C# Discussion Boards - CodeProject

Re: overloading == and !=

8-Dec-04 5:21

Add the following lines to your operator== method:
if (Object.ReferenceEquals(r1, null) || Object.ReferenceEquals(r2, null))
{
return Object.ReferenceEquals(r1, 2);
}

The operator!= is left as an exercise to the reader Smile | :)

Yes, even I am blogging now!

Jan R Hansen8-Dec-04 11:41

Jan R Hansen

8-Dec-04 11:41

HAH !!

Thanks a LOT !!!

I tried that... well, almost.. I just used the == operator like "if (r1 == null)" and of course it just called itself and gave me a stack overflow (great.. Roll eyes | :rolleyes:

). But that's it - use the Object.ReferenceEquals.

Once again, thanks.

This is why I Heart | [heart]

CP

/Jan

Do you know why it's important to make fast decisions? Because you give yourself more time to correct your mistakes, when you find out that you made the wrong one. Chris Meech on deciding whether to go to his daughters graduation or a Neil Young concert

Re: overloading == and !=

Skynyrd8-Dec-04 23:51

Skynyrd

8-Dec-04 23:51

I would implement it the following way:

public static bool operator ==(Row r1, Row r2)
{    
    try    
    {
        if (r1 == null || r2 == null)
            return false;
        bool retval = (r1.m_style == r2.m_style) && 
                      (r1.m_text == r2.m_text) &&
                      (r1.m_sortOrder == r2.m_sortOrder) && 
                      (r1.m_parentId == r2.m_parentId);
        return retval;
    }
    catch
    {  
        return false;
    }
}

public static bool operator !=(Row r1, Row r2)
{    
    return !(r1 == r2);
}

public override bool Equals(object obj)
{
    Row row = obj as Row;
    return this == row;
}

public override int GetHashCode()
{    
    return m_id.GetHashCode();
}

NOTE: Your GetHashCode method is inconsistent with your equality criteria. Ur basing the hash code generation on 'm_id' when in ur == operator ur stating that the two objects are equal only when 'Style', 'Text', 'SortOrder' and 'ParentId' are the same.

This will lead to having two Row objects with the same HashCode (Same 'm_id') not being equal, which should never happen. If, on the other hand, 'm_id' is a unique identifier of your row, then maybe you should consider using it also as your equality criteria.

Always keep in mind that two objects with the same hashchode should be equal.

DataGrid formatting

wtdoor19658-Dec-04 3:27

wtdoor1965

8-Dec-04 3:27

I am trying to use a datagrid with columns of different width. I have found several methods posted on various sites, but unfortunately am unable to make any of them work. The following code seems to be the most straightforward, but none of the formatting is actually applied to the datagrid.

What am I missin?

private void FormView_Load(object sender, System.EventArgs e)
{
string connection = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=reminder.mdb";
//string query ="SELECT Date,Time,Message,TicklerDate,TicklerTime FROM Ticklers";
string query ="SELECT * FROM Ticklers";
// Initialize the connection using the connection string
conn = new OleDbConnection(connection);

// Open the db connection
conn.Open();

//Initiate the OleDbDataAdapter using the SQL select commmand on the db connection
adapter=new OleDbDataAdapter(query,conn);

// Initiate and fill the dataset
ds = new DataSet();
//initiate the datatable
adapter.Fill(ds,"Customers");
dt = ds.Tables[0];
// Get the database schema
adapter.FillSchema(dt, SchemaType.Source);

conn.Close();

// Format the data grid
DataGridTableStyle ts = new DataGridTableStyle();
this.dataGrid1.TableStyles.Clear();

//ts.MappingName="Ticklers";
ts.MappingName=dataGrid1.DataMember;

DataGridTextBoxColumn column1 = new DataGridTextBoxColumn();
column1.MappingName="Index";
column1.HeaderText="Index";
column1.Width = 0;
ts.GridColumnStyles.Add(column1);

DataGridTextBoxColumn column2 = new DataGridTextBoxColumn();
column2.MappingName="Date";
column2.HeaderText="Event Date";
column2.Width = 75;
ts.GridColumnStyles.Add(column2);

DataGridTextBoxColumn column3 = new DataGridTextBoxColumn();
column3.MappingName="Time";
column3.HeaderText="Event Time";
column3.Width = 75;
ts.GridColumnStyles.Add(column3);

DataGridTextBoxColumn column4 = new DataGridTextBoxColumn();
column4.MappingName="Message";
column4.HeaderText="Description";
column4.Width = 150;
ts.GridColumnStyles.Add(column4);

DataGridTextBoxColumn column5 = new DataGridTextBoxColumn();
column5.MappingName="TicklerTime";
column5.HeaderText="Tickler Time";
column5.Width = 75;
ts.GridColumnStyles.Add(column5);

