C# - 防止图片框离开边界

Question

我有一个名为玩家的图片框和4个图片框，它们在游戏开始时充当边界。我有这个代码，如果按下一个键，就会执行：private void HorrorForm_KeyDown(object sender, KeyEventArgs e)        {            int x = player.Location.X;            int y = player.Location.Y;            if (e.KeyCode == Keys.D)                x += 7;            if (e.KeyCode == Keys.A)                x -= 7;            if (e.KeyCode == Keys.S)                y += 7;            if (e.KeyCode == Keys.W)                y -= 7;            if (player.Bounds.IntersectsWith(openspot1.Bounds) || player.Bounds.IntersectsWith(openspot2.Bounds) || player.Bounds.IntersectsWith(openspot3.Bounds) || player.Bounds.IntersectsWith(openspot4.Bounds))            {                player.Location = new Point(player.Location.X - 1, player.Location.Y - 1);            }            player.Location = new Point(x, y);        }如何移动玩家，但阻止他离开边界？

Answer 1

有一种观点与你的代码不正确，至少我认为是这样。

1. 你总是把球员移动到他的新位置。你一定要检查他是否触及了界限。如果他触及边界，你把他向上移动一个像素，向左移动一个像素，只是为了将他移动到7个像素到所选的direktion中。因此，在你检查他是否触及边界的地方，你必须中断，不要执行设置新位置的其余代码。一个简单的将完成这项工作。ifreturn;

2. 如果按下一个键，你将进行边界检查，如果玩家没有触及边界，你将移动玩家。这是错误的顺序。你必须检查玩家在移动后是否会触及边界，只有当他不会触摸边界移动他时。否则，你会把他移入边界，再也不把他赶出去。

所以这是你的代码和一些更正：

private void HorrorForm_KeyDown(object sender, KeyEventArgs e)

{

    int x = player.Location.X;

    int y = player.Location.Y;

    if (e.KeyCode == Keys.D)

        x += 7;

    if (e.KeyCode == Keys.A)

        x -= 7;

    if (e.KeyCode == Keys.S)

        y += 7;

    if (e.KeyCode == Keys.W)

        y -= 7;

    var tempPlayerPosition= player.Bounds; // get the players position and remember it temporary

    tempPlayerPosition.X = x; // change the players temporary pisition to the new one that it will have after the move

    tempPlayerPosition.Y = y;

    //check if the play would touch the boundyries if we use the new temporary pisition

    if (tempPlayerPosition.IntersectsWith(openspot1.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot2.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot3.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot4.Bounds))

    {

        return; //if he would touch the boundary, then do nothing

    }

    player.Location = new Point(x, y); //if he would not touch the boundary, move him to his new location

}

但也许你也想

• 防止在按下不是 W、S、A 或 D 的键时执行代码（即使他没有改变任何值）。

• 使用而不是这样使它更具可读性。switchif

• 而不是每次都写数字7，使用局部变量，所以如果将来会改变，你只需要改变一个值。

所以我的建议是这样的：

private void HorrorForm_KeyDown(object sender, KeyEventArgs e)

{    

    var oneStep = 7; // define the amount of pixel the player will be moved

    var tempPlayerPosition = player.Bounds;// get the players position and remember it temporary

    switch (e.KeyCode) // check which key was presses

    {

        case Keys.D:

            tempPlayerPosition.X += oneStep; // move right

            break;

        case Keys.A:

            tempPlayerPosition.X -= oneStep; // move left

            break;

        case Keys.S:

            tempPlayerPosition.Y += oneStep; // move down

            break;

        case Keys.W:

            tempPlayerPosition.Y -= oneStep; // move up

            break;

         default: // you may wan't to do nothing if there any other key presses...

            return;

    }

    //check if the play would touch the boundyries if we use the new temporary pisition

    if (tempPlayerPosition.IntersectsWith(openspot1.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot2.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot3.Bounds) || 

        tempPlayerPosition.IntersectsWith(openspot4.Bounds))

    {

        return; //if he would touch the boundary, then do nothing

    }

    player.Location = new Point(tempPlayerPosition.X, tempPlayerPosition.Y);   //if he would not touch the boundary, move him to his new location

}

这对你有帮助吗？