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Not sure which forum this should be in, but C# isn't it.
also
Rational Rose != UML
Class Diagram != Table Diagram.
Dalek Dave: There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter.
Pete o'Hanlon: If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.
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Hi,
I've got a form with a gradient background. On that form I places a tabcontrol. But when I a hover a tab of the tabcontrol, the tab starts flickering a lot. Is there any way to stop this flicker?
I have already found some solutions. One of them is to create a custom control which inherits from System.Windows.Forms.Tabcontrol.
I dit this and the flicker is gone, but when I use the following code, the font on my tabs isn't the default font like the rest of my form.
public class DoubleBufferedTabControl : TabControl
{
private System.Drawing.Bitmap buffer;
public DoubleBufferedTabControl()
{
this.SetStyle(ControlStyles.UserPaint | ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
}
protected override void OnPaint(PaintEventArgs e)
{
this.SetStyle(ControlStyles.UserPaint, false);
base.OnPaint(e);
System.Drawing.Rectangle o = e.ClipRectangle;
System.Drawing.Graphics.FromImage(buffer).Clear(System.Drawing.SystemColors.Control);
if (o.Width > 0 && o.Height > 0)
DrawToBitmap(buffer, new System.Drawing.Rectangle(0, 0, Width, o.Height));
e.Graphics.DrawImageUnscaled(buffer, 0, 0);
this.SetStyle(ControlStyles.UserPaint, true);
}
protected override void OnResize(EventArgs e)
{
base.OnResize(e);
buffer = new System.Drawing.Bitmap(Width, Height);
}
}
So if there is no easy way to stop this flicker, how can i get the font on my tabs just like the font of the rest of my form?
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Hi,
1.
The tab labels of TabPages are drawn by the TabControl, using the font in its Font property.
2.
The code you have shown looks horrible:
- I've never seen anything change the ControlStyles inside a Paint handler;
- I doubt your bitmap coordinates are correct; what if the ClipRectangle is not located at (0,0)?
- you create a Graphics (that is expensive and slow) without disposing of it;
- as far as I know DrawToBitmap fails to paint some Controls, I hope you don't have listing controls (ListBox, TreeView, WebBrowser...) on your TabPages.
- does this work at all when printing?
You also forgot to dispose of the bitmap inside OnResize.
3.
I would have tried solving the flickering with a Panel; so rather than putting the TabControl on the Form with background image, put it on a Panel of its own size, then put the Panel on the Form. Not sure it would work but if it does, it would be a lot simpler and faster.
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thanks for the help,
luckily the presented code wasn't mine I've found the code somewhere and I thought it may could be a lead.
I don't want the tabcontrol to be placed on a panel because of the gray bound that would be visible next to the tabs. I could create a transparent panel, but that would probably cause as much flicker as now.
so that leads me back to my first question: is there a way to reduce this flicker?
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There always will be some flickering, it inherently is present due to the fact that parts of a Control needs to be erased and redrawn when something changes. So the trick is to keep the time between start of erasure and end of repaint as short as possible. That means:
- keep Form complexity low (avoid large number of controls, avoid background images, avoid transparency);
- keep computations low (get your data ready before you start repainting; only invalidate what really changes);
- keep memory burden low (avoid creating expensive objects such as Graphics; avoid garbage collection while repainting; make sure to dispose correctly);
- and finally: avoid erasure by using double-buffering (which erases and paints in memory, then copies as fast as it can to the screen).
That's all!
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I am not sure if this is gonna work... But worth a try.
Have you set your form'd doublebuffered property to true? Since you are custom painting the background, it makes sense to use double buffer.
Then try using usual TabControl.
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Yes,
the double buffering of the form is on. But that doesn't help.
the problem is that a classic tabcontrol doesn't have a property doublebuffered. That is why i created a custom control which inherits from TabControl. In that custom control, i set the doublebuffered property to true.
grtz
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I have the following code which prints three RichTextBox controls to a page. The format is Avery 5388 which is the perforated index card stock paper (8.5x11). The print preview shows the text in each box but the lines don't wrap.
