Drawing a circle on an image

Question

I have a program for image segmentation in WinForms Application C#, and I have an image loaded in a pictureBox. I need to draw a small circle(or an ellipse, it does not matter) on that image (inside a region of interest, and allowing it to grow outwards until it reaches the desired boundary).

And the question is how can I draw that circle anywhere on that image? (and if it`s possible to draw that circle in a different color, red for example)

Thank you.

luci marginean · Answer

Thank you for your answer...it's working

Frogleg · Answer

This will draw an ellipse from center point public partial class Form1 : Form { bool _mouseDown = false ; Point origPt newPtcenterPt; int rectWidth rectHeight; Rectangle ellipseRectclearRect; public Form1() { InitializeComponent(); } private void Form1_Load( object sender EventArgs e) { } private void pcbImage_Paint( object sender PaintEventArgs e) { if (ellipseRect != null ) { e.Graphics.DrawEllipse( Pens .Red ellipseRect); } } private void pcbImage_MouseDown( object sender MouseEventArgs e) { _mouseDown = true ; centerPt.X = e.X; centerPt.Y = e.Y; } private void pcbImage_MouseMove( object sender MouseEventArgs e) { if (_mouseDown == true ) { newPt.X = e.X; newPt.Y = e.Y; Graphics g = pcbImage.CreateGraphics(); // draw temp ellipse clearRect = Rectangle .Inflate(ellipseRect 5 5); //erase old ellipse Region rg = new Region (clearRect); //erase old ellipse pcbImage.Invalidate(rg); //erase old ellipse rectWidth = Math .Abs(centerPt.X - newPt.X); // calculate half width of ellipse rectHeight = Math .Abs(centerPt.Y - newPt.Y); // calculate half height of ellipse origPt.X = centerPt.X - rectWidth; origPt.Y = centerPt.Y - rectHeight; ellipseRect = new Rectangle (origPt.X origPt.Y (rectWidth*2)(rectHeight *2)); g.DrawEllipse( Pens .Red ellipseRect); // draw temp ellipse } } private void pcbImage_MouseUp( object sender MouseEventArgs e) { _mouseDown = false ; } }

luci marginean · Answer

sorry I didn't explain myself but I want to draw by hand that circle on that image...now I am using this code to draw with the function e.Graphics.DrawPath This is the code what does the drawing I also have a button(btnLoad) and a pictureBox(pcbImage) where the image is loaded Code: namespace WindowsFormsApplication1 { public partial class frmMain : Form { private System.Drawing.Brush m_objBrush; private Graphics m_objGraphics; private Point lastPoint = Point.Empty; private System.Drawing.Drawing2D.GraphicsPath mousePath; private int mouseX mouseY; Point mouseDownLocation; public frmMain() { mousePath = new System.Drawing.Drawing2D.GraphicsPath(); InitializeComponent(); } private void btnQuit_Click(object sender EventArgs e) { Application.Exit(); } private void frmMain_Load(object sender EventArgs e) { m_objGraphics = this.CreateGraphics(); } private void pcbImage_MouseDown(object sender MouseEventArgs e) { mouseDownLocation = new Point(e.X e.Y); mousePath.StartFigure(); pcbImage.Focus(); pcbImage.Invalidate(); } private void pcbImage_MouseUp(object sender MouseEventArgs e) { pcbImage.Invalidate(); } private void pcbImage_MouseMove(object sender MouseEventArgs e) { mouseX = e.X; mouseY = e.Y; if (e.Button == MouseButtons.Left && e.Button == Button.MouseButtons) { mousePath.AddLine(mouseX mouseY mouseX mouseY); pcbImage.Invalidate(); } } private void pcbImage_Paint(object sender PaintEventArgs e) { e.Graphics.DrawPath(System.Drawing.Pens.Red mousePath); } } }

Frogleg · Answer

try this private void pictureBox1_Paint( object sender PaintEventArgs e) { e.Graphics.DrawEllipse( Pens .Red 10 10 100 100); // e.Graphics.DrawEllipse(Pens.Red X Y width height); } draws a circle 10 pixels across and 10 pixels down from top left corner of picturebox with a diameter of 100 pixels