Re: Designer calls to class constructor several times! - C# Discussion Boards

Programmatically Deleting Data from a File

16-Sep-05 5:16

Ok, you didn't ask how to get the AudioMixer, so I assumed you already knew. The article I linked to has some examples; I don't know offhand because it's a 3rd party extension that I've never used before. I suggest you create another post if you need help creating the AudioMixer.

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JMitchem15-Sep-05 7:37

JMitchem

15-Sep-05 7:37

I am trying to find a way to remove data from a file using C#.

I know how to edit using FileStream.Seek and a StreamWriter, and I know how to append data to the end, but I haven't found a way to actually remove data from the end of a file.

Due to file size and memory constraints, reading the whole thing in, saving it as a new file, and then deleting the old file is not an option.

Is there a way to write an EOF where I specify, and that's that? (if so, how do you actually do that?) Or do I have to go about doing this some other way?

Thanks in advance for the help,

Jonathan Mitchem

Re: Programmatically Deleting Data from a File

Judah Gabriel Himango15-Sep-05 10:22

Re: Programmatically Deleting Data from a File

15-Sep-05 10:22

No matter what you do, you'll have to get the file stream. This is standard. You can Seek to a position (or .Position) the position of the stream, write data to it, then save it, overritting the previous file. That's probably your best bet.

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Judah Himango

JMitchem15-Sep-05 12:10

JMitchem

15-Sep-05 12:10

Thanks.

This issue has now been resolved.

http://www.gotdotnet.com/Community/MessageBoard/Thread.aspx?id=340164&Page=1#340199

Re: Programmatically Deleting Data from a File

Guffa15-Sep-05 11:44

Guffa

15-Sep-05 11:44

Use the SetLength method of the FileStream class.

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Designer calls to class constructor several times!

Lexa198315-Sep-05 7:03

Re: Designer calls to class constructor several times!

15-Sep-05 7:03

I have a control inherited from ComboBox. In constructor I add some items. Now, when my control is have been putted onto form designed calls to constructor and item collection is automatically updates. How can I prevent this action, some directive or attribute that tells to designer not to call to constructor during the design time?

Judah Gabriel Himango15-Sep-05 7:30

Re: Designer calls to class constructor several times!

15-Sep-05 7:30

Please see this page[^] for information about how to write design-time aware code.

Also, the designer will always call the default constructor (i.e. the constructor that takes zero parameters). If you want to create a constructor that gets called only by your code, create a second constructor that takes a parameter.

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-- modified at 13:30 Thursday 15th September, 2005

Lexa198315-Sep-05 8:19

Re: Designer calls to class constructor several times!

15-Sep-05 8:19

There is a lot of information there... unfortunately I have not found what I need, but thanks.
Declare additional constructor with different from void parameters will be not so "right" way. It must be something that resolves this problem...

Judah Gabriel Himango15-Sep-05 10:07

Re: Designer calls to class constructor several times!

15-Sep-05 10:07

If your control inherits from System.ComponentModel.Component (or System.Control, which inherits from System.ComponentModel.Component), then you can get the value from the protected DesignMode property to indicate whether you're in design mode.

public class MyControl : Control
{
   public MyControl()
   {
      // in design mode?
      bool designMode = this.DesignMode;
   }
}

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Judah Himango

Lexa198315-Sep-05 11:21

Put part of a gif file into imagebox?

15-Sep-05 11:21

thanks

that is exactly what I need

Seraphin15-Sep-05 6:58

Seraphin

15-Sep-05 6:58

I have a gif file with 3 pictures, next to next in one image. Seperated by black lines.

Each picture has a width of 100pix, the black seperation line has 2 pix. Max width is 306.

Now I want to copy the first picture into the imagebox. How can I copy the first picture into the imagebox?
I never have worked with sprites, so I don't know how to get this.

