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MouseEventArgs pass different values for mouse position to different click actions?

I'm working on a connect 4 game and I've got the following part done:
I've made the board which is able to display tiles of the board in 3 colors (white, red and yellow). I've also written some code to display a box around the column on which the user is hovering such that he can see where he is placing a dish.
I've also created the code which allows a dish to be added to the board. Both of these processes use the following code:
//Calculate the size of a single cell
int cellX = this.Size.Width / this.Columns;
//calculate the cell which was clicked
int nColumn = (int)Math.Floor((Double)x / cellX);
x is the value of MouseEventArgs.X of the pannel on which this is called. For drawing a boundry box this code works perfectly but for dropping a dish it doesn't. sometimes it drops 1 left of where I want it sometimes one right.
Here is the code for both events:
//draws the bounding box around the column for a given x value.
public void drawBoundingBox(int x)
{
//Calculate the size of a single cell
int cellX = this.Size.Width / this.Columns;
//calculate the cell which was clicked
int nColumn = (int)Math.Floor((Double)x / cellX);
if (nColumn != this.lastColumn)
{
this.Refresh();
Graphics g = CreateGraphics();
Pen pRed = new Pen(Color.Red, 3);
if (nColumn < this.Columns)
{
Rectangle rect = new Rectangle(new Point(nColumn * cellX, 0),
new Size(cellX, this.Size.Height));
g.DrawRectangle(pRed, rect);
}
}
this.lastColumn = nColumn;
}
public Boolean move(int mousePosition) {
int cellX = this.Size.Width / this.Columns;
int nColumn = (int)Math.Floor((Double)mousePosition / cellX);
return board.Move(nColumn);
}
Here is the code for board.move():
public bool Move(int x)
{
bool found = false;
for (int i = Rows - 1; i >= 0 && !found; i--)
{
Console.WriteLine("X equals: " + x + " i equals: " + i);
if (States[i,x] == 0) {
found = true;
States[i, x] = (byte)(((moves++) % 2) + 1);
}
}
return found;
}
Here is a gif showing what I mean:
To me it seams like a rounding error but it's wierd to me that the bounding box works well with the mouse but the clicking action doesn't...

Using Matrix.Rotate more than once C# Winforms

I've been trying to solve a problem I'm having with rotating an oval. The code that I'm posting works, but it's mimicking the kind of code I have to work with for real. Meaning, I can't use the OnPaint override and I'm limited to what I can do in the main code. I'm adding an oval to a graphic layer, and I need to be able to rotate, move and resize the oval. Move and resizing work flawlessly, but rotating doesn't work as I need it to.
If you click in the small box at the 9 oclock position,
the oval will rotate as expected:
The required behavior is to be able to click in the small box at the 12 oclock position, and have the oval rotate again. This does not occur. In order to get the oval to rotate again you need to click in the original 9 oclock position. What I'm really, really trying to find out is how to get the coordinates of the box at the 12 oclock position (or what ever position or location that box ends up after rotating) so that I can rotate it again. Thus far, I have been unable to figure it out. Please try and understand, I'm working with old code that was poorly written and I'm not allowed to change very much of it. What I write must integrate with what's already there. Below is the code snippet that demonstrates what I'm doing. I know I'm missing something obvious, just don't know what. Thanks.
public partial class Form1 : Form
{
int theAngle = 0;
Pen pen2 = new Pen(Color.FromArgb(255, 68, 125, 255), 4);
Pen pen3 = new Pen(Color.Green, 4);
Pen smallPen = new Pen(Color.Black, 1);
PointF center = new PointF(0, 0);
Rectangle rectangle = new Rectangle(20, 20, 100, 30);
Rectangle myRect2 = new Rectangle();
bool mouseBtnDown = false;
Graphics gw;
public Form1()
{
InitializeComponent();
this.MouseDown += mouseDown;
gw = this.CreateGraphics();
}
private void mouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (myRect2.Contains(e.Location))
theAngle+=90;
rotate();
}
if (e.Button == MouseButtons.Right)
{
//oval = false;
//mouseBtnDown = false;
theAngle = 0;
rectangle.X = e.X - 50;
rectangle.Y = e.Y - 15;
rectangle.Width = 100;
rectangle.Height = 30;
center.X = rectangle.Left + (0.5f * rectangle.Width);
center.Y = rectangle.Top + (0.5f * rectangle.Height);
myRect2.Size = new Size(15, 15);
myRect2.Location = new Point(rectangle.Left - 15, (rectangle.Top - (rectangle.Height / 2)) + 15);
drawstuff();
// Invalidate();
}
}
public void rotate()
{
var matrix = new Matrix();
matrix.RotateAt(theAngle, center);
gw.Transform = matrix;
drawstuff();
}
public void drawstuff()
{
gw.SmoothingMode = SmoothingMode.AntiAlias; // Creates smooth lines.
gw.DrawEllipse(pen2, rectangle);
gw.DrawRectangle(smallPen, myRect2);
}
}

