//
// Fl_Anim_GIF_Image class for the Fast Light Tool Kit (FLTK).
//
// Copyright 2016-2023 by Christian Grabner <wcout@gmx.net>.
// Copyright 2024-2025 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
//

#include <FL/Fl.H>
#include <FL/Fl_GIF_Image.H>
#include <FL/Fl_Shared_Image.H>
#include <FL/Fl_Graphics_Driver.H>
#include <FL/fl_string_functions.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <math.h> // round()

#include <FL/Fl_Anim_GIF_Image.H>

/** \class Fl_Anim_GIF_Image

 The Fl_Anim_GIF_Image class supports loading, caching, and drawing of animated
 Compuserve GIF<SUP>SM</SUP> images.

 The class loads all images contained in the file and animates them by cycling
 through them as defined by the delay times in the image file.

 The user must supply an FLTK widget as "container" in order to see the
 animation by specifying it in the constructor or later using the
 canvas() method.
*/

/*static*/
bool Fl_GIF_Image::animate = false;


///////////////////////////////////////////////////////////////////////
//  Internal helper classes/structs
///////////////////////////////////////////////////////////////////////

class Fl_Anim_GIF_Image::FrameInfo {
  friend class Fl_Anim_GIF_Image;

  enum Transparency {
    T_NONE = 0xff,
    T_FULL = 0
  };

  struct RGBA_Color {
    uchar r, g, b, alpha;
    RGBA_Color(uchar r = 0, uchar g = 0, uchar b = 0, uchar a = T_NONE) :
      r(r), g(g), b(b), alpha(a) {}
  };

  enum Dispose {
    DISPOSE_UNDEF = 0,
    DISPOSE_NOT = 1,
    DISPOSE_BACKGROUND = 2,
    DISPOSE_PREVIOUS = 3
  };

  struct GifFrame {
    GifFrame() :
      rgb(0),
      scalable(0),
      average_color(FL_BLACK),
      average_weight(-1),
      desaturated(false),
      x(0),
      y(0),
      w(0),
      h(0),
      delay(0),
      dispose(DISPOSE_UNDEF),
      transparent_color_index(-1) {}
    Fl_RGB_Image *rgb;                // full frame image
    Fl_Shared_Image *scalable;        // used for hardware-accelerated scaling
    Fl_Color average_color;           // last average color
    float average_weight;             // last average weight
    bool desaturated;                 // flag if frame is desaturated
    unsigned short x, y, w, h;        // frame original dimensions
    double delay;                     // delay (already converted to ms)
    Dispose dispose;                  // disposal method
    int transparent_color_index;      // needed for dispose()
    RGBA_Color transparent_color;     // needed for dispose()
  };

  FrameInfo(Fl_Anim_GIF_Image *anim) :
    anim(anim),
    valid(false),
    frames_size(0),
    frames(0),
    loop_count(1),
    loop(0),
    background_color_index(-1),
    canvas_w(0),
    canvas_h(0),
    desaturate(false),
    average_color(FL_BLACK),
    average_weight(-1),
    scaling((Fl_RGB_Scaling)0),
    debug_(0),
    optimize_mem(false),
    offscreen(0) {}
  ~FrameInfo();
  void clear();
  void copy(const FrameInfo& fi);
  double convert_delay(int d) const;
  int debug() const { return debug_; }
  bool load(const char *name, const unsigned char *data, size_t length);
  bool push_back_frame(const GifFrame &frame);
  void resize(int W, int H);
  void scale_frame(int frame);
  void set_frame(int frame);
private:
  Fl_Anim_GIF_Image *anim;          // a pointer to the Image (only needed for name())
  bool valid;                       // flag if valid data
  int frames_size;                  // number of frames stored in 'frames'
  GifFrame *frames;                 // "vector" for frames
  int loop_count;                   // loop count from file
  int loop;                         // current loop count
  int background_color_index;       // needed for dispose()
  RGBA_Color background_color;      // needed for dispose()
  GifFrame frame;                   // current processed frame
  int canvas_w;                     // width of GIF from header
  int canvas_h;                     // height of GIF from header
  bool desaturate;                  // flag if frames should be desaturated
  Fl_Color average_color;           // color for color_average()
  float average_weight;             // weight for color_average (negative: none)
  Fl_RGB_Scaling scaling;           // saved scaling method for scale_frame()
  int debug_;                       // Flag for debug outputs
  bool optimize_mem;                // Flag to store frames in original dimensions
  uchar *offscreen;                 // internal "offscreen" buffer
private:
private:
  void dispose(int frame_);
  void on_frame_data(Fl_GIF_Image::GIF_FRAME &gf);
  void on_extension_data(Fl_GIF_Image::GIF_FRAME &gf);
  void set_to_background(int frame_);
};


