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Refresh the canvas only for certain brushes

I'm trying to graph some circles and lines etc but I only want some lines to refresh on the canvas and the others not to, is there any way around this?
For example the mypen, mypen2 and mypen3, I want them to refresh on canvas but the graphics "g" a little further down I don't want to refresh, I want all the instances to show. How do I do this? Here is my code
private void drawlines()
{
canvas.Refresh();
int j = Int32.Parse(ivalue.Text);
float position1 = canvas.Width / 2;
float position2 = canvas.Height / 2;
float XX = (float)(Math.Round(position1 + Math.Sin(DegreeToRadian(j)) * 100));
float XY = (float)(Math.Round(position2 - Math.Cos(DegreeToRadian(j)) * 100));
float X2 = (position1 + XX);
float XY2 = XY;
System.Drawing.Pen myPen;
System.Drawing.Pen myPen2;
System.Drawing.Pen myPen3;
System.Drawing.Pen myPen4;
myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
myPen2 = new System.Drawing.Pen(System.Drawing.Color.Blue);
myPen3 = new System.Drawing.Pen(System.Drawing.Color.Black);
myPen4 = new System.Drawing.Pen(System.Drawing.Color.Green);
System.Drawing.Graphics formGraphics = canvas.CreateGraphics();
formGraphics.DrawRectangle(myPen,XX, XY,3,3);
formGraphics.DrawRectangle(myPen2, canvas.Width / 2, XY, 3, 3);
formGraphics.DrawRectangle(myPen3, position1, position2, 3, 3);
formGraphics.DrawRectangle(myPen4, position1, XY2, 3, 3);
label1.Text = Convert.ToString(XY);
label1.Refresh();
listBox1.Items.Clear();
listBox1.Items.Add("XX=[" + XX + "] XY=[" + XY + "]");
}
private void Go_Click(object sender, EventArgs e)
{
for (int i = 0; i <= 360; i = i + 1)
{
drawlines();
int linearm = (canvas.Width / 2) - i;
ivalue.Text = Convert.ToString(i);
ivalue.Refresh();
int testx = Int32.Parse(label1.Text);
Graphics g;
g = canvas.CreateGraphics();
Pen p;
Rectangle r;
p = new Pen(Brushes.Green);
r = new Rectangle(linearm,testx, 1, 1);
g.DrawRectangle(p, r);
System.Threading.Thread.Sleep(15);
}
}

I assume you are using winforms? If so you need to change your code to work like this:
To be persistant everything need to be drawin in the Paint event and using its e.Graphics object. (This is the Golden Rule! Corollary: Never use System.Drawing.Graphics formGraphics = canvas.CreateGraphics();)
Everything you want to be drawn must be stored in Lists of classes, sufficient to hold all info you need.
If you were to draw only Rectangles in only one pen a List<Rectangle> would be enough, but for other shapes and pens you will want to create a class to hold those data.
Now you can:
Draw them all in the Paint event, iterating the List<your DrawItemClass>
Remove or set inactive those items in the List you don't want to be drawn any longer..

How to flip alignment of drawn content in a panel

I am using two panels for drawing ruler along the sides (top and left) of a picture box. It works, but now my requirement is to flip the direction of the ruler so that the line starts from the picture box and the text (numbers) are the top. How can I do this?
My code is as follows:
private void panel2_Paint(object sender, PaintEventArgs e)//left Panel
{
Graphics g = e.Graphics;
g.PageUnit = GraphicsUnit.Millimeter;
int step = 1;
int length = panelleft.Height / 3;
int small = 5;
int big = 10;
int number = 10;
int scale = 10;
float stroke = 2.5f;
for (int i = 0; i < length; i += step)
{
float d = 1;
if (i % small == 0)
{
if (i % big == 0)
{
d = 3;
}
else
{
d = 2;
}
}
g.DrawLine(this.pen, 0f, i,d * stroke, i);
if ((i % number) == 0)
{
string text = (i / scale).ToString();
SizeF size = g.MeasureString(text, this.Font, length, this.format);
g.DrawString(text, this.Font, Brushes.Black,d * stroke, i - size.Width-1 / 2 , this.format);
}
}
}
private void panel3_Paint(object sender, PaintEventArgs e)// top panel
{
Graphics g = e.Graphics;
g.PageUnit = GraphicsUnit.Millimeter;
int step = 1;//incremnent
int length = paneltop.Width / 3; //panelinte widthinte pakuthi mathi bcs namml oru point gap vittanu line varakunnath
int small = 5;//cheriya vark ulla length
int big = 10;//valiya vark ulla length
int number = 10;//units 1cm=10 units
float stroke = 2.5f;
for (int i = 0; i < length; i += step)
{
float d = 1;
if (i % small == 0)//cheriya line
{
if (i % big == 0)//valiya line
{
d = 3; //varyude length
}
else
{
d = 2;//varyude length
}
}
g.DrawLine(this.pen, i, 0f, i, d * stroke);//lines varakunnu
if ((i % number) == 0)//0,1,,2
{
string text = (i / number).ToString();//1,2,3 ennu ezhuthan
SizeF size = g.MeasureString(text, this.Font, length, this.format);//ezhuthuna stringnte length ariyan// one digit length 1.618635,2 digit length3.23727
g.DrawString(text, this.Font, Brushes.Black, i - size.Width / 2, d * stroke, this.format);//Y constant ayirikum (d* stroke) ennu koduthath line kazhinju string varan anu alenkil overlapp cheyum
// ( X ) ( Y )
}
}
}
I also want to show a horizontal and vertical line, and they must be pointed to the ruler when the user moves the mouse over the image.
Required output sample:

