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select two point to Draw a circle

I am using visual studio c# windows form, I need help to draw a circle using the Mouse click.. first click will give me the center of the circle equal to the cursor position and the second click will give me a point on the border of the circle equal to the second position of the cursor, the distance between the to points will give me the radius..now I have radius and point ..I can draw a circle ..The code doesn't work because I only can get one position of the cursor no matter how many times I click the mouse
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
int lastX = Cursor.Position.X;//the first click x cursor position
int lastY = Cursor.Position.Y;//the first click y cursor position,
//is there any way to reuse the Cursor.Position for different point ??
int x = Cursor.Position.X;//the second click x cursor position
int y = Cursor.Position.Y;//the second click y cursor position
Graphics g;
double oradius=Math.Sqrt(((lastX-x)^2) +((lastY-y)^2));
//double newy = Math.Sqrt(lastY);
// int newxv = Convert.ToInt32(newx);
int radius= Convert.ToInt32(oradius);
g = this.CreateGraphics();
Rectangle rectangle = new Rectangle();
PaintEventArgs arg = new PaintEventArgs(g, rectangle);
DrawCircle(arg, x, y,radius,radius);
}
private void DrawCircle(PaintEventArgs e, int x, int y, int width, int height)
{
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Red, 3);
e.Graphics.DrawEllipse(pen, x - width / 2, y - height / 2, width, height);
}
}

You need to store the first click as well before you start doing the calculations. One way to do this is to create a class that simply throws an event every second time you pass it x and y coordinates like this:
public class CircleDrawer
{
private int _firstX;
private int _firstY;
private int _secondX;
private int _secondY;
private bool _isSecondClick;
private event EventHandler OnSecondClick;
public void RegisterClick(int x, int y)
{
if(_isSecondClick)
{
_secondX = x;
_secondY = y;
if(OnSecondClick != null)
OnSecondClick(this, null);
}
else
{
_firstX = x;
_firstY = y;
_isSecondClick = true;
}
}
}
You can then in your code simply call your methods:
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
int lastX = Cursor.Position.X;//the first click x cursor position
int lastY = Cursor.Position.Y;//the first click y cursor position,
_circleDrawer.RegisterClick(lastX, lastY);
}
And in your constuctor:
public MyForm()
{
_circleDrawer = new CircleDrawer();
_circleDrawer.OnSecondClick += DrawCircle();
}
public void DrawCircle()
{
// Your drawing code
}

Your lastX and lastY are local variables, and you initialize them in the beginning of the MouseDown event handler. They should be class level variables and should be populated at the end of the MouseDown event handler.
Also, you should test if they already have a value, and only if they have value then draw the circle and then clear them (so that the next circle will have it's own center).
Here is an improvement of your code. Note I've used the using keyword with the graphics object and with the pen - get used to use it every time you are using an instance of anything that's implementing the IDisposable interface.
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
if (_lastPosition != Point.Empty)
{
var currentPosition = Cursor.Position;
var oradius = Math.Sqrt(((_lastPosition.X - currentPosition.X) ^ 2) + ((_lastPosition.Y - currentPosition.Y) ^ 2));
var radius = Convert.ToInt32(oradius);
using (var g = this.CreateGraphics())
{
var arg = new PaintEventArgs(g, new Rectangle());
DrawCircle(arg, currentPosition, radius, radius);
}
_lastPosition = Point.Empty;
}
else
{
_lastPosition = Cursor.Position;
}
}
private void DrawCircle(PaintEventArgs e, Point position, int width, int height)
{
using (var pen = new System.Drawing.Pen(System.Drawing.Color.Red, 3))
{
e.Graphics.DrawEllipse(pen, position.X - width / 2, position.Y - height / 2, width, height);
}
}
Note: This code can be improved even further.

