Form.visible must be true to read .left and .top?

Question

I create a bunch of forms, and I want to save and restore their position on application close/startup.

However, if the form is not visible, then the .top and .left are both 0. Only when it's visible are these properties populated with their 'real' values.

Right now my kludge is to show each form, save the info, then return it to its previous visible state:

        int i;
        bool formVisible;

        // Show all current forms and form positions in array frmTestPanels
        i = 0;
        while (frmTestPanels[i] != null)
        {
            formVisible = frmTestPanels[i].Visible;
            frmTestPanels[i].Visible = true;
            note(frmTestPanels[i].Text + "(" + frmTestPanels[i].Left.ToString() + ", " + frmTestPanels[i].Top.ToString() + ") visible: " + formVisible.ToString());
            frmTestPanels[i].Visible = formVisible;
            i++;
        }
        note(i.ToString() + " forms present");

note() is a simple function that just displays information.

This, of course, results in flashing all the non-visible forms on shut down (possibly on startup as well? Haven't gotten that far...) which is undesirable.

• Is there another way to get the top and left of the form when it's not visible?
• Alternately, is there a better way to save and restore form state?

Answer 1

What about saving the form location when the form is closed by the user, rather than when the application closes?

Answer 2

Can't you just attach an event handler to each form's Move event and keep track of their locations whenever they move? Their position can only change when they're visible anyway but this way you get notified when they move. And then you can just dump your local cache of each Form's position to disk on shutdown.

I don't have a suitable idea for form creation, though, but I think it is possible to show them in a specified initial position. After all there is a Form.StartupPosition property. And Form.Location. According to the documentation, this should work.

Answer 3

You will need to trap the Closing and Minimizing events on the form, and store the position at that point in time.

These fields are not valid when the form is hidden or minimized.

Answer 4

Whenever the user dismisses/hides/closes/makes invisible/whatevers a form, save its location. And only at this point in time. If the user is getting rid of a form, it must have been on the screen and you won't have to worry about it being not visible.

On the other side, don't create a form until the user asks for it for the first time. When each form is created, read its stored location and set it accordingly.

With this scheme if a form is never shown to the user, it's location will never be restored or saved.

Answer 5

If the form is never seen by the user, Top and Left aren't really applicable, are they? Since they're related to the visual position, and there isn't a visual position...

Once the user has been shown the form at least once, you can capture the Top and Left into local variables before hiding it again, and use those local vars for storage of the position when the form is freed. Then you have an initial position for the next time the form is made visible.