Re: Strange GDI+ error - C# Discussion Boards

Re: Opaque Controls Showing Controls Underneath

31-Mar-04 3:56

If you want to apply Visual Styles to a button like that which is applied to forms in Windows XP and newer, then P/Invoke and use the Theme API, which is documented on MSDN (lookup OpenThemeData).

If you're looking for information about how to owner-draw atypical buttons, search CodeProject for many examples (including a pretty decent one for Aqua buttons, or those used in Mac OSX).

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Jesse Squire1-Apr-04 7:39

Jesse Squire

1-Apr-04 7:39

If you are looking to apply the Windows XP Visual Styles, you may want to take a look at Don Kackman's article[^] here on CodeProject. He used Managed C++ to create a .NET wrapper for the Theme API that Heath mentioned.

Hope that helps. Smile | :)

--Jesse

serializing DataColumns

DougW4830-Mar-04 19:57

DougW48

30-Mar-04 19:57

I am trying to read/write stored information in a class to a file. This particular class contains 8 DataColumn variables, which are put into a DataTable. How do I serialize and deserialize this information? It won't write or read the columns themselves, and naturally not the DataTable. I'm lost!

Another Question:
I'm still very new at C#, 5 days using it maybe. The current application I am writing will run on 4 or 5 different computers and all share the same data. Is there an easy way to do this in C#? If so, how...and just ignore the first question Wink | ;)

Thanks for the help.

Re: serializing DataColumns

Mazdak30-Mar-04 20:10

Mazdak

30-Mar-04 20:10

Search for SerializableAttribute Class in MSDN and this site or google. There is an example in MSDN.You can find more here and in google.

Mazy

"Man is different from animals in that he speculates, a high risk activity." - Edward Hoagland

Re: serializing DataColumns

Heath Stewart31-Mar-04 3:53

31-Mar-04 3:53

While you can using either runtime serialization (System.Runtime.Serialization) or XML serialization (System.Xml.Serialization) (there is a fundamental difference, and runtime serialization is much more powerful), it's much easier to use DataSet.ReadXml and DataSet.WriteXml to read and write XML, respectively. See the documentation for those two methods for more information.

If you're sharing data between clients, then there's many things you can do. For one, you can use a database (like SQL Server, in which case use System.Data.SqlClient classes, or MS Access or another database with OLE DB drivers, in which case use System.Data.OleDb...and ODBC and Oracle as specifically supported as well). You could also use .NET Remoting, although this is a pretty advanced topic. Make sure to pick up a book on .NET Remoting, such as "Microsoft .NET Remoting" from http://www.microsoft.com/mspress[^] or "Advanced .NET Remoting" from http://www.ingorammer.com[^]. There's also Web Services, which use HTTP as the transport, but .NET Remoting can give you two-way communication ability (if using a transport channel like the TcpChannel, not the HttpChannel which is, by nature, "one-way", or client request/server response based), meaning that you could have clients handle remote events to know when data has been updated, for example.

The database will definitely be easier and the DataSet serves well in that case, since it represents a disconnected recordset. There's a lot of designer support in VS.NET for data-driven applications, but read about ADO.NET so you understand what's happening behind the scenes.

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Strange GDI+ error

Anonymous30-Mar-04 19:42

Anonymous

30-Mar-04 19:42

I have a gif file, 256 colors, created with Paint Shop Pro.

I do

// Load the bitmap
Bitmap myBitmap = new Bitmap ("toto.gif");
// Cut it
Bitmap frame = myBitmap.Clone(Rectangle);
// Save individual frames
frame.Save("Frame1.gif", Imaging.PixelFormat.Gif);

It works OK. Latter, I want to load the saved frame

// Load the frame again
Bitmap frame = new Bitmap("frame1.gif");

This works also. But, if I try to save it again

frame.Save("Frame2.gif");

I got an external exception in InteropServices, telling me there was a problem with GDI+.dll.

Anybody had the same problem?

Heath Stewart31-Mar-04 3:46

31-Mar-04 3:46

I'm not sure exactly what you're trying to do (which may help to understand the problem and help you solve it), but take a look at the Image.SaveAdd method (which Bitmap would inherit, of course) to see how to save individual frames of an animated GIF, which I'm guessing is what you're trying to accomplish.

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Stephane David31-Mar-04 10:00

Stephane David

31-Mar-04 10:00

I have a storyboard, a single image that contains several frames. My program cut this storyboard in individual frames, of variable size.
I now want to save these individual frames in separate files.

