Add Fl_Grid widget and test and demo programs

- FL/Fl_Grid.H: header file
- src/Fl_Grid.cxx: implementation

- examples/grid-simple.cxx: simple example program
- test/cube.cxx:            use Fl_Grid for layout
- test/grid_alignment.cxx:  test cell alignment and other functions
- test/grid_buttons.cxx:    demo program as discussed in fltk.general
- test/grid_login.cxx:      like test/flex_login.cxx but with Fl_Grid
- test/flex_login.cxx:      modified to match test/grid_login.cxx

1 files changed, 96 insertions, 93 deletions

diff --git a/test/cube.cxx b/test/cube.cxx
index 2dacb5976..bd69bc42c 100644
--- a/test/cube.cxx
+++ b/test/cube.cxx
@@ -3,7 +3,7 @@
 //
 // Modified to have 2 cubes to test multiple OpenGL contexts
 //
-// Copyright 1998-2021 by Bill Spitzak and others.
+// Copyright 1998-2023 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
@@ -26,7 +26,7 @@
 #include <FL/Fl_Slider.H>
 #include <FL/Fl_Sys_Menu_Bar.H>
 #include <FL/Fl_Printer.H>      // demo printing
-
+#include <FL/Fl_Grid.H>         // grid layout
 #include <stdlib.h>
 
 #if !HAVE_GL
@@ -39,8 +39,6 @@ public:
   cube_box(int x,int y,int w,int h,const char *l=0) :Fl_Box(FL_DOWN_BOX,x,y,w,h,l) {
     label("This demo does\nnot work without GL");
   }
-  void begin() {}
-  void end() {}
 };
 #else
 #include <FL/Fl_Gl_Window.H>
@@ -120,11 +118,8 @@ void cube_box::draw() {
   gl_draw(wire ? "Cube: wire" : "Cube: flat", -4.5f, -4.5f );
   glEnable(GL_DEPTH_TEST);
 
-  // if an OpenGL graphics driver is installed, give it a chance
-  // to draw additional graphics
-#if HAVE_GL
+  // draw additional FLTK widgets and graphics
   Fl_Gl_Window::draw();
-#endif
 }
 
 int cube_box::handle(int e) {
@@ -135,121 +130,128 @@ int cube_box::handle(int e) {
   return Fl_Gl_Window::handle(e);
 }
 
-#endif
+// callback for overlay button (Fl_Button on OpenGL scene)
+void show_info_cb(Fl_Widget*, void*) {
+  fl_message("This is an example of using FLTK widgets inside OpenGL windows.\n"
+             "Multiple widgets can be added to Fl_Gl_Windows. They will be\n"
+             "rendered as overlays over the scene.");
+}
+
+// overlay a button onto an OpenGL window (cube_box)
+void overlay_button(cube_box *cube) {
+  cube->begin();
+  Fl_Widget *w = new Fl_Button(10, 10, 120, 30, "FLTK over GL");
+  w->color(FL_FREE_COLOR);
+  w->box(FL_BORDER_BOX);
+  w->callback(show_info_cb);
+  cube->end();
+}
+
+#endif // HAVE_GL
 
 Fl_Window *form;
 Fl_Slider *speed, *size;
 Fl_Button *exit_button, *wire, *flat;
 cube_box  *lt_cube, *rt_cube;
-
 int done = 0; // set to 1 in exit button callback
 
 // exit button callback
-void exit_cb(Fl_Widget *, void *) {
+void exit_cb(Fl_Widget *w, void *) {
   done = 1;
+  w->window()->hide(); // necessary if built w/o GL
 }
 
 // print screen demo
-void print_cb(Fl_Widget *w, void *data)
-{
+void print_cb(Fl_Widget *w, void *data) {
   Fl_Printer printer;
   Fl_Window *win = Fl::first_window();
-  if(!win) return;
-  if( printer.start_job(1) ) return;
-  if( printer.start_page() ) return;
-  printer.scale(0.5,0.5);
-  printer.print_widget( win );
+  if (!win) return;
+  if (printer.start_job(1)) return;
+  if (printer.start_page()) return;
+  printer.scale(0.5, 0.5);
+  printer.print_widget(win);
   printer.end_page();
   printer.end_job();
 }
 
 // Create a form that allows resizing for A and C (GL windows) with B fixed size/centered:
 //
-//                  lt_grp                                rt_grp
 //      |<--------------------------------------->|<---------------------->|
-//      .          lt_cube            ct_grp      :       rt_cube          .
+//      .          lt_cube            center      :       rt_cube          .
 //      .            350                100       :         350            .
 //      .  |<------------------->|  |<-------->|  |<------------------->|  .
 //      ....................................................................
-//      :  .......................  ............  .......................  :
+//      :  .......................  ............  .......................  :  __
 //      :  :                     :  :          :  :                     :  :
-//      :  :          A          :  :    B     :  :          C          :  :
+//      :  :          A          :  :    B     :  :          C          :  :     h = 350
 //      :  :                     :  :          :  :                     :  :
 //      :  :.....................:  :..........:  :.....................:  :  __
 //      :..................................................................:  __ MARGIN
 //
-//      |  |
-//     MARGIN
-//
+//      |  |                     |  |          |  |
+//     MARGIN                    GAP           GAP
 
