Re: problem while using listbox - C# Discussion Boards

12-Feb-08 10:30

On my form1.cs am displaying around 200 images inside a listbox. Each listbox item contains an image but when i am looking on task manager window in winxp my application is using the most memory. I am controlling the onDrawItem like this

protected override void OnDrawItem(DrawItemEventArgs e)
{
Graphics g = e.Graphics;
Bitmap b1 = new Bitmap(400, 300);
((myImageItems )Items[e.Index]).DrawToBitmap(b1, new Rectangle(0, 0, 400, 300));
Bitmap b = new Bitmap(b1,new Size(100,60));
e.Graphics.DrawImage(b1, e.Bounds.X , e.Bounds.Y , b.Width, b.Height);
g.dispose();
b1.dispose();
b.dispose();
}
I do'nt know where to look into this i tried debuggin but no help so far. Any help i appreciate it.
Thanks

Christian Graus12-Feb-08 10:49

Christian Graus

12-Feb-08 10:49

netJP12L wrote:
Graphics g = e.Graphics;

This is SO redundant.

netJP12L wrote:
Bitmap b1 = new Bitmap(400, 300);

Why not use meaningful variable names ? And the using keyword ?

netJP12L wrote:
g.dispose();

You don't dispose of an object that was passed to you on the event args. Creating a local reference to it makes it more likely you would forget that. Use 'using' blocks, instead of calling dispose.

How much memory is it using ? Remember, the memory usage you see represents more than the memory in use right now, perhaps creating these bitmaps and disposing of them over and over is the reason the number is so high ?

Christian Graus - Microsoft MVP - C++

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

netJP12L12-Feb-08 11:22

12-Feb-08 11:22

Thanks for replying Graus, I have edited my codes as you mentioned but still when i start my app the memory is 278,000 and as i click on the downScrollbar its goes up around 350,000+. Can you please help me from your Magic coding. Apart from drawing my own do u think there could be else where problem because all those listbox item i am keeping them in a List of myImageItems

Bitmap imgItm = new Bitmap(400, 300);
Rectangle rect = new Rectangle(0, 0, 400, 300);

protected override void OnDrawItem(DrawItemEventArgs e)
{
using ( Font f = new Font(e.Font.FontFamily, e.Font.Size, FontStyle.Bold))
{
((myImageItems)Items[e.Index]).DrawToBitmap(imgItm , rect);
e.Graphics.DrawImage(imgItm , e.Bounds.X, e.Bounds.Y , 120, 80);
}
}

Christian Graus12-Feb-08 11:29

Christian Graus

12-Feb-08 11:29

350k ? I doubt there's much you can do about it. If it keeps climbing, you've got issues. If what you're describing is the extent of it, then you're probably fine.

Where does the code you've posted use the font you're creating ? Am I missing something ?

netJP12L12-Feb-08 11:55

12-Feb-08 11:55

Thanks once again actually the memory flucate it goes like, starts with 377,000k then when i click quickly couple of times on the downScrollbar it jumps to 415,000k then 500,000k and goes back like 314,000k. The maximum it goes up to 550,000k, haven't seen crossing that. Another thing i noticed that when i click on the downscrollbar button listbox flick and i can see that it's drawing. I put this in the constructor but no result

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

In your last post you were saying "perhaps creating these bitmaps and disposing of them over and over is the reason the number is so high ? " if i do'nt create them how else i can do what i am want to do. Can you please show me in ur examples.

I mistakenly deleted the Font code the are as follows.

e.Graphics.DrawString("Picture" + (e.Index + 1), f, Brushes.Black, e.Bounds, StringFormat.GenericDefault);

One of the most important thing i have seen is that i added 200 images in Ms power point too. but when i look at it its memory like 228,000k. and all those clips load way to faster than my application. What may i do to achieve the same result.

Thanks for readign this much.

Rich Text Box and Fonts in c#

Christian Graus12-Feb-08 13:50

Christian Graus

12-Feb-08 13:50

netJP12L wrote:
if i do'nt create them how else i can do what i am want to do.

By creating them once and keeping them in memory to draw as needed. This would also speed things up, which could help your flicker issues.

netJP12L wrote:
One of the most important thing i have seen is that i added 200 images in Ms power point too. but when i look at it its memory like 228,000k. and all those clips load way to faster than my application. What may i do to achieve the same result.

First of all, you're wasting your time watching memory usage this closely ( it just isn't that accurate, and the fact that it goes back down shows there is no leak ). The best way to use less memory is to use C++, like powerpoint does. But, I am sure it would cache the images and not create them every time, as you are doing, that should be enough to solve the issue.

Ron.Blackwell12-Feb-08 9:39

Ron.Blackwell

12-Feb-08 9:39

I am trying to bold certain paragraphs in a rich text box and have the other text regular then print the document. Can anyone assist me?

