Develop Reference

How to move label's text right to left,when a character hides in left it shows on right?

Here is my key code:
using System;
using System.Windows.Forms;
namespace Scroller
{
public partial class Form1 : Form
{
int i, j;
bool k = false;
public Form1()
{
InitializeComponent();
}
private void timer1_Tick(object sender, EventArgs e)
{
label1.Text = "Time:"+ System.DateTime.Now.ToString();
i--;
j = i + this.Width;
if (i < this.Width && i > 0)
{
label1.Left = i;
}
else
if (i < 0 && k == false)
{
label1.Left = i;
k = true;
}
else
if (i < 0 && k == true)
{
label1.Left = j;
k = false;
}
if (i < 0 - label1.Width)
{
i = this.Width - label1.Width;
}
}
private void Form1_Load(object sender, EventArgs e)
{
label1.Text = "Time:"+ System.DateTime.Now.ToString();
i = this.Width - label1.Width;
label1.Left = i;
}
}
}
The effect that I want to make is the whole time string move right to left. When a pixel of the text disappear on the left side (because it is out of the form's left border),the pixel will shows on the right side.
In other words, the effect can't be make by delete the first character of string and append it to the last.
I knew that it will be easier to use two label to do it. Set one's location in the form and hide the other right by the form. Move them in the same time.
When the first label hit the left border of the form, the second hit the right border of the form. And the first one move out, the second move in. Until the second totally move in, reset their x location.
But I just want to use one label. So I chose to quickly switch the label's location, and try to "cheat" user's eye. The problem is when the label switch between left and right, it flash very obviously. Even though I set timer's interval below 20,the problem still exist.
Could you help me dissolve the flash problem or enlighten me other ways which can just use one label and one timer to make the effect I need?
Thanks. If I didn't describer my problem clear enough or need more code, please let me know.

I don't think you can work out the flashing problem changing the label's location in a windows form.
Another solution would be to set the label width the same size as the form width, make the label text fill all the width using spaces and make the timer always get the last character and put it on the beginning of the string.
Sample code below.
private void timer1_Tick(object sender, EventArgs e)
{
label1.Text = label1.Text.Substring(label1.Text.Length - 1) + label1.Text.Remove(label1.Text.Length - 1);
}
private void Form1_Load(object sender, EventArgs e)
{
// The total spaces required to fill the form vary from form.width and the initial label.text.width
// Width | Spaces
// 177 | 13
// 228 | 30
// 297 | 53
// 318 | 60
// The spacesEnd = 60 work for a form with width 319
int spacesBegin = 0, spacesEnd = 60;
label1.Text = "Time:" + System.DateTime.Now.ToString();
label1.AutoSize = false;
label1.Left = -3;
label1.Width = this.Width - 1;
label1.Height = 15;
label1.BorderStyle = BorderStyle.FixedSingle;
for (int i = 0; i < spacesBegin; i++)
label1.Text = " " + label1.Text;
for (int i = 0; i < spacesEnd; i++)
label1.Text += " ";
Timer timer = new Timer();
timer.Tick += timer1_Tick;
timer.Interval = 50;
timer.Start();
}

C# Drag and Drop labels within FlowLayoutPanels

I have small problem. I want make program where I can drag generated labels between multiple FlowLayoutPanels. But last few days I have tried to make drag and drop working. I tried many tutorials, examples etc. but it is always something bit diferent and I am not able extract only basic code.
It is similar to this program but it is in Visual Basic and I need it in C#. I know it is maybe very simple, but I am newbie.
Thank you for help.