-#define MENUBAR_H 25            // menubar height
-#define MARGIN    20            // fixed margin around widgets
-#define MARGIN2   (MARGIN*2)
-#define MARGIN3   (MARGIN*3)
-
-void show_info_cb(Fl_Widget*, void*) {
-  fl_message("This is an example of using FLTK widgets inside OpenGL windows.\n"
-             "Multiple widgets can be added to Fl_Gl_Windows. They will be\n"
-             "rendered as overlays over the scene.");
-}
+#define MENUBAR_H 25    // menubar height
+#define MARGIN    20    // fixed margin around widgets
+#define GAP       20    // fixed gap between widgets
 
 void makeform(const char *name) {
   // Widget's XYWH's
-  int form_w = 800 + 4 * MARGIN;             // main window width
+  int form_w = 800 + 2 * MARGIN + 2 * GAP;   // main window width
   int form_h = 350 + MENUBAR_H + 2 * MARGIN; // main window height
-  int me_bar_x=0,                    me_bar_y=0,                me_bar_w=form_w,          me_bar_h=MENUBAR_H;                // menubar
-  int lt_grp_x=0,                    lt_grp_y=MENUBAR_H+MARGIN, lt_grp_w=350+100+MARGIN3, lt_grp_h=form_h-MENUBAR_H-MARGIN2; // left group
-  int lt_cub_x=lt_grp_x+MARGIN,      lt_cub_y=lt_grp_y,         lt_cub_w=350,             lt_cub_h=lt_grp_h;                 // left cube box (GL)
-  int ct_grp_x=lt_grp_x+350+MARGIN2, ct_grp_y=lt_grp_y,         ct_grp_w=100,             ct_grp_h=lt_grp_h;                 // center group
-  int rt_grp_x=lt_grp_x+lt_grp_w,    rt_grp_y=lt_grp_y,         rt_grp_w=350+MARGIN,      rt_grp_h=lt_grp_h;                 // right group
-  int rt_cub_x=rt_grp_x,             rt_cub_y=lt_grp_y,         rt_cub_w=350,             rt_cub_h=lt_grp_h;                 // right cube box (GL)
 
   // main window
   form = new Fl_Window(form_w, form_h, name);
-  form->begin();
-    // menu bar
-    Fl_Sys_Menu_Bar *menubar = new Fl_Sys_Menu_Bar(me_bar_x, me_bar_y, me_bar_w, me_bar_h);
-    menubar->add("File/Print window", FL_COMMAND+'p', print_cb);
-    menubar->add("File/Quit",         FL_COMMAND+'q', exit_cb);
-    // left group
-    Fl_Group *lt_grp = new Fl_Group(lt_grp_x, lt_grp_y, lt_grp_w, lt_grp_h);
-    lt_grp->begin();
-      // left GL window
-      lt_cube = new cube_box(lt_cub_x, lt_cub_y, lt_cub_w, lt_cub_h, 0);
+  // menu bar
+  Fl_Sys_Menu_Bar *menubar = new Fl_Sys_Menu_Bar(0, 0, form_w, MENUBAR_H);
+  menubar->add("File/Print window", FL_COMMAND+'p', print_cb);
+  menubar->add("File/Quit",         FL_COMMAND+'q', exit_cb);
+
+  // Fl_Grid (layout)
+  Fl_Grid *grid = new Fl_Grid(0, MENUBAR_H, form_w, 350 + 2 * MARGIN);
+  grid->layout(4, 4, MARGIN, GAP);
+  grid->box(FL_FLAT_BOX);
+
+  // set column and row weights to control resizing behavior
+  int cwe[] = {50,  0,  0, 50}; // column weights
+  int rwe[] = { 0,  0, 50,  0}; // row weights
+  grid->col_weight(cwe, 4);     // set weights for resizing
+  grid->row_weight(rwe, 4);     // set weights for resizing
+
+  // set non-default gaps for special layout purposes and labels
+  grid->row_gap(0,  0);         // no gap below wire button
+  grid->row_gap(2, 50);         // gap below sliders for labels
 
-      lt_cube->begin();
-      Fl_Widget *w = new Fl_Button(10, 10, 120, 30, "FLTK over GL");
-      w->color(FL_FREE_COLOR);
-      w->box(FL_BORDER_BOX );
-      w->callback(show_info_cb);
-      lt_cube->end();
+  // left GL window
+  lt_cube = new cube_box(0, 0, 350, 350);
 