There are many things fundamentally wrong with this code, here is a complete, working example.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private Point clickCurrent = Point.Empty;
private Point clickPrev = Point.Empty;
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
clickPrev = clickCurrent;
clickCurrent = this.PointToClient(Cursor.Position);
if (clickPrev == Point.Empty) return;
Graphics g;
double oradius = Math.Sqrt((Math.Pow(clickPrev.X - clickCurrent.X, 2)) + (Math.Pow(clickPrev.Y - clickCurrent.Y, 2)));
int radius = Convert.ToInt32(oradius);
g = this.CreateGraphics();
Rectangle rectangle = new Rectangle();
PaintEventArgs arg = new PaintEventArgs(g, rectangle);
DrawCircle(arg, clickPrev.X, clickPrev.Y, radius * 2, radius * 2);
clickCurrent = Point.Empty;
}
private void DrawCircle(PaintEventArgs e, int x, int y, int width, int height)
{
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Red, 3);
e.Graphics.DrawEllipse(pen, x - width / 2, y - height / 2, width, height);
}
}

private int _firstX;
private int _firstY;
private int _secondX;
private int _secondY;
private bool _isSecondClick;
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
if (_isSecondClick)
{
_secondX = Cursor.Position.X;
_secondY = Cursor.Position.Y;
var radious1 = Math.Pow(_firstX - _secondX, 2);
var radious2 = Math.Pow(_firstY - _secondY, 2);
var radious = Math.Sqrt(radious1 + radious2);
Graphics g = this.CreateGraphics();
Rectangle rectangle = new Rectangle();
PaintEventArgs arg = new PaintEventArgs(g, rectangle);
DrawCircle(arg, _secondX, _secondY, radious, radious);
}
else
{
_firstX = Cursor.Position.X;
_firstY = Cursor.Position.Y;
_isSecondClick = true;
}
}
private void DrawCircle(PaintEventArgs arg, int x, int y, double width, double height)
{
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Red, 3);
var xL = Convert.ToInt32(x - width / 2);
var yL = Convert.ToInt32(y - height / 2);
var hL = Convert.ToInt32(height);
var wL = Convert.ToInt32(width);
arg.Graphics.DrawEllipse(pen, xL, yL, wL, hL);
}

How to enable zoom in and zoom out on a contentpage in xamarin forms?

How can I enable zoom on a contentpage in xamarin forms? Is it possible to enable it on the entire contentpage? Or is it only possible to zoom in on images?

You can use the pinch gesture inside a ContentPage, here is the official page:
https://developer.xamarin.com/guides/xamarin-forms/user-interface/gestures/pinch/
and for the entire project sample:
https://github.com/xamarin/xamarin-forms-samples/tree/master/WorkingWithGestures/PinchGesture
Here is an example of what you can achieve:
Xamarin.Forms Pinch Example

