We Keep Coding

Foreach stops finding dynamically created controls after some amount of time. Resizing window makes it work again. Why? How can I fix it?

I'm a fairly new c# programmer currently in class and I've been doing this side project that (kind of) accurately represents bouncing balls. I also want it to be able to handle balls that are created on mouse click. I've done all of this and it works, for a few seconds. The original ball always works and always bounces/rolls. Dynamically created balls that are created on mouse click will hop and roll for a little but then they all freeze(not all at the same time) as the foreach statement I use stops recognizing that they are there. Weirdly enough when the window is resized using the bottom they start to work again. Am I missing something or is this a bug I can't fix? Here's the form code and the designer code. If you need anything else let me know.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace testBouncingBallMulti
{
public partial class Form1 : Form
{
const int INITY = 0;
const int INITX = 3;
const int GRAVITY = 1;
public Form1()
{
InitializeComponent();
this.ball0.Tag = new Point(INITX, INITY);
}
byte counter = 1;
private void createBall(object sender, MouseEventArgs e)
{
Label l = new Label();
l.BackColor = System.Drawing.Color.Black;
l.Location = new Point(MousePosition.X - this.Left, MousePosition.Y - this.Top);
this.Controls.Add(l);
l.Size = new System.Drawing.Size(15, 15);
l.Tag = new Point(INITX, INITY);
l.Name = "ball" + Convert.ToString(counter);
counter++;
}
private void physicsLoop1(object sender, EventArgs e)
{
foreach (var ball in this.Controls.OfType<Label>())
{
moveBall(ball);
bounce(ball);
Point? init = ball.Tag as Point?;
Point velocities = init.GetValueOrDefault(new Point(0, 0));
if (velocities.Y == 0 && ball.Location.Y >= ClientSize.Height - 15)
{
return;
}
velocities.Y = velocities.Y + GRAVITY;
ball.Tag = new Point(velocities.X, velocities.Y);
}
}
private void moveBall(Control ball)
{
Point? init = ball.Tag as Point?;
Point velocities = init.GetValueOrDefault(new Point(0,0));
ball.Location = new Point(ball.Location.X + velocities.X, ball.Location.Y + velocities.Y);
}
private void bounce(Control ball)
{
Point? init = ball.Tag as Point?;
Point velocities = init.GetValueOrDefault(new Point(0,0));
if (ball.Location.Y >= ClientSize.Height - 15)
{
if (velocities.Y == 0 && ball.Location.Y >= ClientSize.Height - 15)
{
}
else if (ball.Location.Y > ClientSize.Height - 15)
{
ball.Location = new Point(ball.Location.X, ClientSize.Height - 15);
velocities.Y = -(velocities.Y - 2);
}
}
if (ball.Location.X >= ClientSize.Width - 15)
{
velocities.X = -(velocities.X);
}
if (ball.Location.X <= 0)
{
ball.Location = new Point(0, ball.Location.Y);
velocities.X = -(velocities.X);
}
ball.Tag = new Point(velocities.X, velocities.Y);
}
private void physicsLoop2(object sender, EventArgs e)
{
}
private void physicsLoop3(object sender, EventArgs e)
{
}
}
}
and the designer code:
namespace testBouncingBallMulti
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.components = new System.ComponentModel.Container();
this.timer1 = new System.Windows.Forms.Timer(this.components);
this.ball0 = new System.Windows.Forms.Label();
this.timer2 = new System.Windows.Forms.Timer(this.components);
this.timer3 = new System.Windows.Forms.Timer(this.components);
this.SuspendLayout();
//
// timer1
//
this.timer1.Enabled = true;
this.timer1.Interval = 20;
this.timer1.Tick += new System.EventHandler(this.physicsLoop1);
//
// ball0
//
this.ball0.BackColor = System.Drawing.Color.Black;
this.ball0.Location = new System.Drawing.Point(12, 24);
this.ball0.Name = "ball0";
this.ball0.Size = new System.Drawing.Size(15, 15);
this.ball0.TabIndex = 0;
//
// timer2
//
this.timer2.Tick += new System.EventHandler(this.physicsLoop2);
//
// timer3
//
this.timer3.Tick += new System.EventHandler(this.physicsLoop3);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(504, 396);
this.Controls.Add(this.ball0);
this.Name = "Form1";
this.Text = "Form1";
this.MouseClick += new System.Windows.Forms.MouseEventHandler(this.createBall);
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.Timer timer1;
private System.Windows.Forms.Label ball0;
private System.Windows.Forms.Timer timer2;
private System.Windows.Forms.Timer timer3;
}
}