#define LOG(x) if (debug()) printf x
#define DEBUG(x) if (debug() >= 2) printf x
#ifndef LOG
  #define LOG(x)
#endif
#ifndef DEBUG
  #define DEBUG(x)
#endif


//
// helper class FrameInfo implementation
//

Fl_Anim_GIF_Image::FrameInfo::~FrameInfo() {
  clear();
}


void Fl_Anim_GIF_Image::FrameInfo::clear() {
  // release all allocated memory
  while (frames_size-- > 0) {
    if (frames[frames_size].scalable)
      frames[frames_size].scalable->release();
    delete frames[frames_size].rgb;
  }
  delete[] offscreen;
  offscreen = 0;
  free(frames);
  frames = 0;
  frames_size = 0;
}


double Fl_Anim_GIF_Image::FrameInfo::convert_delay(int d) const {
  if (d <= 0)
    d = loop_count != 1 ? 10 : 0;
  return (double)d / 100;
}


void Fl_Anim_GIF_Image::FrameInfo::copy(const FrameInfo& fi) {
  // copy from source
  for (int i = 0; i < fi.frames_size; i++) {
    if (!push_back_frame(fi.frames[i])) {
      break;
    }
    double scale_factor_x = (double)canvas_w / (double)fi.canvas_w;
    double scale_factor_y = (double)canvas_h / (double)fi.canvas_h;
    if (fi.optimize_mem) {
      frames[i].x = (unsigned short)round(fi.frames[i].x * scale_factor_x);
      frames[i].y = (unsigned short)round(fi.frames[i].y * scale_factor_y);
      int new_w = (int)round(fi.frames[i].w * scale_factor_x);
      int new_h = (int)round(fi.frames[i].h * scale_factor_y);
      frames[i].w = new_w;
      frames[i].h = new_h;
    }
    // just copy data 1:1 now - scaling will be done adhoc when frame is displayed
    frames[i].rgb = (Fl_RGB_Image *)fi.frames[i].rgb->copy();
    frames[i].scalable = 0;
  }
  optimize_mem = fi.optimize_mem;
  scaling = Fl_Image::RGB_scaling(); // save current scaling mode
  loop_count = fi.loop_count; // .. and the loop_count!
}


void Fl_Anim_GIF_Image::FrameInfo::dispose(int frame) {
  if (frame < 0) {
    return;
  }
  // dispose frame with index 'frame_' to offscreen buffer
  switch (frames[frame].dispose) {
    case DISPOSE_PREVIOUS: {
        // dispose to previous restores to first not DISPOSE_TO_PREVIOUS frame
        int prev(frame);
        while (prev > 0 && frames[prev].dispose == DISPOSE_PREVIOUS)
          prev--;
        if (prev == 0 && frames[prev].dispose == DISPOSE_PREVIOUS) {
          set_to_background(frame);
          return;
        }
        DEBUG(("  dispose frame %d to previous frame %d\n", frame + 1, prev + 1));
        // copy the previous image data..
        uchar *dst = offscreen;
        int px = frames[prev].x;
        int py = frames[prev].y;
        int pw = frames[prev].w;
        int ph = frames[prev].h;
        const char *src = frames[prev].rgb->data()[0];
        if (px == 0 && py == 0 && pw == canvas_w && ph == canvas_h)
          memcpy((char *)dst, (char *)src, canvas_w * canvas_h * 4);
        else {
          if ( px + pw > canvas_w ) pw = canvas_w - px;
          if ( py + ph > canvas_h ) ph = canvas_h - py;
          for (int y = 0; y < ph; y++) {
            memcpy(dst + ( y + py ) * canvas_w * 4 + px, src + y * frames[prev].w * 4, pw * 4);
          }
        }
        break;
      }
    case DISPOSE_BACKGROUND:
      DEBUG(("  dispose frame %d to background\n", frame + 1));
      set_to_background(frame);
      break;

