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 Wow! Thank you so much for your detailed answer!
Your assumptions in 1) are correct. Well, they could be synthetic pictures, but only one match is expected.
I must read your message (more times, I've read it three times) slowly and carefully: English is not my mother tongue (obviously); I'm rather new in C# (I usually work with Java); and I've never made complex operations with Bitmaps before, so I have to read about hashing and histogramming them.
But many of the things you say are very useful and will help me to make a method myself rather than copy such-and-such code from anywhere. After all, I'm here to learn. 
I think I will first try to make that method (implementing some of your suggestions, specially 5. and 6b.), accessing pixels in an unsafe way like CG does in his articles (not using GetPixel() nor SetPixel()) for quickness, and see how it works.
It will take some days, I'm making it for myself and not for my boss.  But, when I have something, I will let you all know.
Thank you guys! You are so helpful!
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Hi,
good luck.
Java and C# are pretty close to each other.
of course you don't use GetPixel; use pointers, it is the number one example for a pointer application.
and store bitmap dimensions in local variables, don't call Bitmap.Width or Height all the time!
Luc Pattyn [Forum Guidelines] [My Articles]
The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.
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Thank you! Yep, learning C# is being very easy (I would say that it's even easier than Java), and it's very useful for creating desktop applications, that's why I'm learning it. The productivity is awesome!
I'll try to remove GetPixel from everywhere in my app; not so easy (I'm having problems with nested fors, the inner one trying to lock bits that are already locked by the outer one), but I'm on it...
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verence333 wrote: I'm having problems with nested fors, the inner one trying to lock bits that are already locked by the outer one
That does not make much sense, you should lock the data of the entire image once, then enter your loop(s).
Luc Pattyn [Forum Guidelines] [My Articles]
The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.
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Yup, but the inner loop calls a function that tries to lock the bits, so I have to either modify it (and every reference to it) or create a new one that doesn't lock them. Anyway it's a minor problem. Thank you again!
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I've made a little method to find a Bitmap inside another one. It's fast enough for what I want. Obviously, the elapsed time depends on the size of the Bitmaps, but it takes about 15-30 ms. to find a small one (like a window button inside a Bitmap of a window, for instance) and 150-180 ms. to find a big one (like a window inside a capture of the screen).
I will try to program other strategies that we've been talking about, specially the convolution alternative (which I think would probably be the fastest if done the right way). In the meanwhile, here is the code so you can tell me your comments and suggestions, hoping that it will help anybody that has the same problem (I really did not find any method like this one anywhere on the Internet).
The method receives a small Bitmap which is expected to be contained in another, bigger Bitmap. It returns a Point which represents the upper left corner of the wanted location.
Note that, if the small Bitmap is not contained in the bigger one, it returns a Point(0,0), exactly the same as if it was contained in such a position. This can and should be easily improved, and I would like to read your comments about other improvements (specially concerning the speed issue) since I'm rather new in C# and I usually work with Java.
Thank you!
private Point searchBitmap(Bitmap smallBmp, Bitmap bigBmp)
{
BitmapData smallData = smallBmp.LockBits(new Rectangle(0, 0, smallBmp.Width, smallBmp.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
BitmapData bigData = bigBmp.LockBits(new Rectangle(0, 0, bigBmp.Width, bigBmp.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
int smallStride = smallData.Stride;
int bigStride = bigData.Stride;
int bigWidth = bigBmp.Width;
int bigHeight = bigBmp.Height;
int smallWidth = smallBmp.Width * 3;
int smallHeight = smallBmp.Height;
Point location = new Point(0, 0);
unsafe
{
byte* pSmall = (byte*)(void*)smallData.Scan0;
byte* pBig = (byte*)(void*)bigData.Scan0;
int smallOffset = smallStride - smallBmp.Width * 3;
int bigOffset = bigStride - bigBmp.Width * 3;
bool matchFound = true;
for (int y = 0; y < bigHeight; y++)
{
for (int x = 0; x < bigWidth; x++)
{
byte* pBigBackup = pBig;
byte* pSmallBackup = pSmall;
for (int i = 0; i < smallHeight; i++)
{
int j = 0;
matchFound = true;
for (j = 0; j < smallWidth; j++)
{
if (pBig[0] != pSmall[0])
{
matchFound = false;
break;
}
pBig++;
pSmall++;
}
if (!matchFound) break;
pSmall = pSmallBackup;
pBig = pBigBackup;
pSmall += (smallWidth + smallOffset) * (1 + i);
pBig += (bigWidth * 3 + bigOffset) * (1 + i);
}
if (matchFound)
{
location.X = x;
location.Y = y;
break;
}
else
{
pBig = pBigBackup;
pSmall = pSmallBackup;
pBig+=3;
}
}
if (matchFound) break;
pBig += bigOffset;
}
}
bigBmp.UnlockBits(bigData);
smallBmp.UnlockBits(smallData);
return location;
}
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hi
how can i convert an color image in to black & white
tell me plzzzzzzzzzz
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shekhar258395 wrote: how can i convert an color image in to black & white
Lots of example here[^]
Manas Bhardwaj
Please remember to rate helpful or unhelpful answers, it lets us and people reading the forums know if our answers are any good.
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If your pictures are small you can try the code below, but its performance poor.
public Image BW(Bitmap bmp)
{
for (int i = 0; i < bmp.Width; i++)
{
for (int j = 0; j < bmp.Height; j++)
{
int hede = (bmp.GetPixel(i, j).R + bmp.GetPixel(i, j).G + bmp.GetPixel(i, j).B) / 3;
bmp.SetPixel(i, j, Color.FromArgb(hede, hede, hede));
}
}
return bmp;
}
Instead of using this method try to google for an algorithm
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I need help on how to develop an sms web portal
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Try this: www.ozekisms.com
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Hi all,
I have a generic class internal static class Singleton<T> where T : class. Within the class I declare the following private field private static T _instance;.
Within the generic class contructor I perform the following actions:
Type type = typeof(T);
BindingFlags searchPattern = BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance;
ConstructorInfo constructor = type.GetConstructor(searchPattern, null, Type.EmptyTypes, null);
if (constructor == null)
{
string errorMsg = String.Format("The type {0} does not have a default constructor.", type.FullName);
throw new ArgumentNullException(errorMsg);
}
_instance = (T)constructor.Invoke(new object[0]);
To make use of the class I perform the following line of code:
Singleton < ApplicationProtector > ...
The class ApplicationProtector has a static field within it called expType which is a enum.
How can I make use of this static field expType after creating the instance of the object in the generic class (only when actually running the application and debugging it, can I see the field value which foems part of the _instance):
<br />
...<br />
_instance = (T)constructor.Invoke(new object[0]);<br />
...
The only programmers that are better C# programmers, are those who look like this -> ![Green Alien | [Alien]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/alien.gif) |
Programm3r
My Blog: ^_^
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er...
ApplicationProtector.expType - the same way you would always reference a static member.
Am I missing something? 
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er ... ??
Thanks for the response but....
internal static class Singleton<T> where T : class
{
private static T _instance;
static Singleton()
{
Type type = typeof(T);
BindingFlags searchPattern = BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance;
ConstructorInfo constructor = type.GetConstructor(searchPattern, null, Type.EmptyTypes, null);
if (constructor == null)
{
string errorMsg = String.Format("The type {0} does not have a default constructor.", type.FullName);
throw new ArgumentNullException(errorMsg);
}
_instance = (T)constructor.Invoke(new object[0]);
}
}
| The only programmers that are better C# programmers, are those who look like this -> |
Programm3r
My Blog: ^_^
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Forget about generics, by trying to use an enum defined in that class where you're trying to use it, you've defeated the purpose of your generic singleton wrapper!
What are you trying to achive? The class you've defined should be totally agnostic of the T passed it. It should not need to access any enum in one of the classes. All it should do is attempt to instantiate any class which can be used as a singleton.
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First thing i'd do if I were you is go and read up on the singleton design pattern. The class you have found/written is for that purpose, and that purpose alone. You may have accidentally stumbled upon a tried-and-tested pattern of software design. Thats usually how you come accross such things and will make you a better programmer.
In answer to your question, you would use the fields/methods of your class as follows - assume the "T" passed in is the class MyClass which has an instance method void Foo() and an instance property int Bar.
Singleton<MyClass> singleton = new Singleton<MyClass>();
singleton.Instance.Foo();
singleton.Instance.Bar = 5
Crucially, you would never access a static property/method on MyClass, only instance properties/methods. Thats by convention of course, as I stated originally there is nothing stopping you referencing a static member, MyClass.StaticProperty
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I will keep that in mind. Many thanks for your patience and help.
Kind regards,
| The only programmers that are better C# programmers, are those who look like this -> |
Programm3r
My Blog: ^_^
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It looks to me line you're doing something like this[^] and you could use the "new" constraint for that instead of reflection, are you?
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Hi,
Thanks for the reply.
Well I am making use of reference type contraints and in the link they are making use of constructor type contraints, and making use of singleton = new T(); is not permitted when making use of reference type contraints: Cannot create an instance of the variable type 'T' because it does not have the new() constraint.
Either way making use of constructor type contraints does not allow me to gain usage to the other classes's field as in my example.
| The only programmers that are better C# programmers, are those who look like this -> |
Programm3r
My Blog: ^_^
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I think you're missing the point of what your Singleton class is for. Did you write it, did someone else write it, or did you get that code snippet from somewhere?
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Hmmm ... OK, I am not trying to achieve a Singleton pattern. I have named my class in such a way that caused alot of confusion ... sorry about that.
Back to the drawing board for me with regards to generics ....
| The only programmers that are better C# programmers, are those who look like this -> |
Programm3r
My Blog: ^_^
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see answer above, there's no point posting the same response to me twice!
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Looks like you read[^] this article.
No, only those members that are known to exist for type T are accessible. You only constrained T to class so only members of class are accessible.
If you write an interface IHaveAnExpType, apply it to your class, and then add it as a constraint you would have access to it.
P.S. Dynamic types in C# 4.0 may allow this sort of thing.
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There is cs class that calls native DLL. That class is called from ASP.NET application. How can I step into native DLL while debugging the web project on my computer?
P.S. I can step into the DLL if I run any C# windows project.
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