ProgrammersitP

[PairO'Dice Lost]

Does anyone here have any skill with C systems programming? I've been trying to read file permissions of all files in a directory, but everything comes up [----------] (i.e. 000) when I lstat() and bitwise & to check the flag.

My guess is that the variable you're ANDing the permissions with is incorrect somehow, like you forgot to initialize the value or it's shifted one bit to the left or something. Can you post the code?

[Neftren]

My guess is that the variable you're ANDing the permissions with is incorrect somehow, like you forgot to initialize the value or it's shifted one bit to the left or something. Can you post the code?

It was actually a silly mistake. I was looping through and forgot to update the current path, so it was always one-behind the index (i.e. reading the above directory permissions).

[akma]

I want that everytime I`ll press the print screen key it would automatically save the generated image in some folder.
I`m assuming I can somehow accsess the code preformed by keyboard buttons, but I have no idea how to even approach the issue. Some directions would be greatly appreciated.

[factotum]

If you want to capture a keypress like that then you need to write an application that implements a system-wide keyboard hook. Doing that is really getting down and dirty in the oily bits of Windows, though, not something you want to be doing unless you're really good at this sort of thing.

[Neftren]

I want that everytime I`ll press the print screen key it would automatically save the generated image in some folder.
I`m assuming I can somehow accsess the code preformed by keyboard buttons, but I have no idea how to even approach the issue. Some directions would be greatly appreciated.

I think what you want instead is an AutoHotKey script.

[Grinner]

If you want to capture a keypress like that then you need to write an application that implements a system-wide keyboard hook. Doing that is really getting down and dirty in the oily bits of Windows, though, not something you want to be doing unless you're really good at this sort of thing.

Fortunately for the rest of us, there's AutoIt.

[Neftren]

Fortunately for the rest of us, there's AutoIt.

Hm, this actually looks rather nifty.

---

1

Unrelated note... Does anyone know of a pure-python implementation of Subversion or Mercurial? I'm looking for something similar to Dulwich (for GitHub).

Or even better, a pure-python implementation of Git-Hg and Git-Svn ...

[Grinner]

Hm, this actually looks rather nifty.

Legend has it that AutoHotKey is a fork of an earlier, open source version of AutoIt.

[Razanir]

I'm back with another private/protected/public question:

Why is it recommended to have private variables in an abstract class then use getters and setters in subclasses? I heard this from a TA today and the logic makes no sense. I can understand no non-private variables in most classes, but not for use with subclasses. Why wouldn't you just make them protected if you want those fields to be in the subclass?

[Teddy]

I'm back with another private/protected/public question:

Why is it recommended to have private variables in an abstract class then use getters and setters in subclasses? I heard this from a TA today and the logic makes no sense. I can understand no non-private variables in most classes, but not for use with subclasses. Why wouldn't you just make them protected if you want those fields to be in the subclass?

A quick guess is that it would let someone subclass your class as a means for accessing and manipulating the variables directly without using the getters/setters, which would break the encapsulation.

[Capt Spanner]

I'm back with another private/protected/public question:

Why is it recommended to have private variables in an abstract class then use getters and setters in subclasses? I heard this from a TA today and the logic makes no sense. I can understand no non-private variables in most classes, but not for use with subclasses. Why wouldn't you just make them protected if you want those fields to be in the subclass?

I know this one! I actually did exactly what you had done - some physics variable was being retrieved by many bits, including derived subclasses.

Also - in C++ at least - derived classes don't have access to the base classes private parts*but do have access to the getters and setters for precisely this reason.
* Hehe - "private parts".

A common school of thought is to keep a variable private unless it you have situation:

class Foo {
private:
    Bar x;
public:
    Bar getX() const {return x;}
    void setX(Bar val) {x = val;}
};

You might as well just make x public, right?

However, I have found that I've been in this situation and I've wanted to replace x* with something else (whenever I used it it was being converted into different units which weren't human friendly) so I changed it to get() and set() functions which would do the conversion for me because this conversion was happening thousands of times per frame and became a real bottleneck.

This made me wish I'd kept x private and just used get()/set() functions for it because I could have just changed the class definition. As it was I had to go and change the many references to it by hand. :-(

*It wasn't actually called x. I forget what exactly it was.

