拖放仅在其背景中工作的 CustomControl

Posted 2023-05-08

【中文标题】拖放仅在其背景中工作的 CustomControl

【英文标题】：Drag and drop a CustomControl working only from it's background

【发布时间】：2014-06-25 11:29:03

【问题描述】：

我有一个自定义控件，其中包含一个下方带有标签的按钮。我想让这些控件可以拖动到另一个控件上，以便在 flowlayoutpanel 中按我想要的方式排列它们。 现在只有当我将控件从它的背景（在下图中用黄色标记）拖动到另一个控件的黄色标记区域时才有效，但如果我从按钮或标签区域拖动则不行..

我怎样才能做到这一点，以便我可以移动自定义控件，无论我从哪里抓取它并将其放在另一个控件上。基本上只是一个控件，不像按钮和标签的容器..

这是我目前的代码：

 private void flowLayoutPanel1_DragEnter(object sender, DragEventArgs e)
    
        e.Effect = DragDropEffects.Move;
    

    private void flowLayoutPanel1_DragDrop(object sender, DragEventArgs e)
             
        CustomControl target = sender as CustomControl;
        if (target != null)
        
            int targetIndex = FindCSTIndex(target);
            if (targetIndex != -1)
            
                string pictureBoxFormat = typeof(CustomControl).FullName;
                if (e.Data.GetDataPresent(pictureBoxFormat))
                
                    CustomControl source = e.Data.GetData(pictureBoxFormat) as CustomControl;

                    int sourceIndex = this.FindCSTIndex(source);

                    if (targetIndex != -1)
                        this.flowLayoutPanel1.Controls.SetChildIndex(source, targetIndex);
                
            
        
    

    private int FindCSTIndex(CustomControl cst_ctr)
    
        for (int i = 0; i < this.flowLayoutPanel1.Controls.Count; i++)
            
            CustomControl target = this.flowLayoutPanel1.Controls[i] as CustomControl;

            if (cst_ctr == target)
                return i;
        
        return -1;
    

    private void OnCstMouseMove(object sender, MouseEventArgs e)
    
        if (e.Button == MouseButtons.Left)
        
            CustomControl cst = sender as CustomControl;
            cst.DoDragDrop(cst, DragDropEffects.Move);
        
    

还有自定义控件类：

public class CustomControl : Control

    private Button _button;
    private Label _label;

    public CustomControl(Button button, Label label)
    
        _button = button;
        _label = label;
        button.Width = 50;
        button.Height = 50;
        label.Width = 65;
        button.BackgroundImageLayout = ImageLayout.Stretch;
        Height = button.Height + label.Height;
        Width = 68;

        // Width = Math.Max(button.Width, label.Width);
        Controls.Add(_button);
        _button.Location = new Point(0, 0);
        Controls.Add(_label);
        _label.Location = new Point(0, button.Height);
    

【问题讨论】：

我本想回答您 2 天的问题，但由于某些原因没有回答。您需要处理所有子控件中的拖放事件。可以使其自动化：覆盖（或者订阅）ControlAdded/СontrolRemoved 事件并在那里添加/删除拖放事件。

你能举个例子吗？我不知道该怎么做。。谢谢！

【参考方案1】：

使用 MouseDown 而不是 MouseMove 来启动拖放操作 (MSDN)。您可以在控件代码本身中启动拖放（假设所有CustomControls 都可以拖放），否则您可能想要创建公共方法来签署孩子（暴露孩子是个坏主意，除非你已经在外面使用它们）。

public class CustomControl : Control

    ...

    public CustomControl(Button button, Label label)
    
        ...

        _button.MouseDown += OnMouseDown;
        _label.MouseDown += OnMouseDown;
    

    override void OnMouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
    
        if (e.Button == MouseButtons.Left)
            (sender as Control).DoDragDrop(this, DragDropEffects.Move);
    

未经测试，但应该能给你一些想法。

【参考方案2】：

设法解决它：

private void flowLayoutPanel1_DragDrop(object sender, DragEventArgs e)
    
        Control target = new Control();

        target.Parent = sender as Control;

            if (target != null)
            
                int targetIndex = FindCSTIndex(target.Parent);
                if (targetIndex != -1)
                
                    string cst_ctrl = typeof(CustomControl).FullName;
                    if (e.Data.GetDataPresent(cst_ctrl))

                    
                        Button source = new Button();
                        source.Parent = e.Data.GetData(cst_ctrl) as CustomControl;

                        if (targetIndex != -1)
                            this.flowLayoutPanel1.Controls.SetChildIndex(source.Parent, targetIndex);
                    
                
            
        

    private int FindCSTIndex(Control cst_ctr)
    
        for (int i = 0; i < this.flowLayoutPanel1.Controls.Count; i++)
            
            CustomControl target = this.flowLayoutPanel1.Controls[i] as CustomControl;

            if (cst_ctr.Parent == target)
                return i;
        
        return -1;
    

    private void OnCstMouseMove(object sender, MouseEventArgs e)
    
        if (e.Button == MouseButtons.Left)
        
            Control cst = sender as Control;
            cst.DoDragDrop(cst.Parent, DragDropEffects.Move);