Try this Class , this solution do not scroll when you zoom .
Source found here:
Source Code
public class PinchToZoomContainer : ContentView {
double currentScale = 1;
double startScale = 1;
double xOffset = 0;
double yOffset = 0;
public PinchToZoomContainer ()
{
var pinchGesture = new PinchGestureRecognizer ();
pinchGesture.PinchUpdated += OnPinchUpdated;
GestureRecognizers.Add (pinchGesture);
}
void OnPinchUpdated (object sender, PinchGestureUpdatedEventArgs e)
{
if (e.Status == GestureStatus.Started) {
// Store the current scale factor applied to the wrapped user interface element,
// and zero the components for the center point of the translate transform.
startScale = Content.Scale;
Content.AnchorX = 0;
Content.AnchorY = 0;
}
if (e.Status == GestureStatus.Running) {
// Calculate the scale factor to be applied.
currentScale += (e.Scale - 1) * startScale;
currentScale = Math.Max (1, currentScale);
// The ScaleOrigin is in relative coordinates to the wrapped user interface element,
// so get the X pixel coordinate.
double renderedX = Content.X + xOffset;
double deltaX = renderedX / Width;
double deltaWidth = Width / (Content.Width * startScale);
double originX = (e.ScaleOrigin.X - deltaX) * deltaWidth;
// The ScaleOrigin is in relative coordinates to the wrapped user interface element,
// so get the Y pixel coordinate.
double renderedY = Content.Y + yOffset;
double deltaY = renderedY / Height;
double deltaHeight = Height / (Content.Height * startScale);
double originY = (e.ScaleOrigin.Y - deltaY) * deltaHeight;
// Calculate the transformed element pixel coordinates.
double targetX = xOffset - (originX * Content.Width) * (currentScale - startScale);
double targetY = yOffset - (originY * Content.Height) * (currentScale - startScale);
// Apply translation based on the change in origin.
Content.TranslationX = targetX.Clamp (-Content.Width * (currentScale - 1), 0);
Content.TranslationY = targetY.Clamp (-Content.Height * (currentScale - 1), 0);
// Apply scale factor
Content.Scale = currentScale;
}
if (e.Status == GestureStatus.Completed) {
// Store the translation delta's of the wrapped user interface element.
xOffset = Content.TranslationX;
yOffset = Content.TranslationY;
}
}
}
Helper DoubleExtensions
public static class DoubleExtensions
{
public static double Clamp (this double self, double min, double max)
{
return Math.Min (max, Math.Max (self, min));
}
}

You can try using the Scale Api on the Content page. This seemed to work for me on a small test app.
public App ()
{
// The root page of your application
var scaleUp = new Button {
Text = "Scale Up"
};
scaleUp.Clicked += (sender, e) => {
this.MainPage.Scale += 1;
};
var scaleDown = new Button {
Text = "Scale Down"
};
scaleDown.Clicked += (object sender, EventArgs e) => {
this.MainPage.Scale -= 1;
};
MainPage = new ContentPage {
Content = new StackLayout {
VerticalOptions = LayoutOptions.Center,
Children = {
scaleUp,
scaleDown
}
}
};
}

Trying to use this in conjunction with other controls that take the Pan/scroll gesture seems to fail. ScrollView and ListView for example grab the Pinch gesture even though they themselves don't Pinch but they do scroll/pan. So it seems like Pinch inherits/uses that gesture so it is grabbed by the wrapped control. This seems to make Pinch a very niche feature that can only work on very static views of Label and Image for example, but nothing more complex.

You can use gestures.
Sample here : http://arteksoftware.com/gesture-recognizers-with-xamarin-forms/