You can use the Transform matrix to rotate points. So what I've done is get the 4 corner points of myRect2, rotate them using the same Transform matrix, then assign these to a rectangle. You can then use this new rectangle to check the location. I also changed the call to drawstuff() at the end of the right button click to call rotate(), this way the rotated rectangle can get updated when the ellipse is first placed, and the graphics transform angle gets updated to 0.
public partial class Form1 : Form
{
int theAngle = 0;
Pen pen2 = new Pen(Color.FromArgb(255, 68, 125, 255), 4);
Pen pen3 = new Pen(Color.Green, 4);
Pen smallPen = new Pen(Color.Black, 1);
PointF center = new PointF(0, 0);
Rectangle rectangle = new Rectangle(20, 20, 100, 30);
Rectangle myRect2 = new Rectangle();
Rectangle rotatedRect2 = new Rectangle();
bool mouseBtnDown = false;
Graphics gw;
public Form1()
{
InitializeComponent();
this.MouseDown += mouseDown;
gw = this.CreateGraphics();
}
private void mouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (rotatedRect2.Contains(e.Location))
theAngle += 90;
rotate();
}
if (e.Button == MouseButtons.Right)
{
//oval = false;
//mouseBtnDown = false;
theAngle = 0;
rectangle.X = e.X - 50;
rectangle.Y = e.Y - 15;
rectangle.Width = 100;
rectangle.Height = 30;
center.X = rectangle.Left + (0.5f * rectangle.Width);
center.Y = rectangle.Top + (0.5f * rectangle.Height);
myRect2.Size = new Size(15, 15);
myRect2.Location = new Point(rectangle.Left - 15, (rectangle.Top - (rectangle.Height / 2)) + 15);
rotate();
//drawstuff();
// Invalidate();
}
}
public void rotate()
{
var matrix = new Matrix();
matrix.RotateAt(theAngle, center);
gw.Transform = matrix;
// Get the 4 corner points of myRect2.
Point p1 = new Point(myRect2.X, myRect2.Y),
p2 = new Point(myRect2.X + myRect2.Width, myRect2.Y),
p3 = new Point(myRect2.X, myRect2.Y + myRect2.Height),
p4 = new Point(myRect2.X + myRect2.Width, myRect2.Y + myRect2.Height);
Point[] pts = new Point[] { p1, p2, p3, p4 };
// Rotate the 4 points.
gw.Transform.TransformPoints(pts);
// Update rotatedRect2 with those rotated points.
rotatedRect2.X = pts.Min(pt => pt.X);
rotatedRect2.Y = pts.Min(pt => pt.Y);
rotatedRect2.Width = pts.Max(pt => pt.X) - pts.Min(pt => pt.X);
rotatedRect2.Height = pts.Max(pt => pt.Y) - pts.Min(pt => pt.Y);
drawstuff();
}
public void drawstuff()
{
gw.SmoothingMode = SmoothingMode.AntiAlias; // Creates smooth lines.
gw.DrawEllipse(pen2, rectangle);
gw.DrawRectangle(smallPen, myRect2);
}
}
Something to note. Drawing to the screen like this (using the form's created graphics and drawing using your own draw function) means the ellipses/rectangles are only drawn once. i.e. if you draw a few then minimize your form, when you bring it back up the ellipses will be gone. Not sure if this is what you're after or not. One way to fix this would be to draw the ellipses to a Bitmap and then in the form's Paint event this bitmap is draw to the form.

Getting exception every time I delete an item from rectangle array

I am getting
System.InvalidOperationException: 'Collection was modified; enumeration operation may not execute.
every time I want to remove an item from the array, so I could draw (fill) another rectangle at that place.
Everything is happening on MouseDown event on right click black rectangle should be drawn (filled) and on left white one.
I made 2 lists of rectangles, one for white ones, and one for black ones.
I am getting exception thrown when I try to draw (fill) rectangle of opposite color of the one that is.
Everything is written into a bitmap and later bitmap is draw as an image in Paint event.
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
using (Graphics rectGraphics = Graphics.FromImage(rectBitmap))
{
rBlack = new Rectangle((e.X / 20) * 20, (e.Y / 20) * 20, 20, 20);
rectGraphics.SmoothingMode = SmoothingMode.HighSpeed;
foreach (Rectangle r in whiteRectangles) // place where exception is thrown if I want to fill black rectangle on the place where white is
{
if (r.X - 1 == rBlack.X && r.Y - 1 == rBlack.Y)
{
int index = whiteRectangles.IndexOf(r);
whiteRectangles.RemoveAt(index);
}
rectGraphics.FillRectangle(brushWhite, r);
}
blackRectangles.Add(rBlack);
foreach (Rectangle r in blackRectangles)
{
rectGraphics.FillRectangle(brushBlack, r);
}
}
}
if (e.Button == MouseButtons.Left)
{
using (Graphics rectGraphics = Graphics.FromImage(rectBitmap))
{
rWhite = new Rectangle((e.X / 20) * 20 +1, (e.Y / 20) * 20 +1, 19, 19);
rectGraphics.SmoothingMode = SmoothingMode.HighSpeed;
foreach (Rectangle r in blackRectangles) // place where exception is thrown if I try to fill white rectangle on the place where black is
{
if (r.X + 1 == rWhite.X && r.Y + 1 == rWhite.Y)
{
int index = blackRectangles.IndexOf(r);
blackRectangles.RemoveAt(index);
}
rectGraphics.FillRectangle(brushBlack, r);
}
whiteRectangles.Add(rWhite);
foreach (Rectangle r in whiteRectangles)
{
rectGraphics.FillRectangle(brushWhite, r);
}
}
}
this.Refresh();
}

You probably need to use a for loop instead of a foreach. Set your upper limit using the Count of the list, then delete by index.
for (int i = 0; i < list.Count; i++)
{
//Delete list[i] here
}
Or, in reverse
for (int i = list.Count - 1; i >= 0; i--)
{
//Delete list[i] here
}

Get coordinates points between x and y

I have a jpeg image in a picturebox, on page load i am drawing the rectangle based on the x(150) and y(440) coordinates. now when i mousemove on the picturebox i need to identify the rectangle by their coordinates and highlight the image. for example see the below image ..
lets take the first rectangle, on mouse move any points inside the rectangle i need to perform some actions.. how to find the coordinates between these x and y for the rectangle?..

A rectangle has 4 Points (edges):
Left
Top
Right
Bottom
If your mouse coordinates (MouseEventArgs properties) are between them, the mouse pointer is in the rectangle.
Are the mouse coordinates greater than right or bottom or lower than left / top, your mouse is outside the rectangle.
Taking #samgak`s Comment:
if(
(point.x >= rectangle.min_x) && (point.x <= rectangle.max_x) &&
(point.y >= rectangle.min_y) && (point.y <= rectangle.max_y)) {
//do something
}
and replacing point with e is exactly what you want.
Maybe the following link will help to understand:
How to check if a point is inside a rectangle

Provided images are the same size and assuming it is stored in variable imageSize (of type System.Drawing.Size) then:
Size imageSize = new Size(...) // define the size here
...
int row = point.y / imageSize.height;
int col = point.x / imageSize.width;
var rect = new Rectangle(col * imageSize.Width, row * imageSize.Height, imageSize.Width, imageSize.Height);
You can then use rect to draw you frame around the image (you may want to inflate the rectangle by a couple of pixels)

