Improve and extend fl_contrast() (#370)

- Add internal fl_contrast_cielab() as the new default.
- Keep old function as internal fl_contrast_legacy().
- Add fl_contrast_mode() to switch between fl_contrast() functions.
- Add fl_contrast_level() to fine tune fl_contrast() per mode.
- Add option to register and use a custom contrast function.
- Add test/contrast.cxx test program.
- Move all fl_contrast() related code to a new file src/fl_contrast.cxx.
- Add fl_lightness() convenience function for perceived lightness.
- Add fl_luminance() convenience function for physical luminance.

6 files changed, 511 insertions, 5 deletions

diff --git a/test/.gitignore b/test/.gitignore
index 49b1817e0..1e43541ac 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -30,6 +30,7 @@ clipboard
 clock
 colbrowser
 color_chooser
+contrast
 coordinates
 cube
 CubeView
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 05333ee81..fc8e26ed1 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -72,6 +72,7 @@ CREATE_EXAMPLE (clipboard clipboard.cxx "fltk_images;fltk")
 CREATE_EXAMPLE (clock clock.cxx fltk)
 CREATE_EXAMPLE (colbrowser colbrowser.cxx fltk)
 CREATE_EXAMPLE (color_chooser color_chooser.cxx fltk)
+CREATE_EXAMPLE (contrast contrast.cxx fltk)
 CREATE_EXAMPLE (coordinates coordinates.cxx fltk)
 CREATE_EXAMPLE (cursor cursor.cxx fltk)
 CREATE_EXAMPLE (curve curve.cxx fltk)
diff --git a/test/Makefile b/test/Makefile
index 3b9afa5eb..df0aee017 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -65,6 +65,7 @@ CPPFILES =\
 	clock.cxx \
 	colbrowser.cxx \
 	color_chooser.cxx \
+	contrast.cxx \
 	cube.cxx \
 	CubeMain.cxx \
 	CubeView.cxx \
@@ -159,6 +160,7 @@ ALL =	\
 	clock$(EXEEXT) \
 	colbrowser$(EXEEXT) \
 	color_chooser$(EXEEXT) \
+	contrast$(EXEEXT) \
 	cursor$(EXEEXT) \
 	curve$(EXEEXT) \
 	demo$(EXEEXT) \
@@ -394,6 +396,8 @@ colbrowser$(EXEEXT): colbrowser.o
 
 color_chooser$(EXEEXT): color_chooser.o
 
+contrast$(EXEEXT): contrast.o
+
 cursor$(EXEEXT): cursor.o
 
 curve$(EXEEXT): curve.o
diff --git a/test/contrast.cxx b/test/contrast.cxx
new file mode 100644
index 000000000..5cd340d13
--- /dev/null
+++ b/test/contrast.cxx
@@ -0,0 +1,454 @@
+//
+// Contrast function test program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2022 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+// Note: this test and demo program is work in progress. It is published
+// because it is helpful but it needs some more work to be "perfect" ;-)
+// AlbrechtS
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Radio_Round_Button.H>
+#include <FL/Fl_Color_Chooser.H>
+#include <FL/Fl_Output.H>
+#include <FL/Fl_Hor_Value_Slider.H>
+#include <FL/Fl_Simple_Terminal.H>
+#include <FL/fl_draw.H>
+
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+
+// program version
+
+const char *version = "0.9.0";
+
+// prototypes and forward declarations
+
+static void button_cb(Fl_Widget *w, void *v);
+static Fl_Color calc_contrast(Fl_Color fg, Fl_Color bg, Fl_Fontsize fs);
+
+// class Button
+
+class Button : public Fl_Button {
+  char lbuf[20];      // private label buffer
+  Fl_Color ocol_;     // "original" (label) color
+  int idx_;           // button index (0 - 255)
+public:
+  Button(int X, int Y, int W, int H, int n)
