B - Function Reference

This appendix describes all of the fl_ functions. For a description of the FLTK classes, see Appendix A.

Function List by Name

Function List by Category

fl_alert

Include Files

#include <FL/fl_ask.H>

Prototype

void fl_alert(const char *, ...);

Description

Same as fl_message() except for the "!" symbol.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

fl_ask

Include Files

#include <FL/fl_ask.H>

Prototype

int fl_ask(const char *, ...);

Description

Displays a printf-style message in a pop-up box with an "Yes" and "No" button and waits for the user to hit a button. The return value is 1 if the user hits Yes, 0 if they pick No or another dialog box is still open. The enter key is a shortcut for Yes and ESC is a shortcut for No.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

Note: Use of this function is strongly discouraged, and it will be removed in a later FLTK release. Instead, use fl_choice() and provide unambiguous verbs in place of "Yes" and "No".

fl_beep

Include Files

#include <FL/fl_ask.H>

Prototype

void fl_beep(int type = FL_BEEP_DEFAULT)

Description

Sounds an audible notification; the default type argument sounds a simple "beep" sound. Other values for type may use a system or user-defined sound file:

• FL_BEEP_DEFAULT - Make a generic "beep" sound.
• FL_BEEP_MESSAGE - Make a sound appropriate for an informational message.
• FL_BEEP_ERROR - Make a sound appropriate for an error message.
• FL_BEEP_QUESTION - Make a sound appropriate for a question.
• FL_BEEP_PASSWORD - Make a sound appropriate for a password prompt.
• FL_BEEP_NOTIFICATION - Make a sound appropriate for an event notification ("you have mail", etc.)

fl_choice

Include Files

#include <FL/fl_ask.H>

Prototype

int fl_choice(const char *q, const char *b0, const char *b1, const char *b2, ...);

Description

Shows the message with three buttons below it marked with the strings b0, b1, and b2. Returns 0, if button 0 is hit or another dialog box is still open. Returns 1 or 2 for buttons 1 or 2, respectively. ESC is a shortcut for button 0 and the enter key is a shortcut for button 1. Notice the buttons are positioned "backwards". You can hide buttons by passing NULL as their labels.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

fl_color_average

Include Files

#include <FL/Enumerations.H>

Prototype

Fl_Color fl_color_average(Fl_Color c1, Fl_Color c2, float weight);

Description

Returns the weighted average color between the two colors. The red, green, and blue values are averaged using the following formula:

color = c1 * weight + c2 * (1 - weight)

Thus, a weight value of 1.0 will return the first color, while a value of 0.0 will return the second color.

fl_color_chooser

Include Files

#include <FL/Fl_Color_Chooser.H>

Prototype

int fl_color_chooser(const char *title, double &r, double &g, double &b);
int fl_color_chooser(const char *title, uchar &r, uchar &g, uchar &b);

Description

The double version takes RGB values in the range 0.0 to 1.0. The uchar version takes RGB values in the range 0 to 255. The title argument specifies the label (title) for the window.

fl_color_chooser() pops up a window to let the user pick an arbitrary RGB color. They can pick the hue and saturation in the "hue box" on the left (hold down CTRL to just change the saturation), and the brighness using the vertical slider. Or they can type the 8-bit numbers into the RGB Fl_Value_Input fields, or drag the mouse across them to adjust them. The pull-down menu lets the user set the input fields to show RGB, HSV, or 8-bit RGB (0 to 255).

This returns non-zero if the user picks ok, and updates the RGB values. If the user picks cancel or closes the window this returns zero and leaves RGB unchanged.

If you use the color chooser on an 8-bit screen, it will allocate all the available colors, leaving you no space to exactly represent the color the user picks! You can however use fl_rectf() to fill a region with a simulated color using dithering.

fl_color_cube

Include File

#include <FL/fl_draw.H>

Prototype

Fl_Color fl_color_cube(int r, int g, int b);

Description

Returns a color out of the color cube. r must be in the range 0 to FL_NUM_RED (5) minus 1. g must be in the range 0 to FL_NUM_GREEN (8) minus 1. b must be in the range 0 to FL_NUM_BLUE (5) minus 1.

