Add Fl_Flex widget from Karsten Pedersen (issue #255)

This work is based on the repository and latest commit:
  https://github.com/osen/FL_Flex.git

  commit 36e4ed75a00daac825b87e81295818b4650991f5
  Author: Karsten Pedersen <...>
  Date:   Fri Apr 23 12:06:16 2021 +0000

    Added Fltk (LGPL) license.

This widget is similar to Fl_Pack and supports either one row or one
column of widgets but has some more features. Test and demo programs
are included:

  test/flex_login.cxx: simple "login window" demo program
  test/flex_demo.cxx:  slightly more complex demo program

The original demo programs can still be compiled and built with
the new widget provided you '#include <FL/Fl_Flex.H>'.
Backwards compatible methods are included (except debug()).

The original widget has been modified to match FLTK standards and
enhanced in several ways, including:

- support box frames
- add HORIZONTAL and VERTICAL enum values (as in Fl_Pack)
- add horizontal() method (as in Fl_Pack)
- use type() rather than internal 'direction' variable
- add standard widget constructor (x, y, w, h, label)
- add margin and gap accessors rather than hard coding constants
- improve test and demo programs
- add documentation
- replace <vector> with array as required by FLTK CMP
- rename camelCase method names, keeping old names for compatibility:
  - change 'setSize(Fl_Widget*, int)'   to 'set_size(Fl_Widget*, int)'
  - change 'bool isSetSize(Fl_Widget*)' to 'int set_size(Fl_Widget*)'
- remove debug() method
- add a way to "unset" fixed size: set_size(Fl_Widget *, 0)
- add layout() method to force recalculation of children
- unify resizeRow() and resizeCol() methods to avoid code duplication
- improve widget size calculation.

6 files changed, 351 insertions, 0 deletions

diff --git a/test/.gitignore b/test/.gitignore
index 6947a6d0c..49b1817e0 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -41,6 +41,8 @@ doublebuffer
 editor
 fast_slow
 file_chooser
+flex_demo
+flex_login
 fltk-versions
 fonts
 forms
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 7e295e879..cfc189168 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -81,6 +81,8 @@ CREATE_EXAMPLE (doublebuffer doublebuffer.cxx fltk)
 CREATE_EXAMPLE (editor "editor.cxx;editor.plist" fltk)
 CREATE_EXAMPLE (fast_slow fast_slow.fl fltk)
 CREATE_EXAMPLE (file_chooser file_chooser.cxx "fltk_images;fltk")
+CREATE_EXAMPLE (flex_demo flex_demo.cxx fltk)
+CREATE_EXAMPLE (flex_login flex_login.cxx fltk)
 CREATE_EXAMPLE (fltk-versions fltk-versions.cxx fltk)
 CREATE_EXAMPLE (fonts fonts.cxx fltk)
 CREATE_EXAMPLE (forms forms.cxx "fltk_forms;fltk")
diff --git a/test/Makefile b/test/Makefile
index 49d56e7be..4b4f5691e 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -74,6 +74,8 @@ CPPFILES =\
 	editor.cxx \
 	fast_slow.cxx \
 	file_chooser.cxx \
+	flex_demo.cxx \
+	flex_login.cxx \
 	fltk-versions.cxx \
 	fonts.cxx \
 	forms.cxx \
@@ -163,6 +165,8 @@ ALL =	\
 	editor$(EXEEXT) \
 	fast_slow$(EXEEXT) \
 	file_chooser$(EXEEXT) \
+	flex_demo$(EXEEXT) \
+	flex_login$(EXEEXT) \
 	fltk-versions$(EXEEXT) \
 	fonts$(EXEEXT) \
 	forms$(EXEEXT) \
@@ -420,6 +424,10 @@ file_chooser$(EXEEXT): file_chooser.o $(IMGLIBNAME)
 	$(CXX) $(ARCHFLAGS) $(CXXFLAGS) $(LDFLAGS) file_chooser.o -o $@ $(LINKFLTKIMG) $(LDLIBS)
 	$(OSX_ONLY) ../fltk-config --post $@
 
