Make the value box size of Fl_Value_Slider user settable (STR 3222)

For a very simple test program see STR 3222, File 2:
https://www.fltk.org/strfiles/3222/value_slider.cxx

Known issues:
 - range checking of the value box size is very limited
 - resizing the widget does not change the value box size
 - drawing issues are possible if the value box size and the widget
   size are not compatible (e.g. value box too large)

FL/Fl_Value_Slider.H

@@ -1,5 +1,5 @@
 //
-// Value slider header file for the Fast Light Tool Kit (FLTK).
+// Value Slider header file for the Fast Light Tool Kit (FLTK).
 //
 // Copyright 1998-2022 by Bill Spitzak and others.
 //
@@ -25,30 +25,97 @@
 /**
   The Fl_Value_Slider widget is a Fl_Slider widget
   with a box displaying the current value.
-  \image html value_slider.png
-  \image latex  value_slider.png "Fl_Value_Slider" width=4cm
+  \image html  value_slider.png
+  \image latex value_slider.png "Fl_Value_Slider" width=4cm
 */
 class FL_EXPORT Fl_Value_Slider : public Fl_Slider {
-    Fl_Font textfont_;
-    Fl_Fontsize textsize_;
-    Fl_Color textcolor_;
+  Fl_Font textfont_;
+  Fl_Fontsize textsize_;
+  Fl_Color textcolor_;
+  short value_width_;
+  short value_height_;
+
 protected:
-    void draw();
+  void draw();
+
 public:
-    int handle(int);
-    Fl_Value_Slider(int x,int y,int w,int h, const char *l = 0);
-    /**    Gets the typeface of the text in the value box.  */
-    Fl_Font textfont() const {return textfont_;}
-    /**    Sets the typeface of the text in the value box.  */
-    void textfont(Fl_Font s) {textfont_ = s;}
-    /**    Gets the size of the text in the value box.  */
-    Fl_Fontsize textsize() const {return textsize_;}
-    /**    Sets the size of the text in the value box.  */
-    void textsize(Fl_Fontsize s) {textsize_ = s;}
-    /**    Gets the color of the text in the value box.  */
-    Fl_Color textcolor() const {return textcolor_;}
-    /**    Sets the color of the text in the value box.  */
-    void textcolor(Fl_Color s) {textcolor_ = s;}
+  int handle(int);
+  Fl_Value_Slider(int x, int y, int w, int h, const char *l = 0);
+
+  /** Gets the typeface of the text in the value box. */
+  Fl_Font textfont() const { return textfont_; }
+
+  /** Sets the typeface of the text in the value box. */
+  void textfont(Fl_Font s) { textfont_ = s; }
+
+  /** Gets the size of the text in the value box. */
+  Fl_Fontsize textsize() const { return textsize_; }
+
+  /** Sets the size of the text in the value box. */
+  void textsize(Fl_Fontsize s) { textsize_ = s; }
+
+  /** Gets the color of the text in the value box. */
+  Fl_Color textcolor() const { return textcolor_; }
+
+  /** Sets the color of the text in the value box. */
+  void textcolor(Fl_Color s) { textcolor_ = s; }
+
+  /** Sets the width of the value box in pixels (horizontal mode only).
+
+    Limited range checking is applied but drawing errors may occur if
+    the size \p s is set too high or too low, particularly if the widget
+    is resized (later).
+
+    The programmer is responsible for setting sensible values and
+    widget sizes.
+
+    The default value set by the constructor is 35.
+
+    \param[in]  s  new width of the value box
+
+    \since 1.4.0
+  */
+  void value_width(int s) {
+    if (s > w() - 10)
+      s = w() - 10;
+    if (s < 10)
+      s = 10;
+    value_width_ = (short)s;
+  }
+
+  /** Gets the width of the value box in pixels (horizontal mode only).
+
+    \since 1.4.0
+  */
+  int value_width() const { return (value_width_); }
+
+  /** Sets the height of the value box in pixels (vertical mode only).
+
+    Limited range checking is applied but drawing errors may occur if
+    the size \p s is set too high or too low, particularly if the widget
+    is resized (later).
+
+    The programmer is responsible for setting sensible values and
+    widget sizes.
+
+    The default value set by the constructor is 25.
+
+    \param[in]  s  new height of the value box
+
+    \since 1.4.0
+  */
+  void value_height(int s) {
+    if (s > h() - 10)
+      s = h() - 10;
+    if (s < 10)
+      s = 10;
+    value_height_ = (short)s;
+  }
+  /** Gets the height of the value box in pixels (vertical mode only).
+
+    \since 1.4.0
+  */
+  int value_height() const { return (value_height_); }
 };
 
 #endif

src/Fl_Value_Slider.cxx

@@ -1,7 +1,7 @@
 //
-// Value slider widget for the Fast Light Tool Kit (FLTK).
+// Value Slider widget for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2010 by Bill Spitzak and others.
+// Copyright 1998-2022 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
@@ -30,17 +30,24 @@ Fl_Value_Slider::Fl_Value_Slider(int X, int Y, int W, int H, const char*l)
   textfont_ = FL_HELVETICA;
   textsize_ = 10;
   textcolor_ = FL_FOREGROUND_COLOR;
+  value_width_ = 35;
+  value_height_ = 25;
 }
 
 void Fl_Value_Slider::draw() {
   int sxx = x(), syy = y(), sww = w(), shh = h();
   int bxx = x(), byy = y(), bww = w(), bhh = h();
   if (horizontal()) {
-    bww = 35; sxx += 35; sww -= 35;
+    bww = value_width();
+    sxx += value_width();
+    sww -= value_width();
   } else {
-    syy += 25; bhh = 25; shh -= 25;
+    syy += value_height();
+    bhh = value_height();
+    shh -= value_height();
   }
-  if (damage()&FL_DAMAGE_ALL) draw_box(box(),sxx,syy,sww,shh,color());
+  if (damage() & FL_DAMAGE_ALL)
+    draw_box(box(), sxx, syy, sww, shh, color());
   Fl_Slider::draw(sxx+Fl::box_dx(box()),
                   syy+Fl::box_dy(box()),
                   sww-Fl::box_dw(box()),
@@ -60,15 +67,14 @@ int Fl_Value_Slider::handle(int event) {
   }
   int sxx = x(), syy = y(), sww = w(), shh = h();
   if (horizontal()) {
-    sxx += 35; sww -= 35;
+    sxx += value_width();
+    sww -= value_width();
   } else {
-    syy += 25; shh -= 25;
+    syy += value_height();
+    shh -= value_height();
   }
-  return Fl_Slider::handle(event,
-                           sxx+Fl::box_dx(box()),
-                           syy+Fl::box_dy(box()),
-                           sww-Fl::box_dw(box()),
-                           shh-Fl::box_dh(box()));
+  return Fl_Slider::handle(event, sxx + Fl::box_dx(box()), syy + Fl::box_dy(box()),
+                           sww - Fl::box_dw(box()), shh - Fl::box_dh(box()));
 }