Replace return with continue in
if (velocities.Y == 0 && ball.Location.Y >= ClientSize.Height - 15)
{
return;
}

You need to give some breathing room in your label move procedure to repaint the form. Either use best practice and place your painting into a thread or at least process a windows message or two in your timer loop.

How to draw a static length line at random y values

I'm trying to create a mini game where you must use a "turret" to shoot at a target. Currently I'm stuck on my target line. My aim is to get it to spawn at a set X value but for it to spawn at a random Y value everytime I press the redraw button. However I'm having trouble with my code. Instead of the line always being the same length and spawning at random Y values, it seems to be spawning at random lengths and at random Y values. If anyone could help me figure out where I have gone wrong that would be perfect.
The relevant variables are xTarget, yTarget (the first y value of the line) yTargetEnd (the second y value of the line) targetLine (the static length of the line) and the DrawLine() method call for targetLine.
In my head the way I have it set up makes sense but it doesn't seem to be doing what I expect. I try to set yTarget to a random number and then set yTargetEnd to yTarget + targetLine, so it should always be 50 in length, but that doesn't seem to work at all?
public partial class Form1 : Form
{
Random rnd = new Random { };
double xEnd = 0;
double yEnd = 0;
double xOrigin = 30;
double yOrigin = 450;
double xFire;
double yFire;
double xTarget = 500;
double yTarget;
double yTargetEnd;
double xHor = 30;
double yHor = 350;
double xVert = 130;
double yVert = 450;
double fireLine = 750;
double lineLength = 50;
double targetLine = 50;
public Form1()
{
xEnd = xOrigin + lineLength;
yEnd = yOrigin;
xFire = xOrigin + fireLine;
yFire = yOrigin;
InitializeComponent();
}
private void LineDrawEvent(object sender, PaintEventArgs paint)
{
Graphics drawSurface = paint.Graphics;
Pen turretLine = new Pen(Color.Blue);
Pen graphHorizontal = new Pen(Color.Red);
Pen graphVertical = new Pen(Color.Red);
Pen firedLine = new Pen(Color.Blue);
Pen targetLine = new Pen(Color.Black);
float[] dashValues = { 5, 2 };
firedLine.DashPattern = dashValues;
drawSurface.DrawLine(graphVertical, (int)xOrigin, (int)yOrigin, (int)xHor, (int)yHor);
drawSurface.DrawLine(graphHorizontal, (int)xOrigin, (int)yOrigin, (int)xVert, (int)yVert);
drawSurface.DrawLine(firedLine, (int)xOrigin, (int)yOrigin, (int)xFire, (int)yFire);
drawSurface.DrawLine(targetLine, (int)xTarget, (int)yTarget, (int)xTarget, (int)yTargetEnd);
double angleInRadians = ConvertDegsToRads((double)trckBarAngle.Value);
xEnd = xOrigin + lineLength * Math.Cos(angleInRadians / 2.0);
yEnd = yOrigin - lineLength * Math.Sin(angleInRadians / 2.0);
drawSurface.DrawLine(turretLine, (int)xOrigin, (int)yOrigin, (int)xEnd, (int)yEnd);
this.Refresh();
}
private void trckBarAngle_Scroll(object sender, EventArgs e)
{
lblAngle.Text = "Angle is:" + Convert.ToString((double)trckBarAngle.Value / 2.0);