+flex_demo$(EXEEXT): flex_demo.o
+
+flex_login$(EXEEXT): flex_login.o
+
 fltk-versions$(EXEEXT): fltk-versions.o
 
 fonts$(EXEEXT): fonts.o
diff --git a/test/flex_demo.cxx b/test/flex_demo.cxx
new file mode 100644
index 000000000..fb2b73cef
--- /dev/null
+++ b/test/flex_demo.cxx
@@ -0,0 +1,168 @@
+//
+// Fl_Flex demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2020 by Karsten Pedersen
+// 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
+//
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Flex.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Input.H>
+
+#define DEBUG_GROUP (0)
+
+void debug_group(Fl_Group *g) {
+#if (DEBUG_GROUP)
+  printf("\nFl_Group (%p) has %d children:\n", g, g->children());
+  for (int i = 0; i < g->children(); i++) {
+    Fl_Widget *c = g->child(i);
+    printf("  child %2d: hidden = %-5s, (x,y,w,h) = (%3d, %3d, %3d, %3d), label = '%s'\n",
+           i, c->visible() ? "false" : "true", c->x(), c->y(), c->w(), c->h(),
+           c->label() ? c->label() : "(null)");
+  }
+#endif
+} // debug_group
+
+Fl_Button *createButton(const char *caption) {
+  Fl_Button *rtn = new Fl_Button(0, 0, 120, 30, caption);
+  rtn->color(fl_rgb_color(225, 225, 225));
+  return rtn;
+}
+
+void toggle_cb(Fl_Widget *w, void *v) {
+  static Fl_Box *b = 0;
+  Fl_Widget *o = (Fl_Widget *)v;
+  Fl_Flex *flex = (Fl_Flex *)o->parent();
+  if (o->visible()) {
+    o->hide();
+    w->label("show OK button");
+    flex->child(1)->hide();         // hide Box
+  } else {
+    o->show();
+    w->label("hide OK button");
+    flex->child(1)->show();         // show Box
+  }
+  flex->layout();
+
+  debug_group(flex);
+
+  // Yet another test: modify the first (top) Fl_Flex widget
+
+  flex = (Fl_Flex *)(flex->parent()->child(0));
+  Fl_Group::current(0);
+  if (!b) {
+    b = new Fl_Box(0, 0, 0, 0, "Box3");
+    flex->insert(*b, flex->children() - 1);
+  } else {
+    delete b;
+    b = 0;
+  }
+  flex->layout();
+  debug_group(flex);
+}
+
+Fl_Flex *createRow() {
+  Fl_Flex *row = new Fl_Flex(Fl_Flex::ROW);
+  {
+    Fl_Button *toggle = createButton("hide OK button");
+    toggle->tooltip("hide() or show() OK button");
+    Fl_Box *box2 = new Fl_Box(0, 0, 120, 10, "Box2");
+    Fl_Button * okay = createButton("OK");
+    new Fl_Input(0, 0, 120, 10, "");
+
+    toggle->callback(toggle_cb, okay);
+
+    Fl_Flex *col2 = new Fl_Flex(Fl_Flex::COLUMN);
+    {
+      createButton("Top2");
+      createButton("Bottom2");
+      col2->end();
+      col2->margin(0, 5);
+      col2->box(FL_FLAT_BOX);
+      col2->color(fl_rgb_color(255, 128, 128));
+    }
+
+    row->set_size(box2, 50);
+    row->set_size(col2, 100);
+    row->end();
+
+    // TEST
+    row->box(FL_DOWN_BOX);
+    row->color(FL_GREEN);
+  }
+
+  return row;
+}
+
+int main(int argc, char **argv) {
+
+  Fl_Window *window = new Fl_Double_Window(100, 100, "Simple GUI Example");
+  {
+    Fl_Flex *col = new Fl_Flex(5, 5, 90, 90, Fl_Flex::COLUMN);
+    {
+      Fl_Flex *row = new Fl_Flex(Fl_Flex::ROW);
