为什么当我按住某个键时，我的VB.NET Snake游戏会冻结吗? [英] Why does my VB.NET Snake game freeze when I hold a key down?

问题描述

我正在尝试在VB.NET中制作经典的Snake游戏，但是如果我在游戏中按住某个键(任何键)，则几秒钟后游戏将冻结，直到我释放该键为止.我已经尝试了很多方法来解决此问题，但是没有任何效果，也许是因为我不了解问题所在.

I'm trying to make the classic Snake game in VB.NET, but if I hold a key (any key) during the game, after a few seconds the game freezes until I release the key. I've tried lots to fix this, but nothing works, maybe because I don't understand the problem.

我假设当我按下一个键时，调用Form1_KeyDown函数，并且在几秒钟后，该键进入我被按下"模式时，该函数会不断被调用，因此计时器没有更新的机会.但是就像我说的那样，我可能错了.

I'm assuming that when I hold down a key, the Form1_KeyDown function gets called, and when, after a few seconds, the key goes into "I'm being held down" mode, that function is constantly called, so the timers don't get a chance to update. But like I said, I'm probably wrong.

任何帮助都将不胜感激，我已经为此苦苦挣扎了一段时间.我认为这是所有必需的代码，如果不是，请通知我.

Any help at all would be appreciated, I've been struggling with this for a while. I think this is all the necessary code, please let me know if it isn't.

按键事件的代码:

 Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

    ' Sorts out all the key presses: movement, resetting, pausing

    ' Change direction, unless the player tries to travel backwards into themself
    Select Case e.KeyCode
        Case upKey
            If previousDirection <> "D" Then
                nextDirection = "U"
            End If
        Case leftKey
            If previousDirection <> "R" Then
                nextDirection = "L"
            End If
        Case rightKey
            If previousDirection <> "L" Then
                nextDirection = "R"
            End If
        Case downKey
            If previousDirection <> "U" Then
                nextDirection = "D"
            End If
        Case resetKey
            resetGame()
        Case pauseKey
            paused = Not paused
            If paused Then
                lblPaused.Visible = True
                tmrTime.Stop()
                tmrFruit.Stop()
                tmrMove.Stop()
            Else
                lblPaused.Visible = False
                tmrTime.Start()
                tmrFruit.Start()
                tmrMove.Start()
            End If
    End Select

End Sub

更新/移动蛇的计时器代码(我知道这确实效率很低):

Code for the timer that updates/moves the snake (I'm aware this is really inefficient):

 Private Sub tmrMove_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrMove.Tick

    ' Adds a new head in direction of travel, and removes the tail, giving the illusion of snake movement

    Dim head As Object = bodyParts(bodyParts.Count - 1)
    Dim tail As Object = bodyParts(0)
    Dim newHead As Object

    head.Text = ""

    ' Add new head
    Select Case nextDirection

        Case "R"
            ' If snake goes out of bounds
            If head.Tag(0) + 1 >= numberOfColumns Then
                newHead = grid(0, head.Tag(1))
                If newHead.BackColor = snakeColor Then
                    killSnake()
                End If
            Else
                ' If snake overlaps itself
                If bodyParts.Contains(grid(head.Tag(0) + 1, head.Tag(1))) Then
                    killSnake()
                    Exit Sub
                Else
                    ' If snake is fine
                    newHead = grid(head.Tag(0) + 1, head.Tag(1))
                End If
            End If

            ' If fruit taken
            If newHead.BackColor = fruitColor Then
                eatFruit(newHead, tail)
            End If

        Case "L"
            If head.Tag(0) - 1 < 0 Then
                newHead = grid(numberOfColumns - 1, head.Tag(1))
                If newHead.BackColor = snakeColor Then
                    killSnake()
                End If
            Else
                If bodyParts.Contains(grid(head.Tag(0) - 1, head.Tag(1))) Then
                    killSnake()
                    Exit Sub
                Else
                    newHead = grid(head.Tag(0) - 1, head.Tag(1))
                End If
            End If

            If newHead.BackColor = fruitColor Then
                eatFruit(newHead, tail)
            End If

        Case "U"
            If head.Tag(1) - 1 < 0 Then
                newHead = grid(head.Tag(0), numberOfRows - 1)
                If newHead.BackColor = snakeColor Then
                    killSnake()
                End If
            Else
                If bodyParts.Contains(grid(head.Tag(0), head.Tag(1) - 1)) Then
                    killSnake()
                    Exit Sub
                Else
                    newHead = grid(head.Tag(0), head.Tag(1) - 1)
                End If
            End If

            If newHead.BackColor = fruitColor Then
                eatFruit(newHead, tail)
            End If

        Case "D"
            If head.Tag(1) + 1 >= numberOfRows Then
                newHead = grid(head.Tag(0), 0)
            Else
                If bodyParts.Contains(grid(head.Tag(0), head.Tag(1) + 1)) Then
                    killSnake()
                    Exit Sub
                Else
                    newHead = grid(head.Tag(0), head.Tag(1) + 1)
                End If
            End If

            If newHead.BackColor = fruitColor Then
                eatFruit(newHead, tail)
            End If

        Case Else
            newHead = grid(head.Tag(0), head.Tag(1))

    End Select

    bodyParts.Add(newHead)
    newHead.BackColor = snakeColor
    newHead.Font = headFont
    newHead.Text = headText

    ' Remove tail
    tail.BackColor = gridColor
    bodyParts.RemoveAt(0)

    previousDirection = nextDirection

End Sub

推荐答案

我假设当我按下一个键时，调用Form1_KeyDown函数，并且在几秒钟后，该键进入我被按下"模式时，该函数会不断被调用，因此计时器没有更新的机会.但是就像我说的那样，我可能错了.

I'm assuming that when I hold down a key, the Form1_KeyDown function gets called, and when, after a few seconds, the key goes into "I'm being held down" mode, that function is constantly called, so the timers don't get a chance to update. But like I said, I'm probably wrong.

事实上，你是对的.

在Windows中，一旦按下该键，您将收到一条WM_KEYDOWN消息，然后，在一定的时间间隔之后，您将收到许多WM_KEYDOWN消息，并且它们之间又有一定的间隔.

In Windows you'll get a WM_KEYDOWN message as soon as the key is pressed, and then, after a certain interval, you'll be getting lots of WM_KEYDOWN messages with another certain interval between them.

如果您进入控制面板-键盘"，则可以找到这些间隔.

You can find these intervals if you go to Control Panel - Keyboard.

最简单的解决方法是在密钥处理程序的末尾添加对DoEvents的调用.

尝试完全删除keydown处理程序.而是，通过检查tmrMove_Tick开头中显示nextDirection. "nofollow"> Keyboard.IsKeyDown .

Try removing the keydown handler completely. Instead, figure nextDirection in the beginnig of tmrMove_Tick by examining Keyboard.IsKeyDown.

尝试完全删除keydown处理程序.相反，通过检查GetAsyncKeyState在tmrMove_Tick的开头显示nextDirection，您可以这样声明:

Try removing the keydown handler completely. Instead, figure nextDirection in the beginning of tmrMove_Tick by examining GetAsyncKeyState, which you can declare as follows:

Private Declare Function GetAsyncKeyState Lib "user32" Alias "GetAsyncKeyState" (ByVal vKey As Keys) As Short

Private Shared Function IsKeyDown(ByVal Key As Keys) As Boolean
    Return (GetAsyncKeyState(Key) And &H8000S) = &H8000S
End Function

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