+    : Fl_Button(X, Y, W, H, "") {
+    idx_ = n;
+    box(FL_THIN_DOWN_BOX);
+    label(lbuf);
+    callback(button_cb);
+    color((Fl_Color)n);
+    sprintf(lbuf, "%03d", n);
+    set_labelcolor(n);
+    labelsize(15);
+    labelfont(FL_HELVETICA);
+  }
+
+  void set_labelcolor(Fl_Color col) {
+    ocol_ = col;
+    labelcolor(calc_contrast(col, color(), labelsize()));
+  }
+
+  Fl_Color ocol() {
+    return ocol_;
+  }
+
+  int idx() {
+    return idx_;
+  }
+
+  virtual void draw() {
+    draw_box();
+    // draw small filled rectangle with "original" color
+    fl_color(ocol_);
+    fl_rectf(x() + 5, y() + 5, 10, h() - 10);
+    // measure and draw label
+    int lw = 0, lh = 0;
+    fl_font(labelfont(), labelsize());
+    fl_measure(lbuf, lw, lh);
+    fl_color(labelcolor());
+    fl_draw(lbuf, x() + 15 + (w() - lw - 15) / 2, y() + h() - (h() - lh) / 2 - lh/4);
+    fl_color(FL_BLACK);
+  }
+
+}; // class Button
+
+// global variables
+
+Fl_Simple_Terminal *term = 0;
+
+double g_lfg;                   // perceived lightness of foreground color
+double g_lbg;                   // perceived lightness of background color
+double g_lcref;                 // calculated contrast reference (CIELAB, L*a*b*)
+int g_selected = -1;            // selected button: -1 = none, 0 - 255 = valid button
+
+Fl_Fontsize g_fs = 15;          // fontsize for button labels
+int g_level = 0;                // *init* fl_contrast_level (sensitivity)
+
+int g_algo = FL_CONTRAST_LEGACY;// contrast algorithm: 0 = none, 1 = legacy (1.3.x), 2 = CIELAB, 3 = custom
+const char *alch = "";          // algorithm as char: "LEGACY", "CIELAB" , or "CUSTOM"
+
+Fl_Color lcolor = FL_BLACK;     // label color, set by slider callback
+Button *buttons[256];           // array of color buttons
+Fl_Value_Slider *sliders[6];    // array of sliders (gray, red, green, blue, level, fontsize)
+Fl_Output *color_out = 0;       // color output (RRGGBB)
+
+// Custom contrast algorithm: currently a dummy function (returns fg).
+// This may be used to define a "better" contrast function in user code
+
+static Fl_Color custom_contrast(Fl_Color fg, Fl_Color bg, Fl_Fontsize fs, int) {
+  return fg;
+}
+
+/*
+  Local function to calculate the contrast and store it in some
+  global variables for display purposes and logging.
+
+  This function is a wrapper around fl_contrast() in this demo program.
+*/
+static Fl_Color calc_contrast(Fl_Color fg, Fl_Color bg, Fl_Fontsize fs) {
+
+  // Compute and set global *perceived* lightness L* (Lstar) and contrast for display
+
+  g_lfg      = fl_lightness(fg);
+  g_lbg      = fl_lightness(bg);
+  g_lcref    = g_lfg - g_lbg;     // perceived contrast (light on dark = positive)
+
+  switch (g_algo) {
+    case FL_CONTRAST_NONE:              // 0 = none (return fg)
+    case FL_CONTRAST_LEGACY:            // 1 = legacy (FLTK 1.3.x)
+    case FL_CONTRAST_CIELAB:            // 2 = CIELAB (L*a*b*)
+    case FL_CONTRAST_CUSTOM:            // 3 = Custom
+      return fl_contrast(fg, bg, fs);
+    default:
+      break;
+  }
+  return fg;
+}
+
+// set all button label colors and adjust fontsize (labelsize)
+
+static void update_labels() {
+  for (int i = 0; i < 256; i++) {
+    buttons[i]->set_labelcolor(lcolor);
