Re: Converting a variable to a method so it can be run (somewhat like Eval could do). - C# Discussion Boards

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

3-Jul-07 7:13

Read about Reflection in .NET.

http://msdn2.microsoft.com/en-us/library/f7ykdhsy(VS.80).aspx[^]

In this page, you will see a paragrah beginning with Use MethodInfo to discover information .... This paragraph is your friend.

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If atheism is a religion, then not collecting stamps is a hobby. -- Unknown

Dario Solera3-Jul-07 7:20

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

3-Jul-07 7:20

Reflection is way slow. You should consider to use delegates, which are quite similar to C's function pointers. The topic is not very simple, but delegates are very powerful and elegant. Here[^] is an introductory article on MSDN Magazine.

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Azad Giordano Ratzki3-Jul-07 7:52

Azad Giordano Ratzki

3-Jul-07 7:52

Delegates seem very interesting to me also...although I am having a little difficulty visualizing their usage properly from the MSDN article, is there anyway you could write out a little snippet showing how I could use delegates to call a method whose name is based on a string I enter? Smile | :)

Thanks!

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

Le centriste4-Jul-07 2:09

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

4-Jul-07 2:09

Can you call a delegate with a method name defined in a string?!? Because this seems to be what he wants.

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If atheism is a religion, then not collecting stamps is a hobby. -- Unknown

Dario Solera4-Jul-07 2:51

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

4-Jul-07 2:51

No. Not directly at least.
The point is that invoking methods at runtime by their name is not very clean, in my opinion. Since I guess the methods he wants to invoke are parameterless and with no return value, using delegates would be very easy and would improve the robustness of the code.

Le centriste4-Jul-07 3:29

Re: Converting a variable to a method so it can be run (somewhat like Eval could do).

4-Jul-07 3:29

I agree with you in the way that he should consider using an interface instead instead of calling a method by a name specified in a string.

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If atheism is a religion, then not collecting stamps is a hobby. -- Unknown

Azad Giordano Ratzki3-Jul-07 7:47

Azad Giordano Ratzki

3-Jul-07 7:47

Thank you very much for both of your replies, I had a hunch that Reflection might be something I needed to look into, and I'll definitely give it a shot. Smile | :)

Using a 2D array as a DataSource

Dewald3-Jul-07 6:54

Dewald

3-Jul-07 6:54

Is there a way of using a 2D array as a DataSource to controls such as DataGridView or ListBox?

Re: Using a 2D array as a DataSource

AdRoGe3-Jul-07 7:38

AdRoGe

3-Jul-07 7:38

I seem to recall doing something similar to this with .NET Framework 1.0, or 1.1 (not sure which). I believe I used an ArrayList of ArrayLists for initial data population of the datagrid for a quick test. I never tried manipulating the data of the ArrayList after that. For data manipulation after the initial population I believe I used the native datagrid methods.

connecting to sql questions

crash8933-Jul-07 6:14

crash893

3-Jul-07 6:14

Hi all

At work we have a database that is read only that keeps track of the work we do ( who completed what ticket and so on) I need to take a chunk of the database for the work done by my group then count up certain types of information like who has done how many tickets or how many of one type of problem there was during a certain time.

question 1) can i use the fact that this is read only to my advantage in terms of speed or memory i saw something called sqlreader but i haven't had time to play with it yet

question 2) given the senerio above what would be the most efficient work flow? should i read the database into a dataset then do my filtering from there or something else

unfortunately this is not my strongest subject so all suggestions are appreshated

Re: connecting to sql questions

Le centriste3-Jul-07 7:15

Re: connecting to sql questions

3-Jul-07 7:15

I would choose solution 1, coupled with the use of stored procedure. As a piece of advice, if you are only reading from the tables, use the with (nolock) lock hint in your queries.

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If atheism is a religion, then not collecting stamps is a hobby. -- Unknown

mfmaneef3-Jul-07 9:53

mfmaneef

3-Jul-07 9:53

since your saying "chunk of data" i would prefer using datasets because..if your using datareaders each time u connect to the database whenever u execute a query..but datasets you can work in disconnected mode..

aneef

Problem with 2 forms

mcaos3-Jul-07 6:09

mcaos

3-Jul-07 6:09

Hi!
I have 2 forms:
Form1 and Form2, how I can write the text of a textbox in Form1 in another textbox in form2?
Thank
Bye.