}
private double ConvertDegsToRads(double degrees)
{
return degrees * (Math.PI / 180.0);
}
private void btnFire_Click(object sender, EventArgs e)
{
double angleInDegrees = trckBarAngle.Value;
double angleInRadians = ConvertDegsToRads(angleInDegrees);
xFire = xOrigin + fireLine * Math.Cos(angleInRadians / 2.0);
yFire = yOrigin - fireLine * Math.Sin(angleInRadians / 2.0);
this.Refresh();
}
private void btnRedraw_Click(object sender, EventArgs e)
{
yTargetEnd = yTarget - targetLine;
yTarget = rnd.Next(100, 500);
}
}
Designer-generated code:
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.lblAngle = new System.Windows.Forms.Label();
this.trckBarAngle = new System.Windows.Forms.TrackBar();
this.btnFire = new System.Windows.Forms.Button();
this.btnRedraw = new System.Windows.Forms.Button();
((System.ComponentModel.ISupportInitialize)(this.trckBarAngle)).BeginInit();
this.SuspendLayout();
//
// lblAngle
//
this.lblAngle.AutoSize = true;
this.lblAngle.Location = new System.Drawing.Point(13, 13);
this.lblAngle.Name = "lblAngle";
this.lblAngle.Size = new System.Drawing.Size(46, 17);
this.lblAngle.TabIndex = 0;
this.lblAngle.Text = "label1";
//
// trckBarAngle
//
this.trckBarAngle.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Right)));
this.trckBarAngle.LargeChange = 10;
this.trckBarAngle.Location = new System.Drawing.Point(732, 42);
this.trckBarAngle.Maximum = 360;
this.trckBarAngle.Minimum = -360;
this.trckBarAngle.Name = "trckBarAngle";
this.trckBarAngle.Orientation = System.Windows.Forms.Orientation.Vertical;
this.trckBarAngle.Size = new System.Drawing.Size(56, 495);
this.trckBarAngle.TabIndex = 1;
this.trckBarAngle.Scroll += new System.EventHandler(this.trckBarAngle_Scroll);
//
// btnFire
//
this.btnFire.Location = new System.Drawing.Point(632, 13);
this.btnFire.Name = "btnFire";
this.btnFire.Size = new System.Drawing.Size(75, 23);
this.btnFire.TabIndex = 2;
this.btnFire.Text = "Fire";
this.btnFire.UseVisualStyleBackColor = true;
this.btnFire.Click += new System.EventHandler(this.btnFire_Click);
//
// btnRedraw
//
this.btnRedraw.Location = new System.Drawing.Point(713, 13);
this.btnRedraw.Name = "btnRedraw";
this.btnRedraw.Size = new System.Drawing.Size(75, 23);
this.btnRedraw.TabIndex = 2;
this.btnRedraw.Text = "Redraw";
this.btnRedraw.UseVisualStyleBackColor = true;
this.btnRedraw.Click += new System.EventHandler(this.btnRedraw_Click);
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(800, 549);
this.Controls.Add(this.btnRedraw);
this.Controls.Add(this.btnFire);
this.Controls.Add(this.trckBarAngle);
this.Controls.Add(this.lblAngle);
this.Name = "Form1";
this.Text = "Form1";
this.Paint += new System.Windows.Forms.PaintEventHandler(this.LineDrawEvent);
((System.ComponentModel.ISupportInitialize)(this.trckBarAngle)).EndInit();
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private System.Windows.Forms.Label lblAngle;
private System.Windows.Forms.TrackBar trckBarAngle;
private System.Windows.Forms.Button btnFire;
private System.Windows.Forms.Button btnRedraw;
}