Mandelbrot Conversion [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 8 years ago.
Improve this question
I'm receiving no errors but when I'm running it I'm also unable to see the Mandelbrot it just displays the grey box, I'm currently stuck at this one point thanks for any help, if you see any other parts of my code which contains grammar or coding errors it would be much appreciated if you told me.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
namespace SE_Fractal_Assignment
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public struct HSBColor
{
float h;
float s;
float b;
int a;
public HSBColor(float h, float s, float b)
{
this.a = 0xff;
this.h = Math.Min(Math.Max(h, 0), 255);
this.s = Math.Min(Math.Max(h, 0), 255);
this.b = Math.Min(Math.Max(h, 0), 255);
}
public float H
{
get { return h; }
}
public float S
{
get { return s; }
}
public float B
{
get { return b; }
}
public int A
{
get { return a; }
}
public Color Color
{
get
{
return FromHSB(this);
}
}
public static Color FromHSB(HSBColor hsbColor)
{
float r = hsbColor.b;
float g = hsbColor.b;
float b = hsbColor.b;
if (hsbColor.s != 0)
{
float max = hsbColor.b;
float dif = hsbColor.b * hsbColor.s / 255f;
float min = hsbColor.b - dif;
float h = hsbColor.h * 360f / 255f;
if (h < 60f)
{
r = max;
g = h * dif / 60f + min;
b = min;
}
else if (h < 120f)
{
r = -(h - 120f) * dif / 60f + min;
g = max;
b = min;
}
else if (h < 180f)
{
r = min;
g = max;
b = -(h - 120f) * dif / 60f + min;
}
else if (h < 240f)
{
r = min;
g = -(h - 240f) * dif / 60f + min;
b = max;
}
else if (h < 300f)
{
r = -(h - 240f) * dif / 60f + min;
g = min;
b = max;
}
else if (h <= 360f)
{
r = max;
g = min;
b = -(h - 360f) * dif / 60f + min;
}
else
{
r = 0;
g = 0;
b = 0;
}
}
return Color.FromArgb
(
hsbColor.a,
(int)Math.Round(Math.Min(Math.Max(r, 0), 255)),
(int)Math.Round(Math.Min(Math.Max(g, 0), 255)),
(int)Math.Round(Math.Min(Math.Max(b, 0), 255))
);
}
}
private const int MAX = 256; // max iterations
private const double SX = -2.025; // start value goal
private const double SY = -1.125; // start value imaginary
private const double EX = 0.6; // end value real
private const double EY = 1.125; // end value imaginary
private static int x1, y1, xs, ys, xe, ye;
private static double xstart, ystart, xende, yende, xzoom, yzoom;
private static bool action, rectangle, finished;
private static float xy;
//private Image picture1;
private System.Drawing.Bitmap bitmap;
private Graphics g1;
private Cursor c1, c2;
private HSBColor HSBcol = new HSBColor();
// private HSB HSBcol = new HSB();
private void Form1_Paint(object sender, PaintEventArgs e)
{
g1 = e.Graphics;
g1.DrawImage(bitmap, 0, 0, x1, y1);
g1.Dispose();
}
private void Form1_Load(object sender, EventArgs e)
{
init();
start();
}
public void init()
{
//HSBcol = new HSB();
finished = false;
c1 = Cursors.WaitCursor;
c2 = Cursors.Cross;
x1 = 640;
y1 = 480;
xy = (float)x1 / (float)y1;
bitmap.SetPixel(x1, y1, Color.Blue);
g1 = Graphics.FromImage(bitmap);
finished = true;
// xy = (float)x1 / (float)y1;
//picture = createImage(x1, y1);
//g1 = picture.getGraphics();
}
public void destroy() // delete all instances
{
if (finished)
{
//removeMouseListener(this);
//removeMouseMotionListener(this);
//bitmap = null;
g1 = null;
c1 = null;
c2 = null;
//System.gc(); // garbage collection
GC.Collect();
}
}
public void start()
{
action = false;
rectangle = false;
initvalues();
xzoom = (xende - xstart) / (double)x1;
yzoom = (yende - ystart) / (double)y1;
mandelbrot();
}
public void stop()
{
}
public void paint(Graphics g)
{
update(g);
}
public void update(Graphics g)
{
/* Pen myPen = new Pen(Color.White);
g.DrawImage(bitmap, 0, 0);
if (rectangle)
{
if (xs < xe)
{
if (ys < ye)
{
g.DrawRectangle(myPen, xs, ys, (xe - xs), (ye - ys));
}
}
else
{
g.DrawRectangle(myPen, xs, ys, (xe - xs), (ye - ys));
}
myPen.Dispose();
}*/
}
private void mandelbrot() // calculate all points
{
int x, y;
float h, b, alt = 0.0f;
action = false;
for (x = 0; x < x1; x += 2)
for (y = 0; y < y1; y++)
{
h = pointcolour(xstart + xzoom * (double)x, ystart + yzoom * (double)y);
// color value
if (h != alt)
{
b = 1.0f - h * h; // brightnes
///djm added
///HSBcol.fromHSB(h,0.8f,b);
///
//convert hsb to rgb then make a Java Color
Color color = HSBColor.FromHSB(new HSBColor(h * 255, 0.8f * 255, b * 255));
///g1.setColor(col);
//djm end
//djm added to convert to RGB from HSB
//g1.setColor(Color.getHSBColor(h, 0.8f, b));
//djm test
// Color col = Color.FromArgb(0, 0, 0, 0);
//red = Color.Red;
// green = Color.Green;
// blue = Color.Blue;
//djm
alt = h;
}
Pen pen = new Pen(Color.Aqua);
g1.DrawLine(pen, x, y, x + 1, y);
}
//showStatus("Mandelbrot-Set ready - please select zoom area with pressed mouse.");
//setCursor(c2);
action = true;
}
private float pointcolour(double xwert, double ywert)
// color value from 0.0 to 1.0 by iterations
{
double r = 0.0, i = 0.0, m = 0.0;
int j = 0;
while ((j < MAX) && (m < 4.0))
{
j++;
m = r * r - i * i;
i = 2.0 * r * i + ywert;
r = m + xwert;
}
return (float)j / (float)MAX;
}
private void initvalues() // reset start values
{
xstart = SX;
ystart = SY;
xende = EX;
yende = EY;
if ((float)((xende - xstart) / (yende - ystart)) != xy)
xstart = xende - (yende - ystart) * (double)xy;
}
private void Form1_paint(object sender, PaintEventArgs e)
{
Graphics g = e.Graphics;
g1 = g;
action = false;
rectangle = false;
initvalues();
xzoom = (xende - xstart) / (double)x1;
yzoom = (yende - ystart) / (double)y1;
//picture = g.DrawImage;
//g.DrawImage(picture,0,0);
update(g);
mandelbrot();
}
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
if (action)
{
xs = e.X;
ys = e.Y;
}
}
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
// e.consume();
if (action)
{
xe = e.X;
ye = e.Y;
rectangle = true;
//repaint();
}
}
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
rectangle = false;
}
private void Form1_Click(object sender, MouseEventArgs e)
{
}
public String getAppletInfo()
{
return "fractal.class - Mandelbrot Set a Java Applet by Eckhard Roessel 2000-2001";
}
}
}

