XNA - 鼠标左键被执行多次

Question

XNA - 鼠标左键被执行多次

4

我是编程新手，在开始之前请回答我，为什么更新会执行多次，并像对待傻瓜一样解释它。

无论如何，我现在正在尝试使此代码仅运行一次，因为目前它会执行多次。

 protected override void Update(GameTime gameTime)
    {
        // Allows the game to exit
        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
            this.Exit();

        // TODO: Add your update logic here

         button = Mouse.GetState();




         if (button.X < buttonPosition.X || button.Y < buttonPosition.Y || button.X > buttonPosition.X + font1.MeasureString(buttonText).X ||
             button.Y > buttonPosition.Y + font1.MeasureString(buttonText).Y)
             buttonColour = new Color(0, 0, 0);//if the mouse if not hovering over the font it stays that color
         else
             buttonColour = new Color(0, 255, 255);//changes to this color if it is hovering over text

        if(button.LeftButton==ButtonState.Pressed)
         display = (display == false) ? true : false;  //if display = true it will set it to false
        //if false then it will set it to false



 }

这是绘图方法，如果需要的话。

 protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);
        spriteBatch.Begin();
        spriteBatch.DrawString(font1, buttonText, buttonPosition, buttonColour);   //this is the button leftbutton has to click to trigger the below if statement.
        if (display)
            spriteBatch.DrawString(font1, text, position, Color.White);
        spriteBatch.End();  //it will draw this when leftbutton  clicks the above button

        // TODO: Add your drawing code here

        base.Draw(gameTime);
    }

- Wasiim Ouro-sama

2个回答

0

private KeyboardState currentKeyboardState;
private KeyboardState lastKeyboardState;

lastKeyboardState = currentKeyboardState;
currentKeyboardState = Keyboard.GetState();

public bool IsNewKeyPress(params Keys[] keys)
    {
        return keys.Any(k => (currentstate.IsKeyDown(k) &&
                    laststate.IsKeyUp(k)));
    }

if (IsNewKeyPress(Keys.Space))
        { //Do something }

对于键盘上的任何按键，这个都有效！谢谢兄弟Pierre。

- Playonce

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- Pierre-Luc Pineault · Accepted Answer

您之所以出现这种行为，是因为XNA每秒自动多次调用“Update”方法，大约在每秒60次左右。同样的，对于“Draw”也是如此，它可能会渲染大约60帧每秒。

因此，如果您按下一个按钮一秒钟，该方法将被调用60次，ButtonState.Pressed将在那60次中评估为true。

要解决这个问题，您需要保留按钮的历史记录。这可以通过在每次更新时存储状态来实现:

//Define this at class level
private MouseState lastMouseState = new MouseState();

protected override void Update(GameTime gameTime)
{
    // your other stuff

    MouseState currentState = Mouse.GetState(); //Get the state
    if (currentState.LeftButton == ButtonState.Pressed &&
        lastMouseState.LeftButton == ButtonState.Released) //Will be true only if the user is currently clicking, but wasn't on the previous call.
    {
        display = !display; //Toggle the state between true and false.
    }

    lastMouseState = currentState;
}

现在点击事件只会被注册一次（因为鼠标需要当前处于点击状态，但先前必须处于释放状态）。如果你将来要添加键盘的话，也需要对其进行历史记录。

我还改变了你的显示切换逻辑，这样更加清晰简洁。你的注释中也有错误（应该是 //if false then it will set it to true）。这很正常，注释经常会误导人；尽量少写注释，只有代码才是真理。

如果需要帮助的话，以下是我之前使用的辅助类：

public class InputState : GameComponent
{
    private KeyboardState currentKeyboardState;
    private KeyboardState lastKeyboardState;
    private MouseState lastMouseState;
    private MouseState currentMouseState;

    public InputState(Game game) : base(game)
    {
        game.Components.Add(this);

        currentKeyboardState = new KeyboardState();
        lastKeyboardState = new KeyboardState();
        currentMouseState = new MouseState();
        lastMouseState = new MouseState();
    }

    public override void Update(GameTime gameTime)
    {
        lastKeyboardState = currentKeyboardState;
        currentKeyboardState = Keyboard.GetState();
        lastMouseState = currentMouseState;
        currentMouseState = Mouse.GetState();

        base.Update(gameTime);
    }

    public bool IsNewLeftClick()
    {
        return currentMouseState.LeftButton == ButtonState.Pressed &&
            lastMouseState.LeftButton == ButtonState.Released;
    }

    public bool IsNewRightClick()
    {
        return currentMouseState.RightButton == ButtonState.Pressed &&
            lastMouseState.RightButton == ButtonState.Released;
    }

    public Point GetMousePosition()
    {
        return new Point(currentMouseState.X, currentMouseState.Y);    
    }

    public bool IsNewKeyPress(params Keys[] keys)
    {
        return keys.Any(k => (currentKeyboardState.IsKeyDown(k) &&
                    lastKeyboardState.IsKeyUp(k)));
    }

    public bool IsCurrentlyPressed(params Keys[] keys)
    {
        return keys.Any(k => currentKeyboardState.IsKeyDown(k));
    }
}

它会自动注册为游戏组件，无需添加。状态将被自动更新，只需调用辅助方法即可。

你的最后一个 `if` 将变成：

if (inputState.IsNewLeftClick())
    display = !display;

这样做会更加清晰，并且提供了一种集中处理鼠标/键盘的方式（SRP太棒了）。