Since you have set the Graphics to mm you need to calculate the conversion factor for the controls' pixel sizes:
float dpi = e.Graphics.DpiX;
float factor = 25.4f / dpi;
with this you can simply adapt your DrawString and DrawLine calls like this:
In panel2_Paint:
float w = panelleft.Width * factor;
g.DrawLine(this.pen, w - d * stroke, i, w, i);
g.DrawString(text, this.Font, Brushes.Black,
w - d * stroke - size.Width, i - size.Width - 1 / 2, this.format);
and in panel3_Paint:
float h = paneltop.Height * factor;
g.DrawLine(this.pen, i, h - d * stroke, i, h);
g.DrawString(text, this.Font, Brushes.Black,
i - size.Width / 2, h - d * stroke - size.Height, this.format);
To show the Cursor lines you can use this:
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
Point mp = pictureBox1.PointToClient(Cursor.Position);
if (e.ClipRectangle.Contains(mp))
{
e.Graphics.DrawLine(Pens.Red, 0, mp.Y, e.ClipRectangle.Width, mp.Y);
e.Graphics.DrawLine(Pens.Red, mp.X, 0, mp.X, e.ClipRectangle.Height);
}
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
pictureBox1.Invalidate();
}
Here is the result, using a few assumptions:
panelleft = panel2;
paneltop = panel3;
format = StringFormat.GenericTypographic;
pen = new Pen(Color.Black, 0.25f);
In theory you should use dpiX and dpiY respectively to get two factors.

For the top one, you want to change your DrawLine and your DrawString calls to be inverse of what they currently are.
In the Panel3 paint:
g.DrawLine(this.pen, i, 0f, i, d * stroke);//lines varakunnu
This draws a line from (i, 0) to (i, d*stroke). We want to invert this line, so we will do:
g.DrawLine(this.pen, i, panel3.Height, i, (panel3.Height - d * stroke));//lines varakunnu
We also want to adjust the label as well, so we will change this:
g.DrawString(text, this.Font, Brushes.Black, i - size.Width / 2, d * stroke, this.format);
to
g.DrawString(text, this.Font, Brushes.Black, i - size.Width / 2, (panel3.Height - d * stroke - size.Height), this.format);
or
g.DrawString(text, this.Font, Brushes.Black, i - size.Width / 2, (panel3.Height - d * stroke), this.format);
I'm not sure if you need to compensate for size.Height or not, since I can't test your code.

Mandelbrot Conversion [closed]

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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).

how to make diagram fit with in panel?

hey i am trying to build a windows application in .net,i have to draw factorial image inside the panel
private void Canvas_Paint(object sender, PaintEventArgs e)
{
start_x = Canvas.Width / 2;
start_Y = Canvas.Height / 2;
for (int i = 0; i < 400; i++)
draw_T();
}
public void draw_T()
{
mypen = new Pen(Color.Green, 2F);
my_angle = my_angle + (45);
my_length = 100 + (1);
end_x = (int)(start_x + Math.Cos(my_angle * .0174539676) * my_length);
end_Y = (int)(start_Y + Math.Sin(my_angle * .0174539676) * my_length);
Point[] points =
{
new Point (start_x,start_Y),
new Point (end_x,end_Y)
};
Point[] points1 =
{
new Point ((end_x+start_x)/2,(end_Y+start_Y)/2),
new Point (end_x+50,end_Y-100)
};
start_x = end_x;
start_Y = end_Y;
Graphics g = Canvas.CreateGraphics();
g.DrawLines(mypen, points);
g.DrawLines(mypen, points1);
}
drawing T shape line,then i start to draw another T shape from last end points .But problem is diagram is going outside of the panel.How do i fix drawing inside the panel

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)