+    buttons[i]->labelsize(g_fs);
+  }
+}
+
+static void button_cb(Fl_Widget *w, void *v) {
+  Button *b = (Button *)w;
+  g_selected = b->idx();                          // selected button index
+  Fl_Color ocol = Fl::get_color(b->ocol());       // button's "original" label color (RGB0)
+  Fl_Color fg = Fl::get_color(b->labelcolor());   // button's label color (RGB0)
+  Fl_Color bg = Fl::get_color(b->color());        // button's background color (RGB0)
+  calc_contrast(ocol, bg, g_fs);                  // calculate values to be displayed
+  const char *color = "";                         // calculated label color (text)
+  if (fg == ocol)            color = "fg";
+  else if (fg == 0xffffff00) color = "WHITE";
+  else if (fg == 0x0)        color = "BLACK";
+  term->printf("[%s] fg: %06x, bg: %06x, lfg: %6.2f, lbg: %6.2f, lc: %7.2f, %s => %-5s",
+                  b->label(), ocol >> 8, bg >> 8, g_lfg, g_lbg, g_lcref, alch, color);
+  if (g_algo == FL_CONTRAST_LEGACY ||
+      g_algo == FL_CONTRAST_CIELAB)
+    term->printf(" (level = %3d)\n", g_level);
+  else
+    term->printf("\n");
+}
+
+void lf_cb(Fl_Widget *w, void *v) {
+  term->printf("\n");
+}
+
+// callback for color (gray and R, G, B) sliders
+
+void color_slider_cb(Fl_Widget *w, void *v) {
+  int n = fl_int(v);                        // slider type: 0 = gray, 1 = color
+  unsigned int r, g, b;
+  if (n == 0) {                             // gray slider
+    int val = (int)sliders[0]->value();
+    lcolor = fl_rgb_color(val, val, val);   // set gray value
+    sliders[1]->value(val);                 // set r/g/b values as well
+    sliders[2]->value(val);
+    sliders[3]->value(val);
+    r = g = b = val;
+  } else {                                  // any color slider
+    r = (unsigned int)sliders[1]->value();
+    g = (unsigned int)sliders[2]->value();
+    b = (unsigned int)sliders[3]->value();
+    lcolor = fl_rgb_color(r, g, b);         // set color value
+  }
+  // update button label colors
+  update_labels();
+  // output label color
+  char color_buf[10];
+  sprintf(color_buf, "%02X %02X %02X", r, g, b);
+  color_out->value(color_buf);
+  w->window()->redraw();
+}
+
+// callback for "level" and "fontsize" sliders
+
+void slider_cb(Fl_Widget *w, void *v) {
+  int n = fl_int(v);                            // slider type: 1 = level, 2 = fontsize
+  switch (n) {
+    case 1:                                     // fl_contrast_level()
+      g_level = (int)sliders[n + 3]->value();
+      fl_contrast_level(g_level);               // set/store current contrast level
+      break;
+    case 2:                                     // 2nd slider: fontsize (labelsize)
+      g_fs = (int)sliders[n + 3]->value();
+      break;
+    default:
+      break;
+  }
+  // update button label colors
+  update_labels();
+  w->window()->redraw();
+}
+
+// callback for contrast algorithm (radio buttons)
+
+void algo_cb(Fl_Widget *w, void *v) {
+  int val = fl_int(v);
+  g_algo = val;
+  switch(val) {
+    case FL_CONTRAST_LEGACY: alch = "LEGACY"; fl_contrast_mode(val); break; // legacy 1.3.x
+    case FL_CONTRAST_CIELAB: alch = "CIELAB"; fl_contrast_mode(val); break; // CIELAB L*a*b*
+    case FL_CONTRAST_CUSTOM: alch = "CUSTOM"; fl_contrast_mode(val); break; // custom
