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, 203 insertions, 0 deletions

diff --git a/test/grid_alignment.cxx b/test/grid_alignment.cxx
new file mode 100644
index 000000000..59a5368c3
--- /dev/null
+++ b/test/grid_alignment.cxx
@@ -0,0 +1,203 @@
+//
+// Fl_Grid demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Albrecht Schlosser
+// Copyright 2022-2023 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
+// 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
+//
+
+//
+// This program tests several different alignment features of Fl_Grid.
+//
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Grid.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Input.H>
+#include <FL/Fl_Box.H>
+
+// Test function to change the layout (executed by timer callback)
+
+#define TEST_RELAYOUT (0)
+#define TEST_REMOVE_NOTIFY (0)
+
+#if (TEST_RELAYOUT)
+void relayout_cb(void *v) {
+  Fl_Grid *grid = (Fl_Grid *)v;
+  grid->layout(5, 5, 8, 4);
+  grid->margin(10, 20, 30, 40);
+  grid->layout();
+  grid->redraw();
+}
+#endif
+
+#if TEST_REMOVE_NOTIFY
+
+void remove_cb(void *v) {
+  static int n = 10;
+  n--;
+  Fl_Grid *grid = (Fl_Grid *)v;
+#if (0)             // test 1: remove() the widget -- leaks memory (!)
+  grid->remove(n);
+#else               // test 2: delete the widget -- no leak
+  delete grid->child(0);
+#endif
+  if (n > 0)
+    Fl::repeat_timeout(0.3, remove_cb, v);
+}
+
+#endif
+
+int main(int argc, char **argv) {
+  Fl_Grid::Cell *c;
+  Fl_Box *b;
+  Fl_Double_Window *win = new Fl_Double_Window(440, 350, "FLTK 1.4.0 - Fl_Grid Alignment Test");
+  Fl_Grid *grid = new Fl_Grid(10, 10, 420, 330);
+  grid->layout(7, 7, 8, 4);       // cols, rows, margin, gap
+  grid->box(FL_FLAT_BOX);
+  grid->color(FL_WHITE);
+
+  // add boxes (top and bottom rows)
+
+  for (int col = 0; col < 7; col++) {
+    grid->col_width(col, 50);
+    b = new Fl_Box(0, 0, 20, 20);   // variable size
+    if (col == 5) {
+      b->size(4, 20);               // reduce width
+      grid->col_width(col, 4);      // new min. width
+      grid->col_weight(col, 0);     // no hor. resizing
+    }
+    b->box(FL_FLAT_BOX);
+    b->color(FL_BLUE);
+    grid->widget(b, 0, col);
+
+    if (col == 5)
+      b = new Fl_Box(0, 0, 4, 20);   // variable size
+    else
+      b = new Fl_Box(0, 0, 20, 20);   // variable size
+    b->box(FL_FLAT_BOX);
+    b->color(FL_RED);
+    grid->widget(b, 6, col);
+  }
+
+  // add boxes (left and right columns)
+
+  grid->row_height(0, 40);
+  grid->row_height(6, 40);
+
+  for (int row = 1; row < 6; row++) {
+    grid->row_height(row, 40);
+    b = new Fl_Box(0, 0, 20, 20);           // fixed size, see alignment below
+    b->box(FL_FLAT_BOX);
+    b->color(FL_RED);
+    switch(row) {
+      case 1: grid->widget(b, row, 0, FL_GRID_FILL); break;
+      case 2: grid->widget(b, row, 0, FL_ALIGN_CENTER); break;
+      case 3: grid->widget(b, row, 0, FL_ALIGN_BOTTOM_RIGHT); break;
+      case 4: grid->widget(b, row, 0, FL_ALIGN_BOTTOM_RIGHT); break;