Luc Pattyn3-Jul-07 6:30

Luc Pattyn

3-Jul-07 6:30

There are a lot of ways to do this. The easiest ones are:

- If form B is created by form A, and A has the initiative (e.g. because there is an
event firing in A), let A do the work using a property of B.

- if the initiative is reverse (the slave form B decides when), then the easiest is by
giving it a public event, so the master form A can wire a delegate to it and
un its update method whenever required.

Hope this helps.

Smile | :)

Luc Pattyn

[My Articles] [Forum Guidelines]

mcaos4-Jul-07 0:16

mcaos

4-Jul-07 0:16

Luc Pattyn wrote:
- If form B is created by form A, and A has the initiative (e.g. because there is an
event firing in A), let A do the work using a property of B.

Thaks, but how i can do that? Confused | :confused:

Any example??

By Windows M

Luc Pattyn4-Jul-07 0:29

Luc Pattyn

4-Jul-07 0:29

How does form A change form B's size ? by setting a new value to its Size property.
SImilar for any other property you can imagine (and hence add to a class):

in FormTypeA class:

FormTypeB formB=new FormTypeB();
formB.Show();

...

private void myTextBoxA_TextChanged(object sender, EventArgs e) {
    formB.Size=new Size(500, 600);
    formB.TextBoxText=myTextBoxA.Text;
}

In FormTypeB class:

public string TextBoxText {
    set {
        myTextBoxB.Text=value;
    }
}

May I suggest you work your way through a general C# book...

Smile | :)

Luc Pattyn

[My Articles] [Forum Guidelines]

Contrast solutions for drawing text and lines onto an image

thrakazog3-Jul-07 7:37

thrakazog

3-Jul-07 7:37

Bind the same datasource to both textboxes. That way a change in one will show up immediately in the other.

Jon Hulatt3-Jul-07 5:07

Jon Hulatt

3-Jul-07 5:07

Hi All,

The project i'm working on at the moment needs to draw information on top of a photo. The content of the photo varies massively - the colour and brightness vary a lot.

Can anyone think of a way of colouring the lines and text so that they are visible whatever the background image? and even if a line starts in a bright area and proceeds into a dark area?

My only idea is to use a "negative" approach, but i'm not sure how that can be implemented (easily) in GDI+

Any ideas greatfully received.

Thanks

Jon

using System.Beer;

Re: Contrast solutions for drawing text and lines onto an image

Dario Solera3-Jul-07 7:16

Re: Contrast solutions for drawing text and lines onto an image

3-Jul-07 7:16

You could probably draw two texts/lines varying the pen width and color, so that each element actually has a small visible outline. For the text, you have to add it to a Path object and use the DrawPath method.
Here you can find some help: http://www.bobpowell.net/faqmain.htm[^]

Luc Pattyn3-Jul-07 7:31

Luc Pattyn

3-Jul-07 7:31

Hi,

I know of no general solution. Here are some ideas though:

- for lines, one could draw two parallel lines in different colors
- for text, use a heavy font (either bold or black) and make it sufficiently large
- or for text, draw text twice, same font, same size, slightly offset (x+2, y+2)
using different colors
- smart color selection: built a histogram on your image (pick 100 pixels, convert them
to hue value, and now choose a color with the opposite hue = add 180 degrees, full
saturation, full brightness (unless histogram shows image is bright, then use black).
- on a display, use blinking (500 msec on/off)
- on a display, let the added info be drawn differently (other color, wider, ...)
while the user holds down CTRL key

Hope this helps

Smile | :)

Luc Pattyn

[My Articles] [Forum Guidelines]

Suppress "CAPS Lock is ON" warning in Windows XP

Subrahmanyam K3-Jul-07 4:52

Subrahmanyam K

3-Jul-07 4:52

Hi,

How can the default OS warning message "CAPS Lock is ON" can be suppressed on Windows XP for a password field in C# (.Net FW 2.0).

Note: Windows XP automatically shows the warning message when the CAPS Lock key is turned on for a password field.

Thanks in advance.

Subrahmanyam K

Re: Suppress "CAPS Lock is ON" warning in Windows XP

Dario Solera3-Jul-07 7:08