Any way to fix the wrapping problem?
private void fcPrintDocument_PrintPage( object sender, PrintPageEventArgs e )
{
cardDataTabPage.Focus();
DrawPage( e.Graphics );
}
private void DrawPage( Graphics graphics )
{
Graphics g = graphics;
Pen boxPen = new Pen( Brushes.Black );
int pageWidth = fcPrintDocument.DefaultPageSettings.PaperSize.Width;
int pageHeight = fcPrintDocument.DefaultPageSettings.PaperSize.Height;
RectangleF srcRect = cardDataTabPage.ClientRectangle;
RectangleF destRect = new Rectangle( 0, 0, pageWidth, pageHeight );
float scaleX = destRect.Width / 850;
float scaleY = destRect.Height / 1100;
for ( int i = 0; i < cardDataTabPage.Controls.Count; i++ )
{
if ( cardDataTabPage.Controls[i].GetType() == richTextBox1.GetType() )
{
RichTextBox rich = (RichTextBox)cardDataTabPage.Controls[i];
g.DrawRectangle( boxPen, rich.Bounds );
g.DrawString( rich.Text, rich.Font, Brushes.Black,
rich.Bounds.Left * scaleX, rich.Bounds.Top * scaleY, new StringFormat() );
}
}
}
Thanks.
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Hi,
you're not printing a RichTextBox at all, you are simply painting its textual content, in a single font, style, and color, at a specific point without taking care of width and height. There are DrawString overloads that take a Rectangle and perform a word wrap for you, keeping everything in the allotted width.
If you really want to print an RTB, you need to call some Win32 functions, using P/Invoke.
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I figured it out after I found a reference that states: when passing a RectangleF as one of the parameters, DrawString automatically wraps the text inside the destination's bounding rectangle.
So I changed by method call to:
RectangleF cardBox = new RectangleF( rich.Bounds.X + 5, rich.Bounds.Y + 5, rich.Bounds.Width - 5, rich.Bounds.Height - 5 );
g.DrawString( rich.Text, rich.Font, Brushes.Black, cardBox, frmt );
The 'cardBox' rectangle is deflated by 5 pixels for padding. I also included a StringFormat to center the text on the card.
Mark
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you want -10 to center, not -5, and even that is just an approximation as it will paint flush left.
to really center, you need to use Graphics.MeasureString to find actual width, then adjust Left (and maybe Top) while keeping the original Width and Height.
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Hi,
Just a quick question for people. How do I pass TextWriter through a function?
My main opens a TextWriter called LogWritter.
I want to create a function which has this log file passed to it so I can write to it from within this seperate function. I want my program to look like this:
Main()
{
TextWriter LogWriter = new StreamWriter(LogLocation);
for (i=0... etc loop
{
MyFunction(LogWriter)
}
}
</per>
<pre>
MyFunction(TextWriter LogWriter)
{
LogWriter.WriteLine("Hello World")
}
I would expect Hello World to be written as many times as looped in LogLocation. How come this does not appear to work? When I run this the file in LogLocation remains blank.
Many Thanks
Steve
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You don't flush the text writer or close it. If you check the file before the writer is garbage collected, you can't be certain what will be in the file.
This should fix your problem:
Main()
{
using (TextWriter LogWriter = new StreamWriter(LogLocation))
{
for (i=0... etc loop
{
MyFunction(LogWriter)
}
}
}
MyFunction(TextWriter LogWriter)
{
LogWriter.WriteLine("Hello World")
LogWriter.Flush()
}
Dalek Dave: There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter.
Pete o'Hanlon: If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.
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Awesome! That does the trick! Thank you very much.
Do I have to remember to flush the buffer after everytime I write something, or just at the end of each loop?
Many Thanks
Steve
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Steve-Co wrote: Do I have to remember to flush the buffer after everytime I write something, or just at the end of each loop?
Wherever suits really. The buffer builds up in memory until a flush is performed. so if you sre writing a lot of stuff it will eat memory. Also, you might want to write regularly for robsuness purposes (e.g. application crashes and an unflushed audit log loses vital information). I tend to flush regularly .
You should always close the stream (in my code the using achieves this) this also flushes.
If you are writing a logging block, Google Log4Net, it is free and covers a lot of logging tasks, unless you are doing this out of interest or are required to implement your own.
Dalek Dave: There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter.
Pete o'Hanlon: If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.
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It depends, if you are writing all the rows at once, you don't need to flush the writer after each write.
On the other hand, if time is passing between each write, you might want to flush the writer giving the user the possibility to see the log file updating realtime.
If you look to some existing logging framework, you see they have an auto-flush option used to control this behavior.
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Try something like this:
TextWriter LogWriter = null;
public void Main()
{
string LogLocation = @"c:\bin\test.log";
LogWriter = new StreamWriter(LogLocation);
for (int _loop = 0; _loop <= 10; _loop++)
{
MyWriter(LogWriter);
}
LogWriter.Flush();
LogWriter.Close();
}
void MyWriter(TextWriter LogWriter)
{
LogWriter.WriteLine("Hello World");
}
me, me, me
"The dinosaurs became extinct because they didn't have a space program. And if we become extinct because we don't have a space program, it'll serve us right!"
