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### 16.4 Other Button Routines

The application program can also set a button to be pushed or not itself without a user action. To this end use the routine

    void fl_set_button(FL_OBJECT *obj, int pushed);

`pushed` indicates whether the button should be set to be pushed (1) or released (0). When setting a `FL_RADIO_BUTTON` to be pushed this automatically releases the currently pushed radio button in the same form (or group). Also note that this routine only simulates the visual appearance but does not affect the program flow in any way, i.e., setting a button as being pushed does not invoke its callback or results in the button becoming returned to the program. For that follow up the call of `fl_set_button()` with a call of `fl_trigger_object()` (or `fl_call_object_callback()`).

To figure out whether a button is pushed or not use12

    int fl_get_button(FL_OBJECT *obj);

Sometimes you want to give the button a different meaning depending on which mouse button gets pressed on it. To find out which mouse button was used at the last push (or release) use the routine

    int fl_get_button_numb(FL_OBJECT *obj);

It returns one of the constants `FL_LEFT_MOUSE`, `FL_MIDDLE_MOUSE`, `FL_RIGHT_MOUSE`, `FL_SCROLLUP_MOUSE` or `FL_SCROLLDOWN_MOUSE` (the latter two are from the scroll wheel of the mouse). If the last push was triggered by a shortcut (see below), the function returns the `keysym` (ASCII value if the key used is between 0 and 127) of the key plus `FL_SHORTCUT`. For example, if a button has `<Ctrl>-C` as its shortcut the button number returned upon activation of the shortcut will be `FL_SHORTCUT + 3` (the ASCII value of `<Ctrl>-C` is 3).

It can also be controlled which mouse buttons a buttons reacts to (per default a button reacts to all mouse buttons, including the scroll wheel). To set which mouse buttons the button reacts to use

    void fl_set_button_mouse_buttons(FL_OBJECT *obj, int mbuttons);

`mbuttons` is the bitwise OR of the numbers 1 for the left mouse button, 2 for the middle, 4 for the right mouse button, 8 for moving the scroll wheel up "button" and 16 for scrolling down "button". Per default a button reacts to all mouse buttons.

To determine which mouse buttons a button is reacting to use

    void fl_get_button_mouse_buttons(FL_OBJECT *obj,
                                     unsigned int *mbuttons);

The value returned via `mbuttons` is the same value as would be used in `fl_set_button_mouse_buttons()`.

In a number of situations it is useful to define a keyboard equivalent for a button. You might e.g., want to define that `<Ctrl>Q` has the same meaning as pressing the "Quit" button. This can be achieved using the following call:

    void fl_set_button_shortcut(FL_OBJECT *obj, const char *str,
                                int showUL);

Note that `str` is a string, not a single character. This string is a list of all the characters to become keyboard shortcuts for the button. E.g., if you use string "^QQq" the button will react on the keys `q`, `Q` and `<Ctrl>Q`. (As you see you can use the symbol `^` to indicate the control key. Similarly you can use the symbol `#` to indicate the `<Alt>` key.) Be careful with your choices. When the form also contains input fields you probably don’t want to use the normal printable characters because they can no longer be used for input in the input fields. Shortcuts are always evaluated before input fields. Other special keys, such as `<F1>` etc., can also be used as shortcuts. See Shortcuts, for details. Finally, keep in mind that a button of type `FL_RETURN_BUTTON` is in fact nothing more than a normal button, just with the `<Return>` key set as the shortcut. So don’t change the shortcuts for such a button.

If the third parameter `showUL` is true and one of the letters in the object label matches the shortcut the matching letter will be underlined. This applies to non-printable characters (such as `#A`) as well in the sense that if the label contains the letter `a` or `A` it will be underlined (i.e., special characters such as `#` and `^` are ignored when matching). A false value (0) for `showUL` turns off underlining without affecting the shortcut. Note that although the entire object label is searched for matching character to underline of the shortcut string itself only the first (non-special) character is considered, thus a shortcut string of `"Yy"` for the label `"Yes"` will result in the letter `Y` becoming underlined while for `"yY"` it won’t.

To set the bitmap to use for a bitmap button the following functions can be used:

    void fl_set_bitmapbutton_data(FL_OBJECT *obj, int w, int h,
                                  unsigned char *bits);
    void fl_set_bitmapbutton_file(FL_OBJECT *obj, const char *filename);

Similarly, to set the pixmap to use for a pixmap button the following routines can be used:

    void fl_set_pixmapbutton_data(FL_OBJECT *obj, unsigned char **bits);
    void fl_set_pixmapbutton_file(FL_OBJECT *obj, const char *file);
    void fl_set_pixmapbutton_pixmap(FL_OBJECT *obj, Pixmap id,
                                     Pixmap mask);

To use the first routine, you `#include` the pixmap file into your source code and use the pixmap definition data (an array of char pointers) directly. For the second routine the filename `file` that contains the pixmap definition is used to specify the pixmap. The last routine assumes that you already have a X Pixmap resource ID for the pixmap you want to use. Note that these routines do not free a pixmap already associated with the button. To free the pixmaps use the function

    void fl_free_pixmapbutton_pixmap(FL_OBJECT *obj);

This function frees the pixmap and mask together with all the colors allocated for them.

To get the pixmap and mask that is currently being displayed, use the following routine

    Pixmap fl_get_pixmapbutton_pixmap(FL_OBJECT *obj,
                                      Pixmap &pixmap, Pixmap &mask);

Pixmaps are by default displayed centered inside the bounding box. However, this can be changed using the following routine

    void fl_set_pixmapbutton_align(FL_OBJECT *obj, int align,
                                   int xmargin, int ymargin);

where `align` is the same as that used for labels. See Label Attributes and Fonts, for a list. `xmargin` and `ymargin` are extra margins to leave in addition to the object border width. Note that although you can place a pixmap outside of the bounding box, it probably is not a good idea.

When the mouse enters a pixmap button an outline of the button is shown. If required, a different pixmap (the focus pixmap) can also be shown. To set such a focus pixmap the following functions are available:

    void fl_set_pixmapbutton_focus_data(FL_OBJECT *obj,
                                         unsigned char **bits);
    void fl_set_pixmapbutton_focus_file(FL_OBJECT *obj,
                                        const char *file);
    void fl_set_pixmapbutton_focus_pixmap(FL_OBJECT *obj, Pixmap id,
                                          Pixmap mask);

The meanings of the parameters are the same as that in the regular pixmap routines.

Finally, there’s a function that can be used to enable or disable the focus outline

    void fl_set_pixmapbutton_focus_outline(FL_OBJECT *obj, int yes_no);

See also Pixmap Object, for pixmap color and transparency handling.

To get rid of a focus pixmap of a pixmap button use the function

    void fl_free_pixmap_focus_pixmap(FL_OBJECT *obj);

#### Footnotes

### (12)

`fl_mouse_button()` can also be used.

Next: Button Attributes, Previous: Button Interaction, Up: Part III Button-like Objects [Contents][Index]