Lexa198315-Sep-05 7:09

15-Sep-05 7:09

It's seems that your problem is to separate one peace of entire image from other. If there is width of each peace is constant it will be very easy, but if not, you need to "search for black line"...
What exactly you want to know?

Seraphin15-Sep-05 7:21

Seraphin

15-Sep-05 7:21

I know exactly the positions.

1st 1-300
2nd 303-603
3rd 606-906

no dynamic problem, all pictures positions are placed logical, like sprites.

Lexa198315-Sep-05 8:10

15-Sep-05 8:10

there is your code, I believe it works Smile | :)

<br />
//load needed image from file<br />
Image src = Image.FromFile(/*your image file name*/);<br />
<br />
Graphics gr = Graphics.FromImage(src);<br />
<br />
Point point = new Point(1, 0);<br />
<br />
for (int i=0; i<3; i++)<br />
{<br />
	//handles the pixels of separated image<br />
	Bitmap bitmap = new Bitmap(300, /*your image height*/, gr);<br />
			<br />
	//draw the needed part of entire image<br />
	gr.DrawImageUnscaled(src, point);<br />
<br />
	//make offset to next part<br />
	point.Offset(303, 0);<br />
<br />
	//save the destination image<br />
	bitmap.Save("filename.bmp", System.Drawing.Imaging.ImageFormat.Bmp);<br />
}<br />

Seraphin15-Sep-05 9:45

Seraphin

15-Sep-05 9:45

thx

treeview copy/paste

xilefxilef15-Sep-05 6:50

15-Sep-05 6:50

Hi,
I need to implement node copy/paste functionality in my treeview control. What is a good way of accomplishing this?

Thanx

Re: treeview copy/paste

Chals15-Sep-05 6:51

15-Sep-05 6:51

Hi,

You can not "copy" nodes but you can clone them using the

myTree.Nodes[i].Clone() method

Playing with this you can implement what you need Smile | :)

Re: treeview copy/paste

xilefxilef15-Sep-05 7:36

15-Sep-05 7:36

Thanx, but if I'm looking for sort of 'simple' copy/paste, namely just duplicating a node visually using keys 'cntrl C' and 'cntrl V', do I need to catch a 'keyPress' event or is there another way of doing it?

Re: treeview copy/paste

Chals15-Sep-05 20:22

How to get the last node of a TreeView

15-Sep-05 20:22

You can use the KeyDown event

Chals15-Sep-05 6:48

15-Sep-05 6:48

Hello,

How can I get the last node in the hierarchy of a treeview?

Thanks

xilefxilef15-Sep-05 6:59

15-Sep-05 6:59

If you mean the last child, then:

someParentTreeNode.LastNode

or

int c = treeView1.Nodes.Count
treeView1.Nodes[c-1];

Chals15-Sep-05 20:21

15-Sep-05 20:21

Thx for replying but that wont work

i = Tree.GetNodeCount(true) will return the number of nodes in the tree including the sub trees, but Nodes[i] will throw an exception as Node.Nodes contains only the nodes in the node collection of the node Im searching (yeah its confusing). Say the tree has 500 nodes but only 4 at first level, doing this:

n = Tree.GetNodeCount(true);
TreeNode last = Tree.Nodes[n]; // exception because Tree.Nodes has 4 elements and Im trying to get the 500th.

what I need is the LAST node in the last level of the tree.

xilefxilef17-Sep-05 9:59

17-Sep-05 9:59

Well, then you may need to use recursion. You can try something like this to get to the deepest node of the tree:

private void DepthSearch(TreeNodeCollection nodes, int depth)
{
int newDepth = depth;
for(int i = 0; i < nodes.Count; i++)
{
if(nodes[i].NextNode == null)
{
//your code here;
}
newDepth++;
this.TreeSearch(nodes[i].Nodes, newDepth);
}

}

so,

calling DepthSearch(TreeView.Nodes, 0) and inserting code (where it says 'your code') that populates some data structure with the current node and the depth, should give you the ability to compare the depths and choose the deepest node.