Fl_Window

## class Fl_Window

### Class Hierarchy

    Fl_Group
       |
       +----Fl_Window
               |
               +----Fl_Double_Window, Fl_Gl_Window,
                    Fl_Overlay_Window, Fl_Single_Window

### Include Files

    #include <FL/Fl_Window.H>

### Description

This widget produces an actual window. This can either be a main window, with a border and title and all the window management controls, or a "subwindow" inside a window. This is controlled by whether or not the window has a `parent()`.

Once you create a window, you usually add children `Fl_Widget` 's to it by using `window->add(child)` for each new widget. See `Fl_Group` for more information on how to add and remove children.

There are several subclasses of `Fl_Window` that provide double-buffering, overlay, menu, and OpenGL support.

The window's callback is done if the user tries to close a window using the window manager and `Fl::modal()` is zero or equal to the window. `Fl_Window` has a default callback that calls `Fl_Window::hide()`.

### Methods

Fl_Window ~Fl_Window border clear_border current cursor | free_position fullscreen fullscreen_off hide hotspot | iconize iconlabel label make_current modal | non_modal resize set_modal set_non_modal show | shown size_range xclass

#### Fl_Window::Fl_Window(int w, int h, const char *title = 0)
Fl_Window::Fl_Window(int x, int y, int w, int h, const char *title = 0)

Creates a new window. If `Fl_Group::current()` is not `NULL`, the window is created as a subwindow of the parent window.

The first form of the constructor creates a top-level window and asks the window manager to position the window. The second form of the constructor either creates a subwindow or a top-level window at the specified location, subject to window manager configuration. If you do not specify the position of the window, the window manager will pick a place to show the window or allow the user to pick a location. Use `position(x,y)` or `hotspot()` before calling `show()` to request a position on the screen. See `Fl_Window::resize()` for some more details on positioning windows.

Top-level windows initially have `visible()` set to 0 and `parent()` set to `NULL`. Subwindows initially have `visible()` set to 1 and `parent()` set to the parent window pointer.

`Fl_Widget::box()` defaults to `FL_FLAT_BOX`. If you plan to completely fill the window with children widgets you should change this to `FL_NO_BOX`. If you turn the window border off you may want to change this to `FL_UP_BOX`.

#### virtual Fl_Window::~Fl_Window()

The destructor also deletes all the children. This allows a whole tree to be deleted at once, without having to keep a pointer to all the children in the user code. A kludge has been done so the `Fl_Window` and all of its children can be automatic (local) variables, but you must declare the `Fl_Window` first so that it is destroyed last.

#### void Fl_Window::size_range(int minw, int minh, int maxw=0, int maxh=0, int dw=0, int dh=0, int aspect=0)

Set the allowable range the user can resize this window to. This only works for top-level windows.

- `minw` and `minh` are the smallest the window can be. Either value must be greater than 0.
- `maxw` and `maxh` are the largest the window can be. If either is equal to the minimum then you cannot resize in that direction. If either is zero then FLTK picks a maximum size in that direction such that the window will fill the screen.
- `dw` and `dh` are size increments. The window will be constrained to widths of `minw + N * dw`, where `N` is any non-negative integer. If these are less or equal to 1 they are ignored. (this is ignored on WIN32)
- `aspect` is a flag that indicates that the window should preserve its aspect ratio. This only works if both the maximum and minimum have the same aspect ratio. (ignored on WIN32 and by many X window managers)

If this function is not called, FLTK tries to figure out the range from the setting of `resizable()`:

- If `resizable()` is `NULL` (this is the default) then the window cannot be resized and the resize border and max-size control will not be displayed for the window.
- If either dimension of `resizable()` is less than 100, then that is considered the minimum size. Otherwise the `resizable()` has a minimum size of 100.
- If either dimension of `resizable()` is zero, then that is also the maximum size (so the window cannot resize in that direction).

It is undefined what happens if the current size does not fit in the constraints passed to `size_range()`.

#### virtual void Fl_Window::show()
void Fl_Window::show(int argc, char **argv)

Put the window on the screen. Usually this has the side effect of opening the display. The second form is used for top-level windows and allows standard arguments to be parsed from the command-line.

If the window is already shown then it is restored and raised to the top. This is really convenient because your program can call `show()` at any time, even if the window is already up. It also means that `show()` serves the purpose of `raise()` in other toolkits.

#### virtual void Fl_Window::hide()

Remove the window from the screen. If the window is already hidden or has not been shown then this does nothing and is harmless.

#### int Fl_Window::shown() const

Returns non-zero if `show()` has been called (but not `hide()` ). You can tell if a window is iconified with `(w->shown() && !w->visible())`.

#### void Fl_Window::iconize()

Iconifies the window. If you call this when `shown()` is false it will `show()` it as an icon. If the window is already iconified this does nothing.

Call `show()` to restore the window.

