Growing line from a point in C#

[shimajavar]

Hi every one

I have really got stuck in writting a piece of code.I suppose to create a form with a button on it. when ever button is clicked, a line which is stated from a certain point of the form(200,200) should grow upward.
its the code i have written
namespace ConsoleApplication1
{
class Program :Form
{
int x=202;
int y=202;
public Program()
{
this.Size = new Size(400, 400);
this.BackColor = Color.Wheat;
this.StartPosition = FormStartPosition.CenterScreen;
Button b1 = new Button();
this.Controls.Add(b1);
b1.Click+=new EventHandler(b1_Click);


}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
g.DrawLine(pen, 200, 200, 200, 201);


}
protected void b1_Click(object sender, EventArgs e)
{

x = 200;
y = 20;

}


button doesn't work! any suggestions??
thank u in advanced

[Plater]

There are a few logical/coding errors here.

Lets start with your button click:

protected void b1_Click(object sender, EventArgs e)
{
x = 200;
y = 20;
}
 

You're setting the adsolute value of your variables instead of incrementing them.
Try:

protected void b1_Click(object sender, EventArgs e)
{
   y = y-20;
}
 

Now onto your paint function:

protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
g.DrawLine(pen, 200, 200, 200, 201);
}
 

You are drawing the same line everytime, at no point do you use your x,y values that you are storing.
Try this:

protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
g.DrawLine(pen, 200, 200, x,y);
}
 

That should be enough to get you started.

[shimajavar]

There are many logical/coding falicies here.

Lets start with your button click:

I tried threads as well, do u wantto take a look at the code?

class Program :Form
{
int x1=202;
int y1=202;

int y2;
private Thread animationThread;

public Program()
{
this.Size = new Size(400, 400);
this.BackColor = Color.Wheat;
this.StartPosition = FormStartPosition.CenterScreen;
Button b1 = new Button();
this.Controls.Add(b1);
b1.Click+=new EventHandler(b1_Click);
animationThread = new Thread(new ThreadStart(growingLine));

}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
g.DrawLine(pen, 200, 200, x1, y2);


}
protected void b1_Click(object sender, EventArgs e)
{

animationThread.Start();
}

public void growingLine()
{
y1 = y2;
y2++;
Invalidate();
Thread.Sleep(40);
}

[Plater]

Sorry, I was in the middle of editing my post with the relevant information, please scroll up and have a look.

[shimajavar]

Sorry, I was in the middle of editing my post with the relevant information, please scroll up and have a look.

I tried ur code, actually when i execute it, a line(200,200,200,180) is created.Program doesn't go throght the "b1_click" method

[Plater]

If it drew the line up to 180, then it performed the button click.

Is the line supposed to GROW or MOVE? I gave you code for GROWing

[shimajavar]

I tried ur code, actually when i execute it, a line(200,200,200,180) is created.Program doesn't go throght the "b1_click" method

it should grow by clicking on button , not by opening the form.
Now I have some progress in the code...
class Program :Form
{
int x1=200;
int y1=200;
int y2=200;
private Thread animationThread;

public Program()
{
this.Size = new Size(400, 400);
this.BackColor = Color.Wheat;
this.StartPosition = FormStartPosition.CenterScreen;
Button b1 = new Button();
this.Controls.Add(b1);
b1.Click+=new EventHandler(b1_Click);
animationThread = new Thread(new ThreadStart(growingLine));

}
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
while(y2>50)
{
g.DrawLine(pen, x1, y1, x1, y2);
Thread.Sleep(10);
Invalidate();
y1 = y2;
y2--;
}


}
protected void b1_Click(object sender, EventArgs e)
{
if (animationThread.ThreadState == ThreadState.Unstarted)
{

animationThread.Start();
}
else if (animationThread.ThreadState == ThreadState.Running ||
animationThread.ThreadState == ThreadState.WaitSleepJoin)
{

animationThread.Suspend();
}
else if (animationThread.ThreadState == ThreadState.Suspended)
{

animationThread.Resume();
}

}

public void growingLine()
{
y1 = y2;
y2++;
Invalidate();
Thread.Sleep(40);
}

but , the problem is, i want the line to grow up when i click on the button, but it growa up as soon as the form is open!!