The basic issue comes down to the code simply not matching what you intended. You wrote:
I try to set yTarget to a random number and then set yTargetEnd to yTarget + targetLine
But that's not actually what the code does. Your code does those two things in the opposite order. So the yTargetEnd value is always based on the previous target location, not the newly selected one.
Your code should look like this instead:
private void btnRedraw_Click(object sender, EventArgs e)
{
yTarget = rnd.Next(100, 500);
yTargetEnd = yTarget - targetLine;
}
I.e. write the code so that it matches your specification. :)
Having answered that, there are some other important issues to address in your code:
First and foremost, you are updating the screen in completely the wrong way. You should not call Refresh(), Update(), or Invalidate() from a Paint event handler. Instead, you should have separate logic somewhere, e.g. based on a timer, background thread, etc. that handles control of the state of the data (i.e. your game world), and which invalidates the relevant window or control(s) if and when the data changes in a way that would require them to be redrawn.
Also, you should use the stock Pen objects when possible, and when not possible, either dispose of your custom Pen object or store it somewhere for reuse.
For example:
private static readonly Pen _firedLine =
new Pen(Color.Blue) { DashPattern = new [] { 5f, 2f } };
private void LineDrawEvent(object sender, PaintEventArgs paint)
{
Graphics drawSurface = paint.Graphics;
Pen turretLine = Pens.Blue;
Pen graphHorizontal = Pens.Red;
Pen graphVertical = Pens.Red;
Pen targetLine = Pens.Black;
drawSurface.DrawLine(graphVertical, (int)xOrigin, (int)yOrigin, (int)xHor, (int)yHor);
drawSurface.DrawLine(graphHorizontal, (int)xOrigin, (int)yOrigin, (int)xVert, (int)yVert);
drawSurface.DrawLine(_firedLine, (int)xOrigin, (int)yOrigin, (int)xFire, (int)yFire);
drawSurface.DrawLine(targetLine, (int)xTarget, (int)yTarget, (int)xTarget, (int)yTargetEnd);
double angleInRadians = ConvertDegsToRads((double)trckBarAngle.Value);
xEnd = xOrigin + lineLength * Math.Cos(angleInRadians / 2.0);
yEnd = yOrigin - lineLength * Math.Sin(angleInRadians / 2.0);
drawSurface.DrawLine(turretLine, (int)xOrigin, (int)yOrigin, (int)xEnd, (int)yEnd);
}

How to prevent tearing when scrolling TableLayoutPanel?

I think vertical tearing is the proper term to describe what I'm seeing but here is an screenshot that shows the issue:
I thought the DoubleBuffered property could help with this but it neither setting it on my Form or inheriting TableLayoutPanel and setting it in the constructor seem to have any effect.
I apologize for the following long block of code, but I felt I should include a complete example that demonstrates the issue. You should just be able to copy it and run it to replicate my issue:
public class ScrollTearingDemo : Form
{
private const int ROW_COUNT = 20;
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new ScrollTearingDemo());
}
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
private System.Windows.Forms.TableLayoutPanel tableLayoutPanel1;
public ScrollTearingDemo()
{
InitializeComponent();
this.initializeTable();
}
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
// Moved this here to encapsulate demo in single source file
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.tableLayoutPanel1 = new System.Windows.Forms.TableLayoutPanel();
//this.tableLayoutPanel1 = new BufferedTableLayoutPanel();
this.SuspendLayout();
//
// tableLayoutPanel1
//
this.tableLayoutPanel1 = new System.Windows.Forms.TableLayoutPanel();
this.tableLayoutPanel1.AutoScroll = true;
this.tableLayoutPanel1.CellBorderStyle = System.Windows.Forms.TableLayoutPanelCellBorderStyle.Single;
this.tableLayoutPanel1.ColumnCount = 2;
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle());
this.tableLayoutPanel1.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle());
this.tableLayoutPanel1.Dock = DockStyle.Fill;
this.tableLayoutPanel1.Location = new System.Drawing.Point(0, 0);
this.tableLayoutPanel1.Name = "tableLayoutPanel1";
this.tableLayoutPanel1.TabIndex = 0;
//
// ScrollTearingDemo
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(284, 262);
this.Controls.Add(this.tableLayoutPanel1);
this.DoubleBuffered = true;
this.Name = "ScrollTearingDemo";
this.Text = "ScrollTearingDemo";
this.ResumeLayout(false);
}
private void initializeTable()
{
// There is one more empty row to take up any extra space
// in the event the number of rows does not fill the table.
this.tableLayoutPanel1.RowCount = ROW_COUNT + 1;
for(int j = 0; j < ROW_COUNT;j++)
{
Label markerLabel = new Label();
markerLabel.Dock = System.Windows.Forms.DockStyle.Fill;
markerLabel.TextAlign = ContentAlignment.MiddleRight;
markerLabel.Name = "Label " + j;
markerLabel.Text = markerLabel.Name;
TextBox inputItem = new TextBox();
inputItem.Dock = DockStyle.Fill;
inputItem.Name = "Input " + j;
inputItem.Text = inputItem.Name;
inputItem.TextAlign = HorizontalAlignment.Right;
inputItem.CausesValidation = true;
this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.AutoSize, 25F));
this.tableLayoutPanel1.Controls.Add(markerLabel, 0, j);
this.tableLayoutPanel1.Controls.Add(inputItem, 1, j);
}
// Row style for the empty filler row.
this.tableLayoutPanel1.RowStyles.Add(new System.Windows.Forms.RowStyle(System.Windows.Forms.SizeType.Percent, 0F));
this.ResumeLayout();
}
}
The project this is for is limited to C# 2.0.

