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Bitmap has a GetPixel function returning the color of that pixel:
System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap(...);
System.Drawing.Color color = bitmap.GetPixel(42, 42);
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If you're going to look at more than a very small number of pixels, you do not want to use GetPixel.
It is very slow!
See these CodeProject search results[^] for better ways to do this!
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Hi All,
I have been searching to understand how generations work in .Net Memory management. It has been still a difficult interview question for .Net developers as most of the times we don't have to worry about how Memory Management is handled in .Net internally.
For example if I am running a large scale application then I have a question like in scenario 1. there are 5 objects in Generation 1 and 50 objects in generation 2 and in scenario 2. there are 50 objects in Generation 1 and 5 objects in generation 2 (thinking that generations don't start from 0, they will start from 1), in above two scenarios which scenario would have more performance, and the reason why it will have more performance than the other one.
Any kind of link to answer the above question and any kind of help to understand the generations perfectly and how to use it in achieving the higher performance in our applications is greatly thankful.
Even though it is easy to not worry about memory management in .Net, still I want to understand if I need to handle memory management in .Net managed code what is the best way to do. Please help by enlightening me with this very basic but very complex and important answer.
Thanks a lot in advance.
Thanks & Regards,
Abdul Aleem Mohammad
St Louis MO - USA
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If you want to understand .NET in more depth (including memory management), there's really only one person to go to. Jeffrey Richter really is "da man" in this space - I would start with this[^] book if I were you.
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Hi Abdul,
The answer to your question is that scenario 1 will be more faster, as there are very few elements in Gen 1 than Gen 2, as the frequency of lower generations garbage collection is more than higher one, even the top 1 which is Gen 2, and if we have few elements in Gen 1 then it will be easier and quicker for GC to complete.
BUT, if we consider memory management here and suppose as you mentioned yours is the scalable application then if for each session/user 50 objects are kept in Gen 2, then your 1st scenario will perform slow. Also in that case for new memory request which will occur when any new user will connect then in need of memory GC has to rerun very frequently.
so both the cases have their own pros and cons.
Gen 2 GCs are also considered to be slower.
I will send you more appropriate article for all this stuff.
Regards,
Amit Kumar
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Thanks Amit, the answer you gave me also gives good information. But stillI am looking forward to get that article or link.
Thanks once again.
Thanks & Regards,
Abdul Aleem Mohammad
St Louis MO - USA
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Amit, I'd suggest you go to your Code Project account settings and change "Your Display Name" NOT to be your email address.
This is just inviting spam to that email address.
Code Project is very good about keeping your email address hidden for just that reason.
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Thanks Matt, i didn't think that way.
Thanks,
Amit
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indian143 wrote: It has been still a difficult interview question for .Net developers
Since the vast majority of time that is completely irrelevant for what .Net developer does day to day then presumably by "difficult" comes in terms of the interviewer failing to understand what a developer actually does.
indian143 wrote: Even though it is easy to not worry about memory management in .Net, still I
want to understand if I need to handle memory management in .Net managed code
what is the best way to do.
As long as you are aware that there are a vast array of edge cases which will require some specific knowledge if that edge case appears. You can't even learn a fraction of them. So muddle about a bit with esoteric cases if you want but learn the general day to day stuff well.
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I have one project which is medium size ERP project and i have to use MVC 4 to develop it but am new in mvc development knows only basic mvc programming..so guide me how should i start..?
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Buy a book on MVC and read it. Try out exercises and tutorials . Start small.
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As you said that you already have basic mvc programming experience then you can only refer to articles which will point out the differences in MVC4 and the version which you have already used.
Also if you are not going to use new complex things like Single Page Apps, Async programming, then there is not very much changed.. only refer to URL routing and Actions.
Regards,
Amit Kumar
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Guys i have tried designing a quite different application using vb.net.The function of this application is to detect whick key is pressed in keyboard even when my application is minimised.
for example if iam using notepad to type some text i have to press the keys for giving input to the notepad while pressing each key my application has to detect which key is pressed.
All these are working in my own textbox(I have used key press event for this). but it is not working in other apps and also when it is minimized.
how to solve this problem
Help me Guyzzzz........
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srinivasankrishnaa wrote: but it is not working in other apps and also when it is minimized.
Because your app does not have input-focus.
srinivasankrishnaa wrote: The function of this application is to detect whick key is pressed in keyboard even when my application is minimised.
What you want is a keylogger; this can't be done using events, as Windows does not generate events in your app for things that are happening to other apps.
Code for a keylogger can be found anywhere on the internet. A word of warning though; depending on your location, you'd need to inform the user and/or get his permission to run this software.
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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Google for "VB.NET Global Keyboard Hook".
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As you have suggested i have designed a keylogger using "asynckeystate" function but it is Not detecting semicolon,colon,braces,and whether small letters or capital letters etc.
How to solve this.
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I have no idea as we haven't seen your code. Without seeing the RELEVENT parts of the code, it's impossible to tell you what's going wrong.
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Here is my code:-
Public Class Form1
Public Declare Function GetAsyncKeyState Lib "user32" (ByVal vkey As Int32) As Short
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim k1, k2, k3, k4, k5, k6, k7, k8, k9, k10, k12, k13 As Boolean
k1 = GetAsyncKeyState(Keys.A)
k2 = GetAsyncKeyState(Keys.LControlKey)
k3 = GetAsyncKeyState(Keys.RControlKey)
k4 = GetAsyncKeyState(Keys.F1)
If k1 = True Then
MsgBox("Key A is Pressed")
End If
If k2 = True Then
MsgBox("Key Lcontorl is Pressed")
End If
If k3 = True Then
MsgBox("Key Rcontorl is Pressed")
End If
If k4 = True Then
MsgBox("key F1 is pressed")
End If
End Sub
End Class
This detects whether "Key A" is pressed or not but how to use it to detect whether the key pressed is small "a" or Caps "A" and similarly for other alphabets and also to detect colon,semi-colon,braces etc.
plz help me guys.
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Yeah, this is never going to work. This needs to be scrapped and redone. You SERIOUSLY need to Google for "VB.NET global keyboard hook" and study what you find.
The reason this won't work is because your timer probably isn't going to fire fast enough and if you turn up the frequency this runs, you'll just end up pegging a CPU and still missing keys.
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srinivasankrishnaa wrote: How to solve this.
That's how a KEYlogger works; it logs all the keys that are pressed on a keyboard.
A key is not a character. A capital A is typed by holding the A-key and the SHIFT-key. It'll depend on the loaded keyboard-layout to which characters the pressed *keys* will be translated.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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If So I wil ask one more question
if i press "a" or "A" in my keyboard the current application is displaying the pressed character
now if i press small "a" in my keyboard my current application has to display small "b" and it should not display small "a".when my application is minimized.
how to do this.
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Send key "a" when the user presses your key. Send keys "backspace" and "b" when the user hits that key again.
It'll work "most of the time", and you'll be mucking with focus, some stubborn apps that'll never work (because of the way they're built) and, worst of all, a delay between input and user-feedback.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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I'm looking for recommendations for the best reading articles, white papers, tutorials etc. on Microsoft Extensibiliy Framework. I have a complex modular application to architect, and really need to brush up on more than just compile time exports and imports.
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