是否有一种简单的方法可以在C＃中向所有表单对象添加事件

Question

I have a form with many labels and text boxes. I'd like to have the title highlighted red if any of the fields are modified. Is there an easy way to do this or do you need to add the event callback to each form object individually? Thanks!

Answer 1

Off the top of my head you could do something like this in the form load event to add the events...

foreach (var control in this.Controls)
{
    if (control is Label)
    {
        ((Label)control).TextChanged += Controls_TextChanged;
    }
    else if (control is TextBox)
    {
        ((TextBox)control).TextChanged += Controls_TextChanged;
    }
}

Answer 2

When you're looking at the events associated with each control, you notice that you can 'drop down' a list of all events coded in the form. If you double click on a 'Text Changed' event, for example, it will be controlname_textchanged(...) . However, if you have a generic handler for all, then you could call it textchangedevent(...) . The generic event handler will need to have the sender and event object associated with that event in the parameters.

If you're doing this in a user control and have to update the main form, then you will bubble this up through a public event eventobject youreventname , and bind that event on the main form.

Answer 3

Something like this should work:

foreach (System.Windows.Forms.Control cont in this.Controls)
            cont.Validating += new System.Windows.Forms.ValidationEventHandler(this.Control_Validating_Method)

Then you could test for the control type in the event code and compare the value with the original value.

Answer 4

Yes you can easily add controls to the same event. This example puts the 'Labels' and 'Textboxes' in the same event.

private void Form1_Load(object sender, EventArgs e)
    {
 foreach (Control x in this.Controls)
            {
                if(x is Label)
                    ((Label)x).MouseHover+=new EventHandler(AllLabels_HoverEvent);
                    else if(x is TextBox)
                    ((TextBox)x).MouseHover+=new EventHandler(AllTextboxes_HoverEvent);
            }
}

void AllLabels_HoverEvent(object sender, EventArgs e)
        {
              Label label = (Label)sender;
           // label.dowhateveryouwant...
        }
        void AllTextboxes_HoverEvent(object sender, EventArgs e)
        {
            Textbox textbox = (Textbox)sender;
           // textbox.dowhateveryouwant...
        }

If you need any more clarification please comment below and I will add on to my answer or modify it to suite any particular needs you have. Be careful though if you have controls nested in other containers they won't be in this.Controls .