Powershell:使用Hidlibrary的AsyncCallback事件 [英] Powershell: AsyncCallback Events using Hidlibrary

问题描述

我需要一些在Powershell中实现异步事件的帮助.

I need some help implementing asynchronous events in Powershell.

作为一个更大的HID项目的测试平台，我想使用Powershell从我从亚马逊起飞的USB应急按钮读取数据.完美的解决方案是将数据回调实现为一个事件，然后可以使用Register-ObjectEvent注册该事件.

As a testbed for a larger HID project I want to use Powershell to read the data from a usb panic button that I got off amazon. The perfect solution would implement the data callback as an event that could then be registered using Register-ObjectEvent.

我当前的方法是使用 Hidlibrary 库.我在调用Read()或ReadReport()方法时遇到困难.它们似乎不是典型的异步回调，并且使用 New-ScriptBlockCallback 的标准解决方案不起作用.

My current approach is to use the Hidlibrary library. I am having difficulty invoking both the Read() or ReadReport() methods. They do not appear to be typical asynccallbacks and the standard solution of using New-ScriptBlockCallback does not work.

到目前为止，我所能工作的并允许我拉起一个读柄.

What I have so far that works and allows me to pull a readhandle.

Add-Type -Path .\Projects\UsbPanicButton\HidLibrary.dll
$device = [HidLibrary.HidDevices]::GetDevice('\\?\hid#vid_1130&pid_0202&mi_00#7&29add023&0&0000#{4d1e55b2-f16f-11cf-88cb-001111000030}')
$device.OpenDevice()

这不起作用. (找不到超载)

This does not work. (Cannot find an overload)

$device.ReadReport((New-ScriptBlockCallback {Write-host "HI"}))

如何将ReadReport方法转换为可以注册的事件?

How can I convert the ReadReport method into an event that can be registered?

推荐答案

ReadReport方法签名:

The ReadReport method signature:

public delegate void ReadReportCallback(HidReport report);

不适合New-ScriptBlockCallback.它与采用AsyncCallback参数的方法一起使用. IF 您知道可以在使用ReadReport方法调用期间在创建线程上调用回调:

Isn't a fit for New-ScriptBlockCallback. It works with methods taking an AsyncCallback parameter. IF you know the callback is called on the creating thread during the ReadReport method call you can use:

$device.ReadReport({param($hidReport) $hidReport.ReadStatus })

如果在其他线程上调用它，请尝试使用New-ScriptBlockCallback函数的此修改版本:

If it is called back on a different thread, try this modified version of the New-ScriptBlockCallback function:

function New-ScriptBlockCallback {
    param(
        [parameter(Mandatory=$true)]
        [ValidateNotNullOrEmpty()]
        [scriptblock]$Callback
    )

    if (-not ("CallbackEventBridge" -as [type])) {
        Add-Type @"
            using System;
            using HidLibrary;

            public sealed class CallbackEventBridge
            {
                public event HidDevice.ReadReportCallback CallbackComplete = delegate { };

                private CallbackEventBridge() {}

                private void CallbackInternal(HidReport report)
                {
                    CallbackComplete(report);
                }

                public HidDevice.ReadReportCallback Callback
                {
                    get { return new HidDevice.ReadReportCallback(CallbackInternal); }
                }

                public static CallbackEventBridge Create()
                {
                    return new CallbackEventBridge();
                }
            }
"@
    }
    $bridge = [callbackeventbridge]::create()
    Register-ObjectEvent -input $bridge -EventName callbackcomplete -action $callback -messagedata $args > $null
    $bridge.callback
}

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