Fl_Input

## class Fl_Input

### Class Hierarchy

    Fl_Input_
       |
       +----Fl_Input
               |
               +----Fl_File_Input, Fl_Float_Input,
    	        Fl_Int_Input, Fl_Multiline_Input,
    		Fl_Output, Fl_Secret_Input

### Include Files

    #include <FL/Fl_Input.H>

### Description

This is the FLTK text input widget. It displays a single line of text and lets the user edit it. Normally it is drawn with an inset box and a white background. The text may contain any characters (even 0), and will correctly display anything, using ^X notation for unprintable control characters and \nnn notation for unprintable characters with the high bit set. It assumes the font can draw any characters in the ISO-8859-1 character set.

Mouse button 1 | Moves the cursor to this point. Drag selects characters. Double click selects words. Triple click selects all text. Shift+click extends the selection. When you select text it is automatically copied to the clipboard.
Mouse button 2 | Insert the clipboard at the point clicked. You can also select a region and replace it with the clipboard by selecting the region with mouse button 2.
Mouse button 3 | Currently acts like button 1.
Backspace | Deletes one character to the left, or deletes the selected region.
Enter | May cause the callback, see when().
^A or Home | Go to start of line.
^B or Left | Move left
^C | Copy the selection to the clipboard
^D or Delete | Deletes one character to the right or deletes the selected region.
^E or End | Go to the end of line.
^F or Right | Move right
^K | Delete to the end of line (next \n character) or deletes a single \n character. These deletions are all concatenated into the clipboard.
^N or Down | Move down (for Fl_Multiline_Input only, otherwise it moves to the next input field).
^P or Up | Move up (for Fl_Multiline_Input only, otherwise it moves to the previous input field).
^U | Delete everything.
^V or ^Y | Paste the clipboard
^X or ^W | Copy the region to the clipboard and delete it.
^Z or ^_ | Undo. This is a single-level undo mechanism, but all adjacent deletions and insertions are concatenated into a single "undo". Often this will undo a lot more than you expected.
Shift+move | Move the cursor but also extend the selection.
RightCtrl or Compose | Start a compose-character sequence. The next one or two keys typed define the character to insert (see table that follows.) For instance, to type "á" type [compose][a]['] or [compose]['][a]. The character "nbsp" (non-breaking space) is typed by using [compose][space]. The single-character sequences may be followed by a space if necessary to remove ambiguity. For instance, if you really want to type "ª~" rather than "ã" you must type [compose][a][space][~]. The same key may be used to "quote" control characters into the text. If you need a `^Q` character you can get one by typing [compose][Control+Q]. X may have a key on the keyboard defined as `XK_Multi_key`. If so this key may be used as well as the right-hand control key. You can set this up with the program `xmodmap`. If your keyboard is set to support a foreign language you should also be able to type "dead key" prefix characters. On X you will actually be able to see what dead key you typed, and if you then move the cursor without completing the sequence the accent will remain inserted.

Character Composition Table
Keys | Char | Keys | Char | Keys | Char | Keys | Char | Keys | Char | Keys | Char
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
`sp` | nbsp | `*` | ° | `` A` | À | `D -` | Ð | `` a` | à | `d -` | ð
`!` | ¡ | `+ -` | ± | `' A` | Á | `~ N` | Ñ | `' a` | á | `~ n` | ñ
`%` | ¢ | `2` | ² | `A ^` | Â | `` O` | Ò | `^ a` | â | `` o` | ò
`#` | £ | `3` | ³ | `~ A` | Ã | `' O` | Ó | `~ a` | ã | `' o` | ó
`$` | ¤ | `'` | ´ | `: A` | Ä | `^ O` | Ô | `: a` | ä | `^ o` | ô
`y =` | ¥ | `u` | µ | `* A` | Å | `~ O` | Õ | `* a` | å | `~ o` | õ
`|` | ¦ | `p` | ¶ | `A E` | Æ | `: O` | Ö | `a e` | æ | `: o` | ö
`&` | § | `.` | · | `, C` | Ç | `x` | × | `, c` | ç | `- :` | ÷
`:` | ¨ | `,` | ¸ | `E `` | È | `O /` | Ø | `` e` | è | `o /` | ø
`c` | © | `1` | ¹ | `' E` | É | `` U` | Ù | `' e` | é | `` u` | ù
`a` | ª | `o` | º | `^ E` | Ê | `' U` | Ú | `^ e` | ê | `' u` | ú
`< <` | « | `> >` | » | `: E` | Ë | `^ U` | Û | `: e` | ë | `^ u` | û
`~` | ¬ | `1 4` | ¼ | `` I` | Ì | `: U` | Ü | `` i` | ì | `: u` | ü
`-` |  | `1 2` | ½ | `' I` | Í | `' Y` | Ý | `' i` | í | `' y` | ý
`r` | ® | `3 4` | ¾ | `^ I` | Î | `T H` | Þ | `^ i` | î | `t h` | þ
`_` | ¯ | `?` | ¿ | `: I` | Ï | `s s` | ß | `: i` | ï | `: y` | ÿ

