Re: RectanlgeF.Parse(string s) extension method? [modified] - C# Discussion Boards

Not Active31-May-11 2:03

Not Active

31-May-11 2:03

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Re: RectanlgeF.Parse(string s) extension method? [modified]

Chesnokov Yuriy31-May-11 2:22

Chesnokov Yuriy

31-May-11 2:22

In which way? I'm not asking about parsing string to rectangle logic here.
I need to add new public static method to RectangleF class without modifying it.
Instead of RectangleF there might be any class.

Чесноков

musefan31-May-11 2:26

31-May-11 2:26

maybe...

public static RectangleF Parse(this RectangleF rect, string s)
{
//do something with s
}

very easy to Google this one[^]

EDIT: I got this one a bit wrong. I think thou you just need to return a new instance that is parsed

public static RectangleF Parse(string s)
{
    RectangleF result = new RectangleF();
    //apply parsed values
    return result;
}

In use...

RectangleF rect = RectangleF.Parse("0,0,100,50");

...but as no one else has posted, maybe I have missed the point again

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modified on Tuesday, May 31, 2011 11:40 AM

Pete O'Hanlon31-May-11 2:33

Pete O'Hanlon

31-May-11 2:33

This won't work because he's looking to extend the RectangleF class with an instantiation method. Your code requires an instance already (that's kind of what the this in the extension indicates), so perhaps not quite so easy to Google.

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musefan31-May-11 2:42

31-May-11 2:42

oh yes, my bad completely

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Luc Pattyn31-May-11 2:42

31-May-11 2:42

yes and no.

Extension methods, while requiring a static keyword, are really instance methods; now Parse and TryParse are basically static methods, they operate on a string and return a specific type, they don't operate on that type (the MSDN example is string.WordCount which operates on an existing string and returns an int).

So you could have this definition (note the first argument isn't used at all):

public static class MoreTryParse {
	public static bool TryParse(this RectangleF dummy, string s, out RectangleF rect) {
		float x=0;
		float y=0;
		float w=0;
		float h=0;
		if (s.StartsWith("(") && s.EndsWith(")")) s=s.Substring(1, s.Length-2);
		string[] sa=s.Split(',');
		if (sa.Length==4 && float.TryParse(sa[0], out x) && float.TryParse(sa[1], out y) &&
			float.TryParse(sa[2], out w)&& float.TryParse(sa[3], out h)) {
			rect=new RectangleF(x, y, w, h);
			return true;
		} else {
			rect=new RectangleF(0, 0, 0, 0);
			return false;
		}
	}
}

but then you would have to call it like this:

public void test(string s) {
	RectangleF rect=new RectangleF();
	bool result=rect.TryParse(s, out r1);
	log(s+"  result="+result+"  rect="+rect.ToString());
}

which is a bit silly, as you have to create a dummy RectangleF in order to get the actual one.

Smile | :)

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Chesnokov Yuriy31-May-11 2:47

Chesnokov Yuriy

31-May-11 2:47

But I'm intrested in that calling convention

string s = "0.0,0.0,1.0,1.0";
RectangleF rect = RectangleF.Parse(s);

I wonder if there is any mechanism available to add public static methods to the class?
If not it'd be of value to add it to future revisions of C#

Чесноков

Luc Pattyn31-May-11 2:55

31-May-11 2:55

Chesnokov Yuriy wrote:
add public static methods

No, that is not supported in C#.

Smile | :)

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BobJanova31-May-11 3:04

BobJanova

31-May-11 3:04

I don't think this is possible. I don't see what is wrong with
RectangleF rect = MyParserClass.ParseRectangleF(s);
... though.

Luc Pattyn31-May-11 4:00

31-May-11 4:00

That is fine of course, however it would be even nicer if one could add static extension classes, so one can hide the fact that RectangleF is lacking the static Parse() and TryParse() methods other types are offering (int, float, DateTime, etc).

It could e.g. look like:

public static class MoreTryParse {
	public static bool TryParse(static, string s, out RectangleF rect) {
		...
	}
}

and be called like so:

public void test(string s) {
	RectangleF rect;
	bool result=RectangleF.TryParse(s, out r1);
	log(s+"  result="+result+"  rect="+rect.ToString());
}

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BobJanova31-May-11 23:09

BobJanova

31-May-11 23:09

That's a matter of taste, I think. I don't like extension methods much as it stands because you never know where they are actually defined.