    default: {
        // nothing to do (keep everything as is)
        break;
      }
  }
}


bool Fl_Anim_GIF_Image::FrameInfo::load(const char *name, const unsigned char *data, size_t length) {
  // decode using FLTK
  valid = false;
  anim->ld(0);
  if (data) {
    anim->Fl_GIF_Image::load(name, data, length, true); // calls on_frame_data() for each frame
  } else {
    anim->Fl_GIF_Image::load(name, true); // calls on_frame_data() for each frame
  }

  delete[] offscreen;
  offscreen = 0;
  return valid;
}


void Fl_Anim_GIF_Image::FrameInfo::on_extension_data(Fl_GIF_Image::GIF_FRAME &gf) {
  if (!gf.bptr)
     return;
  const uchar *ext = gf.bptr;
  if (memcmp(ext, "NETSCAPE2.0", 11) == 0) {
    const uchar *params = &ext[11];
    loop_count = params[1] | (params[2] << 8);
    DEBUG(("netscape loop count: %u\n", loop_count));
  }
}


void Fl_Anim_GIF_Image::FrameInfo::on_frame_data(Fl_GIF_Image::GIF_FRAME &gf) {
  if (!gf.bptr)
     return;
  int delay = gf.delay;
  if (delay <= 0)
    delay = -(delay + 1);
  LOG(("on_frame_data: frame #%d/%d, %dx%d at %d/%d, delay: %d, bkgd=%d/%d, trans=%d, dispose=%d\n",
        gf.ifrm + 1, -1, gf.w, gf.h, gf.x, gf.y,
        gf.delay, gf.bkgd, gf.clrs, gf.trans, gf.dispose));

  if (!gf.ifrm) {
    // first frame, get width/height
    valid = true; // may be reset later from loading callback
    canvas_w = gf.width;
    canvas_h = gf.height;
    offscreen = new uchar[canvas_w * canvas_h * 4];
    memset(offscreen, 0, canvas_w * canvas_h * 4);
  }

  if (!gf.ifrm) {
    // store background_color AFTER color table is set
    background_color_index = gf.clrs && gf.bkgd < gf.clrs ? gf.bkgd : -1;

    if (background_color_index >= 0) {
        background_color = RGBA_Color(gf.cpal[background_color_index].r,
                                      gf.cpal[background_color_index].g,
                                      gf.cpal[background_color_index].b);
    }
  }

  // process frame
  frame.x = gf.x;
  frame.y = gf.y;
  frame.w = gf.w;
  frame.h = gf.h;
  frame.delay = convert_delay(delay);
  frame.transparent_color_index = gf.trans && gf.trans < gf.clrs ? gf.trans : -1;
  frame.dispose = (Dispose)gf.dispose;
  if (frame.transparent_color_index >= 0) {
    frame.transparent_color = RGBA_Color(gf.cpal[frame.transparent_color_index].r,
                                         gf.cpal[frame.transparent_color_index].g,
                                         gf.cpal[frame.transparent_color_index].b);
  }
  DEBUG(("#%d %d/%d %dx%d delay: %d, dispose: %d transparent_color: %d\n",
    (int)frames_size + 1,
    frame.x, frame.y, frame.w, frame.h,
    gf.delay, gf.dispose, gf.trans));

  // we know now everything we need about the frame..
  dispose(frames_size - 1);

  // copy image data to offscreen
  const uchar *bits = gf.bptr;
  const uchar *endp = offscreen + canvas_w * canvas_h * 4;
  for (int y = frame.y; y < frame.y + frame.h; y++) {
    for (int x = frame.x; x < frame.x + frame.w; x++) {
      uchar c = *bits++;
      if (c == gf.trans)
        continue;
      uchar *buf = offscreen;
      buf += (y * canvas_w * 4 + (x * 4));
      if (buf >= endp)
        continue;
      *buf++ = gf.cpal[c].r;
      *buf++ = gf.cpal[c].g;
      *buf++ = gf.cpal[c].b;
      *buf = T_NONE;
    }
  }

