如何使計時器向前或向后更改pictureBox1中顯示的圖像？

Question

在form1頂部，我做了：

private bool farwardbackward;
private FileInfo[] fi;

然后，我有4個按鈕單擊事件：

向前：

private void button4_Click(object sender, EventArgs e)
        {
            farwardbackward = true;
            button5.Enabled = true;
            button6.Enabled = true;
            timer5.Start();
        }

和向后：

private void button3_Click(object sender, EventArgs e)
        {
            farwardbackward = false;
            button5.Enabled = true;
            button6.Enabled = true;
            if (current == -1)
                current = fi.Length;
            timer5.Start();
        }

並停止動畫按鈕：

private void button6_Click(object sender, EventArgs e)
        {
            timer5.Stop();
            button6.Enabled = false;
            button5.Text = "Pause Animation";
            button5.Enabled = false;
            Bitmap lastdownloadedimage = new Bitmap(fi[fi.Length -1].FullName);
            pictureBox1.Image = lastdownloadedimage;
        }

最后一個按鈕是暫停/繼續：

private void button5_Click(object sender, EventArgs e)
        {
            b = (Button)sender;

            if (b.Text == "Pause Animation")
            {
                timer5.Enabled = false;
                b.Text = "Continue Animation";
            }
            else
            {
                timer5.Enabled = true;
                b.Text = "Pause Animation";
            }
        }

然后在timer5 tick事件中將其間隔設置為1000ms，我這樣做了：

int current = -1;
        private void timer5_Tick(object sender, EventArgs e)
        {
            if (farwardbackward)
                current = Math.Min(current + 1, fi.Length - 1);
            else
                current = Math.Max(current - 1, 0);

            if (fi.Length > 0)
            {

               Bitmap newbmp = new Bitmap(fi[current].FullName);
               pictureBox1.Image = newbmp;
               pictureBox1.Refresh();
               newbmp.Dispose();
            }            
        }

當我運行程序時，我總是在pictureBox1中看到變量fi的最新/最新圖像。 例如，fi中的第一個圖像是000004.gif，最后一個圖像是050122.gif，我看到050122.gif

現在，當使圖像以動畫gif樣式顯示在pictureBox1中時，邏輯應該是什么？

如果是我第一次單擊按鈕前進，那么現在發生的是它跳轉到圖像000004.gif，然后顯示000005.gif，依此類推...

如果是第一次單擊后退按鈕，那么它將從050122.gif返回到050121.gif，依此類推...

問題是當我向后單擊時，在某些圖像后單擊向前按鈕，然后從原來的圖像繼續並向前移動，但是當到達050122.gif時，它停止了。 並且應該繼續不間斷。 想法是使它不停地移動。 如果到達050122.gif，我不希望它停止。 如果要到達第一個圖像或最后一個圖像，則不斷循環播放。 但是由於某種原因，如果在050122.gif上向后移動時單擊前進按鈕，它將停止。

如果我現在沒記錯的話，是當我在中間單擊以更改動畫方向時。 然后，當到達最后一個圖像或第一個圖像時，它停止。 而且我希望它僅在單擊停止按鈕時才繼續不間斷。

另一件事是在停止按鈕單擊事件中我應該做什么？ 是否應該重置一些值或變量？

這是timer5滴答事件代碼：

int current = -1;
        private void timer5_Tick(object sender, EventArgs e)
        {
            if (fi.Length > 0)
            {
                if (farwardbackward)
                {
                    current = (current >= fi.Length - 1) ? 0 : current++;
                }
                else
                {
                    current = (current <= 0) ? fi.Length - 1 : current--;
                }
                pictureBox1.Image = new Bitmap(fi[current].FullName);
                pictureBox1.Refresh();
            }
        }

單擊以向前或向后移動時，我遇到相同的異常：索引超出數組的范圍

System.IndexOutOfRangeException was caught
  HResult=-2146233080
  Message=Index was outside the bounds of the array.
  Source=My Weather Station
  StackTrace:
       at mws.Form1.timer5_Tick(Object sender, EventArgs e) in d:\C-Sharp\Download File\Downloading-File-Project-Version-012\Downloading File\Form1.cs:line 1317
       at System.Windows.Forms.Timer.OnTick(EventArgs e)
       at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at mws.Program.Main() in d:\C-Sharp\Download File\Downloading-File-Project-Version-012\Downloading File\Program.cs:line 28
  InnerException: 

1317行是：

pictureBox1.Image = new Bitmap(fi[current].FullName);

Answer 1

我認為這對於您的tick方法將是更好的代碼：

if(farwardbackward){
current = (current >= fi.Length-1) ? 0 : current++;
}else{
current = (current <= 0) ? fi.Length-1 : current--;
}
picturebox1.Image = new Bitmap(fi[current].Fullname);
picturebox1.Refresh();

除此之外，我會稍微改變兩個按鈕的方法。

• 停止計時器
• 倒轉布爾
• 重新啟動計時器如果您使用此代碼，您也可以刪除第二個按鈕，僅使用一個！ 您只需要將其文本更改為即可。

@γηράσκωδ'αείπολλάδιδασκόμε：thx，我錯過了這一點

我的解決方案以這種方式很好地工作：

public partial class Form1 : Form
    {
        private string[] fi;
        private int current = 0;
        private Boolean forwardbackward = true;
        private Boolean timerRunning = true;


    public Form1()
    {
        InitializeComponent();
        fi = Directory.GetFiles(@"C://temp/pics");
        timer1.Start();
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        if (fi.Length > 0)
        {
            if (forwardbackward)
            {
                current = (current >= fi.Length - 1) ? 0 : ++current;
            }
            else
            {
                current = (current <= 0) ? fi.Length - 1 : --current;
            }
            pictureBox1.Image = new Bitmap(fi[current]);
            pictureBox1.Refresh();
        }
    }

    private void btn_changeDirection_Click(object sender, EventArgs e)
    {
        timer1.Stop();
        forwardbackward = (forwardbackward) ? false : true;
        timer1.Start();
    }

    private void btn_Pause_Continue_Click(object sender, EventArgs e)
    {
        if (timerRunning)
        {
            timer1.Stop();
            timerRunning = false;
            btn_Pause_Continue.Text = "Continue";
        }
        else
        {
            timer1.Start();
            timerRunning = true;
            btn_Pause_Continue.Text = "Pause";
        }
    }

    private void btn_stop_Click(object sender, EventArgs e)
    {
        timer1.Stop();
    }


}

沒有完美的解決方案，但是它確實可以做到！