如何在 Windows 窗体应用程序上的 Refresh() 之后重绘所有内容

Question

I have 9 rectangles and I need to draw a text inside them, I have two buttons which they are choosing the text that I need to draw into. when I click on the button then click on the rectangle it will take the location of mouse and then check in which rectangle I need to draw into. when I need to draw in another rectangle because of Refresh() it drew the new one and clear the past draw. How can I save it?

public partial class Form1 : Form
    {
        List<Rectangle> rects = new List<Rectangle>();
        Rectangle rectangle = new Rectangle();
        string str;
        Point start;
        int x = 0;
        Point[] points=new Point[100];
        public Form1()
        {
            InitializeComponent();
            for (int i = 0; i < 3; i++)
            {
                for (int j = 0; j < 3; j++)
                {
                    rects.Add( new Rectangle(130 + (j * 130), 130 + (i * 130), 130, 130));

                }
            }
        }


        protected override void OnPaint(PaintEventArgs e)
        {
            foreach(Rectangle rect in rects)
                    e.Graphics.DrawRectangle(Pens.Black, rect.X, rect.Y, rect.Width, rect.Height);

           
                getRectangle(rectangle);
                if (rectangle.Width != 0 && rectangle.Height != 0)
                {
                    using (SolidBrush solidBrush = new SolidBrush(Color.DarkGreen))
                    {
                        using (FontFamily fontFamily = new FontFamily("Arial"))
                        {
                            using (Font font = new Font(fontFamily, 20))
                            {
                                e.Graphics.DrawString(str, font, solidBrush, rectangle.X + 55, rectangle.Y + 55);
                            }
                        }
                    }
                }
            
            base.OnPaint(e);
        }

        private void Cross_Click(object sender, EventArgs e)
        {
            str = "X";

        }

        private void Circle_Click_1(object sender, EventArgs e)
        {
            str = "O";
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            start = e.Location;
            points[x] = start;
            x++;
            Invalidate();
        }

        public void getRectangle(Rectangle rectan)
        {
            rectangle.Width = 0;
            rectangle.Height = 0;
            if (str == "X")
            {
                foreach(Rectangle rect in rects)
                        if (rect.Contains(start))
                        {
                            rectangle.X = rect.X;
                            rectangle.Y = rect.Y;
                            rectangle.Width = rect.Width;
                            rectangle.Height = rect.Height;
                          
                        }
            }
            else if (str == "O")
            {
                
                    foreach (Rectangle rect in rects)
                        if (rect.Contains(start))
                        {
                            rectangle.X = rect.X;
                            rectangle.Y = rect.Y;
                            rectangle.Width = rect.Width;
                            rectangle.Height = rect.Height;

                        }
                
            }
        }

    }

Answer 1

Not sure if I understand correctly, but it seems as though you need to create a database to save your object into. Look into SQL and UML moddeling. Once you are familiar with those consider taking a look at this older post of mine on how to extract data from a database here .

(Sidenote: There are many different ways to generate database entities in code, one of which is Entity Framework , once you get comfortable with SQL you should consider looking into these options)

If you want to temporarily save data (this means during the runtime of your application), consider making objects and fill a List<T> with those objects. Then you can create a loop and retreive those objects. Like so:

//create new class
public class Drawing
{
    public int X { get; private set; }
    public int Y { get; private set; }
    public Drawing(int x, int y)
    {
        this.X = x;
        this.Y = y;
    }
}

//Initiate new object
public List<Drawing> drawings = new List<Drawing>();

//Add this to your loop
drawings.Items.Add(new Drawing() { X= YourX, Y= YourY });

//And foreach loop through your drawings to draw them.
foreach(Drawing drawing in drawings)
{
   //Draw your item here.
}