Real Drag&Drop ist most useful between applications and maybe also between Forms.
Assuming you want to drag Labels between FLPs on the same Form, the code below should get you going..
It takes two FlowLayoutPanels called FLP1 and FLP2 and starts by initializing them with a few Labels.
Note the three mouse events I add to each Label to emulate a Drag&Drop action!
private void Form1_Load(object sender, EventArgs e)
{
// create a few Label with varying Colors for testing..
fillFLP(FLP1, 88);
fillFLP(FLP2, 111);
}
void fillFLP(FlowLayoutPanel FLP, int cc)
{
for (int i = 0; i < 24; i++)
{
Label l = new Label();
// the next 3 lines optional and only are there for testing!
l.AutoSize = false;
l.Text = FLP.Name + " " + i.ToString("00");
l.BackColor = Color.FromArgb(255, cc * 2 - i, 255 - 5 * i, cc + 5 * i);
// add controls and set mouse events:
FLP.Controls.Add(l);
l.MouseDown += l_MouseDown;
l.MouseMove += l_MouseMove;
l.MouseUp += l_MouseUp;
}
}
// the currently moved Label:
Label mvLabel = null;
void l_MouseDown(object sender, MouseEventArgs e)
{
// keep reference
mvLabel = (Label)sender;
}
void l_MouseMove(object sender, MouseEventArgs e)
{
// if we are dragging a label:
if (mvLabel != null)
{
// mouse pos in window coords
Point mvPoint = this.PointToClient(Control.MousePosition);
// the label is still in the FLP, so we start the drg action:
if (mvLabel.Parent != this)
{
mvLabel.Parent = this;
mvLabel.Location = mvPoint;
mvLabel.BringToFront();
}
else
{
// we are already in the form, so we just move
mvLabel.Location = mvPoint;
}
}
}
void l_MouseUp(object sender, MouseEventArgs e)
{
// are we over a FLP? and if so which?
Point MP = Control.MousePosition;
FlowLayoutPanel FLP = null;
Point mLoc1 = FLP1.PointToClient(MP);
Point mLoc2 = FLP2.PointToClient(MP);
if (FLP1.ClientRectangle.Contains(mLoc1)) FLP = FLP1;
else if (FLP2.ClientRectangle.Contains(mLoc2)) FLP = FLP2;
else return; // no! nothing we can do..
// yes, now find out if we are over a label..
// ..or over an empty area
mvLabel.SendToBack();
Control cc = FLP.GetChildAtPoint(FLP.PointToClient(MP));
// if we are over the FLP we can insert at the beginning or the end:
// int mvIndex = 0; // to the beginning
int mvIndex = FLP.Controls.Count; // to the end
// we are over a Label, so we insert before it:
if (cc != null) mvIndex = FLP.Controls.IndexOf(cc);
// move the Label into the FLP
FLP.Controls.Add(mvLabel);
// move it to the right position:
FLP.Controls.SetChildIndex(mvLabel, mvIndex);
// let go of the reference
mvLabel = null;
}
This lets you drag and drop Lables to and fro between two FLPs and also within the FLPs by dropping onto Labels.
Note that you will need a few extra lines if you want to allow dropping between Labels and still position there..

code improvement - naming textboxes generated form numericupdown & button click

I have a problem with a code that is regarding adding controls with numericUpDown ( for example- if numericUpDown value equals to 3, user recievs 3 textboxes).
Thanks to stackoverflow users I improved my code.
Before improvement it looked like this:
private void button1_Click(object sender, EventArgs e)
{
if (numericUpDown1.Value == 1)
{
txtbx1.AutoSize = true;
Controls.Add(txtbx1);
txtbx1.Location = new Point(70, 100);
}
else if (numericUpDown1.Value == 2)
{
txtbx1.AutoSize = true;
Controls.Add(txtbx1);
txtbx1.Location = new Point(70, 100);
txtbx2.AutoSize = true;
Controls.Add(txtbx2);
txtbx2.Location = new Point(70, 130);
}
else if (numericUpDown1.Value == 3)
{
txtbx1.AutoSize = true;
Controls.Add(txtbx1);
txtbx1.Location = new Point(70, 100);
txtbx2.AutoSize = true;
Controls.Add(txtbx2);
txtbx2.Location = new Point(70, 130);
txtx3.AutoSize = true;
Controls.Add(txtbx3);
txtbx3.Location = new Point(70, 160);
}
}
After improvement:
private void button1_Click(object sender, EventArgs e)
{
int y = 100;
int x = 70;
for (int i = 0; i < numericUpDown1.Value; i++)
{
var txtbx = new TextBox();
txtbx.AutoSize = true;
Controls.Add(txtbx);
txtbx.Location = new Point(x, y);
// Increase the y-position for next textbox.
y += 30;
}
}
Now the problem is that I don't know how assign names to genarated textboxes.
(before the improvement I could name them - txtbx1, txtbx2, txtbx3...)
Code to improve:
private void button3_Click(object sender, EventArgs e)
{
try
{
double a, b, c, sum;
a = double.Parse(txtbx1.Text);
b = double.Parse(txtbx2.Text);
c = double.Parse(txtbx3.Text);
sum = a + b + c;
label1.Text = sum.ToString();
}
catch (Exception ex)
{
MessageBox.Show("error");
}
Please note that I'm a beginner, learning c# by watching youtube tutorials ;) I do realize that my question might be silly but I couldn't handle this problem by myself.
In advance thank you for your time and help.

