Keep current view centered on Zoom - C# Discussion Boards

Re: Generic event, or raise event based on generic type.

14-Jan-09 11:59

DaveyM69 wrote:
I've extended it a little so the delegate signature is now (object sender, NotifyEventArgs<t> e)

Yep, I thought of the same, but then I was thinking maybe there should be some other base class for the arguments. For example if we add reason and other enums they could reside in the base class and then the application could extend that to whatever it wants to deliver, complex types, arrays etc.

DaveyM69 wrote:
I might have a look to see if there's some 'magic' way to determine what class called the method

I'd be very interested if you find a solution. I've been looking for a way and not found anything reasonable so I implemented a bit different strategy. The only thing I found when investigating was StackFrame, but it had too severe performance penalty. However, it was a long time ago and based on framework 1.1

DaveyM69 wrote:
Unsubscribe method at least

That would be handy in most cases along with few other methods Smile | :)

DaveyM69 wrote:
I'll pass it by you first as I think this should be a co-author thing with the quality of your help/input

I'd be happy to participate (just brief me how it happens, since never done that before). I must say that the logic for the singleton class isn't what I would do. There's a lot of things to correct, but at the time I was writing it, it was very late in the evening so I decided to do it brute-force.

The need to optimize rises from a bad design.My articles[^]

DaveyM6915-Jan-09 3:13

DaveyM69

15-Jan-09 3:13

Mika Wendelius wrote:
I'd be very interested if you find a solution

There doesn't appear to be a way to get the instance that called the method. I can get the Type easily by using the StackTrace but not the actual instance. I'll keep investigating and ask a new question here, but in the meantime I've just overloaded the Notify method so the instance can be passed, and if not the Type is used.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Re: Generic event, or raise event based on generic type.

Wendelius15-Jan-09 3:19

Re: Generic event, or raise event based on generic type.

15-Jan-09 3:19

I'd say the workaround you used may be sufficient for most of the cases. Do you think there's something in the implementation I could help you with?

The need to optimize rises from a bad design.My articles[^]

DaveyM6915-Jan-09 4:01

DaveyM69

15-Jan-09 4:01

Well there's the base class you mentioned earlier. So far I've just done this.

public enum NotifyReasons
{
    Unspecified = 0,
    Created,
    Updated,
    Removed
}
public class NotifyArgs<T>
{
    #region Fields
    private T m_Value;
    private NotifyReasons m_Reason;
    #endregion

    #region Constructors
    public NotifyArgs(T value)
    {
        m_Value = value;
    }
    public NotifyArgs(T value, NotifyReasons reason)
    {
        m_Value = value;
        m_Reason = reason;
    }
    #endregion

    #region Properties
    public T Value
    {
        get { return m_Value; }
    }
    public NotifyReasons Reason
    {
        get { return m_Reason; }
    }
    #endregion
}

which is created by this method (all the overloads call this method)

private void Notify<T>(object source, NotifyArgs<T> a)
{
    foreach (Subscriber item in m_Subsribers)
        if (item.Type.Equals(typeof(T)))
            item.GetNotifyDelegate<T>()(source, a);
}

I haven't looked at the best way to implement this so it can be extended by the user and still passed through the notifier...

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Re: Generic event, or raise event based on generic type.

Wendelius15-Jan-09 10:27

Re: Generic event, or raise event based on generic type. [modified]

15-Jan-09 10:27

Sorry for the delay. I was going to answer you sooner, but I fell Sleepy | :zzz:

while the putting children to sleep Smile | :)

One change I had in mind is that the list base operation is going to be slow. So if we're targeting for 3.5 I'd suggest that we use this kind of approach for notifying the subscribers.

private System.Collections.Generic.HashSet< Subscriber > _subsribers = new HashSet<subscriber>();
...
public void Notify< T >(T instance) {
   var subscribers = from item in this._subsribers
                     where item.Type.Equals(typeof(T))
                     select item;

   foreach (Subscriber subscriber in subscribers) {
      subscriber.GetNotifyDelegate< T >()(instance);
   }
}</subscriber>

That's based on my version of the singleton so the Notify signature is different from yours but the contents should quite same.

What do you think if we would use another way to communicate? I'm afraid we'll flood the forum at certain point and it's also a bit difficult to change code like this. Perhaps using email so we could transfer the entire projects?

The need to optimize rises from a bad design.My articles[^]

DaveyM6915-Jan-09 23:08

DaveyM69

15-Jan-09 23:08

Mika Wendelius wrote:
Perhaps using email so we could transfer the entire projects

I agree.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

modified on Friday, January 16, 2009 7:57 AM

Re: Generic event, or raise event based on generic type.

