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Deleting Circles drawn on grids in C# Visual studio

I have drawn a grid on form 8 in on paint event of the form as shown below. I have written a class drawRules in which I mentioned to draw the vertical and horizontal lines based on input from the form.
protected override void OnPaint(PaintEventArgs e)
{
Graphics g;
g = e.Graphics;
Pen linePen = new Pen(System.Drawing.Color.CornflowerBlue);
Int32 Num_of_Lines;
Int32 gridLength;
Int32 gridWidth;
bool IsIntValue = Int32.TryParse(Form7.setValue2, out Num_of_Lines);
bool IsIntValue1 = Int32.TryParse(Form7.setValue3, out gridWidth);
bool IsIntValue2 = Int32.TryParse(Form7.setValue4, out gridLength);
this.Size = new Size(Num_of_Lines * gridWidth, Num_of_Lines * gridLength);
if (IsIntValue)
{
if (IsIntValue1)
{
if (IsIntValue2)
{
drawRules.verticalRule vr1 = new drawRules.verticalRule(g, gridWidth, gridLength, Num_of_Lines);
//Draw horizontal line
drawRules.horizontalRule hr1 = new drawRules.horizontalRule(g, gridWidth, gridLength, Num_of_Lines);
}
linePen.Dispose();
base.OnPaint(e);
}
}
}
after this I want to draw circles wherever mouse is clicked for which I mentioned the mouse click event
private void Form8_MouseClick_1(object sender, MouseEventArgs e)
{
int r1 = e.X;
int r2 = e.Y;
Graphics g2;
g2 = this.CreateGraphics();
drawRules newclass1 = new drawRules();
newclass1.addcoordinate(r1, r2, g2);
}
addcoordinate1 is a method in drawRules class which is called to draw circle. Also, i am writing those coordinates in a file
public void addcoordinate(int r1, int r2, Graphics g2)
{
int gridWidth;
int gridLength;
int Num_of_Lines;
bool IsIntValue = Int32.TryParse(Form7.setValue2, out Num_of_Lines);
bool IsIntValue1 = Int32.TryParse(Form7.setValue3, out gridWidth);
bool IsIntValue2 = Int32.TryParse(Form7.setValue4, out gridLength);
Rectangle rectangle = new Rectangle();
PaintEventArgs arg = new PaintEventArgs(g2, rectangle);
Pen redPen1 = new Pen(Color.Red, 3);
DrawCircle(arg, redPen1, r1, r2, 8, 8);
System.IO.StreamWriter objWriter;
objWriter = new System.IO.StreamWriter("test.txt", true);
objWriter.Write(r1);
objWriter.Write(" ");
objWriter.Write(r2);
objWriter.WriteLine();
objWriter.Close();
}
public void DrawCircle(PaintEventArgs e, Pen redpen1, int x, int y, int
width, int height)
{
e.Graphics.DrawEllipse(redpen1, x - width / 2, y - height / 2, width, height);
redpen1.Dispose();
}
Now, I want to delete that circle, for which mouse is double clicked inside circle's area.
Please suggest how to delete the circles without deleting the grids behind. I will be grateful, if someone help me in this.

Don't draw in the code that gets executed when clicking the Button.
Save the coordinates and let the OnPaint methode handle it.
To remove your cirlces just remove them from the list.
private List<Point> circleCoordinates = new List<Point>();
public Form1()
{
InitializeComponent();
}
public void addcoordinate(int r1, int r2)
{
this.circleCoordinates.Add(new Point(r1, r2));
}
protected override void OnPaint(PaintEventArgs e)
{
// linedrawing goes here
foreach (Point point in this.circleCoordinates)
{
e.Graphics.DrawEllipse(Pens.Black, new Rectangle(point, new Size(10, 10)));
}
base.OnPaint(e);
}
private void Form1_MouseDoubleClick(object sender, MouseEventArgs e)
{
for (int i = this.circleCoordinates.Count() - 1; i >= 0; i--)
{
Rectangle ellipseRectangle = new Rectangle(this.circleCoordinates[i].X - 5, this.circleCoordinates[i].Y - 5, 10, 10)
GraphicsPath path = new GraphicsPath();
path.AddEllipse(ellipseRectangle);
if(path.IsVisible(e.Location))
{
this.circleCoordinates.RemoveAt(i);
}
//invalidate form to trigger repainting
this.Invalidate();
}

How to draw rectangle by coordinates of click?