If you need to access them afterwards, you have some options.
I'll guess that your objective is to set label1's text to the sum of the values contained in the specified textbox(es).
On the ValueChanged event of your NumericUpDown, check the delta and consequentely add or remove the required number of TextBoxes to your Form's Controls. To obtain the delta, you'll need to store the previous value of the NumericUpDown, and then subtract it from the current value. (If it was 5, and now it's 4, 4 - 5 = -1. A textbox has been removed).
private int _oldNUDvalue = 0; //or assign it to the default value
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
int delta = (int)numericUpDown1.Value - _oldNUDvalue;
if (delta < 0)
{
for (int i = -delta; i > 0; i--)
{
var tbox = Controls.Find("ntextBox" + (_oldNUDvalue - i), false)[0];
Controls.Remove(tbox);
}
}
else if (delta > 0)
{
for (int i = _oldNUDvalue; i < _oldNUDvalue + delta; i++)
{
var tbox = new TextBox();
tbox.Location = new Point(15, 55 + (30 * i));
tbox.Name = "ntextBox" + i;
Controls.Add(tbox);
}
}
_oldNUDvalue = (int)numericUpDown1.Value;
}
If, however, you only have a maximum number of 3, you could take a slightly different approach. My solution works with n-textboxes.
Finally, to get the TextBoxes' values from code, you have three approaches:
Loop through your Form's controls, check for TextBoxes with their name starting with "ntextBox", and add their values together
Use LINQ to do the same
Access them singularly via "Controls.Find("ntextBoxX", false)", where X is the number of course.
I'll show the LINQ approach as I like it better.
int sum = Controls.Cast<Control>().Sum(c => c.Name.StartsWith("ntextBox") ? int.Parse(c.Text) : 0);
I haven't tested the code, but it should work. Tell me if there are any problems.
EDIT: Tested and it works. For the sake of completeness, I'll add some event logic to the TextBox-adding loop, to make sure that their input is actually numeric.
tbox.TextChanged += HandleNTextBoxInput; // add this line
And elsewhere, add this method:
void HandleNTextBoxInput(object sender, EventArgs e)
{
string text = ((TextBox)sender).Text;
if (!Regex.IsMatch(text, "^[1-9][0-9]*$")) //Text is NOT numeric. Remove [1-9] if you want to keep leading zeros.
{
//Set the Text to 0, for example. Or show a message box. Or whatever.
((TextBox)sender).Text = "0";
}
}

As I mentioned in a comment- this code seems to be maybe too advanced for me.
I have no problem with adding the controls, bu still there is a problem how to get the sum from a button click to a textbox.
I probably made some simple mistakes, or something is missing but I really don't know how to fix this problem.
My code:
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.Text.RegularExpressions;
namespace testprogram
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e) // I'm guessing something is missing over here
{
int sum = Controls.Cast<Control>().Sum(c => c.Name.StartsWith("ntextBox") ? int.Parse(c.Text) : 0);
}
void HandleNTextBoxInput(object sender, EventArgs e)
{
string text = ((TextBox)sender).Text;
if (!Regex.IsMatch(text, "^[1-9][0-9]*$")) //Text is NOT numeric. Remove [1-9] if you want to keep leading zeros.
{
//Set the Text to 0, for example. Or show a message box. Or whatever.
((TextBox)sender).Text = "0";
}
}
private int _oldNUDvalue = 0; //or assign it to the default value
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
{
int delta = (int)numericUpDown1.Value - _oldNUDvalue;
if (delta < 0)
{
for (int i = -delta; i > 0; i--)
{
var tbox = Controls.Find("ntextBox" + (_oldNUDvalue - i), false)[0];
Controls.Remove(tbox);
}
}
else if (delta > 0)
{
for (int i = _oldNUDvalue; i < _oldNUDvalue + delta; i++)
{
var tbox = new TextBox();
tbox.Location = new Point(15, 55 + (30 * i));
tbox.Name = "ntextBox" + i;
tbox.TextChanged += HandleNTextBoxInput;
Controls.Add(tbox);
}
}
_oldNUDvalue = (int)numericUpDown1.Value;
}
}
}
}

How to prevent user to enter a special character in text box?