When a window is iconified/restored (either by these calls or by the user) the `handle()` method is called with `FL_HIDE` and `FL_SHOW` events and `visible()` is turned on and off.

There is no way to control what is drawn in the icon except with the string passed to `Fl_Window::xclass()`. You should not rely on window managers displaying the icons.

#### void Fl_Window::resize(int,int,int,int)

Change the size and position of the window. If `shown()` is true, these changes are communicated to the window server (which may refuse that size and cause a further resize). If `shown()` is false, the size and position are used when `show()` is called. See `Fl_Group` for the effect of resizing on the child widgets.

You can also call the `Fl_Widget` methods `size(x,y)` and `position(w,h)`, which are inline wrappers for this virtual function.

A top-level window can not force, but merely suggest a position and size to the operating system. The window manager may not be willing or able to display a window at the desired position or with the given dimensions. It is up to the application developer to verify window parameters after the `resize` request.

#### void Fl_Window::free_position()

Undoes the effect of a previous `resize()` or `show()` so that the next time `show()` is called the window manager is free to position the window.

#### void Fl_Window::hotspot(int x, int y, int offscreen = 0)
void Fl_Window::hotspot(const Fl_Widget*, int offscreen = 0)
void Fl_Window::hotspot(const Fl_Widget&, int offscreen = 0)

`position()` the window so that the mouse is pointing at the given position, or at the center of the given widget, which may be the window itself. If the optional `offscreen` parameter is non-zero, then the window is allowed to extend off the screen (this does not work with some X window managers).

#### void Fl_Window::fullscreen()

Makes the window completely fill the screen, without any window manager border visible. You must use `fullscreen_off()` to undo this. This may not work with all window managers.

#### int Fl_Window::fullscreen_off(int x, int y, int w, int h)

Turns off any side effects of `fullscreen()` and does `resize(x,y,w,h)`.

#### int Fl_Window::border(int)
uchar Fl_Window::border() const

Gets or sets whether or not the window manager border is around the window. The default value is true. `border(n)` can be used to turn the border on and off, and returns non-zero if the value has been changed. Under most X window managers this does not work after `show()` has been called, although SGI's 4DWM does work.

#### void Fl_Window::clear_border()

`clear_border()` is a fast inline function to turn the border off. It only works before `show()` is called.

#### void Fl_Window::set_modal()

A "modal" window, when `shown()`, will prevent any events from being delivered to other windows in the same program, and will also remain on top of the other windows (if the X window manager supports the "transient for" property). Several modal windows may be shown at once, in which case only the last one shown gets events. You can see which window (if any) is modal by calling `Fl::modal()`.

#### uchar Fl_Window::modal() const

Returns true if this window is modal.

#### void Fl_Window::set_non_modal()

A "non-modal" window (terminology borrowed from Microsoft Windows) acts like a `modal()` one in that it remains on top, but it has no effect on event delivery. There are three states for a window: modal, non-modal, and normal.

#### uchar Fl_Window::non_modal() const

Returns true if this window is modal or non-modal.

#### void Fl_Window::label(const char*)
const char* Fl_Window::label() const

Gets or sets the window title bar label.

#### void Fl_Window::iconlabel(const char*)
const char* Fl_Window::iconlabel() const

Gets or sets the icon label.

#### void Fl_Window::xclass(const char*)
const char* Fl_Window::xclass() const

A string used to tell the system what type of window this is. Mostly this identifies the picture to draw in the icon. Under X, this is turned into a `XA_WM_CLASS` pair by truncating at the first non-alphanumeric character and capitalizing the first character, and the second one if the first is 'x'. Thus "foo" turns into "foo, Foo", and "xprog.1" turns into "xprog, XProg". This only works if called before calling `show()`.

Under Microsoft Windows this string is used as the name of the WNDCLASS structure, though it is not clear if this can have any visible effect. The passed pointer is stored unchanged. The string is not copied.

#### void Fl_Window::make_current()

`make_current()` sets things up so that the drawing functions in `<FL/fl_draw.H>` will go into this window. This is useful for incremental update of windows, such as in an idle callback, which will make your program behave much better if it draws a slow graphic. Danger: incremental update is very hard to debug and maintain!

This method only works for the `Fl_Window` and `Fl_Gl_Window` classes.

#### static Fl_Window* Fl_Window::current()

Returns the last window that was made current.

#### void Fl_Window::cursor(Fl_Cursor, Fl_Color = FL_WHITE, Fl_Color = FL_BLACK)

Change the cursor for this window. This always calls the system, if you are changing the cursor a lot you may want to keep track of how you set it in a static variable and call this only if the new cursor is different.

The type `Fl_Cursor` is an enumeration defined in `<FL/Enumerations.H>`. (Under X you can get any XC_cursor value by passing `Fl_Cursor((XC_foo/2)+1)`). The colors only work on X, they are not implemented on WIN32.