Forms

- MakeForm
- SetForm

Widget MakeForm(Widget parent, int where1, Widget from1 int where2, Widget from2)

This function lets you create a new "form" widget in which to put child widgets. A form widget is a container that holds other widgets. Normally there is no need to call this function, but if you want to have separate "groups" of widgets in your display and you can't lay them out that way with SetWidgetPos() , then using multiple form widgets may be the right thing. In addition, a nifty little box gets drawn around the form widget (and all the children) and this can be a nice visual cue in your interface indicating what groups of widgets belong together. A form widget creates a box that surrounds all the widgets contained inside of it (but the form widget itself is inactive and can't be clicked on by the user).

If you use multiple form widgets in your display, the basic logic of how you create the display is a little different. You can think of form widgets as miniature windows inside a larger window.

Once you create a form widget, any other widgets you create with calls like MakeButton() and MakeLabel() become children of this form widget. Before you create another form widget, you must lay out all the children of the current form widget with calls to SetWidgetPos() . After you lay out all the children of the current widget, then you can create another form widget, and repeat the process (or call SetForm() ).

Form widgets are layed out in a manner similar to regular widgets, except that usually their placement is relative to other form widgets. When you create a new form widget (after the first one), you specify where it should be placed relative to other form widgets that you created. The first form widget is always placed in the top left corner of the window.

The `parent' argument to MakeForm() specifies at what level the new form should be created. If you specify TOP_LEVEL_FORM (which is the usual thing to do) the new form is created at the top level of the window. If you pass another form widget for `parent', then this new form widget will be a child of the other form widget. This lets you create hierarchical "boxes" in your display.

The arguments where1, from1, where2, from2 are the same as in SetWidgetPos() . That is, you specify either NO_CARE, PLACE_UNDER, or PLACE_RIGHT for where1 and where2 and the from1/from2 arguments are the widgets you would like to place something to the right of or under (or they are NULL if you specified NO_CARE). See SetWidgetPos() for more documentation.

Now for an example: Let's say we want a display something like this:

          +------------+   +-----------------------+
          | +--------+ |   | +-------------------+ |
          | |  Btn1  | |   | |                   | |
          | +--------+ |   | |                   | |
          |            |   | |                   | |
          | +--------+ |   | |                   | |
          | |  Btn2  | |   | |                   | |
          | +--------+ |   | |                   | |
          +------------+   | |                   | |
                           | |                   | |
                           | |                   | |
                           | +-------------------+ |
                           +-----------------------+

We have two rectangles (forms) which contain other widgets. Inside the leftmost form are two buttons. The form on the right has a single drawing area. Skipping some of the unnecessary details, we could accomplish the above display with the following code:

      form1 = MakeForm(TOP_LEVEL_FORM, NO_CARE, NULL, NO_CARE, NULL);
      w[0]  = MakeButton("Btn1", NULL, NULL);
      w[1]  = MakeButton("Btn2", NULL, NULL);

      SetWidgetPos(w[1], PLACE_UNDER, w[0], NO_CARE, NULL);

      form2 = MakeForm(TOP_LEVEL_FORM, PLACE_RIGHT, form1, NO_CARE, NULL);
      w[2]  = MakeDrawArea(200, 200, NULL, NULL);

As you can see, we create the first form and specify that we don't care where it goes (the first form widget is always placed in the top left corner of the window). Then we create some widgets to place inside of our new form. Next, and this is important, we layout all the widgets inside of the first form. In this case we only need to make one call to SetWidgetPos() . Then we create the next form, and specify that we want to place it to the right of form1. Finally we create a drawing area widget, which is placed inside of form2.

If you want to create hiearchies of form widgets, you would specify the form widget that should be the parent for the first argument to MakeForm() . This can get quite complicted, so you should make sure you know what you're doing if you want to create big hierarchies.

NOTE: It is important that you layout all your widgets before you create a new form (unless you're creating a child form).

SEE ALSO: SetForm() , MakeWindow()

void SetForm(Widget w)

The SetForm() function allows you to change what is considered the current form. Normally you only use this function to set the current form to be TOP_LEVEL_FORM. You can cause your program to crash if you are not careful about what you set as the current form.

The main purpose of this function is to let you create displays that have both form widgets and other "normal" widgets at the same level. Mainly you would want to do this if you wanted a large drawing area (or some other type of widget) but didn't want to bother creating an form widget just to hold that one widget.

After calling this function, you can position any new widgets relative to other widgets (usually form widgets) created at the top level of the window.

The normal calling sequence is: SetForm(TOP_LEVEL_FORM), although you can specify any other form widget you like. Be careful, as it is possible to confuse the X layout routines and cause your program to crash.

NOTE: Before you call SetForm() and start creating new widgets and positioning them, any previous form widgets should be completely layed out (i.e. you called SetWidgetPos() for all child widgets of any previously created form widgets).

SEE ALSO: MakeForm()