asked on

ParentForm Question

Hi,

I am really looking for the best way to achieve this as I cannot undertsnad how I would approach it.

In my Form1 Code, I create a class, which is NOT nested. In this class I use ParentForm, thinking that upon Initializing the class in the Form Class OnLoad that it would know that Form1 is the ParentForm. Obviously I found that this did not work. So my question is,

Is passing the Form itself as an overload the only way to reference the form I want? Or is there a way where the class can adapt and realise that the parent form is the one whichg intialized it.

Here is my class, and how I have tried to get the parentForm

public class BlackBoard : Form
{
private Form _ParentForm;

public BlackBoard()
{
_ParentForm = ParentForm;
}

public void DrawBlackBoard()
{
Graphics g1 = CreateGraphics();
Rectangle BlackBoard = new Rectangle(10, 150, _ParentForm.Width - 20, _ParentForm.Height - 160);
SolidBrush BlackPaint = new SolidBrush(Color.Black);
g1.FillRectangle(BlackPaint, BlackBoard);
}
}

ozymandias

Why is it important for the one form to have the other as a parent ?
You could add your BlackBoard instance to your main for as an owned form :

BlackBoard b = new BlackBoard();
this.AddOwnedForm(b);

Or create a constructor in yout BlackBoard class like this :

public BlackBoard(Form parentForm) : base(){
this._ParentForm = parentForm;
}

and the call it like this :

BlackBoard b = new BlackBoard(this);

REA_ANDREW

ASKER

Thank you. I now have this but it does not draw the image. If I take it out the class and phycially code the graphic creation in the form load it works but not this way. Could you tell me where I am going wrong please

CLASS:
**********************************************************
public class BlackBoard : Form
{
private Form _ParentForm;

public BlackBoard(Form FormTarget)
{
this._ParentForm = FormTarget;
}

public void DrawBlackBoard()
{
Graphics g1 = CreateGraphics();
Rectangle BlackBoard = new Rectangle(10, 150, 150, 150);
SolidBrush BlackPaint = new SolidBrush(Color.Black);
Pen BlackPen = new Pen(Color.Black);
BlackPen.DashPattern = new float[] { 4.0F, 2.0F, 1.0F, 3.0F };
g1.FillRectangle(BlackPaint, BlackBoard);
g1.DrawRectangle(BlackPen, BlackBoard);
}
}

FORM LOAD
*******************************************************
//This does not draw the rectangle

private void Form1_Load(object sender, EventArgs e)
{
BlackBoard b = new BlackBoard(this);
b.DrawBlackBoard();
}

ozymandias

I'm not sure why it's not drawing.

Gautham Janardhan

where d'u want the to draw the black board in parent for rt? then

Graphics g1 = _ParentForm .CreateGraphics();
Rectangle BlackBoard = new Rectangle(10, 150, 150, 150);
SolidBrush BlackPaint = new SolidBrush(Color.Black);
Pen BlackPen = new Pen(Color.Black);
BlackPen.DashPattern = new float[] { 4.0F, 2.0F, 1.0F, 3.0F };
g1.FillRectangle(BlackPaint, BlackBoard);
g1.DrawRectangle(BlackPen, BlackBoard);
_ParentForm.Invlidate()

ASKER CERTIFIED SOLUTION

Mike Tomlinson

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial