My application has several forms. What I want to do is to be able to switch between them (and only between them) using a pair of predefined keys (say Keys.A + Keys.B), just like ALT + TAB does for Windows (windows are shown in foreground). I tried getting the list of forms and then programmatically call Alt + Tab, but, as expected, this allows to switch between all open windows and not only the ones belonging to the application.
Thanks for any help!
You could implement IMessageFilter and add it to your Application, then globally process the messages of your application.
Here is how you do that.
public class MessageFilter : IMessageFilter
{
public bool PreFilterMessage(ref Message m)
{
switch ((WindowsMessage)m.Msg)
{
case WindowsMessage.WM_KEYDOWN:
case WindowsMessage.WM_SYSKEYDOWN:
{
if (((int)m.WParam | ((int)Control.ModifierKeys)) != 0)
{
Keys keyData = (Keys)(int)m.WParam;
var activeForm = Form.ActiveForm;
var forms = Application.OpenForms.Cast<Form>().Where(x => x.Visible).ToArray();
int active = Array.IndexOf(forms, activeForm);
if (keyData == Keys.A)
{
int next = (active + 1)%forms.Length;
forms[next].Activate();//Activate next
}
else if (keyData == Keys.B)
{
int prev = (active - 1) % forms.Length;
forms[prev].Activate();//Activate previous
}
break;
}
}
return false;
}
}
class MainForm : Form
{
protected override void OnLoad(EventArgs e)
{
Application.AddMessageFilter(new MessageFilter());
}
}
You can find WindowsMessage enumeration here.
If you have multiple windows (forms) opened and they have normal caption or belong to MDI, then Ctrl+F6 is a standard shortcut to switch between them.
Otherwise, making a hotkey, to switch between forms is pretty trivial task:
KeyPreview = true and KeyDown | KeyUp event;Application.OpenForms);