+      row->color(FL_YELLOW);
+      row->box(FL_FLAT_BOX);
+      {
+        createButton("Cancel");
+        new Fl_Box(0, 0, 120, 10, "Box1");
+        createButton("OK");
+        new Fl_Input(0, 0, 120, 10, "");
+
+        Fl_Flex *col1 = new Fl_Flex(Fl_Flex::COLUMN);
+        {
+          createButton("Top1");
+          createButton("Bottom1");
+          col1->end();
+          col1->box(FL_FLAT_BOX);
+          col1->color(fl_rgb_color(255, 128, 128));
+          col1->margin(5, 5);
+        }
+
+        row->end();
+      }
+      col->set_size(createRow(), 90);
+      createButton("Something1");
+      row = new Fl_Flex(Fl_Flex::ROW);
+      {
+        Fl_Button *cancel = createButton("Cancel");
+        Fl_Button *ok = createButton("OK");
+        new Fl_Input(0, 0, 120, 10, "");
+
+        row->set_size(cancel, 100);
+        row->set_size(ok, 100);
+        row->end();
+      }
+      createButton("Something2");
+
+      col->set_size(row, 30);
+      col->margin(0, 6);
+      col->end();
+    }
+    window->resizable(col);
+    window->color(fl_rgb_color(160, 180, 240));
+    window->box(FL_FLAT_BOX);
+    window->end();
+  }
+
+  window->size_range(550, 330);
+  window->resize(0, 0, 640, 480);
+  window->show(argc, argv);
+
+  int ret = Fl::run();
+  delete window;
+  return ret;
+}
diff --git a/test/flex_login.cxx b/test/flex_login.cxx
new file mode 100644
index 000000000..3923bcde3
--- /dev/null
+++ b/test/flex_login.cxx
@@ -0,0 +1,131 @@
+//
+// Fl_Flex demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2020 by Karsten Pedersen
+// 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
+//
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Flex.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Input.H>
+
+Fl_Button *createButton(const char *caption) {
+  Fl_Button *rtn = new Fl_Button(0, 0, 100, 25, caption);
+  rtn->color(fl_rgb_color(225, 225, 225));
+  return rtn;
+}
+
+void buttonsPanel(Fl_Flex *parent) {
+  new Fl_Box(0, 0, 0, 0, "");
+  Fl_Box *w = new Fl_Box(0, 0, 0, 0, "Welcome to Flex Login");
+
+  Fl_Flex *urow = new Fl_Flex(Fl_Flex::ROW);
+  {
+    Fl_Box *b = new Fl_Box(0, 0, 0, 0, "Username:");
+    b->align(FL_ALIGN_INSIDE | FL_ALIGN_RIGHT);
+    Fl_Input *username = new Fl_Input(0, 0, 0, 0, "");
+
+    urow->set_size(username, 180);
+    urow->end();
+  }
+
+  Fl_Flex *prow = new Fl_Flex(Fl_Flex::ROW);
+  {
+    Fl_Box *b = new Fl_Box(0, 0, 0, 0, "Password:");
+    b->align(FL_ALIGN_INSIDE | FL_ALIGN_RIGHT);
+    Fl_Input *password = new Fl_Input(0, 0, 0, 0, "");
+
+    prow->set_size(password, 180);
+    prow->end();
+  }
+
+  Fl_Box *pad = new Fl_Box(0, 0, 0, 0, "");
+
+  Fl_Flex *brow = new Fl_Flex(Fl_Flex::ROW);
+  {
+    new Fl_Box(0, 0, 0, 0, "");
+    Fl_Button *reg = createButton("Register");
+    Fl_Button *login = createButton("Login");
+
+    brow->set_size(reg, 80);
+    brow->set_size(login, 80);
+    brow->gap(20);
+
+    brow->end();
+  }
+
+  Fl_Box *b = new Fl_Box(0, 0, 0, 0, "");
+
