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, 63 insertions, 0 deletions

diff --git a/fluid/app/Image_Asset.h b/fluid/app/Image_Asset.h
new file mode 100644
index 000000000..f5376beaa
--- /dev/null
+++ b/fluid/app/Image_Asset.h
@@ -0,0 +1,63 @@
+//
+// Image Helper header file for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 1998-2025 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
+//
+
+// This class stores the image labels for widgets in fluid.  This is
+// not a class in FLTK itself, and will produce different types of
+// code depending on what the image type is.
+
+
+#ifndef APP_IMAGE_ASSET_H
+#define APP_IMAGE_ASSET_H
+
+#include "io/Code_Writer.h"
+
+#include <FL/Fl_Shared_Image.H>
+
+class Image_Asset {
+
+private:  // member variables
+  bool is_animated_gif_ = false;          ///< It's an animated gif.
+  std::string filename_ { };              ///< Relative path to the image file
+  int refcount_ = 0;                      ///< Reference count
+  Fl_Shared_Image *image_ = nullptr;      ///< The actual image as managed by FLTK
+  std::string initializer_function_ { };  ///< The name of the initializer function
+
+private: // methods
+  Image_Asset(const char *name); // no public constructor
+  ~Image_Asset(); // no public destructor
+  size_t write_static_binary(fld::io::Code_Writer& f, const char* fmt);
+  size_t write_static_text(fld::io::Code_Writer& f, const char* fmt);
+  void write_static_rgb(fld::io::Code_Writer& f, const char* idata_name);
+
+public: // methods
+  static Image_Asset* find(const char *);
+  void dec_ref(); // reference counting & automatic free
+  void inc_ref();
+  Fl_Shared_Image *image() const { return image_; }
+  void write_static(fld::io::Code_Writer& f, int compressed);
+  void write_initializer(fld::io::Code_Writer& f, const char *type_name, const char *format, ...);
+  void write_code(fld::io::Code_Writer& f, int bind, const char *var, int inactive = 0);
+  void write_inline(fld::io::Code_Writer& f, int inactive = 0);
+  void write_file_error(fld::io::Code_Writer& f, const char *fmt);
+  const char *filename() const { return filename_.c_str(); }
+};
+
+// pop up file chooser and return a legal image selected by user,
+// or zero for any errors:
+Image_Asset *ui_find_image(const char *);
+extern const char *ui_find_image_name;
+
+#endif // APP_IMAGE_ASSET_H