如何遍歷Windows窗體表單中的所有控件或如何查找特定控件是否是容器控件？

Question

我會告訴我的要求。 我需要為Windows窗體表單中的每個控件都有一個keydown事件。 如果我必須為所有keydown事件做的事情是相同的，那么最好這樣做而不是為所有控件手動執行它。

所以我基本上可以這樣做：

foreach (Control c in this.Controls)
    c.KeyDown+= new KeyEventHandler(c_KeyDown);

但是在這里，foreach不會循環駐留在groupBox或tabControl中的那些控件。 我的意思是如果表單（this）包含groupBox或其他一些容器控件，那么我可以獲得該特定容器控件的keydown事件。 並且foreach不會foreach駐留在容器控件內的控件。

問題1：如何為表單中的“所有”控件獲取keydown事件？

如果上面的謎題得到解決，那么我的問題就結束了。

這是我可以做的事情：

主要是偽代碼

foreach (Control c in this.Controls)
{
     c.KeyDown += new KeyEventHandler(c_KeyDown);

     if (c is Container control)
           FunctionWhichGeneratesKeyDownForAllItsChildControls(c)
}

我知道如果組框內有組框，我將不得不多次通過FunctionWhichGeneratesKeyDownForAllItsChildControls(c)來獲取所有控件的keydown。 我能做到。 我的問題是，

問題2：如何檢查c是否為容器控件？

Answer 1

一個簡單的遞歸函數應該這樣做。

private void AddEvent(Control parentCtrl)
{
  foreach (Control c in parentCtrl.Controls)
  {
    c.KeyDown += new KeyEventHandler(c_KeyDown);
    AddEvent(c);
  }
}

Answer 2

這與馬格努斯的正確答案相同，但更加充實。 請注意，這會將處理程序添加到每個控件，包括標簽和容器控件。 這些控件似乎不會引發事件，但您可能希望添加邏輯以僅將處理程序添加到接受用戶輸入的控件。

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        RegisterKeyDownHandlers(this);
    }

    private void RegisterKeyDownHandlers(Control control)
    {
        foreach (Control ctl in control.Controls)
        {
            ctl.KeyDown += KeyDownFired;
            RegisterKeyDownHandlers(ctl);
        }
    }

    private void KeyDownFired(object sender, EventArgs e)
    {
        MessageBox.Show("KeyDown fired for " + sender);
    }
}

Answer 3

以下是遍歷控件集合的一些非遞歸選項。 我的具體實現是進行界面驗證，但可以根據您的目的進行調整。

為什么甚至搞亂你說的非遞歸解決方案呢？ 好吧，我在調試一天時遇到堆棧溢出錯誤，所以我看着用循環替換它（這要困難得多）。 事實證明，錯誤是一種僥幸，並且再也沒有發生過

    //recursive
    //This is the simplest implementation, but the most memory hungry
    private IEnumerable<DataObjects.Error> CheckErrors(Control.ControlCollection controls, ErrorProvider errorProvider)
    {
        var errors = new List<DataObjects.Error>();
        foreach (var control in controls.Cast<System.Windows.Forms.Control>())
        {
            //insert your own business logic in here
            var error = errorProvider.GetError(control);
            if (!string.IsNullOrEmpty(error))
            {
                errors.Add(new DataObjects.Error(error, DataObjects.ErrorLevel.Validation));
            }
            //recursive call
            errors.AddRange(CheckErrors(control.Controls, errorProvider));
            //insert your own business logic in here
        }
        return errors;
    }

    //Breadth first - Does NOT require child node to have knowledge of parent
    //Read through the controls at a given level and then blindly delve 
    //deeper until you reach the end of the rainbow
    //order(max-tree-level-size) memory usage?
    //tree-level-size, as in the # of nodes at a given depth
    private IEnumerable<DataObjects.Error> CheckErrors_NonRecursive_NeverLookBack(Control control, ErrorProvider errorProvider)
    {
        var currentControls = control.Controls.Cast<Control>();
        var errors = new List<DataObjects.Error>();

        while (currentControls.Count() > 0)
        {
            foreach (var currentControl in currentControls)
            {
                //insert your own business logic in here
                var error = errorProvider.GetError(currentControl);
                if (!string.IsNullOrEmpty(error))
                {
                    errors.Add(new DataObjects.Error(error, DataObjects.ErrorLevel.Validation));
                }
                //insert your own business logic in here
            }
            //replace currentControls with ALL of the nodes at a given depth
            currentControls = currentControls.SelectMany(x => x.Controls.Cast<Control>());
        }

        return errors;
    }

    //Depth first - Does NOT require child to have knowledge of parent
    //Approximate recursion by keeping a stack of controls, instead of a call stack.
    //Traverse the stack as you would have with recursion
    //order(tree-branch-size) memory usage? tree-branch-size as in the number of nodes 
    //that it takes to get from the root to the bottom of a given branch
    private IEnumerable<DataObjects.Error> CheckErrors_NonRecursive(Control.ControlCollection controls, ErrorProvider errorProvider)
    {
        var controlStack = new Stack<Control.ControlCollection>();
        var controlIndicies = new Stack<int>();
        var errors = new List<DataObjects.Error>();

        controlStack.Push(controls);
        controlIndicies.Push(0);

        while(controlStack.Count() > 0)
        {
            while(controlIndicies.First() < controlStack.First().Count)
            {
                var controlIndex = controlIndicies.Pop();
                var currentControl = controlStack.First()[controlIndex];
                //insert your own business logic in here
                var error = errorProvider.GetError(currentControl);
                if (!string.IsNullOrEmpty(error))
                {
                    errors.Add(new DataObjects.Error(error, DataObjects.ErrorLevel.Validation));
                }
                //insert your own business logic in here

                //update the fact that we've processed one more control
                controlIndicies.Push(controlIndex + 1);
                if(currentControl.Controls.Count > 0)
                {
                    //traverse deeper
                    controlStack.Push(currentControl.Controls);
                    controlIndicies.Push(0);
                }
                //else allow loop to continue uninterrupted, to allow siblings to be processed
            }
            //all siblings have been traversed, now we need to go back up the stack
            controlStack.Pop();
            controlIndicies.Pop();
        }

        return errors;
    }

    //Depth first - DOES require child to have knowledge of parent.
    //Approximate recursion by keeping track of where you are in the control 
    //tree and use the .Parent() and .Controls() methods to traverse the tree.
    //order(depth(tree)) memory usage? 
    //Best of the bunch as far as I can (in memory usage that is)
    private IEnumerable<DataObjects.Error> CheckErrors_NonRecursiveIndicesOnly(Control control, ErrorProvider errorProvider)
    {
        var errors = new List<DataObjects.Error>();
        var controlIndicies = new Stack<int>();
        var controlCount = new Stack<int>();
        Control currentControl = control;
        var currentControls = currentControl.Controls;

        controlCount.Push(currentControls.Count);
        controlIndicies.Push(0);
        while (controlCount.Count() > 0)
        {
            while (controlIndicies.First() < controlCount.First())
            {
                var controlIndex = controlIndicies.Pop();
                currentControl = currentControls[controlIndex];
                //insert your own business logic in here
                var error = errorProvider.GetError(currentControl);
                if (!string.IsNullOrEmpty(error))
                {
                    errors.Add(new DataObjects.Error(error, DataObjects.ErrorLevel.Validation));
                }
                //insert your own business logic in here

                //update the fact that we've processed one more control
                controlIndicies.Push(controlIndex + 1);
                if (currentControl.Controls.Count > 0)
                {
                    //traverse deeper
                    currentControls = currentControl.Controls;
                    controlCount.Push(currentControl.Controls.Count);
                    controlIndicies.Push(0);
                }
                else
                {
                    //allow loop to continue uninterrupted, to allow siblings to be processed
                }
            }
            //all siblings have been traversed, now we need to go back up the stack
            controlCount.Pop();
            controlIndicies.Pop();

            //need to check our position in the stack... once we get back to the top there is no parent of parent.
            if (controlCount.Count() > 0)
            {
                currentControls = currentControl.Parent.Parent.Controls;
            }
            //do nothing, believe it or not once you've gotten to this level you have traversed the entire stack
        }

        return errors;
    }

Answer 4

問題2的答案是使用您正在檢查的控件的GetType（）方法。