  // create RGB image from offscreen
  if (optimize_mem) {
    uchar *buf = new uchar[frame.w * frame.h * 4];
    uchar *dest = buf;
    for (int y = frame.y; y < frame.y + frame.h; y++) {
      for (int x = frame.x; x < frame.x + frame.w; x++) {
        if (offscreen + y * canvas_w * 4 + x * 4 < endp)
          memcpy(dest, &offscreen[y * canvas_w * 4 + x * 4], 4);
        dest += 4;
      }
    }
    frame.rgb = new Fl_RGB_Image(buf, frame.w, frame.h, 4);
  }
  else {
    uchar *buf = new uchar[canvas_w * canvas_h * 4];
    memcpy(buf, offscreen, canvas_w * canvas_h * 4);
    frame.rgb = new Fl_RGB_Image(buf, canvas_w, canvas_h, 4);
  }
  frame.rgb->alloc_array = 1;

  if (!push_back_frame(frame)) {
    valid = false;
  }
}


bool Fl_Anim_GIF_Image::FrameInfo::push_back_frame(const GifFrame &frame) {
  void *tmp = realloc(frames, sizeof(GifFrame) * (frames_size + 1));
  if (!tmp) {
    return false;
  }
  frames = (GifFrame *)tmp;
  memcpy(&frames[frames_size], &frame, sizeof(GifFrame));
  frames_size++;
  return true;
}


void Fl_Anim_GIF_Image::FrameInfo::resize(int W, int H) {
  double scale_factor_x = (double)W / (double)canvas_w;
  double scale_factor_y = (double)H / (double)canvas_h;
  for (int i=0; i < frames_size; i++) {
    if (optimize_mem) {
      frames[i].x = (unsigned short)round(frames[i].x * scale_factor_x);
      frames[i].y = (unsigned short)round(frames[i].y * scale_factor_y);
      int new_w = (int)round(frames[i].w * scale_factor_x);
      int new_h = (int)round(frames[i].h * scale_factor_y);
      frames[i].w = new_w;
      frames[i].h = new_h;
    }
  }
  canvas_w = W;
  canvas_h = H;
}


void Fl_Anim_GIF_Image::FrameInfo::scale_frame(int frame) {
  // Do the actual scaling after a resize if neccessary
  int new_w = optimize_mem ? frames[frame].w : canvas_w;
  int new_h = optimize_mem ? frames[frame].h : canvas_h;
  if (frames[frame].scalable &&
      frames[frame].scalable->w() == new_w &&
      frames[frame].scalable->h() == new_h)
    return;

  Fl_RGB_Scaling old_scaling = Fl_Image::RGB_scaling(); // save current scaling method
  Fl_Image::RGB_scaling(scaling);
  if (!frames[frame].scalable) {
    frames[frame].scalable = Fl_Shared_Image::get(frames[frame].rgb, 0);
  }
  frames[frame].scalable->scale(new_w, new_h, 0, 1);
  Fl_Image::RGB_scaling(old_scaling); // restore scaling method
}


void Fl_Anim_GIF_Image::FrameInfo::set_to_background(int frame) {
  // reset offscreen to background color
  int bg = background_color_index;
  int tp = frame >= 0 ? frames[frame].transparent_color_index : bg;
  DEBUG(("  set_to_background [%d] tp = %d, bg = %d\n", frame, tp, bg));
  RGBA_Color color = background_color;
  if (tp >= 0)
    color = frames[frame].transparent_color;
  if (tp >= 0 && bg >= 0)
    bg = tp;
  color.alpha = tp == bg ? T_FULL : tp < 0 ? T_FULL : T_NONE;
  DEBUG(("  set to color %d/%d/%d alpha=%d\n", color.r, color.g, color.b, color.alpha));
  for (uchar *p = offscreen + canvas_w * canvas_h * 4 - 4; p >= offscreen; p -= 4)
    memcpy(p, &color, 4);
}


void Fl_Anim_GIF_Image::FrameInfo::set_frame(int frame) {
  // scaling pending?
  scale_frame(frame);

  // color average pending?
  if (average_weight >= 0 && average_weight < 1 &&
      ((average_color != frames[frame].average_color) ||
       (average_weight != frames[frame].average_weight))) {
    frames[frame].rgb->color_average(average_color, average_weight);
    frames[frame].average_color = average_color;
    frames[frame].average_weight = average_weight;
  }