I have some error in C# Drawing Application?

i am using visual studio 2010 for making a Drawing Application but the problem is when i try to compile the program it says
1)The type name 'DrawingBoard' does not exist in the type 'DrawingBoard.DrawingBoard' line 33
2)The type name 'Toolbox' does not exist in the type 'DrawingBoard.DrawingBoard' line 34
3)An object reference is required for the non-static field, method, or property 'DrawingBoard.DrawingBoard.EditOption.get' line 74
the code of this program is below i have pointed the errors with the word problem. i would be very Thankful if you help me.
using System.Drawing;
namespace DrawingBoard
{
partial class WinForm
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.splitContainerMain = new System.Windows.Forms.SplitContainer();
this.drawingBoard = new DrawingBoard.DrawingBoard();//problem
this.toolBox = new DrawingBoard.Toolbox.ToolBox();//problem
this.splitContainerMain.Panel1.SuspendLayout();
this.splitContainerMain.Panel2.SuspendLayout();
this.splitContainerMain.SuspendLayout();
this.SuspendLayout();
//
// splitContainerMain
//
this.splitContainerMain.Dock = System.Windows.Forms.DockStyle.Fill;
this.splitContainerMain.Location = new System.Drawing.Point(0, 0);
this.splitContainerMain.Margin = new System.Windows.Forms.Padding(2);
this.splitContainerMain.Name = "splitContainerMain";
//
// splitContainerMain.Panel1
//
this.splitContainerMain.Panel1.Controls.Add(this.drawingBoard);
//
// splitContainerMain.Panel2
//
this.splitContainerMain.Panel2.Controls.Add(this.toolBox);
this.splitContainerMain.Size = new System.Drawing.Size(853, 553);
this.splitContainerMain.SplitterDistance = 532;
this.splitContainerMain.SplitterWidth = 3;
this.splitContainerMain.TabIndex = 37;
//
// drawingBoard
//
this.drawingBoard.AllowDrop = true;
this.drawingBoard.AutoScroll = true;
this.drawingBoard.BackColor = System.Drawing.Color.White;
this.drawingBoard.BackgroundImageAlpha = ((byte)(255));
this.drawingBoard.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Stretch;
this.drawingBoard.BackgroundImageX = 0;
this.drawingBoard.BackgroundImageY = 0;
this.drawingBoard.BoundedCanvasHeight = 1140;
this.drawingBoard.BoundedCanvasWidth = 810;
this.drawingBoard.CanvasOriginX = 0;
this.drawingBoard.CanvasOriginY = 0;
this.drawingBoard.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.Default;
this.drawingBoard.Dock = System.Windows.Forms.DockStyle.Fill;
this.drawingBoard.EditOption = DrawingBoard.EditOption.Select; //problem
this.drawingBoard.GridColor = System.Drawing.Color.Gainsboro;
this.drawingBoard.GridSize = 0;
this.drawingBoard.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Default;
this.drawingBoard.IsBoundedCanvas = true;
this.drawingBoard.Location = new System.Drawing.Point(0, 0);
this.drawingBoard.Name = "drawingBoard";
this.drawingBoard.PaperOutsideColor = System.Drawing.Color.FromArgb(((int)(((byte)(230)))), ((int)(((byte)(230)))), ((int)(((byte)(255)))));
this.drawingBoard.ShowPaperOutside = true;
this.drawingBoard.Size = new System.Drawing.Size(532, 553);
this.drawingBoard.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
this.drawingBoard.StickyEditOption = true;
this.drawingBoard.TabIndex = 3;
this.drawingBoard.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAlias;
this.drawingBoard.Zoom = 1F;
//
// toolBox
//
this.toolBox.AutoSize = true;
this.toolBox.Dock = System.Windows.Forms.DockStyle.Fill;
this.toolBox.Drawingboard = null;
this.toolBox.Location = new System.Drawing.Point(0, 0);
this.toolBox.Margin = new System.Windows.Forms.Padding(4);
this.toolBox.Name = "toolBox";
this.toolBox.Size = new System.Drawing.Size(318, 553);
this.toolBox.TabIndex = 1;
//
// WinForm
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(192)))), ((int)(((byte)(255)))), ((int)(((byte)(192)))));
this.ClientSize = new System.Drawing.Size(853, 553);
this.Controls.Add(this.splitContainerMain);
this.Name = "WinForm";
this.Text = "DrawingBoard";
this.splitContainerMain.Panel1.ResumeLayout(false);
this.splitContainerMain.Panel2.ResumeLayout(false);
this.splitContainerMain.Panel2.PerformLayout();
this.splitContainerMain.ResumeLayout(false);
this.ResumeLayout(false);
}
#endregion
private System.Windows.Forms.SplitContainer splitContainerMain;
private DrawingBoard drawingBoard;
private global::DrawingBoard.Toolbox.ToolBox toolBox;
}
}

