C＃如何每5秒更改矩形的颜色

Question

i have a program that has bouncing squares within a form, i also have to make it so that every 5 seconds the drawn squares change color, i have a timer to update a listbox on the coordinates of each box and a second timer with the interval of 5000 to change the color of the square. now i am trying to figure out how exactly do i change the color of the squares with the timer, i have a method called colorchange with a property called rectcolor

 private Color Rectcolor { get; set; }

 }
    public Color Colorchange()
    {
        Rectcolor =  Color.FromArgb(randcolor.Next(256), randcolor.Next(256), randcolor.Next(256));
        return Rectcolor;
    }

in Form1 i have the timer2 tick event with a foreach going through the boxes

 public partial class Form1 : Form
{
    Random Randcolor = Box.randcolor;
    Random Rand = Box.rand;
    List<Box> Boxes = new List<Box>();

    public Form1()
    {
        InitializeComponent();
        this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        this.SetStyle(ControlStyles.UserPaint, true);

    }
    private void timer2_Tick(object sender, EventArgs e)
    {
        foreach (Box tmp in Boxes)
        {
            tmp.Colorchange();
        }
    }

when i run the program nothing happens with the moving rectangles, how do i make colorchange actually change the color of the rectangle?

Full Box Class Code

class Box
{
    protected Rectangle myRectangle;
    protected int xStep;
    protected int yStep;
    protected Form pForm;
    protected Label myLocation;
    protected Color myColor;
    public static Random rand = new Random();
    public static Random randcolor = new Random();

    public Box(int x, int y, int s, Form pF)
    {
        myColor = new Color();
        myColor = Colorchange();
        myLocation = new Label();
        myLocation.BackColor = Color.Transparent;
        myLocation.Left = x;
        myLocation.Top = y;
        myLocation.ForeColor = Colorchange();
        pF.Controls.Add(myLocation);
        pForm = pF;
        myRectangle = new Rectangle(x, y, s, s);
        myRectangle.X = x;
        myRectangle.Y = y;
        xStep = rand.Next(1, 15);
        yStep = rand.Next(1, 15);
    }

    public int X { get { return myRectangle.X; } }
    public int Y { get { return myRectangle.Y; } }
    private int Width { get { return myRectangle.Width; } }
    private int Height { get { return myRectangle.Height; } }
    private Color Rectcolor { get; set; }
    public void Move()
    {
        myRectangle.X += xStep;
        myRectangle.Y += yStep;
        if (myRectangle.X <= 0)
            xStep *= -1;
        if (myRectangle.X + myRectangle.Width >= pForm.ClientSize.Width)
            xStep *= -1;
        if (myRectangle.Y <= 0)
            yStep *= -1;
        if (myRectangle.Y + myRectangle.Height >= pForm.ClientSize.Height)
            yStep *= -1;
        //if (myRectangle.X >500)
        //    xStep *= -1;

    }
    public Color Colorchange()
    {
        Rectcolor =  Color.FromArgb(randcolor.Next(256), randcolor.Next(256), randcolor.Next(256));
        return Rectcolor;
    }


    public static bool Bounce(Box One, Box Two)
    {
        if (One.X + One.Width < Two.X)
            return false;
        if (Two.X + Two.Width < One.X)
            return false;
        if (One.Y + One.Height < Two.Y)
            return false;
        if (Two.Y + Two.Height < One.Y)
            return false;
        return true;
    }
    //public void collision()
    //{

    //    xStep *= -1;
    //    yStep *= -1;
    //}
    public void Draw(Graphics g)
    {
        g.DrawRectangle(new Pen(Color.Blue), myRectangle);

        myLocation.Top = myRectangle.Y -15;
        myLocation.Left = myRectangle.X+(myRectangle.Width/4);
        myLocation.Text = myRectangle.X.ToString() + ", " + myRectangle.Y.ToString();

    }

i start the timer on the buttone click, i will give you form1

  public partial class Form1 : Form
{
    Random Randcolor = Box.randcolor;
    Random Rand = Box.rand;
    List<Box> Boxes = new List<Box>();

    public Form1()
    {
        InitializeComponent();
        this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
        this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
        this.SetStyle(ControlStyles.UserPaint, true);

    }

    private void button1_Click(object sender, EventArgs e)
    {
        // Box tmp = new Box(100, 100, 40);
        // Boxes.Add(tmp);
        for (int x = 1; x < 10; x++)
        {
            Boxes.Add(
                new Box(
                    Rand.Next(100 + x * 10, this.ClientSize.Width - 100),
                Rand.Next(100 + x * 10, this.ClientSize.Height - 100),
                Rand.Next(100 + x * 15), this));

            //Boxes.Add(new Box(100 + x * 10, 100 + x * 10, x * 15, this));

        }
        timer1.Enabled = true;
        timer2.Enabled = true;

    }

    private void Form1_Paint(object sender, PaintEventArgs e)
    {
        foreach (Box tmp in Boxes)
        {
            tmp.Draw(e.Graphics);

        }
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        listBox1.Items.Clear();
        foreach (Box tmp in Boxes)
        {
            tmp.Move();
            listBox1.Items.Add(tmp.X + ", " + tmp.Y);
        }
        this.Invalidate(false);


    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void timer2_Tick(object sender, EventArgs e)
    {
        foreach (Box tmp in Boxes)
        {
            tmp.Colorchange();
        }
    }

}

}

Answer 1

Your ColorChange() method never really 'applies' the new color to the Rectangle object within your Box class.

Within your Box class you need a new Graphics object. You could set it as field or pass it as parameter for the constructor, as you are using it within the Draw() method anyways.

        private Graphics g;

        ...

        public Box(int x, int y, int s, Form pF)
        {
            g = pF.CreateGraphics();

            ...
        }

You will also have to modify your ColorChange() method, so that the Rectangle gets filled to the desired color:

public Color Colorchange()
{
    this.Rectcolor = Color.FromArgb(randcolor.Next(256), randcolor.Next(256), randcolor.Next(256));

    // You need to fill the rectangle with the desired color again
    this.g.FillRectangle(new SolidBrush(this.Rectcolor), this.myRectangle);
    return Rectcolor;
}

Answer 2

g.DrawRectangle(new Pen(Color.Blue), myRectangle);

this line draws a blue rectangle. Whatever color you've set to "myColor", it draws blue. Changing this to

g.DrawRectangle(new Pen(myColor), myRectangle);

should fix your issue.