Wendelius15-Jan-09 23:25

Keep current view centered on Zoom

15-Jan-09 23:25

Okay, I got the address so you can remove it from the post. I'll send you a message in the evening.

The need to optimize rises from a bad design.My articles[^]

Richard Blythe12-Jan-09 7:16

Richard Blythe

12-Jan-09 7:16

I'm developing a drawing app and I'm using a UserControl as a basis to paint on. Everything is working fine but I'm wanting to keep the current view centered when a ZoomIn/ZoomOut operation occurs. For instance, if the user is working on a Rectangle and wants to zoom in closer, he would want the rectangle to stay in focus instead of scaling out of bounds. In my initial test, I can't figure out how microsoft calculates the position of the scrollbar handle and therefore I can't perform any centering algorithms. I don't want to center the whole document, just the area where the user is currently scrolled to.
Any help would be greatly appreciated!!

Richard

My code this week has no errors. But it's Monday morning and I haven't got out of bed.

Re: Keep current view centered on Zoom [modified]

Luc Pattyn12-Jan-09 8:01

Luc Pattyn

12-Jan-09 8:01

Hi Richard,

I haven't used it myself yet, but it seems to me the documentation on ScrollableControl.AutoScrollPosition explains rather well how scrolling is supposed to work.

This is what I would try:

assume control size is (2w,2h) and current autoscrollposition is (asx,asy)
center point is (w,h) relative to the topleft corner of the visible control, hence (asx+w,asy+h) logically;
when the zoom factor changes by a factor of zf (zoomnew/zoomold), new logical position of center point would be (zf*(asxnew+w),zf*(asynew+h)), but relative position should remain (w,h), hence:

asxnew=(asx+w)/zf-w
asynew=(asy+h)/zf-h

obviously boundary tests would be necessary to prevent "overscrolling" (showing stuff that lies outside
the drawing) if possible.

I hope I got this right and made this somewhat clear...

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

I use ListBoxes for line-oriented text, and PictureBoxes for pictures, not drawings.

modified on Friday, June 10, 2011 12:33 PM

Re: Keep current view centered on Zoom

Richard Blythe12-Jan-09 9:10

Richard Blythe

12-Jan-09 9:10

Thanks for the info. I haven't tried it yet but it sounds logical.

My code this week has no errors. But it's Monday morning and I haven't got out of bed.

Address

boiDev12-Jan-09 6:56

boiDev

12-Jan-09 6:56

Hi .. Everyone

Im trying to a simple address lookup using winform. What im trying to do is have a text box were a user can type in their PostCode/zip code and it will do a simple database(Sql) lookup but you do not have to type in your full postcode/ zip i can b just the first few characters and it still should find the full address information ..

Can any one help me with this because im stuck on this

EliottA12-Jan-09 7:21

12-Jan-09 7:21

Well did you try anything yet? Are you creating this database? Let's see some code, what do you have done so far, which part are you specifically stuck on?

boiDev12-Jan-09 11:25

boiDev

12-Jan-09 11:25

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace AddressFinder
{
public partial class AddressSelecter : Form
{
private static readonly object EventClose = new object();

public event EventHandler OnClose
{
add
{
Events.AddHandler(EventClose,value);
}
remove
{
Events.RemoveHandler(EventClose,value);
}
}

public virtual void OnCloseEvent(EventArgs e)
{
EventHandler handler = (EventHandler) Events[EventClose];
if(handler!=null)
{
handler(this, e);
}
}

public AddressSelecter()
{
InitializeComponent();
}

private string buildingNo;

public string BuildingNo
{
get { return buildingNo; }
set { buildingNo = value; }
}

private string street;

public string Street
{
get { return street; }
set { street = value; }
}

private string city;

public string City
{
get { return city; }
set { city = value; }
}

private string country;

public string Country
{
get { return country; }
set { country = value; }
}

public string PostCode
{
get { return txtPostCode.Text; }
set { txtPostCode.Text = value; }
}

private void button1_Click(object sender, EventArgs e)
{
SqlCommand cmd = new SqlCommand(@"select
b.buildingId,
b.buildingname,
s.streetname,
c.cityname
from
zipcode z
inner join city c on z.CityID = c.CityID
inner join building b on z.zipcodeid = b.zipcodeid
inner join street s on z.zipcodeid = s.zipcodeid
where z.zipcode = @postcode;");
cmd.Parameters.AddWithValue("postcode", txtPostCode.Text);

SqlDataReader reader = Read(cmd);

if (reader.HasRows)
{
while (reader.Read())
{
ItemObject item = new ItemObject();
item.Key =
string.Format("{0}, {1}, {2}", reader.GetString(1), reader.GetString(2), reader.GetString(3));
item.ValueOfKey = reader.GetInt64(0).ToString();

listBox1.Items.Add(item);
}
}
}

private void button2_Click(object sender, EventArgs e)
{
ItemObject selectedObject = (ItemObject)listBox1.SelectedItem;
lblBuilding.Text = selectedObject.ToString();

SqlCommand cmd = new SqlCommand(@"select
b.buildingname,
s.streetname,
c.cityname,
cntry.countryname
from
zipcode z
inner join city c on z.CityID = c.CityID
inner join building b on z.zipcodeid = b.zipcodeid
inner join street s on z.zipcodeid = s.zipcodeid
inner join country cntry on z.countryid = cntry.countryid
where z.zipcode = @postcode and b.buildingId = @buildingId");

cmd.Parameters.AddWithValue("postcode", txtPostCode.Text);
cmd.Parameters.AddWithValue("buildingId", selectedObject.ValueOfKey);

SqlDataReader reader = Read(cmd);

if (reader.HasRows)
{
reader.Read();

BuildingNo = reader.GetString(0);
Street = reader.GetString(1);
City = reader.GetString(2);
Country = reader.GetString(3);
}

lblBuilding.Text = BuildingNo + " " + Street;
lblCity.Text = City;
lblCountry.Text = Country;
}

private static SqlDataReader Read(SqlCommand cmd)
{
SqlConnection connection = new SqlConnection("Data Source=localhost;Database=Geo;Integrated Security=SSPI");

connection.Open();
cmd.Connection = connection;

SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);

return reader;
}

private void btnOk_Click(object sender, EventArgs e)
{
this.Hide();
OnCloseEvent(e);
}
}

public class ItemObject
{
private string key;
private object valueOfKey;

/// <summary>
/// Overloaded constructor.
/// </summary>
/// <param name="key">Key of object.</param>
/// <param name="valueOfKey">Value of object.</param>
public ItemObject(string key, object valueOfKey)
{
this.key = key;
this.valueOfKey = valueOfKey;
}

/// <summary>
/// Default constructor
/// </summary>
public ItemObject()
{
key = string.Empty;
valueOfKey = string.Empty;
}

///<summary>
///Returns a <see cref="T:System.String"></see> that represents the current
///<see cref="T:System.Object">
/// </see>.
///</summary>
///
///<returns>
///A <see cref="T:System.String"></see> that represents the current
///<see cref="T:System.Object">
/// </see>.
///</returns>
public override string ToString()
{
return key;
}

///<summary>
///Serves as a hash function for a particular type.
///</summary>
///
///<returns>
///A hash code for the current <see cref="T:System.Object"></see>.
///</returns>
public override int GetHashCode()
{
return ToString().GetHashCode();
}

/// <summary>
/// Gets or sets Key of object.
/// </summary>
public string Key
{
get { return key; }
set { key = value; }
}

/// <summary>
/// Gets or sets Value of object.
/// </summary>
public object ValueOfKey
{
get { return valueOfKey; }
set { valueOfKey = value; }
}
}
}

I have created the database an every thing. At the moment you have to type in the full post code for it to populate. i want so that you do not have to type in the full post code E.G if the full post code is IG6 6AF you should be able to type any part of it and still be able to search and find the address..

i hope you can help

Thank You

EliottA12-Jan-09 11:29

12-Jan-09 11:29

Use autocomplete on your textbox and bind your postal codes as a datasource, or you can use wildcards for your sql statement albeit you will get multiple results if a search overlaps 2 or more results. I would use wildcards.

boiDev12-Jan-09 11:43

boiDev

12-Jan-09 11:43

Im sorry to bother you .. but do you think that looking at my code is it very good or is no that good .. becuase i have only just started C# 2 weeks ago and i tought my self .. I dont know how to use wildcard .. if they is an example i can follow i would be happy

Smile | :)

EliottA12-Jan-09 12:28

Re: increasing panel size

12-Jan-09 12:28

If youre using access the wildcard is * or if you are using mssql or mysql the wildcard is %

For instance you have a table called names with Lesley, Leyla and mike if you do select * from names where name LIKE e% you will get results of Lesley and Leyla.

You are off to a good start for 2 weeks, look up on good practices and naming conventions.

Edit; its no bother, you are making an effort and thats what counts.

increasing panel size

jananiSreedhar12-Jan-09 6:11

jananiSreedhar

12-Jan-09 6:11

How do i increase the size of the panel dynamically at runtime

User 665812-Jan-09 6:18

User 6658

12-Jan-09 6:18

Set the Width and Height?

modified 12-Sep-18 21:01pm.

Re: increasing panel size

EliottA12-Jan-09 6:23