  // desaturate pending?
  if (desaturate && !frames[frame].desaturated) {
    frames[frame].rgb->desaturate();
    frames[frame].desaturated = true;
  }
}



///////////////////////////////////////////////////////////////////////
//
// Fl_Anim_GIF_Image
//
// An extension to Fl_GIF_Image.
//
///////////////////////////////////////////////////////////////////////


//
// Fl_Anim_GIF_Image global variables
//

/*static*/
double Fl_Anim_GIF_Image::min_delay = 0.;
/*static*/
bool Fl_Anim_GIF_Image::loop = true;



#include <stdio.h>
#include <stdlib.h>
#include <FL/Fl_RGB_Image.H>
#include <FL/Fl_Group.H>
#include <FL/Fl.H>

//
// class Fl_Anim_GIF_Image implementation
//

/** Load an animated GIF image from a file.

 This constructor creates an animated image from a GIF-formatted file.
 Optionally it applies the \ref canvas() method after successful load.
 If \ref DONT_START is not specified in the \p flags parameter it calls
 \ref start() after successful load.

 \param[in] filename  path and name of GIF file in the file system
 \param[in] canvas    a widget that will show and animate the GIF, or \c NULL
 \param[in] flags     see \ref Flags for details, or 0

 \note The GIF image must be decoupled from the canvas by calling
    `myGif->canvas(NULL);` before deleting the canvas.
 */
Fl_Anim_GIF_Image::Fl_Anim_GIF_Image(const char *filename,
                                     Fl_Widget *canvas /* = 0*/,
                                     unsigned short flags /* = 0 */) :
  Fl_GIF_Image(),
  name_(0),
  flags_(flags),
  canvas_(canvas),
  uncache_(false),
  valid_(false),
  frame_(-1),
  speed_(1.),
  fi_(new FrameInfo(this))
{
  fi_->debug_ = ((flags_ & LOG_FLAG) != 0) + 2 * ((flags_ & DEBUG_FLAG) != 0);
  fi_->optimize_mem = (flags_ & OPTIMIZE_MEMORY);
  valid_ = load(filename, NULL, 0);
  if (canvas_w() && canvas_h()) {
    if (!w() && !h()) {
      w(canvas_w());
      h(canvas_h());
    }
  }
  this->canvas(canvas, flags);
  if (!(flags & DONT_START))
    start();
  else
    frame_ = 0;
}


/** Load an animated GIF image from memory.

 This constructor creates an animated image from a GIF-formatted block in
 memory. Optionally it applies the \ref canvas() method after successful load.
 If \ref DONT_START is not specified in the \p flags parameter it calls
 \ref start() after successful load.

 \p imagename can be \c NULL. If a name is given, the image is added to the
 list of shared images and will be available by that name.

 \param[in] imagename   a name given to this image or \c NULL
 \param[in] data        pointer to the start of the GIF image in memory
 \param[in] length      length of the GIF image in memory
 \param[in] canvas      a widget that will show and animate the GIF, or \c NULL
 \param[in] flags       see \ref Flags for details, or 0

 \note The GIF image must be decoupled from the canvas by calling
    `myGif->canvas(NULL);` before deleting the canvas.
 */
Fl_Anim_GIF_Image::Fl_Anim_GIF_Image(const char* imagename, const unsigned char *data,
                                     const size_t length, Fl_Widget *canvas /* = 0 */,
                                     unsigned short flags /* = 0 */) :
  Fl_GIF_Image(),
  name_(0),
  flags_(flags),
  canvas_(canvas),
  uncache_(false),
  valid_(false),
  frame_(-1),
  speed_(1.),
  fi_(new FrameInfo(this))
{
  fi_->debug_ = ((flags_ & LOG_FLAG) != 0) + 2 * ((flags_ & DEBUG_FLAG) != 0);
  fi_->optimize_mem = (flags_ & OPTIMIZE_MEMORY);
  valid_ = load(imagename, data, length);
  if (canvas_w() && canvas_h()) {
    if (!w() && !h()) {
      w(canvas_w());
      h(canvas_h());
    }
  }
  this->canvas(canvas, flags);
  if (!(flags & DONT_START))
    start();
  else
    frame_ = 0;
}


/** Create an empty animated GIF image shell. */
Fl_Anim_GIF_Image::Fl_Anim_GIF_Image() :
  Fl_GIF_Image(),
  name_(0),
  flags_(0),
  canvas_(0),
  uncache_(false),
  valid_(false),
  frame_(-1),
  speed_(1.),
  fi_(new FrameInfo(this)) {
}


/** Release the image and all cached data.

