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elguaro wrote:
developers do forget to catch exceptions or simply choose to ignore them.
You are missing my point. If I choose to catch Exception e, then I will swallow all exceptions, this is an ACTIVE error I make. If I don't put a try/catch at all, then the program will *crash* because I forgot to catch an exception. Simple as that.
elguaro wrote:
for some strange reason in my "real world" no matter how much testing you do, you can only expect the unexcepted in production.
That's perhaps a sign that the test cases need to be broadened  Even then, it's inevitable that some issues will be found by the client, that's just life. As I said, how much better for them to get an exception message that tells you exactly what went wrong on a production machine, rather than a general crash that leaves you spending hours looking at the code, trying to figure out how on earth the app got into a state so it did what they reported ?
elguaro wrote:
just knowing that an error occurred is not good enough when you could have dealt with it
But again, that's the point. We should be able to tell what errors are likely to occur in the majority of cases.
elguaro wrote:
You shoudn't try to infer what exceptions are likely to be thrown just by looking at a method's name.
Sorry, that's not what I meant. I meant that if I, within a function, try to open a file for reading (for example), I should be able to work out what exceptions are likely to occur within that API call, and therefore what exceptions I should be catching.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Christian Graus wrote:
If I don't put a try/catch at all, then the program will *crash* because I forgot to catch an exception
You wouldn't forget if the compiler forced you to put in that try/catch. And that's one crash less in your system.
Christian Graus wrote:
how much better for them to get an exception message that tells you exactly what went wrong on a production machine, rather than a general crash that leaves you spending hours looking at the code
How much better not to have an error in the first place? Maybe the error was something you could have recovered from but forgot to put that try/catch.
Of course having unchecked exceptions is better than not having anything at all. What I'm saying is I'd prefer to have checked exceptions.
We could spend our lifes and never agree on this one ...
Thanks for the discussion ...
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Given that DX9 is an utter joke, I'm using the Media Player control to play video files in my app. The thing is, I want to build a queue of files in my code, and play them, but it seems to do that, I need to load the file, wait for the player state to be set to ready twice, then I can play. This I did, and it works fine on my machines, but not on the clients. Does anyone have any info or know of a good source of info on maintaining a file queue using the WMP SDK ?
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Probably not what you're looking for... WMP is so bloated we took a different approach. We wrapped the MCI calls in C# and maintain our own queueing mechanism. Our "player" is event driven once started and runs on a constantly filling queue which pretty much runs all the time (well, 20 hours a day). An event tells us when the end of the queue is near (3 items) and we re-fill. Each notification from our video component drives the loading and playing of the next media item. There's tons of examples out there for using MCI directly. Sorry, but I don't have alot of WMP experience myself.
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Christian Graus wrote:
Given that DX9 is an utter joke,
Considering that DirectX was written as a fast interface between games and video cards, and not a full featured media player, it's no suprise that it's not doing the job you want it to do.
The Windows Media Player control will do the job, but it's doesn't have a very friendly developer interface.
The best method would be to write your own component using Windows MultiMedia API's. This will give you the best control with the greatest flexibility, but also will force you to write a large amount of code.
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Dave Kreskowiak wrote:
not a full featured media player, it's no suprise that it's not doing the job you want it to do.
Well, actually, if the two classes in the AudioVideoPlayback namespace worked at all, then they would be perfect. I don't need much, just for videos to play, and a callback when they end. I've written an article on the site if you're interested to know all the ways in which this utterly fails to work.
Dave Kreskowiak wrote:
The Windows Media Player control will do the job, but it's doesn't have a very friendly developer interface.
So I have discovered
Dave Kreskowiak wrote:
The best method would be to write your own component using Windows MultiMedia API's. This will give you the best control with the greatest flexibility, but also will force you to write a large amount of code.
I just may spend the weekend doing that. I didn't realise it was an option, that is to say, I did not know they existed. I'll check it out.
thanks.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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I'm taking over an application from a developer that just left the company. The application is mostly "completed" with just a few bugs and a couple pieces of functionality I'll have to add (no big deal). It's really just a datagrid tied to a sequel server through a proper dataset. The user has several types of searches possible and for each one there is a different TableStyle used in the DataGrid but in any case the same dataset is used.
My problem is that they want to sort by clicking on the column headers. I know I can turn that on easy enough (and I have). However, it doesn't "appear" that the DataTable being bound to the dataset of the datagrid is being reordered with the dataview of the datagrid (too many freagin data's). Anyway, I know I could do a Select() against the DataSet() using the "MappingName" of the Column Header. This SHOULD give me the same ordering that the grid control is giving me, right?
