Question

我正在尝试使用包含一些垂直堆叠面板的表单，并且我尝试执行一些拖放操作，以便可以重新排序。到目前为止，除了我无法弄清楚的一个错误之外，它运作良好前提是它是一个必须垂直堆叠的文件列表，但可以根据用户的需要重新排序，以形成我稍后生产的文档的页面列表。

尝试以下代码，您应该获得一个包含6个堆叠面板的表单。单击并向上或向下拖动其中任何一个，它们将重新排序。

问题是，如果您上下拖动 非常快 ，它们会开始相互重叠。
我已经将快捷键CTRL + B放在那里，以便在任何给定时间列出当前的面板顶部位置，并且当您不应该看到时，您会看到重复的数字。

问题在于MouseMove事件。我确定这种情况类似于竞争条件，字典无法跟上，或者索引的计算速度不够快，但我却摸不着头脑。我试过锁定它们但它没有帮助我确信有更好的方法来实现这一点，所以我愿意接受建议，但考虑到这将永远不会超过30个面板，这符合我的需求。

为凌乱而道歉，我打算稍后整理一下！

public Form1()
{
    InitializeComponent();
    this.SuspendLayout();
    this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
    this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
    this.ClientSize = new System.Drawing.Size(284, 601);
    this.DoubleBuffered = true;
    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
    this.MaximizeBox = false;
    this.MaximumSize = new System.Drawing.Size(300, 640);
    this.MinimumSize = new System.Drawing.Size(300, 640);
    this.Name = "Form1";
    this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
    this.Text = "Form1";
    this.Load += new System.EventHandler(this.Form1_Load);
    this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown);
    this.ResumeLayout(false);
}

Dictionary<int, Panel> panelPositions = new Dictionary<int, Panel>();
static Random rnd = new Random();
int y;
int start;
static int index, previndex, currentindex, newindex, maxindex;
bool isDragging;
Panel currentPanel;
static readonly object Lock = new Object();

private void Form1_Load(object sender, EventArgs e)
{
    Width = 300;
    Height = 640;
    int count = 5;
    int currentTop = 0;
    for (int i = 0; i <= count; i++)
    {
        Panel panel = new Panel();
        panel.Width = 300;
        panel.Height = 100;
        panel.Top = currentTop;
        panel.BackColor = RandomColor();
        panel.Margin = Padding.Empty;
        panel.Padding = Padding.Empty;
        panel.BorderStyle = BorderStyle.None;

        Label label = new Label();
        label.Font = new Font("Segoe UI", 24.0f);
        label.Text = (i + 1).ToString();
        label.Top = 20;
        label.Left = 20;
        label.AutoSize = true;

        panel.Controls.Add(label);
        panel.MouseDown += new MouseEventHandler(MouseisDown);
        panel.MouseMove += new MouseEventHandler(MouseMoves);
        panel.MouseUp += new MouseEventHandler(MouseisUp);

        lock (Lock)
        {
            panelPositions.Add(i, panel);
        }

        Controls.Add(panel);

        currentTop += 100;
    }

    lock (Lock)
    {
        maxindex = panelPositions.Count - 1;
    }
}

private void MouseisUp(object sender, MouseEventArgs e)
{
    if (isDragging)
    {
        if (newindex < maxindex)
        {
            currentPanel.Top = newindex * 100;
        }
        else
        {
            currentPanel.Top = maxindex * 100;
        }
    }

    isDragging = false;
}

// I'M SURE THE PROBLEM IS IN HERE SOMEWHERE.
private void MouseMoves(object sender, MouseEventArgs e)
{
    // CHECK THE MOUSE IS STILL DOWN
    if (isDragging)
    {
        // DRAG PANEL VERTICALLY WITH MOUSE
        currentPanel.Location = new Point(currentPanel.Left, e.Y + currentPanel.Top - y);

        // WORK OUT NEW INDEX POSITION
        newindex = 0;
        if ((currentPanel.Top + e.Y) > 0)
        {
            newindex = ((currentPanel.Top + e.Y) / 100);
        }

        // NEW POSITION?
        if (currentindex != newindex)
        {
            // TRACK CHANGES
            previndex = currentindex;
            currentindex = newindex;

            /* PRETTY SURE IT'S THIS BIT THAT'S WRONG */
            // CHECK WE'RE NOT OUT OF BOUNDS
            if (currentindex <= maxindex)
            {
                lock (Lock)
                {
                    // RE-ARRANGE PANEL INDEX
                    panelPositions[previndex] = panelPositions[currentindex];
                    panelPositions[currentindex] = currentPanel;
                    panelPositions[previndex].Top = previndex * 100;
                }
            }
        }
    }
}

private void MouseisDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        currentPanel = sender as Panel;
        isDragging = true;
        currentPanel.BringToFront();
        y = e.Y;
        start = currentPanel.Top;

        int i = 0;
        if (currentPanel.Top > 0)
        {
            i = currentPanel.Top;
            i = (i / 100);
        }
        index = i;

        previndex = i;
        currentindex = i;
    }
    else
    {
        isDragging = false;
    }
}

private Color RandomColor()
{
    Color randColor;

    randColor = Color.FromArgb(RandomRGB(), RandomRGB(), RandomRGB());

    return randColor;
}
private int RandomRGB()
{
    return rnd.Next(1, 256);
}

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Control && e.KeyCode == Keys.B)
    {
        string message = string.Empty;
        int count = panelPositions.Count;
        for (int i = 0; i < count; i++)
        {
            message += @"Panel " + i.ToString() + @": " + panelPositions[i].Top.ToString() + Environment.NewLine;
        }
        MessageBox.Show(message);
    }
}

谢谢！

编辑：我认为当面板超出表单的底部范围时，它会有所作为。如果您在表单中拖动，则问题不会发生。我认为这与之前的索引有关，但我无法看到它。

Answer 1

更改

    // NEW POSITION?
    if (currentindex != newindex)

要

    // NEW POSITION?
    if (currentindex != newindex && newindex <= maxindex)

我想你知道为什么：）

P.s：你的＆＃34;编辑＆＃34;部分有点误导。

由于索引不正确，拖放面板控件重叠

1 个答案: