Problem in load points from text file in C#

Question

1.00/5 (1 vote)

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hi guys
i wrote a code for winform c#
i want to select 28 points in my form (or in a picturebox)
then with a button i can save coorditane of all points in a text file
and it is working and made text file correctly
but problem is when i want to load those points from saved text file (this line of my code have problem =>

Points.Add(new PointF(str));

)

please if u can help me to solve it
other problem is when i select points, my app will draw a line between last 2 points only
i would like to my app show all lines of between all of my points (not only last 2 points)
if u can solve it too
thanks
i am waiting your kindly help

What I have tried:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using System.IO;

namespace howto_segment_intersection
{
    public partial class Form1 : Form
    {
        private Button LoadBtn;
        private Button SaveBtn;
        FileDialog openFileDialog1 = new OpenFileDialog();
        private SaveFileDialog Savefile;
        List<PointF> Points = new List<PointF>();

        public Form1()
        {
            InitializeComponent();
            this.SaveBtn = new Button();
            this.LoadBtn = new Button();
            this.LoadBtn.Anchor = AnchorStyles.Bottom;
            this.LoadBtn.BackColor = Color.DarkGreen;
            this.LoadBtn.FlatAppearance.BorderColor = Color.Gold;
            this.LoadBtn.FlatStyle = FlatStyle.Flat;
            this.LoadBtn.ForeColor = Color.White;
            this.LoadBtn.Location = new System.Drawing.Point(10, 10);
            this.LoadBtn.Name = "LoadBtn";
            this.LoadBtn.Size = new Size(75, 34);
            this.LoadBtn.TabIndex = 8;
            this.LoadBtn.Text = "Load";
            this.LoadBtn.UseVisualStyleBackColor = false;
            this.LoadBtn.Click += new EventHandler(this.LoadBtn_Click);

            this.SaveBtn.Anchor = AnchorStyles.Bottom;
            this.SaveBtn.BackColor = Color.Maroon;
            this.SaveBtn.FlatAppearance.BorderColor = Color.Red;
            this.SaveBtn.FlatStyle = FlatStyle.Flat;
            this.SaveBtn.ForeColor = Color.White;
            this.SaveBtn.Location = new System.Drawing.Point(100, 10);
            this.SaveBtn.Name = "SaveBtn";
            this.SaveBtn.Size = new Size(75, 34);
            this.SaveBtn.TabIndex = 8;
            this.SaveBtn.Text = "Save";
            this.SaveBtn.UseVisualStyleBackColor = false;
            this.SaveBtn.Click += new EventHandler(this.SaveBtn_Click);
            this.Controls.Add((Control)this.SaveBtn);
            this.Controls.Add((Control)this.LoadBtn);
        }

        private void SaveBtn_Click(object sender, EventArgs e)
        {
            this.Savefile = new SaveFileDialog();
            Savefile.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
            Savefile.ShowDialog();
            if (Savefile.ShowDialog() == DialogResult.OK)
            {
                StreamWriter writer = new StreamWriter(Savefile.FileName);
                foreach (var a in Points)
                    writer.WriteLine(a.ToString());
                writer.Close();
            }
        }

        private void LoadBtn_Click(object sender, EventArgs e)
        {
            DialogResult result = openFileDialog1.ShowDialog(); 
            if (result == DialogResult.OK) 
            {
                StreamReader Reader = new StreamReader(openFileDialog1.FileName, true);
                string str = Reader.ReadLine();
                while (str != null)
                {
                    Points.Add(new PointF(str));
                    str = Reader.ReadLine();
                }
                Reader.Close();
                this.Invalidate();
            }
        }

        private void Form1_MouseClick(object sender, MouseEventArgs e)
        {
            Points.Add(new PointF(e.X, e.Y));
            this.Invalidate();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

            if (Points.Count == 2)
            {
                e.Graphics.DrawLine(Pens.Green, Points[0], Points[1]);
            }
            if (Points.Count == 3)
            {
                e.Graphics.DrawLine(Pens.Green, Points[1], Points[2]);
            }
            if (Points.Count == 4)
            {
                e.Graphics.DrawLine(Pens.Green, Points[2], Points[3]);
            }
            if (Points.Count == 5)
            {
                e.Graphics.DrawLine(Pens.Green, Points[3], Points[4]);
            }
            if (Points.Count == 6)
            {
                e.Graphics.DrawLine(Pens.Green, Points[4], Points[5]);
            }
            if (Points.Count == 7)
            {
                e.Graphics.DrawLine(Pens.Green, Points[5], Points[6]);
            }
            if (Points.Count == 8)
            {
                e.Graphics.DrawLine(Pens.Green, Points[6], Points[7]);
            }
            if (Points.Count == 9)
            {
                e.Graphics.DrawLine(Pens.Green, Points[7], Points[8]);
            }
            if (Points.Count == 10)
            {
                e.Graphics.DrawLine(Pens.Green, Points[8], Points[9]);
            }
            if (Points.Count == 11)
            {
                e.Graphics.DrawLine(Pens.Green, Points[9], Points[10]);
            }
            if (Points.Count == 12)
            {
                e.Graphics.DrawLine(Pens.Green, Points[10], Points[11]);
            }
            if (Points.Count == 13)
            {
                e.Graphics.DrawLine(Pens.Green, Points[11], Points[12]);
            }
            if (Points.Count == 14)
            {
                e.Graphics.DrawLine(Pens.Green, Points[12], Points[13]);
            }
            if (Points.Count == 15)
            {
                e.Graphics.DrawLine(Pens.Green, Points[13], Points[14]);
            }
            if (Points.Count == 16)
            {
                e.Graphics.DrawLine(Pens.Green, Points[14], Points[15]);
            }
            if (Points.Count == 17)
            {
                e.Graphics.DrawLine(Pens.Green, Points[15], Points[16]);
            }
            if (Points.Count == 18)
            {
                e.Graphics.DrawLine(Pens.Green, Points[16], Points[17]);
            }
            if (Points.Count == 19)
            {
                e.Graphics.DrawLine(Pens.Green, Points[17], Points[18]);
            }
            if (Points.Count == 20)
            {
                e.Graphics.DrawLine(Pens.Green, Points[18], Points[19]);
            }
            if (Points.Count == 21)
            {
                e.Graphics.DrawLine(Pens.Green, Points[19], Points[20]);
            }
            if (Points.Count == 22)
            {
                e.Graphics.DrawLine(Pens.Green, Points[20], Points[21]);
            }
            if (Points.Count == 23)
            {
                e.Graphics.DrawLine(Pens.Green, Points[21], Points[22]);
            }
            if (Points.Count == 24)
            {
                e.Graphics.DrawLine(Pens.Green, Points[22], Points[23]);
            }
            if (Points.Count == 25)
            {
                e.Graphics.DrawLine(Pens.Green, Points[23], Points[24]);
            }
            if (Points.Count == 26)
            {
                e.Graphics.DrawLine(Pens.Green, Points[24], Points[25]);
            }
            if (Points.Count == 27)
            {
                e.Graphics.DrawLine(Pens.Green, Points[25], Points[26]);
            }
            if (Points.Count == 28)
            {
                e.Graphics.DrawLine(Pens.Green, Points[26], Points[27]);
            }