-      // center group
-      Fl_Group *ct_grp = new Fl_Group(ct_grp_x, ct_grp_y, ct_grp_w, ct_grp_h);
-      ct_grp->begin();
-        wire  = new Fl_Radio_Light_Button(ct_grp_x, ct_grp_y,            100, 25, "Wire");
-        flat  = new Fl_Radio_Light_Button(ct_grp_x, wire->y()+wire->h(), 100, 25, "Flat");
-        speed = new Fl_Slider(FL_VERT_SLIDER, ct_grp_x,           flat->y()+flat->h()+MARGIN, 40, 200, "Speed");
-        size  = new Fl_Slider(FL_VERT_SLIDER, ct_grp_x+40+MARGIN, flat->y()+flat->h()+MARGIN, 40, 200, "Size");
-        exit_button = new Fl_Button(ct_grp_x, form_h-MARGIN-25, 100, 25, "Exit");
-        exit_button->callback(exit_cb);
-      ct_grp->end();
-      ct_grp->resizable(speed);      // only sliders resize vertically, not buttons
-    lt_grp->end();
-    lt_grp->resizable(lt_cube);
-    // right group
-    Fl_Group *rt_grp = new Fl_Group(rt_grp_x, rt_grp_y, rt_grp_w, rt_grp_h);
-    rt_grp->begin();
-      // right GL window
-      rt_cube = new cube_box(rt_cub_x, rt_cub_y, rt_cub_w, rt_cub_h, 0);
-    rt_grp->end();
-    rt_grp->resizable(rt_cube);
-    // right resizer
-    Fl_Box *rt_resizer = new Fl_Box(rt_grp_x-5, rt_grp_y, 10, rt_grp_h);
-    rt_resizer->box(FL_NO_BOX);
+  // center group
+  wire  = new Fl_Radio_Light_Button(    0, 0, 100, 25, "Wire");
+  flat  = new Fl_Radio_Light_Button(    0, 0, 100, 25, "Flat");
+  speed = new Fl_Slider(FL_VERT_SLIDER, 0, 0,  40, 90, "Speed");
+  size  = new Fl_Slider(FL_VERT_SLIDER, 0, 0,  40, 90, "Size");
+  exit_button = new Fl_Button(          0, 0, 100, 25, "Exit");
+  exit_button->callback(exit_cb);
+
+  // right GL window
+  rt_cube = new cube_box(0, 0, 350, 350);
+
+  // assign widgets to grid positions (R=row, C=col) and sizes
+  // RS=rowspan, CS=colspan: R, C, RS, CS, optional alignment
+  grid->widget(lt_cube,      0, 0,  4,  1);
+  grid->widget(wire,         0, 1,  1,  2);
+  grid->widget(flat,         1, 1,  1,  2);
+  grid->widget(speed,        2, 1,  1,  1, FL_GRID_VERTICAL);
+  grid->widget(size,         2, 2,  1,  1, FL_GRID_VERTICAL);
+  grid->widget(exit_button,  3, 1,  1,  2);
+  grid->widget(rt_cube,      0, 3,  4,  1);
+
+#if HAVE_GL
+  overlay_button(lt_cube);  // overlay a button onto the OpenGL window
+#endif // HAVE_GL
 
   form->end();
-  form->resizable(rt_resizer);
+  form->resizable(grid);
   form->size_range(form->w(), form->h()); // minimum window size
 }
 
@@ -257,29 +259,27 @@ int main(int argc, char **argv) {
   Fl::use_high_res_GL(1);
   Fl::set_color(FL_FREE_COLOR, 255, 255, 0, 75);
   makeform(argv[0]);
-  speed->bounds(4,0);
-#if HAVE_GL
+  speed->bounds(4, 0);
   speed->value(lt_cube->speed = rt_cube->speed = 1.0);
-#else
-  speed->value(lt_cube->speed = rt_cube->speed = 0.0);
-#endif
-  size->bounds(4,0.01);
-  size->value(lt_cube->size = rt_cube->size = 3.0);
+  size->bounds(4, 0.2);
+  size->value(lt_cube->size = rt_cube->size = 2.0);
   flat->value(1); lt_cube->wire = 0; rt_cube->wire = 1;
-  form->label("cube");
+  form->label("Cube Demo");
   form->show(argc,argv);
   lt_cube->show();
   rt_cube->show();
+
 #if 0
   // This demonstrates how to manipulate OpenGL contexts.
   // In this case the same context is used by multiple windows (I'm not
   // sure if this is allowed on Win32, can somebody check?).
-  // This fixes a bug on the XFree86 3.0 OpenGL where only one context
-  // per program seems to work, but there are probably better uses for
-  // this!
+  // This fixes a bug on the XFree86 3.0 OpenGL where only one context per
+  // program seems to work, but there are probably better uses for this!
   lt_cube->make_current(); // causes context to be created
   rt_cube->context(lt_cube->context()); // share the contexts
 #endif
+
+#if HAVE_GL
   for (;;) {
     if (form->visible() && speed->value()) {
       if (!Fl::check()) break;   // returns immediately
@@ -295,4 +295,7 @@ int main(int argc, char **argv) {
     if (done) break; // exit button was clicked
   }
   return 0;
+#else
+  return Fl::run();
+#endif
 }