+    case FL_CONTRAST_NONE:
+    default:
+      alch = "none  ";
+      fl_contrast_mode(FL_CONTRAST_NONE);
+      break;
+  }
+  g_level = fl_contrast_level();  // get current contrast level (per mode)
+  sliders[4]->value(g_level);     // set level slider value
+  update_labels();                // update all button labels
+
+  // print selected button's attributes
+  if (g_selected >= 0) {
+    button_cb(buttons[g_selected], (void *)0);
+  }
+  if (w)
+    w->window()->redraw();
+}
+
+// color chooser callback
+void color_cb(Fl_Widget *w, void *v) {
+  Fl_Color_Chooser *cc = (Fl_Color_Chooser *)w;
+  int r = (int)(cc->r() * 255);
+  int g = (int)(cc->g() * 255);
+  int b = (int)(cc->b() * 255);
+  Fl_Color c = fl_rgb_color(r, g, b);
+  Button *bt = buttons[255]; // last button
+  bt->color(c);
+  bt->set_labelcolor(lcolor);
+  bt->redraw();
+}
+
+// ===============================================================
+// ======================   main() program  ======================
+// ===============================================================
+
+int main(int argc, char **argv) {
+
+  const int bw = 58;
+  const int bh = 30;
+  int cw = 16 * bw + 10;
+  int ch = 16 * bh + 10;
+  int ww = cw + 10;
+  int wh = 16 * bh + 135 + 10 + 150 /* terminal */ + 10;
+  Fl_Double_Window window(ww, wh, "fl_contrast test");
+
+  int n = 0;
+  Button **b = buttons;
+  for (int y = 0; y < 16; y++) {
+    for (int x = 0; x < 16; x++) {
+      *b = new Button(x * bw + 10, y * bh + 10, bw, bh, n);
+      (*b)->set_labelcolor(n);
+      b++;
+      n++;
+    }
+  }
+
+  // sliders for label color (gray, red, green, blue)
+
+  const int sx = 10 + bw;
+  const int sw = 5 * bw;
+  const int sh = 25;
+  int sy = ch + 10;
+
+  Fl_Hor_Value_Slider *gray = new Fl_Hor_Value_Slider(sx, sy, sw, sh, "gray");
+  gray->color(0xdddddd00);
+  gray->textsize(13);
+  gray->align(FL_ALIGN_LEFT);
+  gray->value(0);
+  gray->bounds(0, 255);
+  gray->step(1);
+  gray->callback(color_slider_cb, (void *)0);
+  sy += sh + 10;
+
+  Fl_Hor_Value_Slider *red = new Fl_Hor_Value_Slider(sx, sy, sw, sh, "red");
+  red->color(FL_RED);
+  red->textcolor(FL_WHITE);
+  red->textsize(13);
+  red->align(FL_ALIGN_LEFT);
+  red->value(0);
+  red->bounds(0, 255);
+  red->step(1);
+  red->callback(color_slider_cb, (void *)1);
+  sy += sh + 5;
+
+  Fl_Hor_Value_Slider *green = new Fl_Hor_Value_Slider(sx, sy, sw, sh, "green");
+  green->color(FL_GREEN);
+  green->textsize(13);
+  green->align(FL_ALIGN_LEFT);
+  green->value(0);
+  green->bounds(0, 255);
+  green->step(1);
+  green->callback(color_slider_cb, (void *)1);
+  sy += sh + 5;
+
+  Fl_Hor_Value_Slider *blue = new Fl_Hor_Value_Slider(sx, sy, sw, sh, "blue");
+  blue->color(FL_BLUE);
+  blue->textcolor(FL_WHITE);
+  blue->textsize(13);
+  blue->align(FL_ALIGN_LEFT);
+  blue->value(0);
+  blue->bounds(0, 255);
+  blue->step(1);
+  blue->callback(color_slider_cb, (void *)1);
+
+  sliders[0] = gray;
+  sliders[1] = red;
+  sliders[2] = green;
+  sliders[3] = blue;
+
+  // contrast algorithm selection group
+
+  int cgx = 10 + 6*bw + 10;
+  int cgy = ch + 30;
+  int cgw =  90;
+  int cgh = 100;
+  int abh = 25;
+
+  Fl_Group *cg = new Fl_Group(cgx, cgy, cgw, cgh, "fl_contrast:");