Is there a way to automate this? The reason I need the grid's "view" and the datatable to stay in Sync (order wise) is if a user-double clicks a row it opens an editor dialog with alot of custom options that wouldn't really work by in-line editing. Also, if the user sorts by the column header I want to be able to retain the proper selected record (if one was selected) once the list is redrawn.
Any help? I can probably hack something but I'd really like to do it properly. I'm a bit new to using this control and, in fact, Datasets, etc.
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Is there a way in C# to specify the hostname in a sql connection string. I know it can be done in C++, but I have searched the documentation for c# and it doesn't appear to be an option.
I am trying to replace the hostname (which by default is the machine name) with an app name so when I do an SP_WHO I can see exactly what app is responsible for what connection.
Darryl Borden
Principal IT Analyst
darryl.borden@elpaso.com
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It has nothing to do with C# - merely the ADO.NET provider (or OLE DB provider, if using the System.Data.OleDb namespace members).
SQL Server supports a hostname. This is the "Data Source" property, where "Initial Catalog" is the database on that RDBMS.
Example:
string connstr = string.Format("Data Source={0}; Initial Catalog=MyDB; " +
"Integrated Security=SSPI", hostname);
using (SqlConnection = new SqlConnection(connstr))
{
}
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
[My Articles] [My Blog]
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Hi,
Atlast I have implemented my program to convert an array of Pixel data.
step1)- first of all My original image is a 1650x2544 (widthxheight) and i have stored all the pixel data into an array of (2544x1650).
step2)- I have created an empty Bitmap of respective height and width.
step3)- Now i copied respective pixel data fromt the array data into all the 3 planes (R,G,B). as i am creating a monochrome image i am copying the same value for each three R,G,B values.
step4)- returning the image...
can anyone tell me whether wht i am doin is correct...
here is the code...
private void File_Open(object sender, System.EventArgs e)
{
OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.InitialDirectory = "c:\\" ;
openFileDialog.RestoreDirectory = true ;
int[,] PixelData;
int Height=0, Width=0, j;
if(DialogResult.OK == openFileDialog.ShowDialog())
{
ChosenFile=openFileDialog.FileName;
PixelData = ConvertFile(ref Height, ref Width);
m_Bitmap =new Bitmap(Width,Height,PixelFormat.Format24bppRgb);
if (Display (m_Bitmap, PixelData))
{
this.AutoScroll = true;
this.AutoScrollMinSize = new Size ((int)(m_Bitmap.Width * Zoom), (int)(m_Bitmap.Height * Zoom));
this.Invalidate();
}
}
}
int[,] ConvertFile(ref int H, ref int W)
{
int Height=0, Width=0, RGBWidth=0, Value=0, i;
int[] LUT = new int[4096];
FileStream InStream = new FileStream(ChosenFile, FileMode.Open, FileAccess.Read);
long nBytesToRead = InStream.Length;
byte[] ByteArray = new byte[2];
for ( i=0; i<256; ++i)
{
LUT[j]=LUT[j+1]=LUT[j+2]=LUT[j+3]=LUT[j+4]=LUT[j+5]=LUT[j+6]=LUT[j+7]=LUT[j+8]=
LUT[j+9]=LUT[j+10]=LUT[j+11]=LUT[j+12]=LUT[j+13]=LUT[j+14]=LUT[j+15]=i;
j=j+16;
}
for (i=0; i<nbytestoread; i+="2)
{"
int="" nextbyte="(int)" instream.read(bytearray,="" 0,="" 2);
="" if="" (="" i="">=4 && i<=7)
{
if ( i==4)
Height = (int)BinaryToDecimal(ByteArray);
else
Width = (int)(BinaryToDecimal(ByteArray))/2;
}
else if ( i>=128 )
{
break;
}
}
H = Height;
W = Width;
RGBWidth = Width*3;
int[,] PixelData = new int[Height,Width];
for (int x=0; x<height; ++x)
{
for="" (int="" y="0;" y<width;="" ++y)
{
int="" nextbyte="(int)" instream.read(bytearray,="" 0,="" 2);
value="LUT[BinaryToDecimal(ByteArray)];
" pixeldata[x,y]="Value;
i" +="2;
if" (i="">=nBytesToRead)
break;
}
if (i>=nBytesToRead)
break;
}
return PixelData;
}
public static bool Display(Bitmap b, int[,] PixelData)
{
BitmapData bmData = b.LockBits(new Rectangle(0, 0, b.Width, b.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
int stride = bmData.Stride;
System.IntPtr Scan0 = bmData.Scan0;
int j;
unsafe
{
byte * p = (byte *)(void *)Scan0;
int nOffset = stride - b.Width*3;
for ( int y=0; y< b.Height; ++y)
{
for ( int x=0; x< b.Width; ++x)
{
p[0] = (byte)(255-PixelData[y,x]);
p[1] = (byte)(255-PixelData[y,x]);
p[2] = (byte)(255-PixelData[y,x]); p += 3;
}
p += nOffset;
}
}
b.UnlockBits(bmData);
GrayScale (b);
return true;
}
But I am not getting the image tht i am supposed to get...