This part works. The gif are indeed saved.

Later I need to make copies of some of these files, after I've done some processing on memory on them.

So I start by loading the individual frames doing

Bitmap bitmap = new Bitmap("Frame1.gif");

// Then some processing

// Then I save it again

bitmap.Save("Frame1.gif", PixelFormat.gif);

And there it crashes. I have tried to do the save immediatly after the load, in case my processing was messing something, but it still doesn't work.

Conclusion: I cannot save a bitmap immediately after I load it? Confused | :confused:

Heath Stewart31-Mar-04 10:02

31-Mar-04 10:02

That is weird, and I frankly don't know the answer to that. But there is a better, more efficient way of copying files anyway: File.Copy.

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leppie31-Mar-04 6:21

leppie

31-Mar-04 6:21

Search on Google groups, I had the same problem a few years back. Sorry I cant recall the resolution though Frown | :(

^{top secret}

.NET Remoting

Prasad Anand30-Mar-04 18:29

Prasad Anand

30-Mar-04 18:29

Hello,
I have a question on Remoting that follows:

My first server configuration file has entry:
<service>
<wellknown mode="Singleton"
type="RemotingSamples.RemoteClass1,RemoteObject"
objectUri="ServiceEndPoint" />
</service>

My second server configuration file has entry:
<service>
<wellknown mode="Singleton"
type="RemotingSamples.RemoteClass2,RemoteObject"
objectUri="ServiceEndPoint" />
</service>

Now my client configuration file has entry:
<client>
<wellknown displayName="Server1"
type="RemotingSamples.RemoteClass1,RemoteObject"
url="tcp://machine1_ipaddress:8080/ServiceEndPoint" />

<wellknown displayName="Server2"
type="RemotingSamples.RemoteClass2,RemoteObject"
url="tcp://machine2_ipaddress:8086/ServiceEndPoint" />
</client>

I want user to select the server by giving server's machine ipaddress.
Once he gives me the machine_ipaddress I want to create object
of the class the selected server implements, that is when,
machine1_ipaddress is given I have to create instance of RemotingSamples.RemoteClass1
and
when machine2_ipaddress is given I have to create instance of RemotingSamples.RemoteClass2.
How do I do this?
Please give me more details (A simple implementaion if possible.)

Re: .NET Remoting

Heath Stewart31-Mar-04 3:42

reading from sqldatareader

31-Mar-04 3:42

First call RemotingConfiguration.Configure passing the configuration file with your remoting sections. Then you can use RemotingConfiguration.GetRegisteredWellKnownClientTypes to get a WellKnownClientTypeEntry[] array which you can enumerate:

private object GetInstance(string host)
{
  string configfile = AppDomain.Current.SetupInformation.ConfigurationFile;
  RemotingConfiguration.Configure(configfile);
  WellKnownClientTypeEntry[] entries =
    RemotingConfiguration.GetRegisteredWellKnownClientTypes();
  foreach (WellKnownClientTypeEntry entry in entries)
  {
    Uri url = new Uri(entry.ObjectUrl);
    if (string.Compare(host, url.Host, true) == 0)
    {
      object[] args = {new UrlAttribute(entry.ObjectUrl)};
      return Activator.CreateInstance(entry.ObjectType, args);
    }
  }
  return null;
}

Something like that should work, but look through the documentation for the classes and members used to understand exactly what's going on.

Microsoft MVP, Visual C#
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Key Press

DucLinh30-Mar-04 14:54

DucLinh

30-Mar-04 14:54

I designed a form that got 2 textboxes(i named tbUserName & tbPassword) and 2 button (btOK & btCancel).

private void btOK_Click(object sender, System.EventArgs e)
{
MessageBox.Show("Enter Key has been pressed");
}

tbPassword_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
if ((Control.ModifierKeys & Keys.Enter) == Keys.Enter)
btOK_Click(sender, e);
}

but nothing happen.

Please help me as possible as you can.
Thanks.

Mr Duc Linh Nguyen

Re: Key Press

Charlie Williams30-Mar-04 16:02

Charlie Williams

30-Mar-04 16:02

duclinh wrote:
if ((Control.ModifierKeys & Keys.Enter) == Keys.Enter)

The Enter key is not a modifier key, so this will never be true. Here's what you're looking for:

if(e.KeyChar == (char)Keys.Enter)

However, you don't even need to do that. Just set your form's AcceptButton to be btOK and the button will be "clicked" when Enter is pressed in your form.