+  cg->align(FL_ALIGN_TOP);
+  cg->box(FL_FRAME);
+
+  Fl_Radio_Round_Button *anon = new Fl_Radio_Round_Button(cgx, cgy,      cgw, abh, "none");
+  Fl_Radio_Round_Button *aleg = new Fl_Radio_Round_Button(cgx, cgy + 25, cgw, abh, "LEGACY");
+  Fl_Radio_Round_Button *acie = new Fl_Radio_Round_Button(cgx, cgy + 50, cgw, abh, "CIELAB");
+  Fl_Radio_Round_Button *aapc = new Fl_Radio_Round_Button(cgx, cgy + 75, cgw, abh, "CUSTOM");
+  aleg->value(1);
+  anon->callback(algo_cb, (void *)0);
+  aleg->callback(algo_cb, (void *)1);
+  acie->callback(algo_cb, (void *)2);
+  aapc->callback(algo_cb, (void *)3);
+
+  cg->end();
+
+  color_out = new Fl_Output(10 + 10 * bw, ch + 10, 100, 30, "label color:");
+  color_out->align(FL_ALIGN_LEFT);
+  color_out->textfont(FL_COURIER);
+  color_out->textsize(16);
+  color_out->value("00 00 00");
+
+  // light blue "level" slider
+
+  Fl_Hor_Value_Slider *s_level = new Fl_Hor_Value_Slider(10 + 9 * bw, red->y(), 3 * bw - 15, sh, "level");
+  s_level->color(231);
+  s_level->textcolor(224);
+  s_level->textsize(13);
+  s_level->align(FL_ALIGN_LEFT);
+  s_level->step(1);
+  s_level->bounds(0, 100);
+  s_level->value(g_level);
+  s_level->callback(slider_cb, (void *)1);
+  s_level->tooltip("set contrast sensitivity level (0-100), default: 50");
+
+  // labelsize slider
+
+  Fl_Hor_Value_Slider *s_fs = new Fl_Hor_Value_Slider(10 + 9 * bw, green->y(), 3 * bw - 15, sh, "labelsize");
+  s_fs->color(231);
+  s_fs->textcolor(224);
+  s_fs->textsize(13);
+  s_fs->align(FL_ALIGN_LEFT);
+  s_fs->step(1);
+  s_fs->bounds(8, 24);
+  s_fs->value(15);
+  s_fs->callback(slider_cb, (void *)2);
+  s_fs->tooltip("set label/text fontsize");
+
+  sliders[4] = s_level;
+  sliders[5] = s_fs;
+
+  // line feed (LF) button
+
+  Fl_Button *lf = new Fl_Button(10 + 8 * bw, blue->y(), bw, sh, "LF");
+  lf->tooltip("Click to output a linefeed to the log.");
+  lf->callback(lf_cb);
+
+  // color chooser for field #255
+
+  int ccx = 10 + 12 * bw;
+  int ccy = ch + 10;
+  int ccw = 4 * bw;
+  int cch = 120;
+
+  Fl_Color_Chooser *color_chooser = new Fl_Color_Chooser(ccx, ccy, ccw, cch);
+  color_chooser->callback(color_cb);
+  color_chooser->label("bg color [255] @->");
+  color_chooser->rgb(1, 1, 1);
+  color_chooser->mode(1); // byte mode
+  color_chooser->align(FL_ALIGN_LEFT_BOTTOM);
+
+  // simple terminal for output (FLTK 1.4 only)
+
+  int ttx = 10;
+  int tty = color_chooser->y() + cch + 10;
+  int ttw = window.w() - 20;
+  int tth = window.h() - tty - 10;
+
+  term = new Fl_Simple_Terminal(ttx, tty, ttw, tth);
+  term->color(FL_WHITE);
+  term->textcolor(FL_BLACK);
+  term->textsize(13);
+
+  term->printf("FLTK fl_contrast() test program with different contrast algorithms, version %s\n", version);
+  term->printf("FLTK version %d.%d.%d\n", FL_MAJOR_VERSION, FL_MINOR_VERSION, FL_PATCH_VERSION);
+  term->printf(" - Select a foreground (text) color with the gray or red/green/blue sliders (displayed inside each field).\n");
+  term->printf(" - Select an arbitrary background color for field #255 with the color chooser.\n");
+  term->printf(" - Select a colored field (by clicking on it) to display its attributes.\n");
+  term->printf(" - Select the contrast algorithm by clicking on the radio buttons.\n");
