Creae a simple image manager

[Fred_FS]

Hello,
I decided to create a little tutorial on handling images, because often images and sprites are used together in the same object-class and so the image is often reloaded for all objects of the same type, what shouldn't be necessary.
You can read it here.

[Nexus]

Good tutorial!

I have written something similar (ResourceManager) in my library, but it doesn't provide much functionality specific to sf::Image. In your code, I like the possibility to specify multiple directories. I think an option to disable the debug outputs to std::cout would be handy, as well as the possibility to check whether image loading was successful. But you can also leave this as an exercise to the reader

By the way, a mistake I came across: The following code doesn't compile because std::map::erase() doesn't return any iterator.

Code: [Select]

it = images_.erase( it );
Instead, you could write the code below (which is okay because map iterators remain valid for all operations except removal), however I think in that case you may also exit the function.

Code: [Select]

images_.erase(it++);

[Fred_FS]

Thank you .
I had a look on your Resource Manager yesterday. I think, this would be the next step. But my tutorial is for beginners and a look at your code tells me that it is not "beginner's code" .
Those options, you mentioned, are not implemented, because I think that the reader will be also a programmer and he might be able to set some "//" int front of the debug output(or just don't copy it^^). It isn't a real debug output anyway. It just shows you, that the image is not loaded again and again.

A strange mistake. This[/cpp] also tells me that there is no erase-function, which returns an iterator, but my Visual C++ compiler has one . So it works for me.
But of course I fixed it. And you're right. It won't be necesseray to search the whole map, if I find and appropriate entry, and I should leave it.
So it should be enough to use this, shouldn't it?

Code: [Select]


images_.erase(it)
return;


[Nexus]

I had a look on your Resource Manager yesterday. I think, this would be the next step. But my tutorial is for beginners and a look at your code tells me that it is not "beginner's code" .

In fact, my code sometimes looks more complicated than necessary, especially the metaprogramming stuff

But I think our goals are different anyway: You teach people how to write a smart image managing class, while I try to provide something more or less ready to use for a specific purpose.

So it should be enough to use this, shouldn't it?

Code: [Select]


images_.erase(it)
return;


Yes. Now you can also drop the else branch and move the ++it to the loop header.

[Fouf]

You can use the map.find function map.find msdn instead of looping through with an iterator.

guess I can't do links like that :/ oh well.

http://msdn.microsoft.com/en-us/library/92cwhskb(VS.80).aspx

[denismr]

You can use the map.find function map.find msdn instead of looping through with an iterator.

guess I can't do links like that :/ oh well.

http://msdn.microsoft.com/en-us/library/92cwhskb(VS.80).aspx

It's very recommended to use the find function instead of looping through with an iterator because the map is an implementation of a RedBlack Tree or an AVL Tree.
It means that a find operation is O( log2 (N) ) while passing over the entire map is O(N), N = number of items in the map.

Good job!