Honestly, the code is so cluttered and disorganized, it's hard to know all of what might be wrong with it. Sorry to be so blunt.
That said, a couple of obvious problems I see involving your "g1" Graphics instance member.
First, you are using the same field for two purposes: when computing the original image, you expect this to be a Graphics instance you can use to draw into your bitmap. But in the Paint event, you set it to the Graphics instance for the window, into which the painting should be done.
Second, in that Paint event, you dispose the Graphics instance before you return. But the instance you're disposing isn't yours. It belongs to the Forms system, and the only thing you should be doing with it is drawing into it.
There actually appear to be two different Paint event handlers and it's not clear which one you're using. You only dispose the Graphics instance in one of those places, so that may or may not be the real problem.
Personally, I would break the problem down into different elements. For a relative novice, it can be hard enough just to correctly draw a bitmap. It can also be difficult to really grasp how Paint event handling should be done. And of course, there's the Mandelbrot computations themselves. Trying to implement all three things (and more) at the same time can be overwhelming, and will take a lot longer assuming you can figure it out at all.
I would start by writing a simple program that just has a single PictureBox, which when you click a button, your program creates a new Bitmap object, into which you draw something simple (say, a rectangle, circle, or maybe just some text) and then assigns that Bitmap object to the PictureBox.Image property.
Once you have that working, then you can change the drawing part of the code to draw a Mandelbrot image instead.
Finally, once you have that working, then you can work on using the Paint event to draw the bitmap into your window directly instead of using the PictureBox control (the main reason for wanting to do this would presumably be that you eventually want to update the image as it's being drawn...if you only want to show it at the very end, then IMHO the PictureBox is a better approach).