Charlie

if(!curlies){ return; }

pgraeve30-Mar-04 14:39

pgraeve

30-Mar-04 14:39

What is the BEST / HIGHEST PERFORMANCE method of reading data from a SqlDataReader and returning a "default" value if the value from the reader is null. I have several different methods that all work but all involve calling a seperate void to test the values or catch the null exception. I just keep thinking there has to be a better way - i.e., one "slick" and simple line of code; but I can't seem to find it???

Re: reading from sqldatareader

Heath Stewart30-Mar-04 16:42

Why do my graphics still flicker?

30-Mar-04 16:42

if (value == null) return defaultValue;

Don't rely on exceptions for this purpose because they are expensive to catch and thus decrease performance. Also, value types (like numeric types, booleans, DateTime, etc.) can't be null, so you'll already get their default value (0, false, etc.) or DBNull depending on how things are set up).

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adonisv30-Mar-04 14:30

30-Mar-04 14:30

Why won't this double buffer? Sigh | :sigh:

I'm drawing this graph that allows you to either move value sliders or input values and redraw the graph. I've looked at tons of double buffering examples and they all seem to be doing the same or similar type of code. But my graph still flickers. BAH! Cry | :((

[code]public void DrawGraph()
{
this.UpdateGraphVariables();
Point[] pointarray=new Point[5];
Pen newpen = new Pen(Color.Black);

this.m_bmImageOffScreen = new Bitmap(this.Width, this.Height);
this.m_gOffScreen = Graphics.FromImage(this.m_bmImageOffScreen);
this.m_gBuffer=Graphics.FromHwnd(this.Handle);

//computational stuff
//not interesting

I do all my drawing on the bitmap...
//Set point of origin to be 50,50 on the form
this.m_gOffScreen.TranslateTransform(50,130);
this.m_gOffScreen.DrawLine(newpen,1,1,1,150);
this.m_gOffScreen.DrawLine(newpen,1,150,150,150);

//Draw X and y axis
this.m_gOffScreen.DrawLine(newpen,-3,30,3,30);
this.m_gOffScreen.DrawLine(newpen,-3,60,3,60);
this.m_gOffScreen.DrawLine(newpen,-3,90,3,90);
...

//Join the points
pointarray[0]=new Point(30,Convert.ToInt32(a));
pointarray[1]=new Point(60,Convert.ToInt32(b));
pointarray[2]=new Point(90,Convert.ToInt32(c));
pointarray[3]=new Point(120,Convert.ToInt32(d));
pointarray[4]=new Point(150,Convert.ToInt32(f));
this.m_gOffScreen.DrawLines(new Pen(Color.Yellow),pointarray);

Then I attempt to double buffer! D'Oh! | :doh:

if (this.m_bmOldBitmap != null)
{
this.m_bmOldBitmap.Dispose();
}

this.m_bmOldBitmap = this.m_bmImageOffScreen;
this.m_gBuffer.Clear(this.BackColor);

this.m_gBuffer.DrawImage(this.m_bmOldBitmap,30,50);
}[/code]

It still flickers! Dead | X|

Roman Rodov30-Mar-04 14:37

Roman Rodov

30-Mar-04 14:37

In InitializeComponent put SetStyle(ControlStyles.DoubleBuffer);

adonisv30-Mar-04 14:40

30-Mar-04 14:40

I've got that!

SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.DoubleBuffer, true);

Heath Stewart30-Mar-04 16:44

30-Mar-04 16:44

You also need ControlStyles.AllPaintingInWmPaint, which is documented in the ControlStyles enumeration documentation.

Also, that enum is attributed with the FlagsAttribute, which means you can save your code some time and just use:

SetStyle(ControlStyles.AllPaintingInWmPaint |
  ControlStyles.DoubleBuffer | ControlStyles.UserPaint, true);

This gets compiled as a constant value so SetStyle is only called once.

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adonisv31-Mar-04 16:36

31-Mar-04 16:36

Do I do one or the other or do I set the styles AND do the manual double buffering witht the bitmaps and the two graphics objects?

blackthunder00130-Mar-04 14:41

blackthunder001

30-Mar-04 14:41

Have you enabled double buffering in your form?

Do this in your initialisation (I put it in my Form constructor after the IntializeComonent() call.

this.SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true);
this.UpdateStyles();

adonisv30-Mar-04 14:59

30-Mar-04 14:59

Nope, that didn't help. Sigh | :sigh: