Type casting cant convert sysetm.object to system.drawing .point[]

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sir i want to recreate Ink stroke from bezierpoints of ink stroke already saved in db ,but
Iam facing type casting exception cant convert system.object to system.drawing.point.please suggest me how to convert system.object to system.drawing.point[] to recreate the stroke

code is as below

C#

foreach (Stroke S in inkOverlay.Ink.Strokes)
{
  SqlCommand inkcmd;
  cn = new SqlConnection("Data Source=localhost;Initial Catalog=amit;Integrated Security=True;Persist Security Info=True;Packet Size=4096");
  cn.Open();
  inkcmd = new SqlCommand("SELECT BPX,BPY FROM BezierTable where Alphabet= @Alphabet", this.sqlConnection1);
  SqlParameter param = new SqlParameter();
  param.ParameterName = "@Alphabet";
  param.Value = txtImage.Text;
  inkcmd.Parameters.Add(param);
  inkcmd.Connection = cn;
  ArrayList rowList = new ArrayList();
  rdr = inkcmd.ExecuteReader();
  While (rdr.Read())
  {
    object[] values = new object[rdr.FieldCount];
    rdr.GetValues(values);
    rowList.Add(values);
  }
  foreach (object[] row in rowList)
  {
     string[] bezierdetails = new string[row.Length];
     int columnIndex = 0;
     foreach (object column in row)
     {
          bezierdetails[columnIndex++] = Convert.ToString(column);
          Array x = rowList.ToArray();
          Point[] y = (Point[])x;//Typecasting error cant convert system.object to system.drawing.point,p
          Stroke newStroke = inkOverlay.Ink.CreateStroke(y);cant recreate stroke
          newStroke.Move(2000,300);
     }
  }

Posted 28-Jan-11 3:04am

googlejumbo

Updated 28-Jan-11 3:11am

Prerak Patel

v2

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4 solutions

Solution 3

You cannot directly convert an object of type object into a Point array.

Try something like -

C#

Point[] k = new Point[rowList.Count];
foreach(object o in rowList)
{
    k[i] = new Point(rdr[0],rdr[1]);
}

Note: This is pseudo code just to give you an idea. This will not work (nor compile).

Posted 28-Jan-11 3:24am

Abhinav S

Comments

William Winner 28-Jan-11 12:25pm

Actually, that's not true. ArrayList.ToArray() is overloaded and has an option for specifying the type.

Though, your way is still completely valid.

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-01-28T03:20:00

Solution 1

Instead of untyped and obsolete ArrayList use, for example, System.Collections.Generic.List<Point> rowList; your offending line will read: Point[] y = rowList.ToArray(); is this form it will compile because array element's exact type Point is defined by generic parameter.

—SA

Posted 28-Jan-11 3:20am

Sergey Alexandrovich Kryukov

Updated 28-Jan-11 3:49am

v3

Comments

Nish Nishant 28-Jan-11 9:42am

Proposed as answer, and voted 5.

Sergey Alexandrovich Kryukov 28-Jan-11 11:57am

Thanks a lot, hopefully should lead to a resolution.
--SA

Sandeep Mewara 28-Jan-11 12:11pm

Yes, good one... 5!

William Winner · Accepted Answer · 2011-01-28T06:18:00

Solution 4

If you're dead set on an ArrayList, then you need to use the ArrayList.ToArray(Type) method

C#

Point[] y = (Point[])rowList.ToArray(typeof(Point))

Posted 28-Jan-11 6:18am

William Winner

Comments

googlejumbo 30-Jan-11 9:09am

I have tried this code but new exceptions arises "At least one element in source array could not be cast down the destination array type" so please help me out for this error

William Winner 30-Jan-11 16:57pm

Then you've added something to the array that isn't a Point.

Another good reason for the typed List from System.Collection.Generic. It would tell you if you tried to load something besides a point into it.

Indivara · Accepted Answer · 2011-01-28T03:21:00

Solution 2

You can't cast something to what it is not.
Say you have

string name = "some arbitrary string";
object x = name;

This will get you nowhere:
int i = (int)x; // throws an exception
because the framework doesn't know how to convert it.

I didn't run your code (nothing to build it on right now), but you ~~have to~~ could loop through the values and convert them to Point individually. Stuff them in an IList<Point>, or array or whatever, after that.

Posted 28-Jan-11 3:21am

Indivara

Updated 28-Jan-11 13:03pm

v3

Comments

Nish Nishant 28-Jan-11 9:42am

Voted 5.

Sergey Alexandrovich Kryukov 28-Jan-11 9:54am

Indivara,
Your first example with "as" is pointless (regular assignment will work through boxing); this kind of dynamic cast is used for down-casting and returns null if not successful.
You should also explain that "(int)" cast will throw exception in your sample.
--SA

Indivara 28-Jan-11 19:05pm

Thanks, fixed. I was multitasking and being lazy to write a full explanation...

Sergey Alexandrovich Kryukov 28-Jan-11 19:38pm

All right. I actually just up-voted by 5.
--SA

William Winner 28-Jan-11 12:26pm

not true...ArrayList.ToArray is overloaded and has an option for specifying the type.

Sergey Alexandrovich Kryukov 28-Jan-11 12:30pm

Excuse me, I don't understand clearly this part: your "not true" refers to... what?
Thank you.
--SA

William Winner 28-Jan-11 12:47pm

The not true part is where he says, "you have to loop through the values...". What would have been true would be to say, "you could loop through the values.

Sergey Alexandrovich Kryukov 28-Jan-11 13:29pm

Oh, that... Sure.
Thanks for clarification.
--SA

Indivara 28-Jan-11 18:17pm

Thanks for pointing that out. updated.