Add Fl_Scheme_Choice widget and use it in test programs

This widget offers the selection of all known FLTK schemes as a simple
widget based on Fl_Choice.

Some test and demo programs use Fl_Scheme_Choice to enable the developer
or user to switch schemes quickly for comparison.

Todo:
 - add features to add new schemes during runtime (partially done)
 - update status when the scheme is changed by Fl::scheme("...")

4 files changed, 106 insertions, 83 deletions

diff --git a/fluid/alignment_panel.cxx b/fluid/alignment_panel.cxx
index e742640ce..dfe69d114 100644
--- a/fluid/alignment_panel.cxx
+++ b/fluid/alignment_panel.cxx
@@ -179,21 +179,11 @@ nalize labels and tooltips, usually \"gettext_noop\" or \"N_\"");
   } // Fl_Double_Window* project_window
   return project_window;
 }
-void scheme_cb(Fl_Choice *, void *);
+void scheme_cb(Fl_Scheme_Choice *, void *);
 
 Fl_Double_Window *settings_window=(Fl_Double_Window *)0;
 
-Fl_Choice *scheme_choice=(Fl_Choice *)0;
-
-Fl_Menu_Item menu_scheme_choice[] = {
- {"Default", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {"None", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {"Plastic", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {"GTK+", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {"Gleam", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {"Oxy", 0,  0, 0, 0, (uchar)FL_NORMAL_LABEL, 0, 14, 0},
- {0,0,0,0,0,0,0,0,0}
-};
+Fl_Scheme_Choice *scheme_choice=(Fl_Scheme_Choice *)0;
 
 Fl_Check_Button *tooltips_button=(Fl_Check_Button *)0;
 
@@ -258,16 +248,20 @@ static void cb_Close1(Fl_Button*, void*) {
 
 Fl_Double_Window* make_settings_window() {
   { Fl_Double_Window* o = settings_window = new Fl_Double_Window(360, 355, "GUI Settings");
-    { scheme_choice = new Fl_Choice(140, 10, 115, 25, "Scheme: ");
+    { scheme_choice = new Fl_Scheme_Choice(140, 10, 115, 25, "Scheme: ");
+      scheme_choice->box(FL_FLAT_BOX);
       scheme_choice->down_box(FL_BORDER_BOX);
+      scheme_choice->color(FL_BACKGROUND_COLOR);
+      scheme_choice->selection_color(FL_SELECTION_COLOR);
+      scheme_choice->labeltype(FL_NORMAL_LABEL);
       scheme_choice->labelfont(1);
+      scheme_choice->labelsize(14);
+      scheme_choice->labelcolor(FL_FOREGROUND_COLOR);
       scheme_choice->callback((Fl_Callback*)scheme_cb);
-      scheme_choice->menu(menu_scheme_choice);
-      int s;
-      fluid_prefs.get("scheme", s, 0);
-      scheme_choice->value(s);
-      scheme_cb(0, 0);
-    } // Fl_Choice* scheme_choice
+      scheme_choice->align(Fl_Align(FL_ALIGN_LEFT));
+      scheme_choice->when(FL_WHEN_RELEASE);
+      init_scheme();
+    } // Fl_Scheme_Choice* scheme_choice
     { Fl_Group* o = new Fl_Group(20, 43, 330, 161);
       o->labelfont(1);
       o->align(Fl_Align(FL_ALIGN_CENTER));
diff --git a/fluid/alignment_panel.fl b/fluid/alignment_panel.fl
index 4e016220e..4525704ed 100644
--- a/fluid/alignment_panel.fl
+++ b/fluid/alignment_panel.fl
@@ -38,6 +38,9 @@ decl {\#include <FL/Fl_Text_Display.H>} {public local
 decl {\#include <FL/filename.H>} {public local
 }
 
+decl {\#include <FL/Fl_Scheme_Choice.H>} {public local
+}
+
 decl {\#include <FL/Fl_Preferences.H>} {private global
 }
 
@@ -47,11 +50,14 @@ decl {\#include <FL/fl_ask.H>} {private global
 decl {\#include <string.h>} {private global
 }
 
+decl {void init_scheme(void);} {
+  comment {// initialize the scheme from preferences} selected public global
+}
+
 decl {extern struct Fl_Menu_Item *dbmanager_item;} {public local
 }
 