[akma]

I think what you want instead is an AutoHotKey script.

Thanks. I used it, and now I have a problem.

I managed to write a code that would save the print screen image (spoilered below), but I can`t seem to find the right image format.
Will I have to append some bytes so it would fit a specific image format? Is there a format I can save print screen images directly in?

Spoiler

Show

OnClipboardChange:
if A_EventInfo = 2
FileAppend, %ClipboardAll%, D:\print screen\screen.bmp

[Teddy]

Thanks. I used it, and now I have a problem.

I managed to write a code that would save the print screen image (spoilered below), but I can`t seem to find the right image format.
Will I have to append some bytes so it would fit a specific image format? Is there a format I can save print screen images directly in?

Spoiler

Show

OnClipboardChange:
if A_EventInfo = 2
FileAppend, %ClipboardAll%, D:\print screen\screen.bmp

All files have a file header detailing what types of files they represent (and probably some other meta-data too). Without this header, your files are just going to be considered complete nonsense by the operative system. I suggest you either read up on how to save data in specific file formats, or just try to find a program to do it for you.

[nooblade]

So, I was wondering if there was anyone involved or wanting to get into programming in the playground, and just had a few questions:

Spoiler

Show

• Where are you and what are you doing in terms of programming? Employment, education or in your spare time?

[factotum]

What kind of free, simple version control could I sell to my boss? It's a small design firm so I think spending money is out of the question, and we're on the overworked side too.

SVN is free, and TortoiseSVN is an extremely simple to use Windows client for it, so I'd say that.

[Emmerask]

well I consider git to be far superior to svn, though svn is more easy to learn.

Especially if you want to have many different versions then the branching feature will be invaluable.

Though it does take maybe a day to learn git (depending on level of competence)

[Balain]

I found this while listening to "Security Now" Tiobe Software It is a list of 100 programming languages popularity/use

[Razanir]

Can someone help me with some code? Long story, but I'm analyzing the correlation between two different movie rating systems. I would manually sort all the data for χ² for homogeneity, but there's well over 1000 entries. I know there's an error in the output from a manual search (ctrl-F), but I can't figure out where the error would be. Instead of trying to figure it out (I seriously can't tell where it'd go wrong), I figured I'd just ask you guys for help.

(I just need help with incrementing the array. I know the file input part is working)

Rating system 1: A-I, A-II, A-III, L, O
Rating system 2: G, PG, PG-13, R, Not Rated

I have an int[5][5] named arr where I'm storing the counts. 0 is A-I/G, 4 is Not Rated/O

reader.nextLine() = [Movie title, possibly with commas in it], [rating 1] ([rating 2])

[IthilanorStPete]

Can someone help me with some code? Long story, but I'm analyzing the correlation between two different movie rating systems. I would manually sort all the data for χ² for homogeneity, but there's well over 1000 entries. I know there's an error in the output from a manual search (ctrl-F), but I can't figure out where the error would be. Instead of trying to figure it out (I seriously can't tell where it'd go wrong), I figured I'd just ask you guys for help.

(I just need help with incrementing the array. I know the file input part is working)

Rating system 1: A-I, A-II, A-III, L, O
Rating system 2: G, PG, PG-13, R, Not Rated

I have an int[5][5] named arr where I'm storing the counts. 0 is A-I/G, 4 is Not Rated/O

reader.nextLine() = [Movie title, possibly with commas in it], [rating 1] ([rating 2])

I'd say create a temporary String to hold the result from nextLine, parse it to get rating1 and rating2 as integers, then you have arr[rating1][rating2]++.
Side note: you probably want a more specific name than arr, call it ratingCounter or something.

[Grinner]

Rating system 1: A-I, A-II, A-III, L, O
Rating system 2: G, PG, PG-13, R, Not Rated

You forgot the X rating. Or is that not in your database?

[IthilanorStPete]

You forgot the X rating. Or is that not in your database?

Oh, and NC-17 too.

[Mystic Muse]

Need help again (I need to start asking in the middle of the week).

Spoiler

Show

"Code the Add button's Click event procedure so that it adds the amounts entered by the user to an accumulator variable and then displays the variable's value in the lblSales control. Use an arithmetic assignment operator to update the acumulator. Display the total sales with a dollar sign and two decimal places."

The other one I need help with.

Spoiler

Show

Public Class frmMain

Private Sub btnExit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExit.Click
Me.Close()
End Sub

Private Sub btnClickMe_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnClickMe.Click
' blinks the message in the lblMessage control

' declare counter variable
Dim intCount As Integer

' begin counting
intCount = 1
Do While intCount <= 20
If lblMessage.Visible = False Then
lblMessage.Visible = True
Else
lblMessage.Visible = False
End If
Me.Refresh()
System.Threading.Thread.Sleep(250)
' update the counter variable
intCount = intCount + 1
Loop
End Sub
End Class

"Change the pretest loop in the btnClickMe control's Click event procedure to a posttest loop that uses the Until keyword."

A step-by-step guide would be preferable, if possible.

[factotum]

Are you asking us to do your homework for you? Because you won't learn anything if you just follow what we say by rote...

Just a note on the second problem: it's basically just asking you to change the Do While test...Loop construct to a Do...Loop Until test one. You just need to change the test around so it works properly (bear in mind that While keeps going while the test is TRUE, whereas Until keeps going *until* the test is true, e.g. while it's false; also note that putting the test at the end of the loop means the code in the loop will be executed before the test is carried out, so there's a potential off-by-one issue you'll need to figure out).

[Emmerask]

I have a pretty tough nut to crack atm,
For an android project I have to display a route between two or more points on a mapview, in previous projects I just used a webview which worked fine.

This time however due to extra features I have to implement it into a mapactivity (sherlockmapactivity for actionbar in lower api versions)

The route calculation and displaying works all well (if a bit slow with the repsonse parsing but not really an issue).

However I noticed pretty extreme fps drops, further inspection seems to indicate that the mapview redraws every single overlay constantly.

With less complex overlays its no problem but a route is rather complex (and due to a 4.2.2 "bug" (maybe intended) I can´t use path but have to use line instead (which sucks performance wise).

the draw code in the Overlay extending subclass with some effort to reduce the number of lines displayed to enhance performace a bit.
this code is called several times even if the mapview does not change

@Override
    public final void draw(final Canvas c, final MapView mv,final boolean shadow) {
        super.draw(c, mv, false);
        int x1 = -1;
        int y1 = -1;
        int x2 = -1;
        int y2 = -1;

        Log.d(TAG,"DRAW");

        Paint paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeCap(Paint.Cap.ROUND);
        paint.setColor(colour);
        paint.setStrokeWidth(STROKE);

        for ( int i = 0; i < routePoints.size(); i++ )
        {
            int detailInc = 8;
            Point point = new Point();
            mv.getProjection().toPixels( routePoints.get( i ), point );
            x2 = point.x;
            y2 = point.y;
            if ( i > 0 )
            {
                if(x1+detailInc < x2 || y1+detailInc < y2 || x1-detailInc > x2 || y1-detailInc > y2){

                    if(y1 < mv.getHeight()+100 && y1 > -100 && x1 < mv.getWidth()+100 && x1 > -100){
                        c.drawLine( x1, y1, x2, y2, paint );
                    }
                    x1 = x2;
                    y1 = y2;
                }
            }else{
                x1 = x2;
                y1 = y2;
            }

        }
    }

The functionality inside the mapview is pretty standard, just adding it to the overlays.

So has anyone any idea how to fix the constant redraws?

[Emmerask]

Okay I think I found a solution, ItemizedOverlay draw is only called twice when nothing changes (normal + shadow).
So I think I will put the route into an itemized overlay (although google said to put complex shapes into overlay subclass).

that was a bit premature, problem is still there

[akma]

I`m looking at browser games development tools.
There is applets in Java, but I think other things (like flash) will be more suitable. My plan is to try a few tools that are supposed to be good, and from that pick my favourite.
So I know that there are applets in Java, flash, and I heard Ruby is good for web development...
What else is out there? What do you recommend?