To get the closest color to a 8-bit set of R,G,B values use:

fl_color_cube(R * (FL_NUM_RED - 1) / 255,
              G * (FL_NUM_GREEN - 1) / 255,
              B * (FL_NUM_BLUE - 1) / 255);

fl_contrast

Include Files

#include <FL/Enumerations.H>

Prototype

Fl_Color fl_contrast(Fl_Color fg, Fl_Color bg);

Description

Returns the foreground color if it contrasts sufficiently with the background color. Otherwise, returns FL_WHITE or FL_BLACK depending on which color provides the best contrast.

fl_cursor

Include Files

#include <FL/fl_draw.H>

Prototype

void fl_cursor(Fl_Cursor cursor, Fl_Color fg, Fl_Color bg);

Description

Sets the cursor for the current window to the specified shape and colors. The cursors are defined in the <FL/Enumerations.H> header file.

fl_darker

Include Files

#include <FL/Enumerations.H>

Prototype

Fl_Color fl_darker(Fl_Color c);

Description

Returns a darker version of the specified color.

fl_dir_chooser

Include Files

#include <FL/Fl_File_Chooser.H>

Prototype

char *fl_dir_chooser(const char * message, const char *fname, int relative = 0);

Description

The fl_dir_chooser() function displays a Fl_File_Chooser dialog so that the user can choose a directory.

message is a string used to title the window.

fname is a default filename to fill in the chooser with. If this is NULL then the last filename that was choosen is used. The first time the file chooser is called this defaults to a blank string.

relative specifies whether the returned filename should be relative (any non-zero value) or absolute (0). The default is to return absolute paths.

The returned value points at a static buffer that is only good until the next time fl_dir_chooser() is called.

fl_file_chooser

Include Files

#include <FL/Fl_File_Chooser.H>

Prototype

char *fl_file_chooser(const char * message, const char *pattern, const char *fname, int relative = 0);

Description

FLTK provides a "tab completion" file chooser that makes it easy to choose files from large directories. This file chooser has several unique features, the major one being that the Tab key completes filenames like it does in Emacs or tcsh, and the list always shows all possible completions.

fl_file_chooser() pops up the file chooser, waits for the user to pick a file or Cancel, and then returns a pointer to that filename or NULL if Cancel is chosen.

message is a string used to title the window.

pattern is used to limit the files listed in a directory to those matching the pattern. This matching is done by fl_filename_match(). Multiple patterns can be used by separating them with tabs, like "*.jpg\t*.png\t*.gif\t*". In addition, you can provide human-readable labels with the patterns inside parenthesis, like "JPEG Files (*.jpg)\tPNG Files (*.png)\tGIF Files (*.gif)\tAll Files (*)". Pass NULL to show all files.

fname is a default filename to fill in the chooser with. If this is NULL then the last filename that was choosen is used (unless that had a different pattern, in which case just the last directory with no name is used). The first time the file chooser is called this defaults to a blank string.

relative specifies whether the returned filename should be relative (any non-zero value) or absolute (0). The default is to return absolute paths.

The returned value points at a static buffer that is only good until the next time fl_file_chooser() is called.

fl_file_chooser_callback

Include Files

#include <FL/Fl_File_Chooser.H>

Prototype

void fl_file_chooser_callback(void (*cb)(const char *));

Description

Sets a function that is called every time the user clicks a file in the currently popped-up file chooser. This could be used to preview the contents of the file. It has to be reasonably fast, and cannot create FLTK windows.

fl_file_chooser_ok_label

Include Files

#include <FL/Fl_File_Chooser.H>

Prototype

void fl_file_chooser_ok_label(const char *l);

Description

Sets the label that is shown on the "OK" button in the file chooser. The default label (fl_ok) can be restored by passing a NULL pointer for the label string.

fl_filename_absolute

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_absolute(char *to, int tolen, const char *from);
int fl_filename_absolute(char *to, const char *from);

Description

Converts a relative pathname to an absolute pathname. If from does not start with a slash, the current working directory is prepended to from with any occurances of . and x/.. deleted from the result. The absolute pathname is copied to to; from and to may point to the same buffer. fl_filename_absolute returns non-zero if any changes were made.