Hi Samgak /Clijsters,
I have completed my functionality
// page level declaration
private Rectangle SelectedRect;
public List<Rectangle> listRec = new List<Rectangle>();
// on page load add all the rectangle in the rectanglelist.
private void Highlightimage_Load(object sender, EventArgs e)
{
for (int i = 0; i < table.Rows.Count; i++)
{
int x = Convert.ToInt32(table.Rows[i][0]);
int y = Convert.ToInt32(table.Rows[i][1]);
int width = Convert.ToInt32(table.Rows[i][2]);
int height = Convert.ToInt32(table.Rows[i][3]);
SelectedRect.Size = new Size(width, height);
SelectedRect.X = x;
SelectedRect.Y = y;
listRec.Add(SelectedRect);
}
}
// draw the rectangle
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{ Graphics g = e.Graphics;
foreach (Rectangle rec in listRec)
{
Pen p = new Pen(Color.Red);
g.DrawRectangle(p, rec);
}
}
private Rectangle MakeRectangle(int x0, int y0, int x1, int y1)
{
return new Rectangle(
Math.Min(x0, x1),
Math.Min(y0, y1),
Math.Abs(x0 - x1),
Math.Abs(y0 - y1));
}
//finally on mouse move checking the condition
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
foreach (Rectangle rec in listRec)
{
SelectedRect = MakeRectangle(rec.Left, rec.Top, rec.Right, rec.Bottom);
if (
(e.X >= SelectedRect.Left) && (e.X <= SelectedRect.Right) &&
(e.Y >= SelectedRect.Top) && (e.Y <= SelectedRect.Bottom))
{
MessageBox.Show("test");
}
}
}
Also refered this link
Drawing Multiple Rectangles c#
I thought this will help some one.
Thanks
Dev

Draw persistent grid in TabPage (.Net, C#)

I need to display a persistent grid in a TabPage. My problems would be instantly solved if I could draw to the entire non-visible portion of the TabPage and prevent graphics from being erased when scrolling.
The only other solution I can think of is tracking the scroll position in the tab and basing the grid drawn from that.
To get this to draw in the first place, I had to create an EventHandler for TabPage.Paint.
//Code removed
This method draws vertical and horizontal lines to create a grid within the visible tab, but it continues to draw whenever a Paint event occurs (i.e. scrolling), so it creates overlapping lines and aren't aligned to anything but the size of the current visible area of the tab.

Maybe something like this will work for you:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
const int gridSpacing = 20;
const int lineThickness = 1;
Bitmap bmp = new Bitmap(gridSpacing, gridSpacing);
using (System.Drawing.Pen pen = new System.Drawing.Pen(Color.Blue, lineThickness))
{
using (Graphics G = Graphics.FromImage(bmp))
{
G.Clear(this.BackColor);
G.DrawLine(pen, 0, bmp.Height - pen.Width, bmp.Width, bmp.Height - pen.Width); // horizontal
G.DrawLine(pen, bmp.Width - pen.Width, 0, bmp.Width - pen.Width, bmp.Height); // vertical
}
}
foreach (TabPage TP in tabControl1.TabPages)
{
TP.BackgroundImage = bmp;
TP.BackgroundImageLayout = ImageLayout.Tile;
}
}
}

Keep in mind that this solution is just pseudo. You also have to respond to scrolling.
void form_draw()
{
spacingX = offsetX % scale * -1;
spacingY = offsetY % scale * -1;
if (form.HorizontalPosition != lastXPosition && form.VerticalPosition == lastYPosition)
lastStartX += spacingX;
else if (tab.HorizontalScroll.Value == lastXPosition && form.VerticalPosition != lastYPosition)
lastStartY += spacingY;
lastYPosition = form.VerticalPosition;
lastXPosition = form.HorizontalPosition;
for (int i = lastStartY; i < formHeight; i += scale)
form.draw(0, i, formWidth, i);
for (int i = lastStartX; i < formWidth; i += scale)
form.draw(i, 0, i, formWidth);
}