It sounds like you have a namespace issue and it looks like DrawingBoard.DrawingBoard is probably going to cause confusion. Try to rename your namespace to omit duplicate names. Use a format such as Solution.Project.Module. In your case it could be MySolution.DrawingBoard.

Windows Forms C# "Input string was not in a correct format"

I have a simple Windows Forms application which is used to calculate the solutions to a quadratic equation. Since it requires some values to be inputted into three different textboxes and then upon clicking a "Calculate" button, makes some calculations with the inputted values. Upon testing the application, and clicking the "Calculate" button prior to inputting any values, I get a Input string was not in a correct format This is due to trying to parse a non-existent value. Is there any way to avoid this? I tried to construct a conditional based on if the button was clicked and there was no values in the textboxes, to not do anything, but that didn't quite work. Here is my designer code:
namespace QuadraticSolver
{
partial class QuadraticSolver
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.lblPrompt = new System.Windows.Forms.Label();
this.lblA = new System.Windows.Forms.Label();
this.lblB = new System.Windows.Forms.Label();
this.lblC = new System.Windows.Forms.Label();
this.txtA = new System.Windows.Forms.TextBox();
this.txtB = new System.Windows.Forms.TextBox();
this.txtC = new System.Windows.Forms.TextBox();
this.btnCalculate = new System.Windows.Forms.Button();
this.lblSolutions = new System.Windows.Forms.Label();
this.txtSolution1 = new System.Windows.Forms.TextBox();
this.txtSolution2 = new System.Windows.Forms.TextBox();
this.chkImaginary = new System.Windows.Forms.CheckBox();
this.SuspendLayout();
//
// lblPrompt
//
this.lblPrompt.AutoSize = true;
this.lblPrompt.Location = new System.Drawing.Point(12, 9);
this.lblPrompt.Name = "lblPrompt";
this.lblPrompt.Size = new System.Drawing.Size(92, 13);
this.lblPrompt.TabIndex = 0;
this.lblPrompt.Text = "Enter Your Values";
//
// lblA
//
this.lblA.AutoSize = true;
this.lblA.Location = new System.Drawing.Point(12, 49);
this.lblA.Name = "lblA";
this.lblA.Size = new System.Drawing.Size(16, 13);
this.lblA.TabIndex = 1;
this.lblA.Text = "a:";
//
// lblB
//
this.lblB.AutoSize = true;
this.lblB.Location = new System.Drawing.Point(12, 85);
this.lblB.Name = "lblB";
this.lblB.Size = new System.Drawing.Size(16, 13);
this.lblB.TabIndex = 2;
this.lblB.Text = "b:";
//
// lblC
//
this.lblC.AutoSize = true;
this.lblC.Location = new System.Drawing.Point(12, 122);
this.lblC.Name = "lblC";
this.lblC.Size = new System.Drawing.Size(16, 13);
this.lblC.TabIndex = 3;
this.lblC.Text = "c:";
//
// txtA
//
this.txtA.Location = new System.Drawing.Point(34, 46);
this.txtA.Name = "txtA";
this.txtA.Size = new System.Drawing.Size(360, 20);
this.txtA.TabIndex = 4;
//
// txtB
//
this.txtB.Location = new System.Drawing.Point(34, 82);
this.txtB.Name = "txtB";
this.txtB.Size = new System.Drawing.Size(360, 20);
this.txtB.TabIndex = 5;
//
// txtC
//
this.txtC.Location = new System.Drawing.Point(34, 122);
this.txtC.Name = "txtC";
this.txtC.Size = new System.Drawing.Size(360, 20);
this.txtC.TabIndex = 6;
//
// btnCalculate
//
this.btnCalculate.Location = new System.Drawing.Point(175, 154);
this.btnCalculate.Name = "btnCalculate";
this.btnCalculate.Size = new System.Drawing.Size(75, 23);
this.btnCalculate.TabIndex = 7;
this.btnCalculate.Text = "Calculate!";
this.btnCalculate.UseVisualStyleBackColor = true;
this.btnCalculate.Click += new System.EventHandler(this.btnCalculate_Click);
//
// lblSolutions
//
this.lblSolutions.AutoSize = true;
this.lblSolutions.Location = new System.Drawing.Point(31, 226);
this.lblSolutions.Name = "lblSolutions";
this.lblSolutions.Size = new System.Drawing.Size(53, 13);
this.lblSolutions.TabIndex = 8;
this.lblSolutions.Text = "Solutions:";
//
// txtSolution1
//
this.txtSolution1.Location = new System.Drawing.Point(34, 242);
this.txtSolution1.Name = "txtSolution1";
this.txtSolution1.ReadOnly = true;
this.txtSolution1.Size = new System.Drawing.Size(165, 20);
this.txtSolution1.TabIndex = 9;
//
// txtSolution2
//
this.txtSolution2.Location = new System.Drawing.Point(222, 242);
this.txtSolution2.Name = "txtSolution2";
this.txtSolution2.ReadOnly = true;
this.txtSolution2.Size = new System.Drawing.Size(172, 20);
this.txtSolution2.TabIndex = 10;
//
// chkImaginary
//
this.chkImaginary.AutoSize = true;
this.chkImaginary.Location = new System.Drawing.Point(33, 189);
this.chkImaginary.Name = "chkImaginary";
this.chkImaginary.Size = new System.Drawing.Size(71, 17);
this.chkImaginary.TabIndex = 11;
this.chkImaginary.Text = "Imaginary";
this.chkImaginary.UseVisualStyleBackColor = true;
//
// QuadraticSolver
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(406, 285);
this.Controls.Add(this.chkImaginary);
this.Controls.Add(this.txtSolution2);
this.Controls.Add(this.txtSolution1);
this.Controls.Add(this.lblSolutions);
this.Controls.Add(this.btnCalculate);
this.Controls.Add(this.txtC);
this.Controls.Add(this.txtB);
this.Controls.Add(this.txtA);
this.Controls.Add(this.lblC);
this.Controls.Add(this.lblB);
this.Controls.Add(this.lblA);
this.Controls.Add(this.lblPrompt);
this.Name = "QuadraticSolver";
this.Text = "Quadratic Solver";
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private System.Windows.Forms.Label lblPrompt;
private System.Windows.Forms.Label lblA;
private System.Windows.Forms.Label lblB;
private System.Windows.Forms.Label lblC;
private System.Windows.Forms.TextBox txtA;
private System.Windows.Forms.TextBox txtB;
private System.Windows.Forms.TextBox txtC;
private System.Windows.Forms.Button btnCalculate;
private System.Windows.Forms.Label lblSolutions;
private System.Windows.Forms.TextBox txtSolution1;