Larry Niven
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your code looks fine, except flushing something right before closing it does not make much sense, every close implies a flush. Flush() is meant to be called when you do not intend to close right away, it is kind of a restore point, making sure the data so far gets output.
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Thanks but it was just a simplistic example.
me, me, me
"The dinosaurs became extinct because they didn't have a space program. And if we become extinct because we don't have a space program, it'll serve us right!"
Larry Niven
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Thanks for all your advice. Just using the "using", in the first reponse, implements the flush() and close() and it now works as expected now.
Many Thanks
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Hi,
I have an event registered to receive serial port data. to my understanding this is done in a separate thread than the one registered in. Ok now in my serial port data receive event i take the data generate a message and send to a windows message queue. method to implement sending is a static method in a separate class library.
Problems.
When data is received and the static method is called , suddenly a new thread is generated and it keeps on doing that for each data received even though i havent spawned any new thread. i have taken the method from the library pasted it in my current working class scope and the same thing happens.
but if i write the sending stuff in the event itself this doesnot happen and everything works just fine.
So to my understanding a different thread is accessing a different thread so there could be safety issues or something else. Do i need to make some kind of asynchronous calls or any other solution please.
I want the function to remain in class library outside the scope of this class.
Can anyone help me with this matter.
Thank you!!! in advance.
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Hi,
the DataReceived and ErrorReceived events fire on a ThreadPool thread. AFAIK it is always one and the same thread for any given serial port. You do not need to create yet another thread to handle the data; when you want to access some data structures (maybe a collection), you would need thread synchronization, most likely a simple lock would suffice. And when you would like to access some GUI Controls, you would need a Control.InvokeRequired/Control.Invoke pattern.
static is irrelevant in this context.
if your code keeps creating new threads, that does not make sense.
you do not need to add any asynchronous calls.
if you want specific help, post specific information and (part of) actual code.
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I understand your point clearly... this code is a part of a windows service... Please find the code below.
This is the serial data received event(part of a running windows service).
Where i just called a static event and passing in some event arguments (custom made)
private void serialCnn_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
try
{
EventReporter.SendData(new SendSerialDataArguments
{
SerialPortName = ((SerialPort)sender).PortName,
Source = Entity.SerialServer,
Destination = Entity.DataProcessor,
SourceServer = Entity.SerialServer,
TransmittedDataType = TransmittedDataType.RawProcessed,
Data = new Message(((SerialPort)sender).ReadTo("\r"))
});
}
catch (Exception ex)
{
this.MiscFunctions.WriteToLog(Entity.SerialServer, ex);
}
}
The method called is a static method in a class library reference by this windows service.
The method is:
public static void SendData(SendSerialDataArguments args)
{
try
{
args.Data.Formatter = new BinaryMessageFormatter();
args.Data.Label = ((int)args.Source).ToString() + ":" + ((int)args.Destination).ToString()
+ ":" + ((int)TransmittedMessageType.Data).ToString() + ":" + ((int)args.SourceServer).ToString()
+ ":" + ((int)args.TransmittedDataType).ToString() + ":" + args.SerialPortName;
args.Data.Recoverable = true;
switch (args.Destination)
{
case Entity.Application:
{
msgQPL.Send(args.Data, MessageQueueTransactionType.Single);
}
break;
case Entity.DataProcessor:
{
msgQCL.Send(args.Data, MessageQueueTransactionType.Single);
}
break;
}
}
catch (Exception ex)
{
MiscFunctions.WriteToLog(Entity.EventReporter, ex);
}
}
The msgqueue objects msgqcl and msgqpl are also static and defined elsewhere in the same class as static.
I even changed the method to not a static one and disposed msq object in it but same result.
any further help!!!
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Hi,
1. Threading
I don't see anything about threading at all. Hence I don't think there would be a threading problem.
2. static
Your explanation isn't clear at all; there are two simple schemes regarding static:
A. don't make anything static (possible exception: a method that does not need any class member data could be made static to enforce that)
B. make everything static (that is impossible if you need two or more of something)
If you try to have a half-static approach, every method declared static can only access class members that are static themselves. That is all that is to it.
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Again i understand ure explanation clearly...
There isn't suppose to be any new thread spawned and doing something static doesn't matter either.
But the thing odd is that if i do the same thing(i.e. sending messages to msq in the serial port data received event, this doesn't result in the continuous spawning of new threads.
Nothing seems to add up y new threads are created if i just take the same code and place it in a class library rather than in the serialport data received event.
i have commented the code in the serial port data received event. which i executed instead of the event reporter event and everything went f9. May be there is some problem with this serial port data received thread accessing methods outside its thread.perhaps.
again any further solutions invited.
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