New Fl_ICO_Image class to read Windows .ico icon files

Many thanks to @darealshinji for contributing all the code
for this new FLTK image class (see branch Fl_ICO_Image of https://github.com/darealshinji/fltk).

3 files changed, 61 insertions, 5 deletions

diff --git a/FL/Fl_BMP_Image.H b/FL/Fl_BMP_Image.H
index 63dd301df..462d61957 100644
--- a/FL/Fl_BMP_Image.H
+++ b/FL/Fl_BMP_Image.H
@@ -1,7 +1,7 @@
 //
 // BMP image header file for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2021 by Bill Spitzak and others.
+// Copyright 1998-2022 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
@@ -34,7 +34,7 @@ public:
 
 protected:
 
-  void load_bmp_(class Fl_Image_Reader &rdr);
+  void load_bmp_(class Fl_Image_Reader &rdr, int ico_height = 0, int ico_width = 0);
 
 };
 
diff --git a/FL/Fl_ICO_Image.H b/FL/Fl_ICO_Image.H
new file mode 100644
index 000000000..9693cc545
--- /dev/null
+++ b/FL/Fl_ICO_Image.H
@@ -0,0 +1,55 @@
+//
+// ICO image header file for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2022 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:
+//
+//     http://www.fltk.org/COPYING.php
+//
+// Please report all bugs and problems on the following page:
+//
+//     http://www.fltk.org/str.php
+//
+
+// https://en.wikipedia.org/wiki/ICO_(file_format)
+// http://www.daubnet.com/en/file-format-ico
+
+#ifndef Fl_ICO_Image_H
+#  define Fl_ICO_Image_H
+#  include "Fl_BMP_Image.H"
+
+/**
+ The Fl_ICO_Image class supports loading, caching, and drawing of Windows icon (.ico) files.
+ */
+class FL_EXPORT Fl_ICO_Image : public Fl_BMP_Image {
+
+public:
+  /** Windows ICONDIRENTRY structure  */
+   struct IconDirEntry {
+    int bWidth;         ///<  Image width
+    int bHeight;        ///<  Image height
+    int bColorCount;    ///<  Number of colors (0 if  ≥ 8bpp)
+    int bReserved;      ///<  Reserved
+    int wPlanes;        ///<  Color Planes
+    int wBitCount;      ///<  Bits per pixel
+    int dwBytesInRes;   ///<  Resource size in bytes
+    int dwImageOffset;  ///<  Offset to the image
+  };
+
+  Fl_ICO_Image(const char *filename, int id = -1, const unsigned char *data = NULL, const size_t datasize = 0);
+  ~Fl_ICO_Image();
+/** Gives the number of icons of various resolutions present in the ICO object */
+  int idcount() { return idcount_; }
+  /** Returns the array of idcount() loaded IconDirEntry structures */
+  IconDirEntry * const icondirentry() const { return icondirentry_; }
+
+private:
+  int idcount_;
+  struct IconDirEntry *icondirentry_;
+  void load_ico_(class Fl_Image_Reader &rdr, int id);
+};
+
+#endif // Fl_ICO_Image_H
diff --git a/FL/Fl_PNG_Image.H b/FL/Fl_PNG_Image.H
index f0910a515..1b5e32179 100644
--- a/FL/Fl_PNG_Image.H
+++ b/FL/Fl_PNG_Image.H
@@ -1,7 +1,7 @@
 //
 // PNG image header file for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2021 by Bill Spitzak and others.
+// Copyright 1998-2022 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
@@ -28,13 +28,14 @@
   and alpha-based transparency.
 */
 class FL_EXPORT Fl_PNG_Image : public Fl_RGB_Image {
-
+  friend class Fl_ICO_Image;
 public:
 
   Fl_PNG_Image(const char* filename);
   Fl_PNG_Image (const char *name_png, const unsigned char *buffer, int datasize);
 private:
-  void load_png_(const char *name_png, const unsigned char *buffer_png, int datasize);
+  Fl_PNG_Image(const char *filename, int offset); // used by Fl_ICO_Image
+  void load_png_(const char *name_png, int offset, const unsigned char *buffer_png, int datasize);
 };
 
 // Support functions to write PNG image files (since 1.4.0)