I have pictureBox click event. I get coordinates of click and try t draw circle:
private void pictureMain_Click(object sender, EventArgs e){
MouseEventArgs me = (MouseEventArgs)e;
Point coordinates = me.Location;
int x = coordinates.X;
int y = coordinates.Y;
// Create pen.
Pen blackPen = new Pen(Color.Red, 2);
// Create rectangle for ellipse.
Rectangle rect = new Rectangle(x, y, 50, 50);
g.DrawEllipse(blackPen, rect);
}
But it draws circle not in coordinates(x,y) of picturebox. It places circle in another place.

Try this:
private void pictureBox1_Click (object sender, EventArgs e)
{
Point ellipseCenter = ((MouseEventArgs) e).Location;
Size ellipseSize = new Size (50, 50);
Point rectPosition = new Point (ellipseCenter.X - ellipseSize.Width / 2, ellipseCenter.Y - ellipseSize.Height / 2);
Rectangle rect = new Rectangle (rectPosition, ellipseSize);
using (Graphics grp = Graphics.FromImage (pictureBox1.Image))
{
grp.DrawEllipse (Pens.Red, rect);
}
pictureBox1.Refresh ();
}

Drawn shape/line fires on MouseEnter

i have PictureBox, how can I draw a shape/line that fires on MouseEnter event and change color or do more.
private void ImgViewer_Paint(object sender, PaintEventArgs e)
{
var graph = e.Graphics;
using (var pen = new Pen(Color.FromArgb(0, 255, 0)))
graph.DrawLine(pen, x1, y1, x2, y2);
}
this code is not enough, i guess

If you know the equation of the shape you could calculate whether the mouse is within or outside the shape area. Note that this is easy if the shape is consisted of the straight lines or circles (ellipses) for which the geometrical equations are relatively simple. For instance if your shape is a triangle with x and y coordinates (10,10), (50,10) and (30,50) than you should derive the equations of the lines using the equation of the line in two points:
y-y1 = ((y2-y1)/(x2-x1))*(x-x1)
the equations of the lines of our triangle would be:
y=1
y=2*x-10
y=-2*x+110
We should draw that triangle on some canvas, let's say on the PictureBox with FixedSingle border. Add the Paint event handler
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Point[] p = new Point[3];
p[0] = new Point(10,10);
p[1] = new Point(50,10);
p[2] = new Point(30,50);
e.Graphics.DrawLines(Pens.Black, p);
e.Graphics.FillPolygon(Brushes.Red, p);
}
We should add the MouseMove event handler for the PictureBox
bool inside = false;
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Y > 10 && e.Y < 2 * e.X - 10 && e.Y < -2 * e.X + 110)
{
if (!inside)
{
inside = true;
HandleMouseEnter();
}
}
else
inside = false;
}
void HandleMouseEnter()
{
MessageBox.Show("Mouse inside");
}
In if statement whether the mouse cursor is within the triangle (note that the coordinate origin in C# is on the top-left corner but it is similar to the real geometry). The HandleMouseEnter is the method that handles the mouse enter.
You could use similar approach for an arbitrary shape but you should have geometry equations that describe it.

Draw a Polygon using Mouse Points in C#

I need to be able to draw a polygon using mouse click locations.
Here is my current code:
//the drawshape varible is called when a button is pressed to select use of this tool
if (DrawShape == 4)
{
Point[] pp = new Point[3];
pp[0] = new Point(e.Location.X, e.Location.Y);
pp[1] = new Point(e.Location.X, e.Location.Y);
pp[2] = new Point(e.Location.X, e.Location.Y);
Graphics G = this.CreateGraphics();
G.DrawPolygon(Pens.Black, pp);
}
Thanks

Ok here is some sample code:
private List<Point> polygonPoints = new List<Point>();
private void TestForm_MouseClick(object sender, MouseEventArgs e)
{
switch(e.Button)
{
case MouseButtons.Left:
//draw line
polygonPoints.Add(new Point(e.X, e.Y));
if (polygonPoints.Count > 1)
{
//draw line
this.DrawLine(polygonPoints[polygonPoints.Count - 2], polygonPoints[polygonPoints.Count - 1]);
}
break;
case MouseButtons.Right:
//finish polygon
if (polygonPoints.Count > 2)
{
//draw last line
this.DrawLine(polygonPoints[polygonPoints.Count - 1], polygonPoints[0]);
polygonPoints.Clear();
}
break;
}
}
private void DrawLine(Point p1, Point p2)
{
Graphics G = this.CreateGraphics();
G.DrawLine(Pens.Black, p1, p2);
}