 Also removes the animation timer.
 */
Fl_Anim_GIF_Image::~Fl_Anim_GIF_Image() /*  */ {
  Fl::remove_timeout(cb_animate, this);
  delete fi_;
  free(name_);
}


/** Link the image back to a widget for automated animation.

 This method sets current widget, that is used to display the frame images.
 The \p flags parameter specifies whether the canvas widget is resized to the
 animation dimensions and/or its \ref image() method will be used to set the
 current frame image during animation.

 \param[in] canvas a pointer to the widget that will show the animation
 \param[in] flags see \ref Flags

 \note The GIF image must be decoupled from the canvas by calling
    `myGif->canvas(NULL);` before deleting the canvas.
 */
void Fl_Anim_GIF_Image::canvas(Fl_Widget *canvas, unsigned short flags/* = 0*/) {
  if (canvas_)
    canvas_->image(0);
  canvas_ = canvas;
  if (canvas_ && !(flags & DONT_SET_AS_IMAGE))
    canvas_->image(this); // set animation as image() of canvas
  if (canvas_ && !(flags & DONT_RESIZE_CANVAS))
    canvas_->size(w(), h());
  if (flags_ != flags) {
    flags_ = flags;
    fi_->debug_ = ((flags & LOG_FLAG) != 0) + 2 * ((flags & DEBUG_FLAG) != 0);
  }
  // Note: 'Start' flag is *NOT* used here,
  //       but an already running animation is restarted.
  frame_ = -1;
  if (Fl::has_timeout(cb_animate, this)) {
    Fl::remove_timeout(cb_animate, this);
    next_frame();
  }
  else if ( fi_->frames_size ) {
    set_frame(0);
  }
}


/** Gets the current widget, that is used to display the frame images.
 \return a pointer to a widget
 */
Fl_Widget *Fl_Anim_GIF_Image::canvas() const {
  return canvas_;
}


/** Return the width of the animation canvas.
 \return the width in pixel units
 */
int Fl_Anim_GIF_Image::canvas_w() const {
  return fi_->canvas_w;
}


/** Return the height of the animation canvas.
 \return the width in pixel units
 */
int Fl_Anim_GIF_Image::canvas_h() const {
  return fi_->canvas_h;
}


/*static*/
void Fl_Anim_GIF_Image::cb_animate(void *d) {
  Fl_Anim_GIF_Image *b = (Fl_Anim_GIF_Image *)d;
  b->next_frame();
}


void Fl_Anim_GIF_Image::clear_frames() {
  fi_->clear();
  valid_ = false;
}


/** Applies a color average to all frames.

 The color_average() method averages the colors in the image with
 the provided FLTK color value.

 \param[in] c blend color
 \param[in] i a value between 0.0 and 1.0 where 0 results in the blend color,
      and 1 returns the original image
 */
void Fl_Anim_GIF_Image::color_average(Fl_Color c, float i) /*  */ {
  if (i < 0) {
    // immediate mode
    i = -i;
    for (int f=0; f < frames(); f++) {
      fi_->frames[f].rgb->color_average(c, i);
    }
    return;
  }
  fi_->average_color = c;
  fi_->average_weight = i;
  //  Do not call set_frame()! If this is called with an indexed color before
  //  the display connection is open, it will possible average *this* frame
  //  with a different RGB value than the following frames.
  //  See Fl_Image::inactive().
  // set_frame();
}


/** Copy and resize the animation frames.

 The virtual copy() method makes a copy of the animated image and resizes all
 of its frame images to W x H using the current resize method.

