无法读取通过ADF扫描的第二页 [英] Cannot read second page scanned via ADF

问题描述

我有一个Brother多功能网络打印机/扫描仪/传真机(型号MFC-9140CDN).我正在尝试将以下代码用于WIA，以检索通过文档进纸器扫描的项目:

const int FEEDER = 1;

var manager=new DeviceManager();
var deviceInfo=manager.DeviceInfos.Cast<DeviceInfo>().First();
var device=deviceInfo.Connect();
device.Properties["Pages"].set_Value(1);
device.Properties["Document Handling Select"].set_Value(1);

var morePages=true;
var counter=0;
while (morePages) {
    counter++;
    var item=device.Items[1];
    item.Properties["Bits Per Pixel"].set_Value(1);
    item.Properties["Horizontal Resolution"].set_Value(300);
    item.Properties["Vertical Resolution"].set_Value(300);

    var img=(WIA.ImageFile)item.Transfer();
    var path=String.Format(@"C:\Users\user1\Documents\test_{0}.tiff",counter);
    img.SaveFile(path);

    var status=(int)device.Properties["Document Handling Status"].get_Value();
    morePages = (status & FEEDER) > 0;
}

首次使用Transfer方法时，所有页面都将通过文档进纸器.第一个页面用img.SaveFile保存到传入的路径，但是所有后续页面都不可用-device.Items.Count为1，尝试device.Items[2]会引发异常.

在下一次迭代中，调用Transfer会引发一个异常-可以理解，因为供稿器中现在没有页面.

如何获取已扫描到进纸器中的后续图像?

(N.B.遍历所有设备属性，还有另一个未命名的属性，其ID为38922.我无法找到对此属性的任何引用.)

更新

我在与 WIA_DPS_SCAN_AHEAD_PAGES ，但这很有意义，因为根据文档，此属性是可选的.

我尝试使用TWAIN(强烈建议通过 NTwain 库)使用同一问题.

解决方案

这是一个网络扫描仪，我正在使用WSD驱动程序.

一旦我安装了制造商的驱动程序，其行为便符合预期-在ADF中浏览一页，然后将控制权返回给程序.

(即使现在，当我使用WIA的CommonDialog.ShowSelectDevice方法时，扫描仪也可以使用两次，一次使用Windows驱动程序，一次使用Brother驱动程序；当我选择WSD驱动程序时，仍然可以看到问题.)

I have a Brother mutlifunction networked printer/scanner/fax (model MFC-9140CDN). I am trying to use the following code with WIA, to retrieve items scanned in with the document feeder:

const int FEEDER = 1;

var manager=new DeviceManager();
var deviceInfo=manager.DeviceInfos.Cast<DeviceInfo>().First();
var device=deviceInfo.Connect();
device.Properties["Pages"].set_Value(1);
device.Properties["Document Handling Select"].set_Value(1);

var morePages=true;
var counter=0;
while (morePages) {
    counter++;
    var item=device.Items[1];
    item.Properties["Bits Per Pixel"].set_Value(1);
    item.Properties["Horizontal Resolution"].set_Value(300);
    item.Properties["Vertical Resolution"].set_Value(300);

    var img=(WIA.ImageFile)item.Transfer();
    var path=String.Format(@"C:\Users\user1\Documents\test_{0}.tiff",counter);
    img.SaveFile(path);

    var status=(int)device.Properties["Document Handling Status"].get_Value();
    morePages = (status & FEEDER) > 0;
}

When the Transfer method is reached for the first time, all the pages go through the document feeder. The first page gets saved with img.SaveFile to the passed-in path, but all the subsequent pages are not available - device.Items.Count is 1, and trying device.Items[2] raises an exception.

In the next iteration, calling Transfer raises an exception -- understandably, because there are now no pages in the feeder.

How can I get the subsequent images that have been scanned into the feeder?

(N.B. Iterating through all the device properties, there is an additional unnamed property with the id of 38922. I haven't been able to find any reference to this property.)

Update

I couldn't find a property on the device corresponding to WIA_IPS_SCAN_AHEAD or WIA_DPS_SCAN_AHEAD_PAGES, but that makes sense because this property is optional according to the documentation.

I tried using TWAIN (via the NTwain library, which I highly recommend) with the same problem.

解决方案

This is a networked scanner, and I was using the WSD driver.

Once I installed the manufacturer's driver, the behavior is as expected -- one page goes through the ADF, after which control is returned to the program.

(Even now, when I use WIA's CommonDialog.ShowSelectDevice method, the scanner is available twice, once using the Windows driver and once using the Brother driver; when I choose the WSD driver, I still see the issue.)

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