Thanks

Re: Rich Text Box and Fonts in c#

Giorgi Dalakishvili12-Feb-08 9:50

Giorgi Dalakishvili

12-Feb-08 9:50

Use RichTextBox.SelectionFont, RichTextBox.SelectionStart, RichTextBox.SelectionLength and RichTextBox.SelectedText properties.

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how to add object to listview

netJP12L12-Feb-08 8:03

12-Feb-08 8:03

I want to add an object in my listview i can add string but not any controls

Object obj = new Object();

listviewItem itm = new listviewItem(obj);

listview1.Items.Add(itm);

Thanks

Not Active12-Feb-08 8:27

Not Active

12-Feb-08 8:27

What are you trying to do? Confused | :confused:

only two letters away from being an asset

netJP12L12-Feb-08 8:34

12-Feb-08 8:34

I have seen ListBox.Items.Add which takes an object i want to do the same thing with the listview but listview doesn't take anyother objects other than string. so i can control the drawing of each listviewitems.

DaveyM6912-Feb-08 8:43

DaveyM69

12-Feb-08 8:43

MSDN[^]
It takes a string or a ListViewItem. Create your own class inheritting from ListViewItem and do the manipulation you require in there. When returning an Item(s) just cast it to your class type and any extra properties/methods etc will be available.

Dave

Ravenet12-Feb-08 14:38

Ravenet

12-Feb-08 14:38

Hi Guy

I think Listview directlly not support add object.You one option to do this, create a own object with inherit in ListViewItem,add ur a collection or any other kind of list. after add to that listViewItem into ListView.
i hope this is help to u.

Thanks

Cheers
RRave
MCTS,MCPD

Not Active12-Feb-08 16:48

Not Active

12-Feb-08 16:48

Something like what DaveyM69 suggested. SIX hours ago.

only two letters away from being an asset

NameOf method?

Skippums12-Feb-08 7:40

Skippums

12-Feb-08 7:40

I have had to, on a number of occasions, do something like the following:

switch (a.GetType().FullName) {
    case "System.Int32":
        ...
        break;
    case "MyNamespace.SubNamespace.MyClass":
        ...
        break;
    ...
}

The problem is that if I change class name or the namespace of MyClass, the above breaks without generating a compile-time error. The way that I would like to perform the above is by using the type itself, and have "case typeof(MyClass):", but that DOES generate a compile-time error. I am wondering, then, if there is some method like typeof that gets a constant string representing the class name at compile time, so I could change the above code to...

switch (a.GetType().FullName) {
    case nameof(int):
        ...
        break;
    case nameof(MyClass):
        ...
        break;
    ...
}

This way, I would get compile-time errors instead of run-time errors if I changed the classname but didn't update the above code. Thanks,

Sounds like somebody's got a case of the Mondays

-Jeff

Eslam Afifi12-Feb-08 8:12

Eslam Afifi

12-Feb-08 8:12

switch cases take constants so you can't call a function in a switch case, so you'll use if statements

if (a.GetType() == typeof(Int32))<br />
    ...<br />
else if (a.GetType() == typeof(MyClass))<br />
    ...

Eslam Afifi

Ravenet12-Feb-08 14:41

Ravenet

12-Feb-08 14:41

Hi Guys

this is correct way when we are compare own object or own defiened class object with runtime. typeof keyword is very very useful.

Thanks

Cheers
RRave
MCTS,MCPD

Eslam Afifi13-Feb-08 2:32

Eslam Afifi

13-Feb-08 2:32

I just want to add that this code provide direct type comparison. If you want to compare the inheritance hierarchy use the is keyword as Luc Pattyn mentioned here.

Eslam Afifi

TJoe12-Feb-08 8:13

TJoe

12-Feb-08 8:13

1. You can use if-else/if statements, instead of a switch
2. Or you may be able to use:

case typeof(MyClass).FullName:

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Not Active12-Feb-08 8:14

Not Active

12-Feb-08 8:14

Once you start relying on the fully qualified name of your class as a string value in another class or application they are pretty much bound to one another.

only two letters away from being an asset

Luc Pattyn12-Feb-08 14:41

Luc Pattyn

12-Feb-08 14:41

Hi Jeff,

you should try not to rely on type names, since doing so will fail for derived types.
The way to go most often is using the "is" or "as" keywords, as in:

if (obj is Font) {
    ... do someting fonty (probably will need a cast)
} else if (obj is Panel) {
    ... deal with a Panel (probably will need a cast)
} etc.

Font fnt=obj as Font;  // generates null if obj isn't a Font
if (fnt!=null) {
   ... do someting fonty to fnt (no extra cast required)
}
Panel pan=obj as Panel;
if (pan!=null) {
    ...
}

The above will also match mySpecialPanel and the like, something typename-dependent code
would typically not do.

Smile | :)

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