如果不在主代码流中,ActiveX组件调用的回调函数不会触发
本文关键字:函数 回调 调用 组件 代码 ActiveX 如果不 | 更新日期: 2023-09-27 18:12:27
我有一个ActiveX组件,它扫描照片,将文件保存到客户端硬盘上的临时文件中,并上传照片。
我有一个"TwainMan"实例,它执行扫描部分,在扫描完成后,触发"imagescans"事件。这是我的主要代码流:
scanner = new TwainMan();
scanner.ImageScanned += new ImageScannedEventHandler(Scanner_ImageScanned);
执行此操作的代码放置在EventHandler委托方法" scanner_imagescans "中:
private void Scanner_ImageScanned(object Sender, ImageScannedEventArgs e)
{
this.tempFileName = scanner.ToTempFile(e.Image);
MessageBox.Show("Scanned picture stored on the following location:'n" + this.tempFileName);
Upload(this.tempFileName); // works just fine
TriggerJSCallback(); // here is where the problem appears!
}
在triggerjcallback方法中,我只触发JS回调:
private void TriggerJSCallback()
{
EventHandler DataPreparingFinished = this.DataPreparingFinished;
if (null != DataPreparingFinished) { DataPreparingFinished(this.tempFileName); }
}
请注意,如果我触发jcallback "DataPreparingFinished"从主流程中,JS回调监听器(定义在我的html页面)工作得很好,但问题出现,如果触发"DataPreparingFinished"从" scanner_imagescan "委托内触发,因此不是从主代码流。
我做错了什么?有人能帮忙吗?
这是html页面内的JS Callback定义,在标签内。
<script for="AXTwain" event="DataPreparingFinished(args)" language="javascript" type="text/javascript">
function AXTwain::DataPreparingFinished(args) {
alert("JS ALERT: SUCCESS!!! JS Callback working properly." + args);
// alert("The temp file is stored on: " + AXTwain.TempFileName);
}
</script>
如果我展示更多的代码可能会更好,这样你就能更好地了解我的问题到底是什么。
让我们从头开始…
下面是我的HTML页面,其中包括我的ActiveXObject实例化和JS回调/侦听器函数。
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>ActiveX TWAIN test page</title>
<object id="AXTwain" name="AXTwain" classid="clsid:d8ea830e-38b0-4f3b-8be4-39c417c27583"></object>
</head>
<body onload="myload();">
<h1 style="color:green;">AXTwain test page</h1>
<script type ="text/javascript">
function myload() {
if (AXTwain != null) {
AXTwain.AcquireImage();
}
}
</script>
<script for="AXTwain" event="DataPreparingFinished(args)" language="javascript" type="text/javascript">
// The "for" attribute should be set to the name of instance of your COM component.
// The "event" attribute should be set to the JavaScript function signature for the event.
// The name of the JavaScript function is the instance name of your COM component, followed
// by double colons, followed by the JavaScript signature of the event.
function AXTwain::DataPreparingFinished(args) {
alert("JS ALERT: SUCCESS!!! JS Callback working properly." + args);
}
</script>
</body>
</html>
下面是我的ActiveX包装器类…
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace AXImageAcquisition
{
#region ActiveX attributes
[ProgId("AXImageAcquisition.AXTwain_01")]
[Guid("d8ea830e-38b0-4f3b-8be4-39c417c27583")]
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
[ComSourceInterfaces(typeof(IComEvents))]
#endregion
public class AXTwain
{
#region Class Properties and Settings
private TwainMan scanner;
private String tempFileName;
public String TempFileName
{
get { return this.tempFileName; }
}
[ComVisible(false)]
public delegate void EventHandler(string args);
public event EventHandler DataPreparingFinished;
public bool imageScanned = false;
#endregion
#region Class Constructors
public AXTwain()
{}
#endregion
#region Class Methods
[ComVisible(true)]
public void AcquireImage()
{
this.DataPreparingFinished += new EventHandler(Delegate_DataPreparingFinished);
this.scanner = new TwainMan();
this.scanner.ImageScanned += new ImageScannedEventHandler(Scanner_ImageScanned);
TriggerJSCallback(); // HERE IN THE MAIN CODE FLOW THE MESSAGE GETS TO JS!!!
}
/// <summary>
/// Delegate that defines functionality for the ImageScanned event, defined in TwainMan class.
/// </summary>
/// <param name="Sender"></param>
/// <param name="e"></param>
public void Scanner_ImageScanned(object Sender, ImageScannedEventArgs e)
{
this.tempFileName = scanner.ToTempFile(e.Image);
Upload(this.tempFileName);
TriggerJSCallback(); // HERE (NOT IN THE MAIN CODE FLOW) THE MESSAGE NEVER GETS TO JS!!! WHYYYY? :(
}
/// <summary>
/// TODO!!!
/// </summary>
/// <param name="tempFileName"></param>
private void Upload(string tempFileName)
{
// TODO
}
/// <summary>
/// Test method for the DataPreparingFinished trigger.
/// </summary>
public void TriggerJSCallback()
{
EventHandler DataPreparingFinished = this.DataPreparingFinished;
if (null != DataPreparingFinished) DataPreparingFinished(this.tempFileName);
}
/// <summary>
/// Delegate that defines functionality for the DataPreparingFinished event, which is defined in IComEvents.
/// </summary>
/// <param name="msg">Arguments passing from C# to JS.</param>
void Delegate_DataPreparingFinished(string msg)
{
// MessageBox.Show("Delegate_DataPreparingFinished message! (C# code).'n Input message: " + msg);
}
#endregion
}
}
如果你需要更多的代码,我也可以复制/粘贴剩下的代码,这是TwainMan类和它的依赖。然而,所有这些都是从代码项目教程中获取的。顺便说一句,感谢作者。
这很难确定,因为我没有从c#中编写ActiveX组件,但在c++中,如果从主线程以外的线程调用,这样的回调将具有完全相同的效果。ActiveX通常期望所有调用都发生在主线程上。有一些方法可以让其他线程也与ActiveX一起工作,但是c#可能会自动为你做这件事,所以这在c#中可能并不总是准确的。
我建议你想办法在主线程上触发这个函数;我知道在Silverlight中有很多方法可以使用DispatcherTimer;也许你能找到类似的东西?无论如何,这就是我要尝试的。