how to use backgroundworker thread call the API GetWindowRect?

Question

3.00/5 (2 votes)

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how to use backgroundworker thread call the API GetWindowRect?
can anybody give me a demo,tanks~!

C#

[DllImport("user32.dll")]
    private static extern int GetWindowRect(int hwnd, ref Rect lpRect);

    private void bgw_DoWork(object sender, DoWorkEventArgs e)
    {

        while (bgw.WorkerSupportsCancellation)
        {
            GetWindowRect(hWnd,ref lpRect);
        }


    }

the question importance is not at define hWnd and lpRect,
i just give a demo.
the API GetWindowRect must based on GUI thread,but backgroundworker is another thread not based on GUI thread.
how can solve this quetion, can anybody compilation right.
even though i use System.Windows.Forms.Control.Invoke method，
but the method only have two overload,one is not have params,
another's params is object array.
how can i use ref params in object array?

Posted 28-Sep-13 1:24am

xuyunhai

Updated 28-Sep-13 4:44am

v7

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Comments

[no name] 28-Sep-13 7:44am

You need to P/Invoke it then call it like http://msdn.microsoft.com/en-us/library/windows/desktop/ms633519%28v=vs.85%29.aspx

xuyunhai 28-Sep-13 8:48am

no,can't solve this question.

BillWoodruff 28-Sep-13 9:10am

Why not ?

[no name] 28-Sep-13 9:46am

Well why can't you? We have no idea why you are unable to write some code or do some research or what you have tried to do for your self. You will never get anywhere unless you actually try to do it. Your "questions" show a definite lack of any kind of effort on your part. Do you expect us to spoon feed you?

xuyunhai 28-Sep-13 10:34am

maybe the question to you is very simple,but i search in google,but couldn't slove,so ask the quesion in here.

[no name] 28-Sep-13 10:47am

That has nothing to do with anything. You just post vague descriptions of so-called problems and expect us to read your mind. Can you tell what someone from half way around the world is thinking? Can you somehow see what the code is that is displayed on their screen? Can you view the error messages that their compiler is displaying? No you cannot and neither can we. If you are having compilation errors, you have to tell us what those errors are instead of trying to get us to read your mind.

xuyunhai 28-Sep-13 10:50am

i update the question,try to descripe clearly.
thanks to read again.

[no name] 28-Sep-13 11:02am

Your "update" has nothing to do with anything. You are still expecting us to read your mind. And you are expecting us to read you mind based on a code snippet that has absolutely nothing at all to do with the errors that you are getting. What is that the you think that the Windows API function GetWindowRect using parameters the are specific to C++ not C# have to do with Control.Invoke? You really need to stop what ever it is that you are doing and get yourself a book on basic .NET windows programming and work through it. Obviously you expect us to teach you programming in a forum posting and that is not going to happen.

xuyunhai 28-Sep-13 11:06am

maybe you can't solve,i just ask a question,if you can find a book that can solve this question,i will read 1000 times.

xuyunhai 28-Sep-13 11:12am

Unable have the ability to solve problems, still to belittle others, belittle problem

[no name] 28-Sep-13 13:53pm

You are just a troll looking to start trouble.

xuyunhai 28-Sep-13 20:47pm

Unable have the ability to solve problems?
or just use mouth to solve the question ?

BillWoodruff 28-Sep-13 9:11am

Why do you need to use a BackGroundWorker thread to call GetSystemRect ? What have you tried so far, and why doesn't what you have tried work ? Show some code.

xuyunhai 28-Sep-13 9:49am

<pre lang="c#">
[DllImport("user32.dll")]
private static extern int GetWindowRect(int hwnd, ref Rect lpRect);

private void bgw_DoWork(object sender, DoWorkEventArgs e)
{

while (bgw.WorkerSupportsCancellation)
{
GetWindowRect(hWnd,ref lpRect);
}

}
</pre>
produces compilation error.
you can test above code demo.

[no name] 28-Sep-13 10:23am

Of course if produces a compilation error. Where have you defined hWnd and lpRect?

xuyunhai 28-Sep-13 10:30am

the question importance is not at define hWnd and lpRect,
i just give a demo.
the API GetWindowRect must based on GUI thread,but backgroundworker is another thread not based on GUI thread.
how can solve this quetion,you can try it,and take sure your code can compilation right.

[no name] 28-Sep-13 10:44am

Okay so you do expect us to spoon feed you based on some random bit of code that you just make up? Well good luck with that.

xuyunhai 28-Sep-13 11:03am

i just ask a question

xuyunhai 28-Sep-13 11:07am

that's funny,just a question

xuyunhai 28-Sep-13 11:14am

Unable have the ability to solve problems, still to belittle others, belittle problem

2 solutions

Solution 1

I "guess" your problem can be solved by simply refactoring the code.
1. By the code given, the two parameter must be defined somewhere, in your case, are they defined in class.
2. You can simply write a function with no parameter to call the GetWindowRect, and call that function in your background worker through control.invoke or dispatcher.invoke. Syntactically, compiler should not complain.
3. I am not sure what you are trying to achieve by calling the getWindowRect this way? Background worker should be used to do some asynchronous call (triggered by network event or continuously working on something). SO you want to monitor your windows size continuously? You can use the windows size change event (check MSDN for exact event name).
4. Good luck.

Posted 28-Sep-13 7:09am

JohnnyChiu

Comments

xuyunhai 28-Sep-13 20:58pm

1. the GetWindowRect is Mircosoft API,i couldn't change the parameter.
2. even if i write a function with no parameter to call the GetWindowRect,but the GetWindowRect API is based on GUI thread,so when i run the it,will throw error.
3.maybe i don't need to monitor windows size continuously,just once.

xuyunhai 28-Sep-13 21:53pm

tanks for
1. By the code given, the two parameter must be defined somewhere, in your case, are they defined in class.

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xuyunhai · Accepted Answer · 2013-09-28T15:46:00

Solution 2

C#

[DllImport("user32.dll")]
private static extern int GetWindowRect(int hwnd, ref System.Drawing.Rectangle lpRect);

System.Drawing.Rectangle lpRect = new Rectangle();
GetWindowRect(hWnd,ref lpRect);

Posted 28-Sep-13 15:46pm

xuyunhai