Shapes not visible while drawing on mouse drag C# - visual-studio-2005

Question

I'm a new developer.I'm trying to make a simple program in which we can draw multiple shapes like Rectangle, Ellipse, Line, etc. The problem which I'm facing right now is that when I click the mouse and drag to draw on mouseDown and mouseMove event I'm not able to see the shape. The shape appears on the pictureBox only when I leave the mouse.
I want the shape to appear and move with the mouse as the user draws it just like in paint application by Microsoft.
I tried using Refresh() function while drawing but it removes the old shapes which was already drawn in the pictureBox.
Below is the code I'm using. need some suggestions.
bool draw = false;
bool isMouseDown = false;
int x, y, lx, ly = 0;
Item currItem;
Pen pen = new Pen(Color.Red,1);
public enum Item
{
Rectangle, Ellipse, Line, Pencil, Eraser
}
private void btnROIDraw_Click(object sender, EventArgs e)
{
if (menuStripRoi.Visible == false)
{
menuStripRoi.Visible = true;
}
else
{
menuStripRoi.Visible = false;
draw = false;
}
}
private void pictureBoxROI_MouseDown(object sender, MouseEventArgs e)
{
x = e.X;
y = e.Y;
isMouseDown = true;
//draw = true;
}
private void pictureBoxROI_MouseUp(object sender, MouseEventArgs e)
{
lx = e.X;
ly = e.Y;
if (draw)
{
Graphics g = pictureBoxROI.CreateGraphics();
switch (currItem)
{
case Item.Rectangle:
g.DrawRectangle(pen, x, y, e.X - x, e.Y - y);
break;
case Item.Ellipse:
g.DrawEllipse(pen, x, y, e.X - x, e.Y - y);
break;
case Item.Line:
g.DrawLine(pen, x, y, e.X, e.Y);
break;
}
g.Dispose();
}
isMouseDown = false;
}
private void pictureBoxROI_MouseMove(object sender, MouseEventArgs e)
{
if (isMouseDown)
{
if (draw)
{
Graphics g = pictureBoxROI.CreateGraphics();
switch (currItem)
{
case Item.Pencil:
g.FillEllipse(new SolidBrush(Color.Red), e.X - x + x, e.Y - y + y, 2, 2);
break;
case Item.Eraser:
g.FillEllipse(new SolidBrush(pictureBoxROI.BackColor), e.X - x + x, e.Y - y + y, 20, 20);
break;
}
g.Dispose();
}
}
}
private void pictureBoxROI_Paint(object sender, PaintEventArgs e)
{
}
private void clearToolStripMenuItem_Click(object sender, EventArgs e)
{
pictureBoxROI.Refresh();
}
private void rectangleToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Rectangle;
draw = true;
}
private void ellipseToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Ellipse;
draw = true;
}
private void lineToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Line;
draw = true;
}
private void pencilToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Pencil;
draw = true;
}
private void eracerToolStripMenuItem_Click(object sender, EventArgs e)
{
currItem = Item.Eraser;
draw = true;
}
private void newToolStripMenuItem_Click(object sender, EventArgs e)
{
pictureBoxROI.Refresh();
pictureBoxROI.Image = null;
}
private void openToolStripMenuItem_Click(object sender, EventArgs e)
{
OpenFileDialog o = new OpenFileDialog();
o.Filter = "Png files|*.png|jpeg files|*jpg|bitmaps|*.bmp";
if (o.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
pictureBoxROI.Image = (Image)Image.FromFile(o.FileName).Clone();
}
}
private void saveToolStripMenuItem_Click(object sender, EventArgs e)
{
Bitmap bmp = new Bitmap(pictureBoxROI.Width, pictureBoxROI.Height);
Graphics g = Graphics.FromImage(bmp);
Rectangle rect = pictureBoxROI.RectangleToScreen(pictureBoxROI.ClientRectangle);
g.CopyFromScreen(rect.Location, Point.Empty, pictureBoxROI.Size);
g.Dispose();
SaveFileDialog s = new SaveFileDialog();
s.Filter = "Png files|*.png|jpeg files|*jpg|bitmaps|*.bmp";
if (s.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
if (File.Exists(s.FileName))
{
File.Delete(s.FileName);
}
if (s.FileName.Contains(".jpg"))
{
bmp.Save(s.FileName, ImageFormat.Jpeg);
}
else if (s.FileName.Contains(".png"))
{
bmp.Save(s.FileName, ImageFormat.Png);
}
else if (s.FileName.Contains(".bmp"))
{
bmp.Save(s.FileName, ImageFormat.Bmp);
}
}
}

Answer 1

Found a solution to my question.
This article explains in detail everything about drawing with GDI+. Worth having a look
http://www.codeproject.com/Articles/17893/Extensions-to-DrawTools