[Plater]

You are creating an endless loop in your onPaint() function by moving it and then telling it to paint again.

[shimajavar]

You are creating an endless loop in your onPaint() function by moving it and then telling it to paint again.

There is a while loop in OnPaint:while(y2>20)....
how if i move OnPaint in the other class?

class Program :Form
{

private Thread animationThread;
private GrowingLine growingline;

public Program()
{
this.Size = new Size(400, 400);
this.BackColor = Color.Wheat;
this.StartPosition = FormStartPosition.CenterScreen;
Button b1 = new Button();
this.Controls.Add(b1);
b1.Click+=new EventHandler(b1_Click);
growingline = new GrowingLine();
animationThread = new Thread(new ThreadStart(growingline.StartGrowing));

}

protected void b1_Click(object sender, EventArgs e)
{
if (animationThread.ThreadState == ThreadState.Unstarted)
{

animationThread.Start();
}
else if (animationThread.ThreadState == ThreadState.Running ||
animationThread.ThreadState == ThreadState.WaitSleepJoin)
{

animationThread.Suspend();
}
else if (animationThread.ThreadState == ThreadState.Suspended)
{

animationThread.Resume();
}

}

public static void Main(string[] args)
{
Application.Run(new Program());
Application.Exit();
}
private void InitializeComponent()
{
this.SuspendLayout();
//
// Program
//
this.ClientSize = new System.Drawing.Size(292, 266);
this.Name = "Program";
this.Load += new System.EventHandler(this.Program_Load);
this.ResumeLayout(false);

}

private void Program_Load(object sender, EventArgs e)
{

}


}
class GrowingLine:Panel
{
int x1;
int y1;
int y2;

public GrowingLine()
{
x1 = 200;
y1 = 200;
y2 = 200;
}

protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
Brush brush = new SolidBrush(Color.Black);
Pen pen = new Pen(brush, 4);
while (y2 > 60)
{
g.DrawLine(pen, x1, y1, x1, y2);
Thread.Sleep(10);
Invalidate();
y1 = y2;
y2--;
g.Dispose();
}
}

public void StartGrowing()
{
y1 = y2;
y2++;
Invalidate();
Thread.Sleep(40);
}


}


OnPaint doesn't work in this case.

[Plater]

I think you really need to go back and read some tutorials on the basics, event handling and the onPaint event...

[shimajavar]

I think you really need to go back and read some tutorials on the basics, event handling and the onPaint event...

do u have any suggestions? (tutorials?)

[Plater]

I was able to accomplish the task with the code I provided (slightly modified to have it grow upward automatically)

private int x = 200;
private int y = 202;
 
        private void myform_Load(object sender, EventArgs e)
        {
            Button bt = new Button();
            bt.Name = "bt";
            bt.Text = "Up";
            bt.Click += new EventHandler(bt_Click);
            this.Controls.Add(bt);
        }
 
        void bt_Click(object sender, EventArgs e)
        {
            AnimateUp();
        }
 
        private void AnimateUp()
        {
            int NumSteps = 10;
            int StepSize = 10;
            for (int i = 0; i < NumSteps; i++)
            {
                y = y - StepSize;
                this.Invalidate();
                this.Refresh();
                System.Threading.Thread.Sleep(100); 
 
            }
        }
 
        private void myform_Paint(object sender, PaintEventArgs e)
        {
            Graphics g=e.Graphics; 
            Pen blackpen = new Pen(Color.Black,4);
            g.DrawLine(blackpen, 200, 200, x, y);
        }
 

msdn has lots of great tutorials and help on .NET

[shimajavar]

This code has the same problem as mine..no line is painted on the form!!!

[Plater]

Works fine for me.
Did you set that paint function to be the paint event handler for the form?

[shimajavar]

nah...How should i do it?

[Plater]

in the form_load event add:
this.Paint += new PaintEventHandler(myform_Paint);

[shimajavar]

I got this error:

No overload for 'myform_Paint' mtaches delegate 'System.Windows.Forms.PaintEventHandler'.

[Plater]

Are you sure you're in .net?
What version of visual studio are you using?
These are pretty basic tasks.

Here's what I used:

[shimajavar]

I use visual c# 2008