[Emmerask]

Okay for those interested I "solved" my issue, well the mapview still redraws constantly but I managed to
a) understand android 4.2.2 behaviour regarding what it draws on the map and what not
b)increase the draw performance by roughly 2000%

firstly android 4.2.2 only draws objects where either the beginning or the end are within the displayed area plus half the span (or the center point plus the span).
With this information you can once again use path instead of line (which is a ton faster to draw and has build in optimization).

the most important parts of the RouteOverlay:

the draw override:

  @Override
    public boolean draw(final Canvas c, MapView mv,final boolean shadow, long when) {
        super.draw(c, mv, false);
        if(shadow){
            return false;
        }
        paint.setColor(colour);
        paint.setAlpha(ALPHA);
        paint.setAntiAlias(true);
        paint.setStrokeWidth(STROKE);
        paint.setStyle(Paint.Style.STROKE);
        optimize(mv);
        redrawPath(mv);
        c.drawPath(path, paint);

        return false;

    }

the optimize method which removes all geopoints outside the displayable bounds

  private List<GeoPoint> optimize(MapView mv){
        optimizedRoutePoints = new ArrayList<GeoPoint>();
        GeoPoint leftTop = new GeoPoint(mv.getMapCenter().getLatitudeE6()-mv.getLatitudeSpan(),mv.getMapCenter().getLongitudeE6()-mv.getLongitudeSpan());
        GeoPoint rightBottom = new GeoPoint(mv.getMapCenter().getLatitudeE6()+mv.getLatitudeSpan(),mv.getMapCenter().getLongitudeE6()+mv.getLongitudeSpan());
        for(int i = 0; i < routePoints.size();i++){
            if(routePoints.get(i).getLatitudeE6() > leftTop.getLatitudeE6() && routePoints.get(i).getLatitudeE6() < rightBottom.getLatitudeE6()
                    && routePoints.get(i).getLongitudeE6() > leftTop.getLongitudeE6() && routePoints.get(i).getLongitudeE6() < rightBottom.getLongitudeE6() )
            {
                optimizedRoutePoints.add(routePoints.get(i));
            }

        }
        return optimizedRoutePoints;
    }

redrawPath:

 private void redrawPath(MapView mv){
        final Projection prj = mv.getProjection();
        path.rewind();
        final Iterator<GeoPoint> it = optimizedRoutePoints.iterator();
        prj.toPixels(it.next(), p);
        path.moveTo(p.x, p.y);
        while (it.hasNext()) {
            prj.toPixels(it.next(), p);
            path.lineTo(p.x, p.y);
        }
        path.setLastPoint(p.x, p.y);
    }

One could optimize it further by having the mapview implement a zoom and motion listener and saving restoring the optimized route so that optimize is only called when the mapview has actually changed, but I´m perfectly happy with the current result even on my very low end test android, so I see no need for it atm

[Deathslayer7]

Does anyone know the best way for a mechanical engineer to learn the following:

BASH in Linux
Creating Make files using FORTRAN

To be more specific, I have already self taught myself quite a bit in BASH, but there is so much more I do not know. I have a little helpful cheat sheet with command line codes and such, but it barely scratches the basics.

I can get by moving around in directories, creating/moving/renaming them. I can get by with transferring files (via a GUI). Still having problems doing it by line based.

I can create FORTRAN files, compile them, and create an executable file which I can then run from the BASH.

My point is, is there a very good, very helpful cheat sheet which explains in depth every command along with every subcommand that you can use to define it even more?

Or is it better to learn from someone who knows BASH and have them teach me?

Same with creating Make files in FORTRAN?

[Grinner]

I`m looking at browser games development tools.
There is applets in Java, but I think other things (like flash) will be more suitable. My plan is to try a few tools that are supposed to be good, and from that pick my favourite.
So I know that there are applets in Java, flash, and I heard Ruby is good for web development...
What else is out there? What do you recommend?

You can do some really cool things with Javascript/WebGL. Add HTML5, and you could make a full game engine.

[PairO'Dice Lost]

My point is, is there a very good, very helpful cheat sheet which explains in depth every command along with every subcommand that you can use to define it even more?

Ta-da! It's not completely comprehensive, but it's much better than most.