thanks in advance,
Suman
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Read my image processing articles in the C# Multimedia section to see how you can access bytes within the image without the copy stage you're taking.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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Hi Graus,...
hmm... atlast I succeded in doin it... and i am able to view the image...and save it as a bitmap..
thanks alot for ur support and advices and sorry for disturbing u so many times on this issue...
ok then catch u later over my project doubts...
Suman
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Hi Graus,
I am trying to plot the histogram of an image.... i am able to calculate all the values required to plot the histogram... but i dont know how to plot it in C#... can u advise me wht i have to do to pop-up a window and show the plot in it ( i mean to plot the graph in it)....
Thanks in advance,
Suman
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My boss has given me an order to display our word documents in PDF format.. Anyway of doing this in C##?
Any advice would be appreciated..
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I believe there's a couple of .NET pdf tools that advertise on the site. There's nothing built in.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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i am developing an image processing application as an assignment. i need help. how to rotate an image to any degree from 0 to 360. i have used the buildin method
new Bitmap(fileDialog.FileName).RotateFlip(RotateFlipType.Rotate180FlipNone);
but these r limited options. further more it would be great if unsafe code would be used.
Ahmad Zafar
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ahmadzafar wrote:
further more it would be great if unsafe code would be used.
ROTFL. Brilliant. You're right, you'll need to use unsafe code, I just like that you WANT to
If you read my article on displacement filters (C#/Multimedia section), you'll see a swirl filter. That filter rotates an image by an amount that increases as you go out from the centre. If you took out the code that changes the rate of rotation, it will rotate images for you, I'm pretty sure. If not, let me know, and I'll walk you through it. I find it works best to use polar co-ordinates, then it's simply a case of applying a rotation. As occurs in my article, you should offer at least bilinear filtering, because you're going to get mostly non-perfect pixels when you rotate an image.
Christian
I have several lifelong friends that are New Yorkers but I have always gravitated toward the weirdo's. - Richard Stringer
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did you try using the Graphics.RotateTrasform(float angle) method? if you're actually drawing the image onscreen, i think it's very usefull
there are no facts, only interpretations
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sir thank u very much for ur help and guidance but there is one problem ... i dont want to use Graphics.DrawImage or any such coz my idea is to chnage the image in the PictureBox and rotate it actually
can u plz help as i read all ur 6 articles on image processing and they really helped especially tht all of them have unsafe code in them. kindly sir guide me in rotating an image to any degree in a picBox using unsafe code
Ahmad Zafar
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u'r welcome.
the "quick and dirty" way is to use DrawImage and rotate the graphics, and then copy those graphics to a new bitmap. i think you will have to use unmanaged gdi for this (creating Device Context etc.) Otherwise u need to do the dirty work yourself
ahmadzafar wrote:
i read all ur 6 articles
I think u'r confusing me with the guy who replied above me. He has great articles, I have none.
by the way, unsafe code is used here, i think, for performance (speed), when u'r accessing each pixel's content.
there are no facts, only interpretations
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sir how r u ... one more thing i wanted to know ... u have any idea how to compress an image size?
Ahmad Zafar
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Does anyone know how this can be done? I'm currently using System.IO.Path.GetTempFileName( ) which returns a filename in the short format but I would prefer it to be in the long format. So any ideas?
Wenn ist das Nunstück git und Slotermeyer? Ja! Beierhund das oder die Flipperwaldt gersput!
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Unfortunately there is no built-in managed way to get this result.
You'll have to use P/invoke to call GetLongFileName().
mav
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I have a main worker thread that spawns a child thread to do some listening. What I'd like to happen is to have the child thread raise an event in the parent, but it seems it can only raise events in it's own thread.
Is there any way to have one thread raise events in another thread? Is this even possible?
Thanks
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