Question

当我在面板中单击鼠标时，我的代码会画一个球。现在，我想要的是当我点击面板时，不仅会出现一个球，而且还会以某种速度移动。现在我并不关心球是否越过了面板的边界。我该怎么做？

public partial class Form1 : Form
{
    ArrayList dotPts = new ArrayList();

    public Form1()
    {
        InitializeComponent();
    }

    private void mainPanel_Paint(object sender, PaintEventArgs e)
    {
        foreach (Point p in dotPts)
        { 
            e.Graphics.FillEllipse(Brushes.Black, p.X, p.Y, 20, 20); 
        }
    }

    private void mainPanel_MouseUp(object sender, MouseEventArgs e)
    {
        Graphics g = Graphics.FromHwnd(this.Handle);
        dotPts.Add(new Point(e.X - 10, e.Y - 10));
        mainPanel.Invalidate();
    }
}

的InitializeComponent（）：

private void InitializeComponent()
    {
        this.mainPanel = new System.Windows.Forms.Panel();
        this.SuspendLayout();
        // 
        // mainPanel
        // 
        this.mainPanel.BackColor = System.Drawing.SystemColors.GradientInactiveCaption;
        this.mainPanel.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
        this.mainPanel.Location = new System.Drawing.Point(12, 12);
        this.mainPanel.Name = "mainPanel";
        this.mainPanel.Size = new System.Drawing.Size(790, 424);
        this.mainPanel.TabIndex = 0;
        this.mainPanel.Paint += new System.Windows.Forms.PaintEventHandler(this.mainPanel_Paint);
        this.mainPanel.MouseUp += new System.Windows.Forms.MouseEventHandler(this.mainPanel_MouseUp);
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(821, 447);
        this.Controls.Add(this.mainPanel);
        this.Name = "Form1";
        this.Text = "Form1";
        this.ResumeLayout(false);

    }

Answer 1

你需要一个计时器。在Tick事件处理程序中计算对象的新位置并调用面板的Invalidate（）方法，以便重新绘制它。如果闪烁太明显，您可以使用PictureBox而不是Panel。

也可以使用ArrayList。这需要成为一个List<Ball>，其中Ball类存储位置以及速度矢量。加上你将来添加的任何其他属性，如颜色或半径。

Answer 2

随着时间的推移，让某些东西平稳移动的一般解决方案是制作一个计时器对象，以便通过每个刻度的速度（或其一部分）来改变球的位置：

  ball.x += xVelocity;
  ball.y += yVelocity;

Answer 3

我有一个示例（快速和脏）代码我试图给你一个想法..（在LINQPAD中运行）

void Main()
{
    Application.Run(new Form1());
}

public class Form1 :Form
{   
    float time3 =0, time =0,time2=1000000,height=20,width=20;int a = -1;
    PointF Location = new PointF(0,0);
    PointF Velocity = new PointF(50,50);
    DateTime dt;
    float x=0;
    System.Timers.Timer tmr = new System.Timers.Timer();
    System.Timers.Timer gmlp = new System.Timers.Timer();
    public Form1()
    {
        this.Size = new Size(700,700);      
        Label lb = new Label();

        tmr.Interval =20;
        tmr.Elapsed += (s,e) => {   

            //if(Location.X >= 500) Velocity.X *= a;

            //if(time3 >= 1000) time=0; else 
            time3 +=20;// (DateTime.Now.Ticks - dt.Ticks)/10000;
            Location.X = Velocity.X * (time3/1000);
            Location.Y = Velocity.Y * (time3/1000);
            this.Invalidate();
            if(time >= time2) {tmr.Stop(); tmr.Enabled = false; gmlp.Stop(); gmlp.Enabled = false;}
        };
        this.DoubleBuffered =true;


        gmlp.Interval = 1000;
        gmlp.Elapsed += (s,e) => {
            //dt = dt.AddSeconds(1);
            lb.Text =  
            "time: " + time + 
            "\ntime2: " + time2 +
            "\ntime3: " +time3 + 
            "\nlocx: " +Location.X +
            "\ntimespan: " + (DateTime.Now.Ticks - dt.Ticks)/10000 + 
            "\nx moved: " + (Location.X - x);
        };
        gmlp.Enabled = true;
        gmlp.Start();
        tmr.Enabled =true;
        tmr.Start();
        lb.Location = new Point(20,20);
        lb.Size = new Size(80,200);
        this.Controls.Add(lb);
        dt = DateTime.Now;
    }

    protected override void OnPaint(PaintEventArgs pe)
    {    
        base.OnPaint(pe);
        pe.Graphics.FillEllipse(Brushes.Tomato, new Rectangle((int)Location.X,(int)Location.Y,(int)height,(int)width));     
    }
}

如何使用WinForms绘制在面板中移动的球？

3 个答案: