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, 207 insertions, 0 deletions

diff --git a/fluid/app/Snap_Action.h b/fluid/app/Snap_Action.h
new file mode 100644
index 000000000..e555f9a44
--- /dev/null
+++ b/fluid/app/Snap_Action.h
@@ -0,0 +1,207 @@
+//
+// Snap action 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_FD_SNAP_ACTION_H
+#define _FLUID_FD_SNAP_ACTION_H
+
+#include <string>
+
+class Window_Node;
+class Widget_Node;
+struct Fl_Menu_Item;
+class Fl_Preferences;
+
+extern Fl_Menu_Item main_layout_submenu_[];
+
+namespace fld {
+enum class Tool_Store; // fld::
+namespace io {
+class Project_Reader; // fld::io::
+class Project_Writer; // fld::io::
+} // namespace io
+} // namespace fld
+
+namespace fld {
+namespace app {
+
+/**
+ \brief Collection of layout settings.
+
+ Presets contain default fonts and font sizes for labels and text. They
+ can be used to guide widget positions using margins, grids, and gap sizes.
+ There are three Presets available in one Suite, marked "application",
+ "dialog", and "toolbox".
+ */
+class Layout_Preset {
+public:
+  int left_window_margin;   ///< gap between the window border and the widget
+  int right_window_margin;
+  int top_window_margin;
+  int bottom_window_margin;
+  int window_grid_x;        ///< a regular grid across the window with its origin in the top left window corner
+  int window_grid_y;
+
+  int left_group_margin;    ///< gap between the border of a widget and its parent group
+  int right_group_margin;
+  int top_group_margin;
+  int bottom_group_margin;
+  int group_grid_x;         ///< a regular grid across the group with its origin in the top left group corner
+  int group_grid_y;
+
+  int top_tabs_margin;      ///< preferred top edge tab size inside Fl_Tabs
+  int bottom_tabs_margin;   ///< preferred bottom edge tab size inside Fl_Tabs
+
+  int widget_min_w;         ///< minimum widget width
+  int widget_inc_w;         ///< widget width increments starting from widget_min_w
+  int widget_gap_x;         ///< preferred horizontal gap between widgets
+  int widget_min_h;
+  int widget_inc_h;
+  int widget_gap_y;
+
+  int labelfont;            ///< preferred font for labels
+  int labelsize;            ///< preferred size for labels
+  int textfont;             ///< preferred font for text elements
+  int textsize;             ///< preferred size for text elements
+
+  void write(Fl_Preferences &prefs);
+  void read(Fl_Preferences &prefs);
+  void write(fld::io::Project_Writer*);
+  void read(fld::io::Project_Reader*);
+
+  int textsize_not_null();
+};
+
+extern Layout_Preset *default_layout_preset;
+
+/**
+ \brief A collection of layout presets.
+
+ A suite of layout presets is designed to cover various use cases when
+ designing UI layouts for applications.
+ There are three Presets available in one Suite, marked "application",
+ "dialog", and "toolbox".
+ */
+class Layout_Suite {
+public:
+  char *name_;                  ///< name of the suite
+  char *menu_label;             ///< label text used in pulldown menu
+  Layout_Preset *layout[3];  ///< presets for application, dialog, and toolbox windows
+  fld::Tool_Store storage_;       ///< storage location (see fld::Tool_Store::INTERNAL, etc.)
+  void write(Fl_Preferences &prefs);
+  void read(Fl_Preferences &prefs);
+  void write(fld::io::Project_Writer*);
+  void read(fld::io::Project_Reader*);
+  void update_label();
+  void storage(fld::Tool_Store s) { storage_ = s; update_label(); }
+  void name(const char *n);
+  void init();
+  ~Layout_Suite();
+public:
+
+};
+
+
+/**
+ \brief Manage all layout suites that are available to the user.
+
+ FLUID has two built-in suites. More suites can be cloned or added and stored
+ as a user preference, as part of an .fl project file, or in a separate file
+ for import/export and sharing.
+ */
+class Layout_List {
+public:
+  Fl_Menu_Item *main_menu_;
+  Fl_Menu_Item *choice_menu_;
+  Layout_Suite *list_;
+  int list_size_;
+  int list_capacity_;
+  bool list_is_static_;
+  int current_suite_;
+  int current_preset_;
+  std::string filename_;
+public:
+  Layout_List();
+  ~Layout_List();
+  void update_dialogs();
+  void update_menu_labels();
+  int current_suite() const { return current_suite_; }
+  void current_suite(int ix);
+  void current_suite(std::string);
+  int current_preset() const { return current_preset_; }
+  void current_preset(int ix);
+  Layout_Suite &operator[](int ix) { return list_[ix]; }
+  int add(const char *name);
+  void rename(const char *name);
+  void capacity(int);
+
+  int load(const std::string &filename);
+  int save(const std::string &filename);
+  void write(Fl_Preferences &prefs, fld::Tool_Store storage);
+  void read(Fl_Preferences &prefs, fld::Tool_Store storage);
+  void write(fld::io::Project_Writer*);
+  void read(fld::io::Project_Reader*);
+  int add(Layout_Suite*);
+  void remove(int index);
+  void remove_all(fld::Tool_Store storage);
+  Layout_Preset *at(int);
+  int size();
+};
+
+/**
+ \brief Structure holding all the data to perform interactive alignment operations.
+ */
+typedef struct Snap_Data {
+  int dx, dy;           ///< distance of the mouse from its initial PUSH event
+  int bx, by, br, bt;   ///< bounding box of the original push event or current bounding box when drawing
+  int drag;             ///< drag event mask
+  int x_dist, y_dist;   ///< current closest snapping distance in x and y
+  int dx_out, dy_out;   ///< current closest snapping point as a delta
+  Widget_Node *wgt;  ///< first selected widget
+  Window_Node *win;  ///< window that handles the drag action
+  int ex_out, ey_out;   ///< chosen snap position
+} Snap_Data;
+
+/**
+ \brief Find points of interest when moving the bounding box of all selected widgets.
+ */
+class Snap_Action {
+protected:
+  int check_x_(Snap_Data &d, int x_ref, int x_snap);
+  int check_y_(Snap_Data &d, int y_ref, int y_snap);
+  void check_x_y_(Snap_Data &d, int x_ref, int x_snap, int y_ref, int y_snap);
+  void clr() { ex = dx = 0x7fff;  }
+public:
+  int ex, ey, dx, dy, type, mask;
+  Snap_Action() : ex(0x7fff), ey(0x7fff), dx(128), dy(128), type(0), mask(0) { }
+  virtual ~Snap_Action() { }
+  virtual void check(Snap_Data &d) = 0;
+  virtual void draw(Snap_Data &d) { }
+  virtual bool matches(Snap_Data &d);
+public:
+  static int eex, eey;
+  static Snap_Action *list[];
+  static void check_all(Snap_Data &d);
+  static void draw_all(Snap_Data &d);
+  static void get_resize_stepsize(int &x_step, int &y_step);
+  static void get_move_stepsize(int &x_step, int &y_step);
+  static void better_size(int &w, int &h);
+};
+
+} // namespace app
+} // namespace fld
+
+
+#endif // _FLUID_FD_SNAP_ACTION_H