### Methods

Fl_Input ~Fl_Input cursor_color | index size | static_value textcolor | textfont textsize | value when

#### Fl_Input::Fl_Input(int x, int y, int w, int h, const char *label = 0)

Creates a new `Fl_Input` widget using the given position, size, and label string. The default boxtype is `FL_DOWN_BOX`.

#### virtual Fl_Input::~Fl_Input()

Destroys the widget and any value associated with it.

#### const char *Fl_Input::value() const
int Fl_Input::value(const char*)
int Fl_Input::value(const char*, int)

The first form returns the current value, which is a pointer to the internal buffer and is valid only until the next event is handled.

The second two forms change the text and set the mark and the point to the end of it. The string is copied to the internal buffer. Passing `NULL` is the same as "". This returns non-zero if the new value is different than the current one. You can use the second version to directly set the length if you know it already or want to put nul's in the text.

#### int Fl_Input::static_value(const char*)
int Fl_Input::static_value(const char*, int)

Change the text and set the mark and the point to the end of it. The string is not copied. If the user edits the string it is copied to the internal buffer then. This can save a great deal of time and memory if your program is rapidly changing the values of text fields, but this will only work if the passed string remains unchanged until either the `Fl_Input` is destroyed or `value()` is called again.

#### int Fl_Input::size() const

Returns the number of characters in `value()`. This may be greater than `strlen(value())` if there are nul characters in it.

#### char Fl_Input::index(int) const

Same as `value()[n]`, but may be faster in plausible implementations. No bounds checking is done.

#### Fl_When Fl_Widget::when() const
void Fl_Widget::when(Fl_When)

Controls when callbacks are done. The following values are useful, the default value is `FL_WHEN_RELEASE`:

- `0`: The callback is not done, but `changed()` is turned on.
- `FL_WHEN_CHANGED`: The callback is done each time the text is changed by the user.
- `FL_WHEN_RELEASE`: The callback will be done when this widget loses the focus, including when the window is unmapped. This is a useful value for text fields in a panel where doing the callback on every change is wasteful. However the callback will also happen if the mouse is moved out of the window, which means it should not do anything visible (like pop up an error message). You might do better setting this to zero, and scanning all the items for `changed()` when the OK button on a panel is pressed.
- `FL_WHEN_ENTER_KEY`: If the user types the Enter key, the entire text is selected, and the callback is done if the text has changed. Normally the Enter key will navigate to the next field (or insert a newline for a `Fl_Mulitline_Input`), this changes the behavior.
- `FL_WHEN_ENTER_KEY|FL_WHEN_NOT_CHANGED`: The Enter key will do the callback even if the text has not changed. Useful for command fields.

#### Fl_Color Fl_Input::textcolor() const
void Fl_Input::textcolor(Fl_Color)

Gets or sets the color of the text in the input field.

#### Fl_Font Fl_Input::textfont() const
void Fl_Input::textfont(Fl_Font)

Gets or sets the font of the text in the input field.

#### uchar Fl_Input::textsize() const
void Fl_Input::textsize(uchar)

Gets or sets the size of the text in the input field.

#### Fl_Color Fl_Input::cursor_color() const
void Fl_Input::cursor_color(Fl_Color)

Get or set the color of the cursor. This is black by default.