C# KeyDown 问题

Question

我正在尝试制作一个包含三个按钮的菜单（按顺序：播放、选项、退出），其中只有选定的按钮有边框，并且由向上和向下箭头控制。不幸的是，按下 atm 按钮时似乎没有任何反应。这是代码：

public partial class
{
    int i = 0;
    List<Button> menuButtons = new List<Button>();
    Button selectedButton = new Button();

    public Menu()
    {
        InitializeComponent();

        menuButtons.Add(btnPlay);
        menuButtons.Add(btnOptions);
        menuButtons.Add(btnExit);

        selectedButton = menuButtons[i];

        if (menuButtons[i] == selectedButton)
        {
            menuButtons[i].FlatAppearance.BorderSize = 1;
        }
    }

    private void Menu_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Down)
        {
            if (i < menuButtons.Count)
            {
                i++;
            }
            else if (i >= menuButtons.Count)
            {
                i = 0;
            }
        }

        if (e.KeyCode == Keys.Up)
        {
            if (i > 0)
            {
                i--;
            }
            else if (i <= 0)
            {
                i = menuButtons.Count;
            }
        }

        if (e.KeyCode == Keys.Enter)
        {
            switch (i)
            {
                case 0:
                    btnPlay.PerformClick();
                    break;
                case 1:
                    btnOptions.PerformClick();
                    break;
                case 2:
                    btnExit.PerformClick();
                    break;
            }
        }
    }

祝你有愉快的一天:)

Answer 1

您的代码中有两个问题。第一个在前两个 if 语句中。您正在正确更改索引，但没有将边框设置为新选择的按钮。您必须移除先前选定按钮的边框并设置新选定按钮的边框。

第二个是您忘记为您的按钮设置点击事件，所以当点击它们时它们什么都不做。您的代码应该是这样的：

public partial class
{
    int i = 0;
    List<Button> menuButtons = new List<Button>();
    Button selectedButton = new Button();

    public Menu()
    {
        InitializeComponent();

        //Assigning click events for the buttons.
        btnPlay.Click += BtnPlay_Click;
        btnOptions.Click += BtnOptions_Click;
        btnExit.Click += BtnExit_Click;

        menuButtons.Add(btnPlay);
        menuButtons.Add(btnOptions);
        menuButtons.Add(btnExit);

        selectedButton = menuButtons[i];

        if (menuButtons[i] == selectedButton)
        {
            menuButtons[i].FlatAppearance.BorderSize = 1;
        }
    }

    private void Menu_KeyDown(object sender, KeyEventArgs e)
    {
        //Removing border from previously selected button.
        menuButtons[i].FlatAppearance.BorderSize = 0; 

        if (e.KeyCode == Keys.Down)
        {
            if (i < menuButtons.Count)
            {
                i++;
            }
            else if (i >= menuButtons.Count)
            {
                i = 0;
            }
        }

        if (e.KeyCode == Keys.Up)
        {
            if (i > 0)
            {
                i--;
            }
            else if (i <= 0)
            {
                i = menuButtons.Count;
            }
        }

        //Setting border for the newly selected button.
        menuButtons[i].FlatAppearance.BorderSize = 1;

        if (e.KeyCode == Keys.Enter)
        {
            switch (i)
            {
                case 0:
                    btnPlay.PerformClick();
                    break;
                case 1:
                    btnOptions.PerformClick();
                    break;
                case 2:
                    btnExit.PerformClick();
                    break;
            }
        }
    }

    private void BtnExit_Click(object sender, EventArgs e)
    {
        //Code for the Exit button.
    }

    private void BtnOptions_Click(object sender, EventArgs e)
    {
        //Code for the Options button.
    }

    private void BtnPlay_Click(object sender, EventArgs e)
    {
        //Code for the Play button.
    }
}

PS：注意构造函数中selectedButton变量和if语句等不必要的代码。它们不影响功能，但可能会妨碍后期代码维护。

C# KeyDown 问题

C# KeyDown Issue

c#

events

keydown

winforms