+  term->printf(" - Tune the contrast algorithm with the light blue \"level\" slider (default: 50).\n");
+
+  // set contrast mode and level, update button label colors
+
+  fl_contrast_mode(g_algo);
+  fl_contrast_function(custom_contrast);  // dummy function
+  algo_cb(NULL, fl_voidptr(g_algo));      // updates button labels
+
+  window.resizable(window);
+  window.end();
+  window.show(argc, argv);
+  return Fl::run();
+}
diff --git a/test/demo.menu b/test/demo.menu
index 2d5750634..16cce02da 100644
--- a/test/demo.menu
+++ b/test/demo.menu
@@ -61,7 +61,6 @@
 @main:Fluid\n(UI design tool):fluid valuators.fl
 
 @main:Cool\nDemos...:@e
-	@e:X Color\nBrowser:colbrowser rgb.txt
 	@e:Mandelbrot:mandelbrot
 	@e:Fractals:fractals
 	@e:Puzzle:glpuzzle
@@ -72,17 +71,19 @@
 	@e:Clipboard\nViewer:clipboard
 
 @main:Other\nTests...:@o
-	@o:Color Choosers:color_chooser
 	@o:File Chooser:file_chooser
 	@o:Native File Chooser:native-filechooser
-	@o:Font Tests...:@of
-		@of:Fonts:fonts
-		@of:UTF-8:utf8
 	@o:HelpDialog:help_dialog help_dialog.html
 	@o:Input Choice:input_choice
 	@o:Preferences:preferences
 	@o:Threading:threads
 	@o:XForms Emulation:forms
+	@o:Colors and Fonts...:@of
+		@of:X Color\nBrowser:colbrowser rgb.txt
+		@of:Color Chooser:color_chooser
+		@of:Color Contrast:contrast
+		@of:Fonts:fonts
+		@of:UTF-8 Fonts:utf8
 
 @main:Tutorial\nfrom\nManual...:@j
 	@j:ask\n(modified):ask
diff --git a/test/makedepend b/test/makedepend
index a013aae50..f51a7416a 100644
--- a/test/makedepend
+++ b/test/makedepend
@@ -459,6 +459,51 @@ color_chooser.o: ../FL/platform.H
 color_chooser.o: ../FL/platform_types.h
 color_chooser.o: ../FL/x11.H
 color_chooser.o: list_visuals.cxx
+contrast.o: ../FL/Enumerations.H
+contrast.o: ../FL/Fl.H
+contrast.o: ../FL/Fl_Bitmap.H
+contrast.o: ../FL/Fl_Box.H
+contrast.o: ../FL/Fl_Button.H
+contrast.o: ../FL/Fl_Cairo.H
+contrast.o: ../FL/fl_casts.H
+contrast.o: ../FL/Fl_Choice.H
+contrast.o: ../FL/Fl_Color_Chooser.H
+contrast.o: ../FL/fl_config.h
+contrast.o: ../FL/Fl_Device.H
+contrast.o: ../FL/Fl_Double_Window.H
+contrast.o: ../FL/fl_draw.H
+contrast.o: ../FL/Fl_Export.H
+contrast.o: ../FL/Fl_Graphics_Driver.H
+contrast.o: ../FL/Fl_Group.H
+contrast.o: ../FL/Fl_Hor_Value_Slider.H
+contrast.o: ../FL/Fl_Image.H
+contrast.o: ../FL/Fl_Input.H
+contrast.o: ../FL/Fl_Input_.H
+contrast.o: ../FL/Fl_Light_Button.H
+contrast.o: ../FL/Fl_Menu_.H
+contrast.o: ../FL/Fl_Menu_Item.H
+contrast.o: ../FL/Fl_Output.H
+contrast.o: ../FL/Fl_Pixmap.H
+contrast.o: ../FL/Fl_Plugin.H
+contrast.o: ../FL/Fl_Preferences.H
+contrast.o: ../FL/Fl_Radio_Round_Button.H
+contrast.o: ../FL/Fl_Rect.H
+contrast.o: ../FL/Fl_Return_Button.H
+contrast.o: ../FL/Fl_RGB_Image.H
+contrast.o: ../FL/Fl_Round_Button.H
+contrast.o: ../FL/Fl_Scrollbar.H
+contrast.o: ../FL/Fl_Simple_Terminal.H
+contrast.o: ../FL/Fl_Slider.H
+contrast.o: ../FL/Fl_Text_Buffer.H
+contrast.o: ../FL/Fl_Text_Display.H
+contrast.o: ../FL/fl_types.h
+contrast.o: ../FL/fl_utf8.h
+contrast.o: ../FL/Fl_Valuator.H
+contrast.o: ../FL/Fl_Value_Input.H
+contrast.o: ../FL/Fl_Value_Slider.H
+contrast.o: ../FL/Fl_Widget.H
+contrast.o: ../FL/Fl_Window.H
+contrast.o: ../FL/platform_types.h
 cube.o: ../config.h
 cube.o: ../FL/Enumerations.H
 cube.o: ../FL/Fl.H