Fluid: restructuring and rejuvenation of the source code.

* Add classes for application and project
* Removed all globals from Fluid.h
* Extracting args and project history into their own classes
* Moving globals into Application class
* Initialize values inside headers for some classes.
* Undo functionality wrapped in a class inside Project.
* File reader and writer are now linked to a project.
* Avoid global project access
* Nodes (former Types) will be managed by a new Tree class.
* Removed static members (hidden globals) form Node/Fl_Type.
* Adding Tree iterator.
* Use nullptr instead of 0, NULL, or 0L
* Renamed Fl_..._Type to ..._Node, FL_OVERRIDE -> override
* Renaming ..._type to ...::prototype
* Splitting Widget Panel into multiple files.
* Moved callback code into widget panel file.
* Cleaning up Fluid_Image -> Image_asset
* Moving Fd_Snap_Action into new namespace fld::app::Snap_Action etc.
* Moved mergeback into proj folder.
* `enum ID` is now `enum class Type`.

1 files changed, 82 insertions, 0 deletions

diff --git a/fluid/nodes/Grid_Node.h b/fluid/nodes/Grid_Node.h
new file mode 100644
index 000000000..4363164ee
--- /dev/null
+++ b/fluid/nodes/Grid_Node.h
@@ -0,0 +1,82 @@
+//
+// Grid Node header file for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2023-2025 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
+//
+
+#ifndef FLUID_NODES_GRID_NODE_H
+#define FLUID_NODES_GRID_NODE_H
+
+#include "nodes/Group_Node.h"
+#include <FL/Fl_Grid.H>
+
+// ---- Grid_Node --------------------------------------------------- MARK: -
+
+class Fl_Grid_Proxy : public Fl_Grid {
+protected:
+  typedef struct { Fl_Widget *widget; Cell *cell; } Cell_Widget_Pair;
+  Cell_Widget_Pair *transient_;
+  int num_transient_;
+  int cap_transient_;
+  void transient_make_room_(int n);
+  void transient_remove_(Fl_Widget *w);
+public:
+  Fl_Grid_Proxy(int X,int Y,int W,int H);
+  ~Fl_Grid_Proxy();
+  void resize(int,int,int,int) override;
+  void draw() override;
+  void draw_overlay();
+  void move_cell(Fl_Widget *child, int to_row, int to_col, int how = 0);
+  Cell* any_cell(Fl_Widget *widget) const;
+  Cell* transient_cell(Fl_Widget *widget) const;
+  Cell* transient_widget(Fl_Widget *wi, int row, int col, int row_span, int col_span, Fl_Grid_Align align = FL_GRID_FILL);
+  Cell* widget(Fl_Widget *wi, int row, int col, Fl_Grid_Align align = FL_GRID_FILL);
+  Cell* widget(Fl_Widget *wi, int row, int col, int rowspan, int colspan, Fl_Grid_Align align = FL_GRID_FILL);
+};
+
+class Grid_Node : public Group_Node
+{
+public:
+  typedef Group_Node super;
+  static Grid_Node prototype;
+public:
+  Grid_Node();
+  const char *type_name() override {return "Fl_Grid";}
+  const char *alt_type_name() override {return "fltk::GridGroup";}
+  Widget_Node *_make() override { return new Grid_Node(); }
+  Fl_Widget *widget(int X,int Y,int W,int H) override;
+  Type type() const override { return Type::Grid; }
+  bool is_a(Type inType) const override { return (inType==Type::Grid) ? true : super::is_a(inType); }
+  void write_properties(fld::io::Project_Writer &f) override;
+  void read_property(fld::io::Project_Reader &f, const char *) override;
+  void write_parent_properties(fld::io::Project_Writer &f, Node *child, bool encapsulate) override;
+  void read_parent_property(fld::io::Project_Reader &f, Node *child, const char *property) override;
+  Fl_Widget *enter_live_mode(int top=0) override;
+  void leave_live_mode() override;
+  void copy_properties() override;
+  void copy_properties_for_children() override;
+  void write_code1(fld::io::Code_Writer& f) override;
+  void write_code2(fld::io::Code_Writer& f) override;
+  void add_child(Node*, Node*) override;
+  void move_child(Node*, Node*) override;
+  void remove_child(Node*) override;
+  void layout_widget() override;
+  void child_resized(Widget_Node *child);
+  void insert_child_at(Fl_Widget *child, int x, int y);
+  void insert_child_at_next_free_cell(Fl_Widget *child);
+  void keyboard_move_child(Widget_Node*, int key);
+
+  static class Fl_Grid *selected();
+};
+
+#endif // FLUID_NODES_GRID_NODE_H