How background threads operate frame web pages

crystal0330 · Posted on 1/22/2019 9:43:08 PM

First of all, if I execute the following statement with a UI thread, there is no problem
      private  void button9_Click_1(object sender, EventArgs e)
      {
         mshtml. HTMLDocument doc = GetIe("URL"); GetIe is a method to get IE documents at a specified URL;
         doc.frames.item(0).document.all.item("txtLimits").innerText = "123";
      }
However, if I put it in a background thread, it throws an exception: InvalidCastException, the specified conversion is invalid, the code is as follows
private async void button9_Click_1(object sender, EventArgs e)
      {
         Action action = new Action(test12);
         await Task.Run(action);
      }
      private void test12()
      {
         mshtml. HTMLDocument doc = GetIe("URL");
         doc.frames.item(0).document.all.item("txtLimits").innerText = "123";
      }

。。。 How to write the correct one?

summer · Posted on 1/23/2019 8:03:26 AM

@小渣渣

Little scum · Posted on 1/23/2019 9:08:36 AM

Login is visible.

Change

Login is visible.

Try

crystal0330 · Posted on 1/23/2019 10:04:56 PM

Xiao Zhao posted on 2019-1-23 09:08
Change

Try

Thank you very much, the problem is solved, it's just that I'm new to async and don't understand why it's written like this, it would be more perfect if you could explain it.

crystal0330 · Posted on 1/24/2019 6:38:37 AM

This post was last edited by crystal0330 on 2019-1-24 06:55

Xiao Zhao posted on 2019-1-23 09:08
Change

Try

Hello, I also encountered a problem in the future:

Login is visible.

ClickYes is a method that allows you to move the mouse to the OK button in the pop-up window and click twice

Login is visible.

Now I have two problems:
1. Write like this,ClickYes can only letThe second click of the mouse, that is, the first click is not executed, if it is in the UI thread, it can be clicked twice;
2. I hit a breakpoint in the ClickYes method, and after the program was interrupted, I pressed F11 again, and did not execute the next code in ClickYes. So how to debug step by step?

crystal0330 · Posted on 1/24/2019 2:33:03 PM

Xiao Zhao posted on 2019-1-23 09:08
Change

Try

Hello, I just tried again, and when I write like this, the winform interface is stuck again, which is the same effect as using the UI thread directly...

[WinForm] How background threads operate frame web pages

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