我想在图片框C＃上绘制Square

Question

I want to draw Square on Image not the rectangle when I perform mouse move operation to Top, Left, Bottom, Right direction its Height and Width will be increase in same length.

below is my code it does not display square I want exact code for Square

    public Form1()
    {
        InitializeComponent();
    }

    Rectangle currRect;
    Point endPoint;
    bool isDrag;
    Point startPoint;
    private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
    {
        startPoint = new Point(e.X, e.Y); //
        if (e.Button == MouseButtons.Left)
        {
            currRect = new Rectangle();
            currRect.X = startPoint.X;
            currRect.Y = startPoint.Y;
            isDrag = true;
        }
    }

    private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
        if (isDrag)
        {
            endPoint = new Point(e.X, e.Y);
            currRect.Width = endPoint.X - startPoint.X;
            currRect.Height = endPoint.Y - startPoint.Y;
        }
    }

    private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
    {
        isDrag = false;
        Graphics graphics = this.pictureBox1.CreateGraphics();
        graphics.DrawRectangle(new Pen(Brushes.Red), currRect.X, currRect.Y, currRect.Width, currRect.Height);

    }

also one thing when I going to increase the size of square its starting point or we can say that its Top,Left co-ord remains steady or constant when I am increasing in Top, Left, Bottom, Right direction.

this starting point is not steady when I move the mouse cursor its starting point gets change i don't want this so please help me to figure out from this situation

Answer 1

Your code is drawing a rectangle, not a square. If you want to draw a square, you need to make the width and height identical.

If you modify your pictureBox1_MouseMove method to this, you can draw a square with the length equal to the maximum of the width and height:

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (isDrag)
    {
        endPoint = new Point(e.X, e.Y);
        int maxLength = Math.Max(endPoint.X - startPoint.X, endPoint.Y - startPoint.Y);
        currRect.Width = maxLength;
        currRect.Height = maxLength;
    }
}

---

EDIT: Here is the solution that you can use to draw your square from any direction:

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (isDrag)
    {
        endPoint = new Point(e.X, e.Y);
        currRect.X = Math.Min(startPoint.X, endPoint.X);
        currRect.Y = Math.Min(startPoint.Y, endPoint.Y);
        int maxLength = Math.Max(Math.Abs(startPoint.X - endPoint.X), Math.Abs(startPoint.Y - endPoint.Y));
        currRect.Width = maxLength;
        currRect.Height = maxLength;
    }
}

Answer 2

Replace

graphics.DrawRectangle(new Pen(Brushes.Red), currRect.X, currRect.Y, currRect.Width, currRect.Height);

By:

graphics.DrawRectangle(new Pen(Brushes.Red), currRect.X, currRect.Y, Math.Min(currRect.Width, currRect.Height), Math.Min(currRect.Width, currRect.Height));

Secondly, I don't see how the starting point changes?