Drawing a straight line from points

I am trying to make a simple chart application and I have stumbled upon a problem. I have an array of points which represent a 45 degree line (y = x) of 100 points. I then try to draw the line by converting each point's value to its pixel value and then draw lines from one point to another using graphic.DrawLines().
The the basic code:
struct MyPoint
{
double X { set; get; }
double Y { set; get; }
}
List<MyPoint> Values;
List<System.Drawing.Point> Points;
for (int i = 0; i < Values.Count; i++)
{
// convert point value to pixel coordinate
int x = (int)((Values[i].X - MinimumX) * (double)Control.Width / (MaximumX - MinimumX) + 0.5);
int y = (int)((Values[i].Y - MinimumY) * (double)Control.Height / (MaximumY - MinimumY)) + 0.5;
Points.Add(new System.Drawing.Point(x, y));
}
graphic.DrawLines(pen, Points.ToArray());
Note: MaximumX and MaximumY are 100 (number of points) and minimums are 0.
The thing is that this kind of line is not very straight :) So my question is, how would I draw a straight line through those points, so that it would look the same as
graphic.DrawLine(pen, 0, 0, Control.Width-1, Control.Height-1);
Thanks in advance!

Since you are doing a graph, I have a basic framework for fitting values within a control like this example:
public struct MyPoint
{
public double X { set; get; }
public double Y { set; get; }
public PointF ToPoint()
{
return new PointF((float)X, (float)Y);
}
}
/// <summary>
/// For http://stackoverflow.com/questions/19459519/drawing-a-straight-line-from-points
/// </summary>
public partial class Form1 : Form
{
List<MyPoint> points;
public Form1()
{
InitializeComponent();
// Initialize points to draw
points=new List<MyPoint>(100);
for (int i=0; i<=100; i++)
{
double θ=2*Math.PI*(i/100.0);
double x=(1+θ/Math.PI)*Math.Cos(θ);
double y=(1+θ/Math.PI)*Math.Sin(θ);
points.Add(new MyPoint() { X=x, Y=y });
}
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
// smooth graphics
e.Graphics.SmoothingMode=SmoothingMode.AntiAlias;
// set margins inside the control client area in pixels
var margin=new System.Drawing.Printing.Margins(16, 16, 16, 16);
// set the domain of (x,y) values
var range=new RectangleF(-3, -3, 6, 6);
// scale graphics
ScaleGraphics(e.Graphics, pictureBox1, range, margin);
// convert points to pixels
PointF[] pixels=points.Select((v) => v.ToPoint()).ToArray();
// draw arrow axes
using (var pen=new Pen(Color.Black, 0))
{
pen.EndCap=System.Drawing.Drawing2D.LineCap.ArrowAnchor;
e.Graphics.DrawLine(pen, range.Left, 0.0f, range.Right, 0.0f);
e.Graphics.DrawLine(pen, 0.0f, range.Top, 0.0f, range.Bottom);
}
// draw bounding rectangle (on margin)
using (var pen=new Pen(Color.LightGray, 0))
{
pen.DashStyle=DashStyle.Dash;
e.Graphics.DrawRectangle(pen, Rectangle.Round(range));
}
// draw curve
using (var pen = new Pen(Color.Blue, 0))
{
//e.Graphics.DrawLines(pen, pixels);
e.Graphics.DrawCurve(pen, pixels);
}
}
/// <summary>
/// Scales the Graphics to fit a Control, given a domain of x,y values and side margins in pixels
/// </summary>
/// <param name="g">The Graphics object</param>
/// <param name="control">The Control</param>
/// <param name="domain">The value domain</param>
/// <param name="margin">The margin</param>
void ScaleGraphics(Graphics g, Control control, RectangleF domain, Margins margin)
{
// Find the drawable area in pixels (control-margins)
int W=control.Width-margin.Left-margin.Right;
int H=control.Height-margin.Bottom-margin.Top;
// Ensure drawable area is at least 1 pixel wide
W=Math.Max(1, W);
H=Math.Max(1, H);
// Find the origin (0,0) in pixels
float OX=margin.Left-W*(domain.Left/domain.Width);
float OY=margin.Top+H*(1+domain.Top/domain.Height);
// Find the scale to fit the control
float SX=W/domain.Width;
float SY=H/domain.Height;
// Transform the Graphics
g.TranslateTransform(OX, OY);
g.ScaleTransform(SX, -SY);
}
private void pictureBox1_SizeChanged(object sender, EventArgs e)
{
// redraw on resize
pictureBox1.Refresh();
}
}