Your declaration wouldn't do the job, it doesn't declare anywhere that it's a static extension on RectangleF. It would have to be

public static bool TryParse(static RectangleF, string s, out RectangleF rect) { ... }

or perhaps

public static bool TryParse(static<T>, string s, out RectangleF rect) where T:RectangleF { ... }

... allowing you to extend entire generic hierarchy subtrees where it was convenient to do so.

Luc Pattyn1-Jun-11 0:17

1-Jun-11 0:17

yes, public static bool TryParse(static RectangleF, string s, out RectangleF rect) { ... } is what I meant.

BobJanova wrote:
you never know where they are actually defined.

the IDE can worry about that, you don't have to.

Smile | :)

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Shameel31-May-11 3:05

31-May-11 3:05

Although we declare extension methods to be static, they actually work on instances (note that we specify the 'this' keyword in the first parameter). I would love to have the feature you're asking for, so we can use Rectangle.Parse(str). In your case, the neater alternative is to create a static Parser class and have a ToRectangeF method like this:

static class Parser {
    static RectangeF ToRectangeF(string s) {
        ....
    }
}

Clicking a button with SendMessage [modified]

Pete O'Hanlon31-May-11 3:39

Pete O'Hanlon

31-May-11 3:39

Perhaps an implementation like this[^], which I discussed with him when he originally raised this question this morning.

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musefan30-May-11 23:36

30-May-11 23:36

Hi All,

I am trying to simulate a button click using the SendMessage function of the Win32API. My application is C# WinForms .net 4.0 (the application performing the automation)

EDIT: The application I am trying to automate is not of my own work and I have no control over source code in any way.

First of all I am using FindWindow to get the handle to the window I want, I know this is working as the value of the handle is correct (as found using Spy++)

Next I am getting the handle of the child control (the button I want to click), again I know I am getting the correct value here.

Then I use SetActiveWindow() and pass in the window handle (which appears to work fine)

Then I use SendMessage() to simulate a mouse left button down and a mouse left button up. For now I just want to simulate the "Cancel" button for testing, which when clicked manually will simply close the form. My code however does nothing, the thing that is annoying me thou is that the "Cancel" button actually gets focus (just like it would if it had been clicked manually) but no action is taken.

Does anybody know why this could be happening? Is it possible that the application is question could be detecting I am using the SendMessage function and deciding not to process the relevant code? sort of like a "prevent automation" feature.

Thanks for any help, and the relevant code for SendMessage is as follows (also note, I have tried PostMessage too)

[DllImport("user32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

uint WM_LBUTTONDOWN = 0x0201;
uint WM_LBUTTONUP = 0x0202;
uint BM_SETSTATE = 0x00F3;
uint BN_CLICKED = 245;

void Function()
{
     //Code to get handles here

     //I have tried all variations of the following (so with some commented etc.)
     SendMessage(hwndButton, WM_LBUTTONDOWN, IntPtr.Zero, IntPtr.Zero);
     SendMessage(hwndButton, WM_LBUTTONUP, IntPtr.Zero, IntPtr.Zero);
     SendMessage(hwndButton, BM_SETSTATE, IntPtr.Zero, IntPtr.Zero);
     SendMessage(hwndButton, BN_CLICKED, IntPtr.Zero, IntPtr.Zero);
}

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modified on Tuesday, May 31, 2011 11:59 AM

Shameel31-May-11 0:15

31-May-11 0:15

Did you try BM_CLICK instead?

musefan31-May-11 0:42

31-May-11 0:42

I think BM_CLICK is the same as I have BN_CLICKED (seen different name in different places). I have used a value of 245, if you know a different value for BM_CLICK then please let me know and I will give that a try

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Shameel31-May-11 0:55

31-May-11 0:55

Not sure if your BN_CLICKED and BM_CLICK are same, but here is what the documentation at http://msdn.microsoft.com/en-us/library/bb775985(VS.85).aspx[^] says:
"Simulates the user clicking a button. This message causes the button to receive the WM_LBUTTONDOWN and WM_LBUTTONUP messages, and the button's parent window to receive a BN_CLICKED notification code."

I believe that the parent must be notified of the event for it to handle the event and BM_CLICK does this.

Shameel31-May-11 0:58

31-May-11 0:58

And I just verified that BM_CLICK is 245 (0x00F5) in winuser.h

musefan31-May-11 2:22