 \param[in] W, H new size in FLTK pixel units
 \return the resized copy of the animation
 */
Fl_Image *Fl_Anim_GIF_Image::copy(int W, int H) const /*  */ {
  Fl_Anim_GIF_Image *copied = new Fl_Anim_GIF_Image();
  // copy/resize the base image (Fl_Pixmap)
  // Note: this is not really necessary, if the draw()
  //       method never calls the base class.
  if (fi_->frames_size) {
    Fl_Pixmap *gif = (Fl_Pixmap *)Fl_GIF_Image::copy(W, H);
    copied->Fl_GIF_Image::data(gif->data(), gif->count());
    copied->alloc_data = gif->alloc_data;
    gif->alloc_data = 0;
    delete gif;
  }

  if (name_) copied->name_ = fl_strdup(name_);
  copied->flags_ = flags_;
  copied->frame_ = frame_;
  copied->speed_ = speed_;

  copied->w(W);
  copied->h(H);
  copied->fi_->canvas_w = W;
  copied->fi_->canvas_h = H;
  copied->fi_->copy(*fi_); // copy the meta data

  copied->uncache_ = uncache_; // copy 'inherits' frame uncache status
  copied->valid_ = valid_ && copied->fi_->frames_size == fi_->frames_size;
  copied->scale_frame(); // scale current frame now
  if (copied->valid_ && frame_ >= 0 && !Fl::has_timeout(cb_animate, copied))
    copied->start(); // start if original also was started
  return copied;
}


int Fl_Anim_GIF_Image::debug() const {
  return fi_->debug();
}


/** Return the delay of frame `[0-frames() -1]` in seconds.

 \param[in] frame index into frame list
 \return delay to next frame in seconds
 */
double Fl_Anim_GIF_Image::delay(int frame) const {
  if (frame >= 0 && frame < frames())
    return fi_->frames[frame].delay;
  return 0.;
}


/** Set the delay of frame `[0-frames() -1]` in seconds.

 \param[in] frame index into frame list
 \param[in] delay to next frame in seconds
 */
void Fl_Anim_GIF_Image::delay(int frame, double delay) {
  if (frame >= 0 && frame < frames())
    fi_->frames[frame].delay = delay;
}


/** Desaturate to all frames of the animation.
 */
void Fl_Anim_GIF_Image::desaturate() /*  */ {
  fi_->desaturate = true;
  set_frame();
}


/** Draw the current frame of the animation.

 \param[in] x, y, w, h target rectangle
 \param[in] cx, cy source offset
 */
void Fl_Anim_GIF_Image::draw(int x, int y, int w, int h,
                             int cx/* = 0*/, int cy/* = 0*/) /*  */ {
  if (this->image()) {
    if (fi_->optimize_mem) {
      int f0 = frame_;
      while (f0 > 0 && !(fi_->frames[f0].x == 0 && fi_->frames[f0].y == 0 &&
                       fi_->frames[f0].w == this->w() && fi_->frames[f0].h == this->h()))
        --f0;
      for (int f = f0; f <= frame_; f++) {
        if (f < frame_ && fi_->frames[f].dispose == FrameInfo::DISPOSE_PREVIOUS) continue;
        if (f < frame_ && fi_->frames[f].dispose == FrameInfo::DISPOSE_BACKGROUND) continue;
        Fl_RGB_Image *rgb = fi_->frames[f].rgb;
        if (rgb) {
          float s = Fl_Graphics_Driver::default_driver().scale();
          rgb->scale(int(s*fi_->frames[f].w), int(s*fi_->frames[f].h), 0, 1);
          rgb->draw(int(x + s*fi_->frames[f].x), int(y + s*fi_->frames[f].y), w, h, cx, cy);
        }
      }
    }
    else {
      this->image()->scale(Fl_GIF_Image::w(), Fl_GIF_Image::h(), 0, 1);
      this->image()->draw(x, y, w, h, cx, cy);
    }
  } else {
    // Note: should the base class be called here?
    //       If it is, then the copy() method must also
    //       copy the base image!
    Fl_GIF_Image::draw(x, y, w, h, cx, cy);
  }
}


/** Return the current frame.

 \return the current frame index in the range for 0 to `frames()-1`.
 \return -1 if the image has no frames.
 */
int Fl_Anim_GIF_Image::frame() const {
  return frame_;
}


/** Set the current frame.