+  parent->set_size(w, 60);
+  parent->set_size(urow, 30);
+  parent->set_size(prow, 30);
+  parent->set_size(pad, 1);
+  parent->set_size(brow, 30);
+  parent->set_size(b, 30);
+}
+
+void middlePanel(Fl_Flex *parent) {
+  new Fl_Box(0, 0, 0, 0, "");
+
+  Fl_Box *box = new Fl_Box(0, 0, 0, 0, "Image");
+  box->box(FL_BORDER_BOX);
+  box->color(fl_rgb_color(0, 200, 0));
+  Fl_Box *spacer = new Fl_Box(0, 0, 0, 0, "");
+
+  Fl_Flex *bp = new Fl_Flex(Fl_Flex::COLUMN);
+  buttonsPanel(bp);
+  bp->end();
+
+  new Fl_Box(0, 0, 0, 0, "");
+
+  parent->set_size(box, 200);
+  parent->set_size(spacer, 10);
+  parent->set_size(bp, 300);
+}
+
+void mainPanel(Fl_Flex *parent) {
+  new Fl_Box(0, 0, 0, 0, "");
+
+  Fl_Flex *mp = new Fl_Flex(Fl_Flex::ROW);
+  middlePanel(mp);
+  mp->end();
+
+  new Fl_Box(0, 0, 0, 0, "");
+
+  parent->set_size(mp, 200);
+}
+
+int main(int argc, char **argv) {
+
+  Fl_Window *window = new Fl_Double_Window(100, 100, "Simple GUI Example");
+  {
+    Fl_Flex *col = new Fl_Flex(5, 5, 90, 90, Fl_Flex::COLUMN);
+    mainPanel(col);
+    col->end();
+
+    window->resizable(col);
+    window->color(fl_rgb_color(250, 250, 250));
+    window->end();
+  }
+
+  window->resize(0, 0, 640, 480);
+  window->size_range(550, 250);
+  window->show(argc, argv);
+
+  int ret = Fl::run();
+  delete window;
+  return ret;
+}
diff --git a/test/makedepend b/test/makedepend
index 3fbcd2262..a3e88fdd3 100644
--- a/test/makedepend
+++ b/test/makedepend
@@ -857,6 +857,46 @@ file_chooser.o: ../FL/Fl_Valuator.H
 file_chooser.o: ../FL/Fl_Widget.H
 file_chooser.o: ../FL/Fl_Window.H
 file_chooser.o: ../FL/platform_types.h
+flex_demo.o: ../FL/Enumerations.H
+flex_demo.o: ../FL/Fl.H
+flex_demo.o: ../FL/Fl_Bitmap.H
+flex_demo.o: ../FL/Fl_Box.H
+flex_demo.o: ../FL/Fl_Button.H
+flex_demo.o: ../FL/Fl_Cairo.H
+flex_demo.o: ../FL/fl_casts.H
+flex_demo.o: ../FL/fl_config.h
+flex_demo.o: ../FL/Fl_Double_Window.H
+flex_demo.o: ../FL/Fl_Export.H
+flex_demo.o: ../FL/Fl_Flex.H
+flex_demo.o: ../FL/Fl_Group.H
+flex_demo.o: ../FL/Fl_Image.H
+flex_demo.o: ../FL/Fl_Input.H
+flex_demo.o: ../FL/Fl_Input_.H
+flex_demo.o: ../FL/fl_types.h
+flex_demo.o: ../FL/fl_utf8.h
+flex_demo.o: ../FL/Fl_Widget.H
+flex_demo.o: ../FL/Fl_Window.H
+flex_demo.o: ../FL/platform_types.h
+flex_login.o: ../FL/Enumerations.H
+flex_login.o: ../FL/Fl.H
+flex_login.o: ../FL/Fl_Bitmap.H
+flex_login.o: ../FL/Fl_Box.H
+flex_login.o: ../FL/Fl_Button.H
+flex_login.o: ../FL/Fl_Cairo.H
+flex_login.o: ../FL/fl_casts.H
+flex_login.o: ../FL/fl_config.h
+flex_login.o: ../FL/Fl_Double_Window.H
+flex_login.o: ../FL/Fl_Export.H
+flex_login.o: ../FL/Fl_Flex.H
+flex_login.o: ../FL/Fl_Group.H
+flex_login.o: ../FL/Fl_Image.H
+flex_login.o: ../FL/Fl_Input.H
+flex_login.o: ../FL/Fl_Input_.H
+flex_login.o: ../FL/fl_types.h
+flex_login.o: ../FL/fl_utf8.h
+flex_login.o: ../FL/Fl_Widget.H
+flex_login.o: ../FL/Fl_Window.H
+flex_login.o: ../FL/platform_types.h
 fltk-versions.o: ../FL/Enumerations.H
 fltk-versions.o: ../FL/Fl.H
 fltk-versions.o: ../FL/fl_ask.H