DataGridTextBoxColumn column6 = new DataGridTextBoxColumn();
column6.MappingName="TicklerDate";
column6.HeaderText="Tickler Date";
column6.Width = 75;
ts.GridColumnStyles.Add(column6);

dataGrid1.TableStyles.Add(ts);

// Bind the datatable to the datagrid control
this.dataGrid1.DataSource=dt;

// Show the datagrid
this.dataGrid1.Visible=true;

} Confused | :confused:

ngb

Bitmap Rendering speed

Tristan Rhodes8-Dec-04 3:17

8-Dec-04 3:17

I'm making a graphical display, but the image refresh is very jerky. I added a tick counter to the behaviour thread, and it takes 0ms, so the issue was not there.

On adding it to the graphical thread however, I discovered that rendering tends to jump a lot, on average a few small objects take 16ms, but jump to 35-40 once or twice a second. When I add a large image to the rendered scene, (640x480 or higher), the rendering time increases to 70, and jumps to over 100 a couple of times a second.

I'm using the following threaded loop:

<br />
int start = Environment.TickCount;<br />
				g.DrawImage(Background,0,0);<br />
r.Draw(g, new Point(0,0));<br />
s.Draw(g, new Point(0,0));<br />
t.Draw(g, new Point(0,0));<br />
				pb_Display.Refresh();<br />
tb_Text.Text = (Environment.TickCount - start).ToString();<br />

Note: I'm rendering this image to a picturebox Image, and redrawing the image on every itteration. I'm still looking for a better way to do this.

I have two questions about this, why does this jump occur?

And are there any techniques to increase the speed at which rendering occurs?

CHeers

Tris

Daniel Turini8-Dec-04 5:32

8-Dec-04 5:32

The Catalyst wrote:
And are there any techniques to increase the speed at which rendering occurs?
If you care about speed, use GDI or DirectX (in extreme cases) for drawing.
GDI calls should provide enough speed for most uses.

The Catalyst wrote:
Note: I'm rendering this image to a picturebox Image, and redrawing the image on every itteration. I'm still looking for a better way to do this.
Actually, you should only call Invalidate/Update on the control and let it redraw itself when needed (on the Paint event or an overrided OnPaint method). This will keep you from drawing faster than the video card/driver can handle. You'll need only to draw 60 times per second, as the video does not refresh more than this. This means that times you have around 160ms to draw, and flip the buffer when the monitor's vertical retrace happen. What do I mean about "flip the buffer"? Do a bit of search and read about double-buffering, and you'll understand better how to achieve high frame rates, even with a slow drawing.
The .NET framework offers suport for double-buffering, but I suggest you to read more about how it works before using it.

Yes, even I am blogging now!

Tristan Rhodes8-Dec-04 13:04

8-Dec-04 13:04

I'm already double buffering it actualy, but thanks for the point.

I will look at GDI, I don't think i'll need DirectDraw. Although I did notice they took it out of the latest version of the DirectX9 SDK. Why do that?

Cheers

Tris

Tristan Rhodes9-Dec-04 4:06

9-Dec-04 4:06

I did a little investigation, and the native .NET draw methods are all based on GDI plus, so there's not much I can do there. I'm downloading the DX9 SDK now.

I think you might be wrong about the 160ms... when I wrote the following code:

start = Enviroment.TickCount;
Thread.Sleep(Timespan.FromSeconds(1));
MessageBox.Show((Enviroment.TickCount - Start).ToString());

It displayed 1000.

Therefore, to get 30fps, I would need to do all the rendering in less than 33.3 ms. Which currently, I'm unable to do, even on a simple scene.

I'll look into DX9, and see what I can do, but do you have any more suggestions?

Cheers

Tris

Daniel Turini9-Dec-04 4:26

9-Dec-04 4:26

The Catalyst wrote:
I did a little investigation, and the native .NET draw methods are all based on GDI plus, so there's not much I can do there.
The problem is with the "plus" part: GDI+ is not hardware accelerated (although some top-notch cards do accelerate it), while the standard GDI is. GDI is way more difficult to use, and you'll need to resort to API calls. Search for BitBlt and you'll understand what I mean. BitBlt performance is almost the same as DirectDraw, as it's intercepted by the video card and uses its capabilities fully. GDI+ is suitable only for drawings that don't need speed.
About the frame rate, you're right: I divided 1000 ms / 60 and I don't know why I got 160ms, when I should get 16ms. Probably a typo on calculator Smile | :)

Yes, even I am blogging now!

Tristan Rhodes9-Dec-04 5:21

9-Dec-04 5:21

I was being such a Schmuck. I was rendering to the bitmap and then setting it to the image... no wonder it crippled my drawing process.