I want to prevent one particular character * (asterisk) from being entered or pasted into a text box.
I tried:
key_press event - but it does not handle the case when user pastes an asterisk to the text box.
text_changed event - but when I remove the character, the cursor position goes back to the beginning of the text.
So I am wondering how to handle it, preferably in one event.

use the text changed event, but save the location of the cursor (the SelectionStart and SelectionEnd properties) before you remove the asterisk, then re set the cursor position (less the number of asterisks removed before the cursor).
private void textBox1_TextChanged(object sender, TextChangedEventArgs e)
{
var currentText = textBox1.Text;
var selectionStart = textBox1.SelectionStart;
var selectionLength = textBox1.SelectionLength;
int nextAsterisk;
while ((nextAsterisk = currentText.IndexOf('*')) != -1)
{
if (nextAsterisk < selectionStart)
{
selectionStart--;
}
else if (nextAsterisk < selectionStart + selectionLength)
{
selectionLength--;
}
currentText = currentText.Remove(nextAsterisk, 1);
}
if (textBox1.Text != currentText)
{
textBox1.Text = currentText;
textBox1.SelectionStart = selectionStart;
textBox1.SelectionLength = selectionLength;
}
}

This question may be of use to you. What you're looking for seems like either a MaskedTextBox or a TextBox with custom Validation logic. You should not simply erase an asterisk characters when it is input, because if a user has selected text, then typed an asterisk, they will have replaced the selected text with an asterisk before you have the chance to remove it.

You can set the cursor postion. For example:
textBox1.SelectionStart = textBox1.Text.Length;
EDIT:
Ok i took some time to write you a solution that works quite good. It keeps the edit cursor at the proper position and also covers the situation in which user pastes some * chars between chars.
int position = this.textBox1.SelectionStart;
string str = this.textBox1.Text;
int hit = 0;
for (int i = 0; i < position; i++)
{
if (str[i].Equals('*'))
hit++;
}
str = str.Replace("*", "");
this.textBox1.Text = str;
this.textBox1.SelectionLength = 0;
this.textBox1.SelectionStart = position - hit;

Here is the solution i found:-
On Text_changed event, here is what i am doing:-
txt1.Text = txt1.Text.Replace("*", string.Empty);
txt1.Select(txt1.Text.Length, 0);
Updated code:-
On Text_changed event:-
int curpos = 0;
bool isReplaced = false;
private void txt1_TextChanged(object sender, EventArgs e)
{
if (txt1.Text.Contains('*'))
{
curpos = txt1.SelectionStart;
isReplaced = true;
}
txt1.Text = txt1.Text.Replace("*", string.Empty);
if (isReplaced)
{
txt1.Select(curpos.Equals(0) ? 0 : curpos -1, 0);
isReplaced = false;
}
}
Final code and Tested :-
if (txt1.Text.Contains('*'))
{
foreach (char c in txt1.Text)
if (c.Equals('*'))
barredCharCount += 1;
curPosition = txt1.SelectionStart;
isTextReplaced = true;
}
txt1.Text = txt1.Text.Replace("*", string.Empty);
if (isTextReplaced)
{
txt1.Select(curPosition.Equals(0) ? 0 : curPosition - barredCharCount, 0);
isTextReplaced = false;
curPosition = barredCharCount = 0;
Console.Beep(); //does not work on 64 bit system
}
This piece of code is tested and working perfectly...

displaying line number in rich text box c#

I have a Multiline richtextbox control into which i want to integrate the feature of adding a line number. i have considered many approaches
Add a label and updating the line numbers as the line count changes
Add a picturebox along with to draw string on it.
Add another textbox along with and show line numbers on it
Add listbox along and display line numbers in it.
I got two doubts.
The richtextbox which i'm using is a custom made control and derieves from RichTextBox class. How can i add multiple controls to it.
What is the best approach to show line numbers for the multiline text in c#

