How can I put a checkBox in the form and not to break the control loop?

问题

I have been working on a little game and I encountered with this problem and I can't figure out how to solve it. Everything worked fine until I put a checkBox on the form. How can I reach that to use the checkBox and the control at the same time and not to break the control loop with the checkBox.

Here is my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;

namespace Mozgás_Gyakorlás
{
    public partial class Form1 : Form
    {
        enum Position
        {
            Left, Right, Up, Down
        }
        public int x = 262;
        public int y = 318;
        private Position pozíció;
        public Form1()
        {
            InitializeComponent();
            pozíció = Position.Left;
        }

        public void pictureBox4_Paint(object sender, PaintEventArgs e)
        {
            timer2.Start();
            e.Graphics.FillRectangle((Brushes.Blue), x, y, 20, 20);
            checkBox1.PerformLayout();
        }

        private void timer2_Tick(object sender, EventArgs e)
        {
            if(pozíció == Position.Right)
            {
                x += 3;
            }
            if(pozíció == Position.Left)
            {
                x -= 3;
            }
            if(pozíció == Position.Up)
            {
                y -= 3;
            }
            if(pozíció == Position.Down)
            {
                y += 3;
            }
            pictureBox4.Invalidate();
        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode == Keys.Up)
            {
                pozíció = Position.Up;
            }
            if(e.KeyCode == Keys.Down)
            {
                pozíció = Position.Down;
            }
            if(e.KeyCode == Keys.Left)
            {
                pozíció = Position.Left;
            }
            if(e.KeyCode == Keys.Right)
            {
                pozíció = Position.Right;
            }
        }

        private void checkBox1_Click(object sender, EventArgs e)
        {
            if (checkBox1.Checked == true)
            {
                pictureBox4.Image = Image.FromFile(@"D:\Táblázat2.JPG");
            }
            else
            {
                pictureBox4.Image = null;
            }
        }

    }
}

回答1:

Here's some points that might help.

The Timer should be started/stopped in the Form's constructor/Load event or on a Button click and not in the Paint event.

public Form1()
{
    InitializeComponent();
    pozíció = Position.Left;
    timer2.Start();
}

The Timer.Tick event:

private void timer2_Tick(object sender, EventArgs e)
{
    //Hint: You might want to keep the rectangle within the canvas.
    pozíció = x < 0 ? Position.Right : x + 21 > pictureBox4.ClientRectangle.Right ? Position.Left : pozíció;
    pozíció = y < 0 ? Position.Down : y + 21 > pictureBox4.ClientRectangle.Bottom ? Position.Up : pozíció;

    switch (pozíció)
    {
        case Position.Right:
            x += 3;
            break;
        case Position.Left:
            x -= 3;
            break;
        case Position.Up:
            y -= 3;
            break;
        case Position.Down:
            y += 3;
            break;
        default:
            x = 0;
            y = 0;
            break;
    }
    pictureBox4.Invalidate();
}

You can write the enum block as follows:

enum Position
{
    Left = 37,
    Up,
    Right,
    Down,
}

Where 37 is the KeyCode of the Left key, and consequently Up = 38, Right = 39, and Down = 40. So you can shrink the KeyDown event as follows:

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Left ||
        e.KeyCode == Keys.Up ||
        e.KeyCode == Keys.Right ||
        e.KeyCode == Keys.Down)
    {
        pozíció = (Position)e.KeyCode;
        pictureBox4.Invalidate();
    }
}

To show/hide the image, handle the CheckedChanged instead:

private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
    pictureBox4.Image = checkBox1.Checked ? Táblázat2 : null;
}

Presuming that the Táblázat2 is a class level variable = Image.FromFile(@"D:\Táblázat2.JPG"); assigned in the Form's constructor.

The Paint event:

private void pictureBox4_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.FillRectangle(Brushes.Blue, x, y, 20, 20);
}

Alternatively, and as you are handling the Paint event, you can get rid of the CheckedChanged event of the CheckBox control and draw the image yourself:

private void pictureBox4_Paint(object sender, PaintEventArgs e)
{
    var g = e.Graphics;

    if (checkBox1.Checked)
    {
        var sz = Táblázat2.Size;
        var r = e.ClipRectangle;

        g.SmoothingMode = SmoothingMode.HighQuality;

        g.DrawImage(Táblázat2,
        new Rectangle((r.Width - sz.Width) / 2, (r.Height - sz.Height) /2, sz.Width, sz.Height),
        new Rectangle(0, 0, sz.Width, sz.Height),
        GraphicsUnit.Pixel);
    }
    g.FillRectangle(Brushes.Blue, x, y, 20, 20);
}

and just in case the timer is not enabled:

private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
    pictureBox4.Invalidate();
}

Good luck.

来源：https://stackoverflow.com/questions/59337141/how-can-i-put-a-checkbox-in-the-form-and-not-to-break-the-control-loop

标签

checkbox

timer

move

keydown