I think the problem is because your points are Integers. Precisions are lost.
Trying using
float x = (float)((Values[i] ...
List<System.Drawing.PointF> PointFs;
instead of
int x = (int)((Values[i] ...
List<System.Drawing.Point> Points;

You probably need something like this:
private void DrawLine()
{
int xInitial = 0, yInitial = 0, xFinal = Control.Width - 1, yFinal = Control.Height - 1;
int dx = xFinal - xInitial, dy = yFinal - yInitial, steps, k, xf, yf;
float xIncrement, yIncrement, x = xInitial, y = yInitial;
if (Math.Abs(dx) > Math.Abs(dy))
steps = Math.Abs(dx);
else
steps = Math.Abs(dy);
xIncrement = dx / (float)steps;
yIncrement = dy / (float)steps;
for (k = 0; k < steps; k++)
{
x += xIncrement;
xf = (int)x;
y += yIncrement;
yf = (int)y;
Points.Add(new System.Drawing.Point(xf, yf));
}
graphic.DrawLines(pen, Points.ToArray());
}
For more details see:
Bresenham's line algorithm
If your points already calculated correctly by algorithm, than simple:
int x = (int) Values[i].X;
int y = (int) Values[i].Y;
Should be enough.

here is my solution:
System.Drawing.Pen myPen;
myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
System.Drawing.Graphics formGraphics = this.CreateGraphics();
formGraphics.DrawLine(myPen, 0, 0, 200, 200);
myPen.Dispose();
formGraphics.Dispose();

Transcribing a polygon on a circle

i am currently try to inscribe diagonals of a decagon inside a circle
like this
in c# my approach would be creating a circle
e.Graphics.DrawEllipse(myPen, 0, 0, 100, 100);
and draw lines inside using
e.Graphics.DrawLine(myPen, 20, 5, 50, 50);
after that i would draw a decagon polygon.
currently im stuck at how to divide the circle into 10 parts/ finding the correct coordiantes of the points on the circumference of the circles because im not good in math,
i want to know how would i know the next point in a circumference of the circle the size of my circle is indicated above.
and also i want also to ask a better approach for my problem.
Thank you :)