-Function {make_project_window()} {open
-} {
+Function {make_project_window()} {} {
   Fl_Window project_window {
     label {Project Settings} open
     xywh {472 246 399 298} type Double hide
@@ -168,50 +174,23 @@ set_modflag(-1, -1);}
 decl {extern void i18n_cb(Fl_Choice *,void *);} {public local
 }
 
-decl {void scheme_cb(Fl_Choice *, void *);} {public local
+decl {void scheme_cb(Fl_Scheme_Choice *, void *);} {public local
 }
 
 Function {make_settings_window()} {open
 } {
   Fl_Window settings_window {
-    label {GUI Settings}
-    xywh {442 538 360 355} type Double hide resizable
+    label {GUI Settings} open
+    xywh {701 666 360 355} type Double hide resizable
     code0 {o->size_range(o->w(), o->h());} non_modal
   } {
     Fl_Choice scheme_choice {
       label {Scheme: }
       callback scheme_cb open
       xywh {140 10 115 25} down_box BORDER_BOX labelfont 1
-      code0 {int s;}
-      code1 {fluid_prefs.get("scheme", s, 0);}
-      code2 {scheme_choice->value(s);}
-      code3 {scheme_cb(0, 0);}
-    } {
-      MenuItem {} {
-        label Default
-        xywh {0 0 35 25}
-      }
-      MenuItem {} {
-        label None
-        xywh {0 0 35 25}
-      }
-      MenuItem {} {
-        label Plastic
-        xywh {0 0 35 25}
-      }
-      MenuItem {} {
-        label {GTK+}
-        xywh {10 10 35 25}
-      }
-      MenuItem {} {
-        label Gleam
-        xywh {20 20 35 25}
-      }
-      MenuItem {} {
-        label Oxy
-        xywh {30 30 35 25}
-      }
-    }
+      code0 {init_scheme();}
+      class Fl_Scheme_Choice
+    } {}
     Fl_Group {} {open
       xywh {20 43 330 161} labelfont 1 align 0
     } {
@@ -327,7 +306,7 @@ Function {make_shell_window()} {open
         tooltip {save the design to the .fl file before running the command} xywh {82 39 136 19} down_box DOWN_BOX labelsize 12
       }
       Fl_Check_Button shell_writecode_button {
-        label {save source code} selected
+        label {save source code}
         tooltip {generate the source code and header file before running the command} xywh {82 59 120 19} down_box DOWN_BOX labelsize 12
       }
       Fl_Check_Button shell_writemsgs_button {
diff --git a/fluid/alignment_panel.h b/fluid/alignment_panel.h
index 5f6e35e74..845260289 100644
--- a/fluid/alignment_panel.h
+++ b/fluid/alignment_panel.h
@@ -25,6 +25,11 @@
 #include <FL/Fl_Text_Buffer.H>
 #include <FL/Fl_Text_Display.H>
 #include <FL/filename.H>
+#include <FL/Fl_Scheme_Choice.H>
+/**
+ // initialize the scheme from preferences
+*/
+void init_scheme(void);
 extern struct Fl_Menu_Item *dbmanager_item;
 #include <FL/Fl_Double_Window.H>
 #include <FL/Fl_Preferences.H>
@@ -63,10 +68,10 @@ extern Fl_Input *i18n_static_function_input;
 Fl_Double_Window* make_project_window();
 extern Fl_Menu_Item menu_i18n_type_chooser[];
 extern void i18n_cb(Fl_Choice *,void *);
-extern void scheme_cb(Fl_Choice *, void *);
+extern void scheme_cb(Fl_Scheme_Choice *, void *);
 extern Fl_Double_Window *settings_window;
-extern void scheme_cb(Fl_Choice*, void*);
-extern Fl_Choice *scheme_choice;
+extern void scheme_cb(Fl_Scheme_Choice*, void*);
+extern Fl_Scheme_Choice *scheme_choice;
 extern Fl_Check_Button *tooltips_button;
 extern Fl_Check_Button *completion_button;
 extern Fl_Check_Button *openlast_button;
@@ -77,7 +82,6 @@ extern Fl_Spinner *recent_spinner;
 extern Fl_Check_Button *use_external_editor_button;
 extern Fl_Input *editor_command_input;
 Fl_Double_Window* make_settings_window();
-extern Fl_Menu_Item menu_scheme_choice[];
 extern Fl_Double_Window *shell_window;
 extern Fl_Input *shell_command_input;
 extern Fl_Check_Button *shell_savefl_button;
diff --git a/fluid/fluid.cxx b/fluid/fluid.cxx
index 62c3e9636..47266b63f 100644
--- a/fluid/fluid.cxx
+++ b/fluid/fluid.cxx
@@ -1475,34 +1475,80 @@ Fl_Menu_Item Main_Menu[] = {
 