+      case 5: grid->widget(b, row, 0, FL_ALIGN_TOP_RIGHT); break;
+      default: break;
+    }
+
+    b = new Fl_Box(0, 0, 20, 20);
+    b->box(FL_FLAT_BOX);
+    b->color(FL_GREEN);
+    c = grid->widget(b, row, 6, FL_ALIGN_CENTER);
+  }
+
+  // two more boxes to demonstrate widget alignment inside the cell
+
+  for (int row = 4; row < 6; row++) {
+    b = new Fl_Box(0, 0, 20, 20);           // fixed size, see alignment below
+    b->box(FL_FLAT_BOX);
+    b->color(FL_MAGENTA);
+    c = grid->widget(b, row, 1);            // default alignment: FL_GRID_FILL
+    if (row == 4)
+      c->align(FL_ALIGN_BOTTOM_LEFT);       // alignment uses widget size
+    if (row == 5)
+      c->align(FL_ALIGN_TOP_LEFT);          // alignment uses widget size
+  }
+
+  // one vertical box (line), spanning 5 rows
+
+  b = new Fl_Box(0, 0, 2, 2);               // extends vertically
+  b->box(FL_FLAT_BOX);
+  b->color(FL_BLACK);
+  grid->widget(b, 1, 5, 5, 1, FL_GRID_VERTICAL | FL_ALIGN_RIGHT);
+
+  // add a textbox with label or title, spanning 5 cells, centered
+
+  b = new Fl_Box(0, 0, 1, 1);               // variable size
+  b->label("Hello, Fl_Grid !");
+  b->labelfont(FL_BOLD + FL_ITALIC);
+  b->labelsize(30);
+  b->labeltype(FL_SHADOW_LABEL);
+  grid->widget(b, 1, 1, 1, 5);              // rowspan = 1, colspan = 5
+
+  // add a footer textbox, spanning 3 cells, right aligned
+
+  b = new Fl_Box(0, 0, 1, 10);               // variable size
+  b->label("FLTK/test/grid_alignment.cxx");
+  b->labelfont(FL_COURIER);
+  b->labelsize(11);
+  b->align(FL_ALIGN_INSIDE | FL_ALIGN_RIGHT);
+  grid->widget(b, 5, 2, 1, 3, FL_GRID_HORIZONTAL | FL_ALIGN_BOTTOM);
+
+  // input widgets with fixed size and alignment inside the cell
+
+  Fl_Input *i1 = new Fl_Input(0, 0, 100, 30, "Username:");
+  c = grid->widget(i1, 2, 3, 1, 2);         // widget, col, row, colspan, rowspan
+  c->align(FL_GRID_HORIZONTAL);             // widget alignment in cell
+
+  Fl_Input *i2 = new Fl_Input(0, 0, 100, 30, "Password:");
+  c = grid->widget(i2, 3, 3, 1, 2);         // widget, col, row, colspan, rowspan
+  c->align(FL_GRID_HORIZONTAL);             // widget alignment in cell
+
+  // the login button spans 2 columns
+
+  Fl_Button *bt = new Fl_Button(0, 0, 10, 30, "Login");
+  grid->widget(bt, 4, 3, 1, 2, FL_GRID_HORIZONTAL); // widget, col, row, colspan, rowspan, alignment
+
+  grid->row_weight(1, 90);
+  grid->row_weight(2,  0);
+  grid->row_weight(3,  0);
+  grid->row_weight(4,  0);
+
+  grid->col_weight(0, 30);
+  grid->col_weight(4, 90);
+
+  grid->row_gap(5, 12);
+
+  grid->end();
+  grid->layout();
+  grid->debug(0);
+  // grid->show_grid(1);     // enable to display grid helper lines
+  win->end();
+  win->resizable(grid);
+  win->size_range(440, 350);
+  win->show(argc, argv);
+
+#if (TEST_RELAYOUT)
+  Fl::add_timeout(5.0, relayout_cb, grid);
+#endif
+
+#if (TEST_REMOVE_NOTIFY)
+  Fl::add_timeout(3.0, remove_cb, grid);
+#endif
+
+  // return Fl::run();
+  int ret = Fl::run();
+  grid->clear_layout();
+  delete win;
+  return ret;
+}