Just for grits and shins, here's a generic implementation that will inscribe an X-sided polygon into the Rectangle you pass it. Note that in this approach I'm not actually calculating any absolute points. Instead, I am translating the origin, rotating the surface, and drawing the lines only with respect to the origin using a fixed length and an angle. This is repeated in a loop to achieve the end result below, and is very similar to commanding the Turtle in Logo:
public partial class Form1 : Form
{
PictureBox pb = new PictureBox();
NumericUpDown nud = new NumericUpDown();
public Form1()
{
InitializeComponent();
this.Text = "Inscribed Polygon Demo";
TableLayoutPanel tlp = new TableLayoutPanel();
tlp.RowCount = 2;
tlp.RowStyles.Clear();
tlp.RowStyles.Add(new RowStyle(SizeType.AutoSize));
tlp.RowStyles.Add(new RowStyle(SizeType.Percent, 100));
tlp.ColumnCount = 2;
tlp.ColumnStyles.Clear();
tlp.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
tlp.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
tlp.Dock = DockStyle.Fill;
this.Controls.Add(tlp);
Label lbl = new Label();
lbl.Text = "Number of Sides:";
lbl.TextAlign = ContentAlignment.MiddleRight;
tlp.Controls.Add(lbl, 0, 0);
nud.Minimum = 3;
nud.Maximum = 20;
nud.AutoSize = true;
nud.ValueChanged += new EventHandler(nud_ValueChanged);
tlp.Controls.Add(nud, 1, 0);
pb.Dock = DockStyle.Fill;
pb.Paint += new PaintEventHandler(pb_Paint);
pb.SizeChanged += new EventHandler(pb_SizeChanged);
tlp.SetColumnSpan(pb, 2);
tlp.Controls.Add(pb, 0, 1);
}
void nud_ValueChanged(object sender, EventArgs e)
{
pb.Refresh();
}
void pb_SizeChanged(object sender, EventArgs e)
{
pb.Refresh();
}
void pb_Paint(object sender, PaintEventArgs e)
{
// make circle centered and 90% of PictureBox size:
int Radius = (int)((double)Math.Min(pb.ClientRectangle.Width, pb.ClientRectangle.Height) / (double)2.0 * (double).9);
Point Center = new Point((int)((double)pb.ClientRectangle.Width / (double)2.0), (int)((double)pb.ClientRectangle.Height / (double)2.0));
Rectangle rc = new Rectangle(Center, new Size(1, 1));
rc.Inflate(Radius, Radius);
InscribePolygon(e.Graphics, rc, (int)nud.Value);
}
private void InscribePolygon(Graphics G, Rectangle rc, int numSides)
{
if (numSides < 3)
throw new Exception("Number of sides must be greater than or equal to 3!");
float Radius = (float)((double)Math.Min(rc.Width, rc.Height) / 2.0);
PointF Center = new PointF((float)(rc.Location.X + rc.Width / 2.0), (float)(rc.Location.Y + rc.Height / 2.0));
RectangleF rcF = new RectangleF(Center, new SizeF(1, 1));
rcF.Inflate(Radius, Radius);
G.DrawEllipse(Pens.Black, rcF);
float Sides = (float)numSides;
float ExteriorAngle = (float)360 / Sides;
float InteriorAngle = (Sides - (float)2) / Sides * (float)180;
float SideLength = (float)2 * Radius * (float)Math.Sin(Math.PI / (double)Sides);
for (int i = 1; i <= Sides; i++)
{
G.ResetTransform();
G.TranslateTransform(Center.X, Center.Y);
G.RotateTransform((i - 1) * ExteriorAngle);
G.DrawLine(Pens.Black, new PointF(0, 0), new PointF(0, -Radius));
G.TranslateTransform(0, -Radius);
G.RotateTransform(180 - InteriorAngle / 2);
G.DrawLine(Pens.Black, new PointF(0, 0), new PointF(0, -SideLength));
}
}
}
I got the formula for the length of the side here at Regular Polygon Calculator.

One way of dealing with this is using trigonometric functions sin and cos. Pass them the desired angle, in radians, in a loop (you need a multiple of 2*π/10, i.e. a = i*π/5 for i between 0 and 9, inclusive). R*sin(a) will give you the vertical offset from the origin; R*cos(a) will give you the horizontal offset.
Note that sin and cos are in the range from -1 to 1, so you will see both positive and negative results. You will need to add an offset for the center of your circle to make the points appear at the right spots.
Once you've generated a list of points, connect point i to point i+1. When you reach the ninth point, connect it to the initial point to complete the polygon.

I don't test it, but i think it is ok.
#define DegreeToRadian(d) d * (Pi / 180)
float r = 1; // radius
float cX = 0; // centerX
float cY = 0; // centerY
int numSegment = 10;
float angleOffset = 360.0 / numSegment;
float currentAngle = 0;
for (int i = 0; i < numSegment; i++)
{
float startAngle = DegreeToRadian(currentAngle);
float endAngle = DegreeToRadian(fmod(currentAngle + angleOffset, 360));
float x1 = r * cos(startAngle) + cX;
float y1 = r * sin(startAngle) + cY;
float x2 = r * cos(endAngle) + cX;
float y2 = r * sin(endAngle) + cY;
currentAngle += angleOffset;
// [cX, cY][x1, y1][x2, y2]
}
(fmod is c++ function equals to floatNumber % floatNumber)