The first form accepts a maximum length (tolen) for the destination buffer, while the second form assumes that the destination buffer is at least FL_PATH_MAX characters in length.

fl_filename_expand

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_expand(char *to, int tolen, const char *from);
int fl_filename_expand(char *to, const char *from);

Description

This function replaces environment variables and home directories with the corresponding strings. Any occurrence of $X is replaced by getenv("X"); if $X is not defined in the environment, the occurrence is not replaced. Any occurence of ~X is replaced by user X's home directory; if user X does not exist, the occurrence is not replaced. Any resulting double slashes cause everything before the second slash to be deleted.

The result is copied to to, and from and to may point to the same buffer. fl_filename_expand() returns non-zero if any changes were made.

The first form accepts a maximum length (tolen) for the destination buffer, while the second form assumes that the destination buffer is at least FL_PATH_MAX characters in length.

fl_filename_ext

Include Files

#include <FL/filename.H>

Prototype

const char *fl_filename_ext(const char *f);

Description

Returns a pointer to the last period in fl_filename_name(f), or a pointer to the trailing nul if none is found.

fl_filename_isdir

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_isdir(const char *f);

Description

Returns non-zero if the file exists and is a directory.

fl_filename_list

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_list(const char *d, dirent ***list, Fl_File_Sort_F *sort = fl_numericsort);

Description

This is a portable and const-correct wrapper for the scandir() function. d is the name of a directory; it does not matter if it has a trailing slash or not. For each file in that directory a "dirent" structure is created. The only portable thing about a dirent is that dirent.d_name is the nul-terminated file name. An array of pointers to these dirent's is created and a pointer to the array is returned in *list. The number of entries is given as a return value. If there is an error reading the directory a number less than zero is returned, and errno has the reason; errno does not work under WIN32.

The name of directory always ends in a forward slash '/'.

The sort argument specifies a sort function to be used when on the array of filenames. The following standard sort functions are provided with FLTK:

• fl_alphasort - The files are sorted in ascending alphabetical order; upper- and lowercase letters are compared according to their ASCII ordering - uppercase before lowercase.
• fl_casealphasort - The files are sorted in ascending alphabetical order; upper- and lowercase letters are compared equally - case is not significant.
• fl_casenumericsort - The files are sorted in ascending "alphanumeric" order, where an attempt is made to put unpadded numbers in consecutive order; upper- and lowercase letters are compared equally - case is not significant.
• fl_numericsort - The files are sorted in ascending "alphanumeric" order, where an attempt is made to put unpadded numbers in consecutive order; upper- and lowercase letters are compared according to their ASCII ordering - uppercase before lowercase.

You can free the returned list of files with the following code:

for (int i = return_value; i > 0;) {
  free((void*)(list[--i]));
}

free((void*)list);

fl_filename_match

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_match(const char *f, const char *pattern);

Description

Returns non-zero if f matches pattern. The following syntax is used by pattern:

• * matches any sequence of 0 or more characters.
• ? matches any single character.
• [set] matches any character in the set. Set can contain any single characters, or a-z to represent a range. To match ] or - they must be the first characters. To match ^ or ! they must not be the first characters.
• [^set] or [!set] matches any character not in the set.
• {X|Y|Z} or {X,Y,Z} matches any one of the subexpressions literally.
• \x quotes the character x so it has no special meaning.
• x all other characters must be matched exactly.

fl_filename_name

Include Files

#include <FL/filename.H>

Prototype

const char *fl_filename_name(const char *f);

Description

Returns a pointer to the character after the last slash, or to the start of the filename if there is none.

fl_filename_relative

Include Files

#include <FL/filename.H>

Prototype

int fl_filename_relative(char *to, int tolen, const char *from);
int fl_filename_relative(char *to, const char *from);

Description

Converts an absolute pathname to an relative pathname. The relative pathname is copied to to; from and to may point to the same buffer. fl_filename_relative returns non-zero if any changes were made.

The first form accepts a maximum length (tolen) for the destination buffer, while the second form assumes that the destination buffer is at least FL_PATH_MAX characters in length.

fl_filename_setext

Include Files

#include <FL/filename.H>

Prototype

char *fl_filename_setext(char *to, int tolen, const char *ext);
char *fl_filename_setext(char *to, const char *ext);

Description

Replaces the extension in to with the extension in ext. Returns a pointer to to.

