C# panel move with collision

问题

I am new to C# and Winforms and try to make a moving panel. It should move right until the end of my window and then back left. It should bounce from side to side. But the only thing happened after hours of trying is that it moves left and stops.

Using this form tools:

Timer = tmrMoveBox (interval: 50)
Panel = pnlBox
Label = lblXY (for showing the X and Y coordinates in the form)

Here are my first best try:

private void tmrMoveBox(object sender, EventArgs e)
{
    if (pnlBox.Location.X <= 316)
    {
        for (int i = 0; i <= 316; i++)
        {
            pnlBox.Location = new Point(
                pnlBox.Location.X + 2, pnlBox.Location.Y);
            string BoxLocationToString = pnlBox.Location.ToString();
            lblXY.Text = BoxLocationToString;
        }
    }

    else if (pnlBox.Location.X >= 0)
    {
        for (int i = 0; i >= 316; i++)
        {
            pnlBox.Location = new Point(
                pnlBox.Location.X - 2, pnlBox.Location.Y);
            string BoxLocationToString = pnlBox.Location.ToString();
            lblXY.Text = BoxLocationToString;
        }
    }
}

And the second best try:

private void tmrMoveBox(object sender, EventArgs e)
{
    int runBox = 1;

    if(runBox == 1)
    {
        while (pnlBox.Location.X <= 316)
        {
            pnlBox.Location = new Point(
                pnlBox.Location.X + 2, pnlBox.Location.Y);
            string BoxLocationString = pnlBox.Location.ToString();
            lblXY.Text = BoxLocationString;
            runBox = 0;
        }
    }
    else
    {
        while(pnlBox.Location.X > 0)
        {
            pnlBox.Location = new Point(
            pnlBox.Location.X - 2, pnlBox.Location.Y);
            string BoxLocationString = pnlBox.Location.ToString();
            lblXY.Text = BoxLocationString;
            runBox = 1;
        }
    }
}

Tried to use a while loop too but then the panel just disappears. I'm no expert and just set this moving panel as a goal for myself. Hope anyone can give me a tip.

EDIT:

Form1.Designer.cs

 this.timer1.Interval = 50;
 this.timer1.Tick += new System.EventHandler(this.tmrMoveBox);
 this.timer1.Start();
 this.timer1.Step = 2;

回答1:

Create a Timer and subscribe to Tick event. Also create new int property Step.

System.Windows.Forms.Timer t = new System.Windows.Forms.Timer();
int Step;

Form1 () 
{
     InitializeComponent()
    ....
     t.Interval = 15000; // specify interval time as you want
     t.Tick += new EventHandler(timer_Tick); 
     t.Start();

     this.Step = 2; 
}

And in ticks event handler put your logic, without while

void timer_Tick(object sender, EventArgs e)
{
        if (pnlBox.Location.X >= 316)
        {
            Step = -2;
        }
        if (pnlBox.Location.X <= 0) 
        {
            Step = 2;
        }

        pnlBox.Location = new Point(
        pnlBox.Location.X + Step , pnlBox.Location.Y);
        string BoxLocationString = pnlBox.Location.ToString();
        lblXY.Text = BoxLocationString;
}

So your box will move on one step per one timer tick.

回答2:

Here is the code I used:

int d= 10;
private void timer1_Tick(object sender, EventArgs e)
{
    //Reverse the direction of move after a collision
    if(panel1.Left==0 || panel1.Right==this.ClientRectangle.Width)
        d = -d;

    //Move panel, also prevent it from going beyond the borders event a point.
    if(d>0)
        panel1.Left = Math.Min(panel1.Left + d, this.ClientRectangle.Width - panel1.Width);
    else
        panel1.Left = Math.Max(panel1.Left + d, 0);
}

Note:

To check the collision you should check:

Collision with left: panel1.Left==0
Collision with right: panel1.Right==this.ClientRectangle.Width

You should not allow the panel goes beyond the borders even a point, so:

The maximum allowed value for your panel left is this.ClientRectangle.Width - panel1.Width
The minimum allowed value for your panel left is 0

Also It's better to use this.ClientRectangle.Width instead of using hard coded 316.

来源：https://stackoverflow.com/questions/33985322/c-sharp-panel-move-with-collision

标签

winforms

panel

collision