My own example. All is fine, but wordwrap must be disabled :(
int maxLC = 1; //maxLineCount - should be public
private void rTB_KeyUp(object sender, KeyEventArgs e)
{
int linecount = rTB.GetLineFromCharIndex( rTB.TextLength ) + 1;
if (linecount != maxLC)
{
tB_line.Clear();
for (int i = 1; i < linecount+1; i++)
{
tB_line.AppendText(Convert.ToString(i) + "\n");
}
maxLC = linecount;
}
}
where rTB is my richtextbox and tB is textBox next to rTB
J.T. jr

this code helped me thank you, needed to convert visual basic but could:
Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp
Dim maxlc As Integer = 1
Dim linecount As Integer = TextBox1.GetLineFromCharIndex(TextBox1.Height) + 1
If linecount <> maxlc Then
TextBox2.Clear()
For i = 0 To linecount - 1 Step 1
TextBox2.AppendText(Convert.ToString(i) + vbNewLine)
Next i
maxlc = linecount
End If
End Sub

public int getWidth()
{
int w = 25;
// get total lines of richTextBox1
int line = richTextBox1.Lines.Length;
if (line <= 99)
{
w = 20 + (int)richTextBox1.Font.Size;
}
else if (line <= 999)
{
w = 30 + (int)richTextBox1.Font.Size;
}
else
{
w = 50 + (int)richTextBox1.Font.Size;
}
return w;
}
public void AddLineNumbers()
{
// create & set Point pt to (0,0)
Point pt = new Point(0, 0);
// get First Index & First Line from richTextBox1
int First_Index = richTextBox1.GetCharIndexFromPosition(pt);
int First_Line = richTextBox1.GetLineFromCharIndex(First_Index);
// set X & Y coordinates of Point pt to ClientRectangle Width & Height respectively
pt.X = ClientRectangle.Width;
pt.Y = ClientRectangle.Height;
// get Last Index & Last Line from richTextBox1
int Last_Index = richTextBox1.GetCharIndexFromPosition(pt);
int Last_Line = richTextBox1.GetLineFromCharIndex(Last_Index);
// set Center alignment to LineNumberTextBox
LineNumberTextBox.SelectionAlignment = HorizontalAlignment.Center;
// set LineNumberTextBox text to null & width to getWidth() function value
LineNumberTextBox.Text = "";
LineNumberTextBox.Width = getWidth();
// now add each line number to LineNumberTextBox upto last line
for (int i = First_Line; i <= Last_Line + 2; i++)
{
LineNumberTextBox.Text += i + 1 + "\n";
}
}
private void Form1_Load(object sender, EventArgs e)
{
LineNumberTextBox.Font = richTextBox1.Font;
richTextBox1.Select();
AddLineNumbers();
}
private void richTextBox1_SelectionChanged(object sender, EventArgs e)
{
Point pt = richTextBox1.GetPositionFromCharIndex(richTextBox1.SelectionStart);
if (pt.X == 1)
{
AddLineNumbers();
}
}
private void richTextBox1_VScroll(object sender, EventArgs e)
{
LineNumberTextBox.Text = "";
AddLineNumbers();
LineNumberTextBox.Invalidate();
}
private void richTextBox1_TextChanged(object sender, EventArgs e)
{
if (richTextBox1.Text == "")
{
AddLineNumbers();
}
}
private void richTextBox1_FontChanged(object sender, EventArgs e)
{
LineNumberTextBox.Font = richTextBox1.Font;
richTextBox1.Select();
AddLineNumbers();
}
private void LineNumberTextBox_MouseDown(object sender, MouseEventArgs e)
{
richTextBox1.Select();
LineNumberTextBox.DeselectAll();
}
private void Form1_Resize(object sender, EventArgs e)
{
AddLineNumbers();
}

WORKS 100%!!! But you need to add richTextBox2 for line numbers, if you want change it to other
form like listbox, anyway it served me well.
private void richTextBox1_keyDown(object sender, KeyEventArgs e)
{
for (int i = 0; i <= richTextBox1.Lines.Count(); i++)
{
if (!(e.KeyCode == Keys.Back))
{
if (!richTextBox2.Text.Contains(i.ToString()))
{
richTextBox2.Text += i.ToString() + "\n";
}
}
else
{
richTextBox2.Clear();
}
}
}