private System.Windows.Forms.TextBox txtSolution2;
private System.Windows.Forms.CheckBox chkImaginary;
}
}
Here is my program's code which does the actual data manipulation:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace QuadraticSolver
{
public partial class QuadraticSolver : Form
{
public QuadraticSolver()
{
InitializeComponent();
}
private void btnCalculate_Click(object sender, EventArgs e)
{
if (txtA.Text == "" || txtB.Text == "" || txtC.Text == "")
{
string stringSol = "Please enter some values!";
txtSolution1.Text = stringSol;
txtSolution2.Text = stringSol;
}
double aValue = double.Parse(txtA.Text);
double bValue = double.Parse(txtB.Text);
double cValue = double.Parse(txtC.Text);
double solution1Double, solution2Double;
//Quadratic Formula: x = (-b +- sqrt(b^2 - 4ac)) / 2a
//Calculate discriminant
double insideSquareRoot = (bValue * bValue) - 4 * aValue * cValue;
if (insideSquareRoot < 0)
{
//No real solution
solution1Double = Double.NaN;
solution2Double = Double.NaN;
txtSolution1.Text = solution1Double.ToString();
txtSolution2.Text = solution2Double.ToString();
}
else if (insideSquareRoot == 0)
{
//One real solution
double sqrtOneSolution = Math.Sqrt(insideSquareRoot);
solution1Double = (-bValue + sqrtOneSolution) / (2 * aValue);
solution2Double = double.NaN;
txtSolution1.Text = solution1Double.ToString();
txtSolution2.Text = solution2Double.ToString();
}
else if (insideSquareRoot > 0)
{
//Two real solutions
double sqrtTwoSolutions = Math.Sqrt(insideSquareRoot);
solution1Double = (-bValue + sqrtTwoSolutions) / (2 * aValue);
solution2Double = (-bValue - sqrtTwoSolutions) / (2 * aValue);
txtSolution1.Text = solution1Double.ToString();
txtSolution2.Text = solution2Double.ToString();
}
}
}
}

You can use the double.TryParse method.
This is better than checking for == "" since it will tell you that you can not parse "Hello" as a double too.
You also need to return from the event handler if one of the TryParse returns false.

You may consider using a NumericUpDown control instead. You are guaranteed the input from this control will be numeric. All the code that is required is then:
double userNumber = myNumUpDown.Value;
You can even restrict the number input to ensure it falls within your defined range
myNumUpDown.Minimum = 300;
myNumUpDown.Maximum = 500;
Along with many other things. Finally, it even comes with up/down GUI controls so your users can be super lazy and enter the number with their mouse!

You can try this format,
replace the textbox1 with your textbox name.
int a = textbox1.Text != "" ? Convert.ToInt32(textbox1.Text) : 0;
int b = textbox2.Text != "" ? Convert.ToInt32(textbox2.Text) : 0;
int total = a + b;
you can reassign the result this way:
textbox3 = total.toString();

if (txtA.Text == "" || txtB.Text == "" || txtC.Text == "")
{
string stringSol = "Please enter some values!";
txtSolution1.Text = stringSol;
txtSolution2.Text = stringSol;
return;
}