 /**
  Change the app's and hence preview the design's scheme.
- The scheme setting is stored inthe app preferences.
+
+ The scheme setting is stored in the app preferences
+ - in key \p 'scheme_name' since 1.4.0
+ - in key \p 'scheme' (index: 0 - 4) in 1.3.x
+
+ This callback is triggered by changing the scheme in the
+ Fl_Scheme_Choice widget (\p Edit/GUI Settings).
+
+ \see init_scheme() for choice values and backwards compatibility
  */
-void scheme_cb(Fl_Choice *, void *) {
+void scheme_cb(Fl_Scheme_Choice *choice, void *) {
   if (batch_mode)
     return;
 
-  switch (scheme_choice->value()) {
-    case 0 : // Default
-      Fl::scheme(NULL);
-      break;
-    case 1 : // None
-      Fl::scheme("none");
-      break;
-    case 2 : // Plastic
-      Fl::scheme("plastic");
-      break;
-    case 3 : // GTK+
-      Fl::scheme("gtk+");
-      break;
-    case 4 : // Gleam
-      Fl::scheme("gleam");
-      break;
-    case 5 : // Oxy
-      Fl::scheme("oxy");
-      break;
-  }
-
-  fluid_prefs.set("scheme", scheme_choice->value());
+  // set the new scheme only if the scheme was changed
+  const char *new_scheme = choice->text(choice->value());
+
+  if (Fl::is_scheme(new_scheme))
+    return;
+
+  Fl::scheme(new_scheme);
+  fluid_prefs.set("scheme_name", new_scheme);
+
+  // Backwards compatibility: store 1.3 scheme index (1-4).
+  // We assume that index 0-3 (base, plastic, gtk+, gleam) are in the
+  // same order as in 1.3.x (index 1-4), higher values are ignored
+
+  int scheme_index = scheme_choice->value();
+  if (scheme_index <= 3)                          // max. index for 1.3.x (Gleam)
+    fluid_prefs.set("scheme", scheme_index + 1);  // compensate for different indexing
+}
+
+/**
+  Read Fluid's scheme preferences and set the app's scheme.
+
+  Since FLTK 1.4.0 the scheme \b name is stored as a character string
+  with key "scheme_name" in the preference database.
+
+  In FLTK 1.3.x the scheme preference was stored as an integer index
+  with key "scheme" in the database. The known schemes were hardcoded in
+  Fluid's sources (here for reference):
+
+    | Index | 1.3 Scheme Name | Choice | 1.4 Scheme Name |
+    |-------|-----------------|-------|-----------------|
+    | 0 | Default (same as None) | n/a | n/a |
+    | 1 | None (same as Default) | 0 | base |
+    | 2 | Plastic | 1 | plastic |
+    | 3 | GTK+ | 2 | gtk+ |
+    | 4 | Gleam | 3 | gleam |
+    | n/a | n/a | 4 | oxy |
+
+  The new Fluid tries to keep backwards compatibility and reads both
+  keys (\p scheme and \p scheme_name). If the latter is defined, it is used.
+  If not the old \p scheme (index) is used - but we need to subtract one to
+  get the new Fl_Scheme_Choice index (column "Choice" above).
+*/
+void init_scheme() {
+  int scheme_index = 0;                     // scheme index for backwards compatibility (1.3.x)
+  char *scheme_name;                        // scheme name since 1.4.0
+  fluid_prefs.get("scheme_name", scheme_name, "XXX"); // XXX means: not set => fallback 1.3.x
+  if (!strcmp(scheme_name, "XXX")) {
+    fluid_prefs.get("scheme", scheme_index, 0);
+    if (scheme_index > 0) {
+      scheme_index--;
+      scheme_choice->value(scheme_index);   // set the choice value
+    }
+    if (scheme_index < 0)
+      scheme_index = 0;
+    else if (scheme_index > scheme_choice->size() - 1)
+      scheme_index = 0;
+    scheme_name = const_cast<char *>(scheme_choice->text(scheme_index));
+    fluid_prefs.set("scheme_name", scheme_name);
+  }
+  Fl::scheme(scheme_name);
 }
 
 /**