声音播放器问题？ 布尔语句应执行声音

Question

I've ran into a bit of an issue I can't seem to resolve, the test for if KeyPressed == false does play the 'car_still.wav', however the test for if KeyPressed == true doesn't play anything at all.

How do I go about fixing the issue mentioned above and also,

How can I integrate a player/player2.Stop() into either of the if statements (if one sound plays, the other one stops) because right now I'm getting an error "The name 'player' does not exist in the current context".

Thank you in advance.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    private int carX;
    private int roadTilesY = -193;
    int speedY;
    int time;
    bool keyPressed;
    System.Media.SoundPlayer player;
    System.Media.SoundPlayer player2; 


    public Form1()
    {
        InitializeComponent();
        gameSounds();
        carX = this.Width / 2 - 30;
        speedY = 0;
        time = 0;
    }

    private void gameSounds()
    {
        if (!keyPressed)
        {
            player = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_still.wav");
            player.PlayLooping();
        }
        else
        {
            player2 = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_speeding.wav");
            player2.PlayLooping();
            if (player != null)
                player.Stop();
        }
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        PlayerCar.Invalidate();
        PlayerCar.Location = new Point(carX, PlayerCar.Location.Y);
        RoadTileAnimation();
        npcCarMovement();
        if (keyPressed == true)
        {
            label1.Text = "Key pressed";
        }
        if (keyPressed == false)
        {
            label1.Text = "key not pressed";
        }

        label2.Text = "" + speedY;


    }

    private void RoadTileAnimation()
    {
        roadTilesY = roadTilesY - speedY;

        if (roadTilesY >= -50)
        {
            roadTilesY = -193;
        }

        roadTiles.Location = new Point(roadTiles.Location.X, roadTilesY);

    }


    private void Form1_KeyDown(object sender, KeyEventArgs e)
    {

        if (e.KeyCode == Keys.Left)
        {
           carX = carX - 15;
           if ((carX + PlayerCar.Width) > this.Width)
           {
               carX = this.Width - PlayerCar.Width - 10;
           }

        }

        if (e.KeyCode == Keys.Right)
        {
            carX = carX + 15;
            if ((carX + PlayerCar.Width) > this.Width)
            {
                carX = this.Width - PlayerCar.Width - 10;
            }
        }

        if (e.KeyCode == Keys.Up)
        {

            speedY = speedY - 1;
            keyPressed = true;
        }

        if (e.KeyCode == Keys.Down)
        {
            speedY = speedY + 3;
            if (speedY > 0)
            {
                speedY = 0;
            }
            keyPressed = true;

        }
    }

    private void timer2_Tick(object sender, EventArgs e)
    {
        if (speedY != 0)
        {

            time++;
            time = time - speedY / 8;
            timeLabel.Text = time.ToString() + " m";
        }
    }

    private void Form1_KeyUp(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Up)
        {
            keyPressed = false;
        }

        if (e.KeyCode == Keys.Down)
        {
            keyPressed = false;
        }

        if (e.KeyCode == Keys.Left)
        {
            keyPressed = false;
        }

        if (e.KeyCode == Keys.Right)
        {
            keyPressed = false;
        }
    }
    private void npcCarMovement()
    {
        npcCar.Invalidate();
        npcCar.Location = new Point(npcCar.Location.X, npcCar.Location.Y + 2);
        npcCar.Location = new Point(npcCar.Location.X, npcCar.Location.Y - speedY);

    }
}
}

Answer 1

You are creating your SoundPlayers in your Conditional Statements, If they are going to be in use for the entire time of your application create them at the class level. Look at this MSDN Article for an explanation

public partial class Form1 : Form
{
    System.Media.SoundPlayer player; //Note that they are created here
    System.Media.SoundPlayer player2; //They will be visible to the entire class
    bool keyPressed;
    public Form1()
    {
        InitializeComponent();
    }

    private void gameSounds()
    {
        if (!keyPressed) //Note that these Booleans are either true/false no need to compare to true or false
        {
            player = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_still.wav");
            player.PlayLooping();
        }
        else //this will be run if keypressed is true
        {
            player2 = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_speeding.wav");
            player2.PlayLooping();
            if(player != null) 
                player.Stop(); 
        }
    }

}

---

Change base on clarification in the comments:

What is happening is when you stop the other soundplayer it stops them all. I would personally put a check to see if your keyPressed variable is already in the same state as what you are wanting to send and if it is not send it. I have modified your gameSounds routine to this:

private void gameSounds()
{
    if (!keyPressed)
    {
        player2.Stop();
        player.PlayLooping();
    }
    else 
    {
        player.Stop();
        player2.PlayLooping();
    }
}

I also put the entire definition for player and player2 in your class level declarations:

System.Media.SoundPlayer player = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_still.wav");
System.Media.SoundPlayer player2 = new System.Media.SoundPlayer(@"C:\Users\Parker\Desktop\Game\car_speeding.wav");

I do not see where you are calling the gameSounds method except in your Form_Load EventHandler but I would make sure that if it the keyPressed variable was already in the same state that you don't keep hitting your gamesounds method just let the sound loop until you change the state of keyPressed.

These are the methods that I was using to test:

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (!keyPressed)
    {
        keyPressed = true;
        gameSounds();
    }
}

private void Form1_KeyUp(object sender, KeyEventArgs e)
{
    if(keyPressed)
    {
        keyPressed = false;
        gameSounds();
    }

}

Answer 2

At it's root, this is a scoping issue. Basically, whenever you write {}, you create a new scope. A line within a given scope has access to that scope, and any scopes it is nested in.

In your if statement, you create the player object (which now lives inside the scope of that if statement). In the else statement, there is no knowledge of the player object because it isn't in a scope accessible to the else block.

To fix this, declare it as a class level variable. You can still assign it in the if statement, just be sure to check for null in the else. You could technically declare it in the function scope (this would make the error go away) but it would be set to null the next time the function is run(and possibly garbage collected) because as soon as the function goes out of scope (returns) all local variables are lost, they have "gone out of scope".