            foreach (PointF pt in Points)
            {
                DrawPoint(e.Graphics, pt, Brushes.Red, Pens.Black);
            }
      
        }
        private void DrawPoint(Graphics gr, PointF pt, Brush brush, Pen pen)
        {
            const int RADIUS = 5;
            gr.FillEllipse(brush,
                pt.X - RADIUS, pt.Y - RADIUS,
                2 * RADIUS, 2 * RADIUS);
            gr.DrawEllipse(pen,
                pt.X - RADIUS, pt.Y - RADIUS,
                2 * RADIUS, 2 * RADIUS);
        }
    }
}

Posted 31-Jul-21 20:22pm

payam mohammadi

Updated 31-Jul-21 23:07pm

v2

Add a Solution

4 solutions

Solution 1

Look at the documentation: PointF Struct (System.Drawing) | Microsoft Docs[^]. It clearly shows that the constructor does not take a string.

As to your other question your code is completely wrong. You should create a loop that iterates through the points collection and draws a line between each and every pair in the collection.

[edit]
Don't convert numbers (especially floating point) to strings in order to save them to a file. Write them out as their binary values so you get the exact values back when you reload them. You can even use the built in serialize/deserialize classes provided by .NET
[/edit]

Posted 31-Jul-21 21:13pm

Richard MacCutchan

Updated 31-Jul-21 22:12pm

v3

Solution 2

There is no overload of the PointF struct which takes a string parameter.
Think about it: if you pass a string to a method that needs two floating point values, how does it know which value is which or even that there are two separate values in the string at all?
What you are going to have to do is look at the file and find out what is actually stored, then break it up and use TryParse methods to "recover" the X and Y values.
Hint: PointF.ToString generates strings that look like this for my current culture (though the number format may change in yours):

{X=12.3, Y=55.9}

So you need to extract the numbers from that.
There are many ways to do that: String.Split, String.Substring (with IndexOf or IndexOfAny), and Regex are the ones which spring to mind here.

Posted 31-Jul-21 21:23pm

OriginalGriff

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RickZeeland · Accepted Answer · 2021-07-31T21:45:00

Try like this:

string fileName = "points.txt";
List<PointF> Points = new List<PointF>();

for (int i = 0; i < 10; i++)
{
    Points.Add(new PointF(i, (float)i / 2));
}

StreamWriter writer = new StreamWriter(fileName);
foreach (var a in Points)
    writer.WriteLine($"{a.X};{a.Y}");
writer.Close();


Points.Clear();
StreamReader Reader = new StreamReader(fileName, true);
string str = Reader.ReadLine();

while (str != null)
{
    Console.WriteLine(str);
    var x = Convert.ToDouble(str.Split(';')[0]);
    var y = Convert.ToDouble(str.Split(';')[1]);
    Points.Add(new PointF((float)x, (float)y));
    str = Reader.ReadLine();
}


Reader.Close();

payam mohammadi · Accepted Answer · 2021-07-31T23:07:00

Solution 5

thanks
with your Code problem of load points is completely solved
but a new challenge
i can draw point on main form and i can save them on a file and then load from file
but when i insert a picturebox in my form
and send all of codes of form to picturebox
For example (All codes of

private void Form1_MouseClick(object sender, MouseEventArgs e)

to

<pre>        private void picturebox1_MouseClick(object sender, MouseEventArgs e)

but my app can not draw points on picture box (only can in main form!)

Posted 31-Jul-21 23:07pm

payam mohammadi

Updated 31-Jul-21 23:09pm

v3

Comments

RickZeeland 1-Aug-21 5:27am

See: https://stackoverflow.com/questions/2729751/how-do-i-draw-a-circle-and-line-in-the-picturebox
The second answer shows how to use the paint event of the picture box.
(you should post this as a new question btw)

Richard Deeming 2-Aug-21 5:42am

Your new question is not a "solution" to your old question.

And by marking your post as "the answer" to your question, it looks like you are trying to abuse the system.