I'm now rendering to a bitmap and flipping it to a graphics object derived from the window handle. I've added a few dozen objects to the screen and it's still taking only 16ms to render.

There are however a few issues with the regular jump to 32ms, which is still frustrating. I've tried adding a GC.Collect() command after each graphics itteration to ease things out, and that worked a bit, but i've also had to add a 10ms wait on the rendering loop to finish the smoothing, anything else and it still jumps regularly occasionaly.

Daniel Turini9-Dec-04 7:18

9-Dec-04 7:18

The Catalyst wrote:
ut i've also had to add a 10ms wait on the rendering loop to finish the smoothing,
Sorry, but I don't understand: why do you need this delay? Aren't you just invalidating the picture control?
About the delays, it's hard to predict what's going on in a GC environment. Beware that adding GC.Collect() to a loop may do more harm than good to time predictability: it may move objects to Gen 2 too soon, and increase the delays, instead of reducing them.

Yes, even I am blogging now!

TextChanged vs Click

realmontanakid8-Dec-04 2:23

8-Dec-04 2:23

Hi
I got a little Form with a Textbox. With a Barcode Scanner I
put a Database ID into this Textbox. By onclick the Button "Show"
the DatabaseRecord will be shown in a new Form. It works great.
But I think the user should not click a Button. It's too much work Smile | :)

So I made a TextCahanged Event on this Textbox. The Scanner read the
Barcode and the Record should be shown. But it don't work! Why??

This is for the Button:

private void btnShow_Click(object sender, System.EventArgs e)
{
string id = this.textBoxScan.Text;
frmShow x = new frmShow(id);
x.Show();

this.textBoxScan.Text="";

}

This for the TextChanged:

private void textBoxScan_TextChanged(object sender, System.EventArgs e)
{
string id = this.textBoxScan.Text;
frmShow x = new frmShow(id);
x.Show();

this.textBoxScan.Text="";
}

And this happens on the second Form:

public frmShow(string id)
{
InitializeComponent();
string x = null;
x = id;

dc.Connection(System.Convert.ToInt32(x));

fnGetDataBindingForTextBoxes();
}

dc is an Instance from the Connection Class.

Stefan Troschuetz8-Dec-04 2:40

Stefan Troschuetz

8-Dec-04 2:40

Don't know why the TextChanged event handler didn't work (maybe it's not submitted correctly.?).
Anyway, as you want to automatically show the second form after reading with the Barcode scanner in my opinion the textbox is pretty useless, because you write a value to it and in the TextChanged event show your form and clear the textbox. So why not showing the form directly after reading from the scanner.
Besides, you should dispose your form after using it, so the resources get cleaned up. Or use the using statement as shown by the following code snippet:

using(frmShow x = new frmShow(id))
{
x.Show();
}

www.troschuetz.de

realmontanakid8-Dec-04 4:14

8-Dec-04 4:14

But how can I call an Application or Form by only scanning a Barcode?
It's only an low Cost Scanner. During Debugging my App. a green Arrow
appears in the Solution Explorer of the second Form. The Message is
that the Code have called another Function. When this Function is done,
the next one will be called.
The mark the following row..

dc.Connection(System.Convert.ToInt32(x));

Stefan Troschuetz8-Dec-04 4:31

Stefan Troschuetz

8-Dec-04 4:31

In your first post you wrote: "I got a little Form with a Textbox. With a Barcode Scanner I put a Database ID into this Textbox."
Thought you already do the latter in your application, so that instead of putting the Database ID into the textbox and catching the TextChanged event to open an extra form you could directly open the extra form.
Or what exactly do you mean with the phrase: "With a Barcode Scanner I put a Database ID into this Textbox."

www.troschuetz.de

realmontanakid8-Dec-04 4:59

8-Dec-04 4:59

The Cursor is set in the TextBox. I read the Barcode and the Value
appears in the TextBox. Submit the Button and the new Form, that includes
the Record, will be open. The Barcode was created from a Database ID.
ID 222 -> create a Barcode from 222 -> print a label with the Barcode
and put it on Hardware. If the Hardware is defected, we want to audit wether
Warranty is given.

Dave Kreskowiak8-Dec-04 4:50

Dave Kreskowiak

8-Dec-04 4:50

Does your BarCode scanner send an ENTER key after the code? Most scanners can be configured to send a termination character after the code. If not, the TextChanged event won't fire until the user hits enter in the TextBox or, like in your case, clicks a button to do it.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

realmontanakid8-Dec-04 5:19

8-Dec-04 5:19

I got it.. I think so..

I can not clean the TextBox when I use the TextChanged Event.
this.textBoxScan.Text="";

When I delete this row from my Code it works. But I need
an empty TextBox.Ahrgggg...