The first form accepts a maximum length (tolen) for the destination buffer, while the second form assumes that the destination buffer is at least FL_PATH_MAX characters in length.

fl_gray_ramp

Include File

#include <FL/fl_draw.H>

Prototype

Fl_Color fl_gray_ramp(int i);

Description

Returns a gray color value from black (i == 0) to white (i == FL_NUM_GRAY - 1). FL_NUM_GRAY is defined to be 24 in the current FLTK release. To get the closest FLTK gray value to an 8-bit grayscale color 'I' use:

fl_gray_ramp(I * (FL_NUM_GRAY - 1) / 255)

fl_inactive

Include File

#include <FL/Enumerations.H>

Prototype

Fl_Color fl_inactive(Fl_Color c);

Description

Returns the inactive, dimmed version of the give color

fl_input

Include Files

#include <FL/fl_ask.H>

Prototype

const char *fl_input(const char *label, const char *deflt = 0, ...);

Description

Pops up a window displaying a string, lets the user edit it, and returns the new value. The function returns NULL if the Cancel button is hit or another dialog box is still open. The returned pointer is only valid until the next time fl_input() is called. Due to back-compatibility, the arguments to any printf commands in the label are after the default value.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

fl_lighter

Include Files

#include <FL/Enumerations.H>

Prototype

Fl_Color fl_lighter(Fl_Color c);

Description

Returns a lighter version of the specified color.

fl_message

Include Files

#include <FL/fl_ask.H>

Prototype

void fl_message(const char *, ...);

Description

Displays a printf-style message in a pop-up box with an "OK" button, waits for the user to hit the button. The message will wrap to fit the window, or may be many lines by putting \n characters into it. The enter key is a shortcut for the OK button.

The message text is limited to 1024 characters.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

fl_message_font

Include Files

#include <FL/fl_ask.H>

Prototype

void fl_message_font(Fl_Font fontid, uchar size);

Description

Changes the font and font size used for the messages in all the popups.

fl_message_icon

Include Files

#include <FL/fl_ask.H>

Prototype

Fl_Widget *fl_message_icon();

Description

Returns a pointer to the box at the left edge of all the popups. You can alter the font, color, label, or image before calling the functions.

fl_open_uri

Include Files

#include <FL/filename.H>

Prototype

void fl_open_uri(const char *uri, char *msg = (char *)0, int msglen = 0);

Description

fl_open_uri() opens the specified Uniform Resource Identifier (URI) using an operating-system dependent program or interface. For URIs using the "ftp", "http", or "https" schemes, the system default web browser is used to open the URI, while "mailto" and "news" URIs are typically opened using the system default mail reader and "file" URIs are opened using the file system navigator.

On success, the (optional) msg buffer is filled with the command that was run to open the URI; on Windows, this will always be "open uri".

On failure, the msg buffer is filled with an English error message.

fl_password

Include Files

#include <FL/fl_ask.H>

Prototype

const char *fl_password(const char *label, const char *deflt = 0, ...);

Description

Same as fl_input(), except an Fl_Secret_Input field is used.

Note: Common dialog boxes are application modal. No more than one common dialog box can be open at any time. Requests for additional dialog boxes are ignored.

fl_register_images

Include File

#include <FL/Fl_Shared_Image.H>

Prototype

void fl_register_images();

Description

Registers the extra image file formats that are not provided as part of the core FLTK library for use with the Fl_Shared_Image class.

This function is provided in the fltk_images library.

fl_rgb_color

Include File

#include <FL/fl_draw.H>

Prototype

Fl_Color fl_rgb_color(uchar r, uchar g, uchar b);
Fl_Color fl_rgb_color(uchar g);

Description

Returns the 24-bit RGB color value for the specified 8-bit RGB or grayscale values.

fl_show_colormap

Include Files

#include <FL/fl_show_colormap.H>

Prototype

Fl_Color fl_show_colormap(Fl_Color oldcol)

Description

fl_show_colormap() pops up a panel of the 256 colors you can access with fl_color() and lets the user pick one of them. It returns the new color index, or the old one if the user types ESC or clicks outside the window.

User Comments [ Add Comment ]

From Roker, 15:52 Oct 04, 2007 (score=3)

How the file_chooser_callback finds its canvas to display the file preview?
[ Reply ]