First, add this code:
List<Point> points = new List<Point>();
On the object you are drawing on, capture the OnClick event. One of the arguments should have the X and Y coordinates of the click. Add them to the points array:
points.Add(new Point(xPos, yPos));
And then finally, where you're drawing the lines, use this code:
if (DrawShape == 4)
{
Graphics G = this.CreateGraphics();
G.DrawPolygon(Pens.Black, points.ToArray());
}
EDIT:
Ok, so the above code isn't exactly correct. First of all, its most likely a Click event instead of a OnClick event. Second, To get the mouse position, you need two variables declared up with the points array,
int x = 0, y = 0;
Then have a mouse move event:
private void MouseMove(object sender, MouseEventArgs e)
{
x = e.X;
y = e.Y;
}
Then, in your Click event:
private void Click(object sender, EventArgs e)
{
points.Add(new Point(x, y));
}

Drawing circles with System.Drawing

I have this code that draws a Rectangle ( Im trying to remake the MS Paint )
case "Rectangle":
if (tempDraw != null)
{
tempDraw = (Bitmap)snapshot.Clone();
Graphics g = Graphics.FromImage(tempDraw);
Pen myPen = new Pen(foreColor, lineWidth);
g.DrawRectangle(myPen, x1, y1, x2-x1, y2-y1);
myPen.Dispose();
e.Graphics.DrawImageUnscaled(tempDraw, 0, 0);
g.Dispose();
}
But what if I want to draw a circle, what will change?
g.DrawRectangle(myPen, x1, y1, x2-x1, y2-y1);

There is no DrawCircle method; use DrawEllipse instead. I have a static class with handy graphics extension methods. The following ones draw and fill circles. They are wrappers around DrawEllipse and FillEllipse:
public static class GraphicsExtensions
{
public static void DrawCircle(this Graphics g, Pen pen,
float centerX, float centerY, float radius)
{
g.DrawEllipse(pen, centerX - radius, centerY - radius,
radius + radius, radius + radius);
}
public static void FillCircle(this Graphics g, Brush brush,
float centerX, float centerY, float radius)
{
g.FillEllipse(brush, centerX - radius, centerY - radius,
radius + radius, radius + radius);
}
}
You can call them like this:
g.FillCircle(myBrush, centerX, centerY, radius);
g.DrawCircle(myPen, centerX, centerY, radius);

Try the DrawEllipse method instead.

You'll need to use DrawEllipse if you want to draw a circle using GDI+.
An example is here: http://www.websupergoo.com/helpig6net/source/3-examples/9-drawgdi.htm

You should use DrawEllipse:
//
// Summary:
// Draws an ellipse defined by a bounding rectangle specified by coordinates
// for the upper-left corner of the rectangle, a height, and a width.
//
// Parameters:
// pen:
// System.Drawing.Pen that determines the color, width,
// and style of the ellipse.
//
// x:
// The x-coordinate of the upper-left corner of the bounding rectangle that
// defines the ellipse.
//
// y:
// The y-coordinate of the upper-left corner of the bounding rectangle that
// defines the ellipse.
//
// width:
// Width of the bounding rectangle that defines the ellipse.
//
// height:
// Height of the bounding rectangle that defines the ellipse.
//
// Exceptions:
// System.ArgumentNullException:
// pen is null.
public void DrawEllipse(Pen pen, int x, int y, int width, int height);

if you want to draw circle on button then this code might be use full.
else if you want to draw a circle on other control just change the name of control and also event. like here event button is called. if you want to draw this circle in group box call the Groupbox event.
regards
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
this.button1.Location = new Point(108, 12);
// this.Paint += new PaintEventHandler(Form1_Paint);
this.button1.Paint += new PaintEventHandler(button1_Paint);
}
void button1_Paint(object sender, PaintEventArgs e)
{
Graphics g = this.button1.CreateGraphics();
Pen pen = new Pen(Color.Red);
g.DrawEllipse(pen, 10, 10, 20, 20);
}
}

With this code you can easily draw a circle...
C# is great and easy my friend
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
Graphics myGraphics = base.CreateGraphics();
Pen myPen = new Pen(Color.Red);
SolidBrush mySolidBrush = new SolidBrush(Color.Red);
myGraphics.DrawEllipse(myPen, 50, 50, 150, 150);
}
}

private void DrawEllipseRectangle(PaintEventArgs e)
{
Pen p = new Pen(Color.Black, 3);
Rectangle r = new Rectangle(100, 100, 100, 100);
e.Graphics.DrawEllipse(p, r);
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
DrawEllipseRectangle(e);
}

PictureBox circle = new PictureBox();
circle.Paint += new PaintEventHandler(circle_Paint);
void circle_Paint(object sender, PaintEventArgs e)
{
e.Graphics.DrawEllipse(Pens.Red, 0, 0, 30, 30);
}