如何检查按钮 1 不会移出图片框 1 边界/边框

Question

这是计时器1中的代码，按钮在pictureBox1上随机移动，但有时它会移出边界。

我试图首先检查 pictureBox1 的顶部边界/边框，但它不起作用，有时会离开图片框区域。

这是计时器中的原始代码：

private void timer1_Tick(object sender, EventArgs e)
        {
            if (currentPosition.X != randomPoint.X)
            {
                if (currentPosition.X > randomPoint.X)
                    currentPosition.X -= 1;
                else
                    currentPosition.X += 1;
                button1.Location = currentPosition;
            }
            else if (currentPosition.Y != randomPoint.Y)
            {
                if (currentPosition.Y > randomPoint.Y)
                    currentPosition.Y -= 1;
                else
                    currentPosition.Y += 1;
                button1.Location = currentPosition;
            }
            else
            {
                randomPoint.X = r.Next(0, pictureBox1.Width - button1.Width - 1);
                randomPoint.Y = r.Next(0, pictureBox1.Height - button1.Height - 1);
            }
        }

这是在我尝试添加 pictureBox1 顶部的检查之后：

private void timer1_Tick(object sender, EventArgs e)
        {
            int maxScreenHeight = pictureBox1.Height - button1.Size.Height;
            int maxScreenWidth = pictureBox1.Width - button1.Size.Width;
            if (button1.Top < 0)
                button1.Top = 0;
            else if (button1.Top > maxScreenHeight)
                button1.Top = maxScreenHeight;
            else
            {
                if (currentPosition.X != randomPoint.X)
                {
                    if (currentPosition.X > randomPoint.X)
                        currentPosition.X -= 1;
                    else
                        currentPosition.X += 1;
                    button1.Location = currentPosition;
                }
                else if (currentPosition.Y != randomPoint.Y)
                {
                    if (currentPosition.Y > randomPoint.Y)
                        currentPosition.Y -= 1;
                    else
                        currentPosition.Y += 1;
                    button1.Location = currentPosition;
                }
                else
                {
                    randomPoint.X = r.Next(0, pictureBox1.Width - button1.Width - 1);
                    randomPoint.Y = r.Next(0, pictureBox1.Height - button1.Height - 1);
                }
            }
        }

但它不起作用。如何检查左上角和右下角？所以按钮不会移出界限？

Answer 1

我首先关心的是，你使用了太多的if-elseif-else分支，而不需要。IMO在逻辑中有一个地板，许多代码部分可能大多数时候根本不输入。

此外，什么可能太迂腐了，但你浪费资源总是计算随机数调用的上限。同样，这只是我的观点，最好只预先计算一次这些值并保持它们已知，而无需一直要求它们的计算，无论处理器需要做的多么少，都更容易

。

编辑：是的，正如 valter 提到的，您可以将 pictureBox 作为按钮的父级，或者只是为随机数设置下限：这将是LOWER_LIMITs

然后，我认为这应该是您尝试提出的代码：

namespace stackoverflow.com/questions/22135510
{
    public partial class Form1 : Form
    {
        public int X_UPPER_LIMIT = 0;
        public int Y_UPPER_LIMIT = 0;
        public int X_LOWER_LIMIT = 0; 
        public int Y_LOWER_LIMIT = 0; 
        public Point randomPoint = new Point();
        public Point newPosition = new Point();
        public Random r = new Random();
        public Form1()
        {
            InitializeComponent();
            //care here, remove the pitureBox1.Location effects, if pictureBox is parent to the button
            X_UPPER_LIMIT = pictureBox1.Location.X + pictureBox1.Width - button1.Width - 1
            Y_UPPER_LIMIT = pictureBox1.Location.Y + pictureBox1.Height - button1.Height - 1;
            X_LOWER_LIMIT = pictureBox1.Location.X + 1; //set this to 0, if pictureBox is parent of button
            Y_LOWER_LIMIT = pictureBox1.Location.Y + 1; //set this to 0, if pictureBox is parent of button
            timer1.Start();
        }
        private void button1_Click(object sender, EventArgs e)
        {
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            //first, lets call the randoms at the start of tick
            randomPoint.X = r.Next(X_LOWER_LIMIT, X_UPPER_LIMIT);
            randomPoint.Y = r.Next(Y_LOWER_LIMIT, Y_UPPER_LIMIT);
            newPosition.X = button1.Location.X;
            newPosition.Y = button1.Location.Y;
            //now, lets update positions, if they are not equal
            if (button1.Location.X != randomPoint.X)
            {
                if (button1.Location.X > randomPoint.X)
                    newPosition.X--;
                else
                    newPosition.X++;
            }
            if (button1.Location.Y != randomPoint.Y)
            {
                if (button1.Location.Y > randomPoint.Y)
                    newPosition.Y--;
                else
                    newPosition.Y++;
            }
            button1.Location = newPosition;
        }
    }
}

旁注：我最终编写并运行了这个，对我有用。