常简单：当按下一个按钮，一个摄像头拍摄照片，然后在图片中显示

I'm using WIALib to access my webcam. The code I'm developing is pretty simple: when a button is pressed a webcam picture is taken, and then displayed in a picture box.

我已经可以一起拍照我的摄像头，但是它尚未完全自动化。我发现，检索由摄像头拍摄的照片的唯一方法，是用这样的：

I can already take pictures with my webcam, but it isn't yet fully automated. The only way I found to retrieve the pictures taken by the webcam, is using this:

wiaPics = wiaRoot.GetItemsFromUI( WiaFlag.SingleImage, WiaIntent.ImageTypeColor ) as CollectionClass;

但是，这要求用户选择图片。我总是想拍摄的最后一张照片。所以我想是这样的：

But this asks the user to select the picture. And I always want the last picture taken. So I'm trying this way:

string imageFileName = Path.GetTempFileName(); // create temporary file for image

wiaItem = wiaRoot.TakePicture(); // take a picture

Cursor.Current = Cursors.WaitCursor; // could take some time

this.Refresh();

wiaItem.Transfer(imageFileName, false); // transfer picture to our temporary file

pictureBox1.Image = Image.FromFile(imageFileName); // create Image instance from file

Marshal.ReleaseComObject(wiaItem);

但这种方法TakePicture（）返回null，所以我可以将图像无法传输。最奇怪的是，照片是该方法TakePicture后真正实现了（）被调用，因为如果我去手动摄像头的画面是存在的！我只是不明白为什么它不返回一个值

But the method TakePicture() returns null, and so I can't transfer the image. The strangest thing is that the picture was really taken after the method TakePicture() was called, since if I go to the webcam manually the picture is there! I just don't get it why it doesn't return a value.

总之，我要么需要这两种方法之一：
1.使用TakePicture （）工作，返回值我可以使用。
2.访问网络摄像头的图片自动列表中，这样我就可以找回拍摄的最后一张照片。

To summarize, I either need one of this two: 1. Get TakePicture() to work, returning a value I can use. 2. Access the list of the webcam's pictures automatically, so I can retrieve the last picture taken.

您的帮助，最好的问候和感谢米卡埃尔。

Best regards and thanks for the help, Micael.

推荐答案

从我所看到的， wiaItem = wiaRoot.TakePicture（）是沿着走错误的道路。试试这个：

From what I can see, wiaItem = wiaRoot.TakePicture() is going down the wrong path. Try this:

string imageFileName;
wiaRoot.TakePicture( out takenFileName);
pictureBox1.Image = Image.FromFile(imageFileName);

TakePicture节省了画面的到文件的，并返回新的文件的名称。作为输出参数

TakePicture saves a picture to a file, and returns the new file's name as an output parameter.

修改根据您的评论 - 您使用的是Windows 7的版本WiaLib的？如果是这样，尝试这样的事情：

Edit per your comment - are you using the "windows 7 version" of WiaLib? If so, try something like this:

var manager = new DeviceManagerClass();
Item wiaItem;
Device device = null;
foreach (var info in manager.DeviceInfos)
{
    if (info.DeviceID == DESIRED_DEVICE_ID)
    {
        device = info.Connect();
        wiaItem = device.ExecuteCommand(CommandID.wiaCommandTakePicture);
    }
}

在这里您使用的众所周知的GUID （也由COM互操作包装暴露），而不是TakePicture。它的工作对我的摄像头，在任何情况下。

where you use the ExecuteCommand with the well known guid (also exposed from the COM interop wrapper) rather than TakePicture. It worked for my webcam, in any case.

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