 \param[in] frame index into list of frames
 */
void Fl_Anim_GIF_Image::frame(int frame) {
  if (Fl::has_timeout(cb_animate, this)) {
    Fl::warning("Fl_Anim_GIF_Image::frame(%d): not idle!\n", frame);
    return;
  }
  if (frame >= 0 && frame < frames()) {
    set_frame(frame);
  }
  else {
    Fl::warning("Fl_Anim_GIF_Image::frame(%d): out of range!\n", frame);
  }
}


/** Get the number of frames in a GIF file or in a GIF compressed data block.

 The static frame_count() method is just a convenience method for
 getting the number of images (frames) stored in a GIF file.

 As this count is not readily available in the GIF header, the
 whole GIF file has be parsed (which is done here by using a
 temporary Fl_Anim_GIF_Image object for simplicity).
 So this call may be slow with large files.

 If \p imgdata is \c NULL, the image will be read from the file. Otherwise, it will
 be read from memory.

 \param[in] name      path and name of GIF file in the file system, ignored
                      when reading from memeory
 \param[in] imgdata   pointer to the start of the GIF image in memory, or
                      \c NULL to read from a file
 \param[in] imglength length of the GIF image in memory, or \c 0

 \return the number of frames in the animation
 */
int Fl_Anim_GIF_Image::frame_count(const char *name, const unsigned char *imgdata /* = NULL */, size_t imglength /* = 0 */) {
  Fl_Anim_GIF_Image temp;
  temp.load(name, imgdata, imglength);
  int frames = temp.valid() ? temp.frames() : 0;
  return frames;
}


/** Return the frame position of a frame.

 Usefull only if loaded with 'optimize_mem' and
 the animation also has size optimized frames.

 \param[in] frame index into frame list
 \return x position in FLTK pixle units
 */
int Fl_Anim_GIF_Image::frame_x(int frame) const {
  if (frame >= 0 && frame < frames())
    return fi_->frames[frame].x;
  return -1;
}


/** Return the frame position of a frame.

 Usefull only if loaded with 'optimize_mem' and
 the animation also has size optimized frames.

 \param[in] frame index into frame list
 \return y position in FLTK pixle units
 */
int Fl_Anim_GIF_Image::frame_y(int frame) const {
  if (frame >= 0 && frame < frames())
    return fi_->frames[frame].y;
  return -1;
}


/** Return the frame dimensions of a frame.

 Usefull only if loaded with 'optimize_mem' and
 the animation also has size optimized frames.

 \param[in] frame index into frame list
 \return width in FLTK pixle units
 */
int Fl_Anim_GIF_Image::frame_w(int frame) const {
  if (frame >= 0 && frame < frames())
    return fi_->frames[frame].w;
  return -1;
}


/** Return the frame dimensions of a frame.

 Usefull only if loaded with 'optimize_mem' and
 the animation also has size optimized frames.

 \param[in] frame index into frame list
 \return height in FLTK pixle units
 */
int Fl_Anim_GIF_Image::frame_h(int frame) const {
  if (frame >= 0 && frame < frames())
    return fi_->frames[frame].h;
  return -1;
}


/** Use frame_uncache() to set or forbid frame image uncaching.

 If frame uncaching is set, frame images are not offscreen cached
 for re-use and will be re-created every time they are displayed.
 This saves a lot of memory on the expense of cpu usage and
 should be carefully considered. Per default frame caching will
 be done.

 \param[in] uncache true to disable caching
 */
void Fl_Anim_GIF_Image::frame_uncache(bool uncache) {
  uncache_ = uncache;
}


/** Return the active frame_uncache() setting.
 \return true if caching is disabled
 */
bool Fl_Anim_GIF_Image::frame_uncache() const {
  return uncache_;
}


/** Get the number of frames in the animation.
 \return the number of frames
 */
int Fl_Anim_GIF_Image::frames() const {
  return fi_->frames_size;
}


/** Return the current frame image.
 \return a pointer to the image or NULL if this is not an animation.
 */
Fl_Image *Fl_Anim_GIF_Image::image() const {
  return frame_ >= 0 && frame_ < frames() ? fi_->frames[frame_].rgb : 0;
}


/** Return the image of the given frame index.

 \param[in] frame_ index into list of frames
 \return image data or NULL if the frame number is not valid.
 */
Fl_Image *Fl_Anim_GIF_Image::image(int frame_) const {
  if (frame_ >= 0 && frame_ < frames())
    return fi_->frames[frame_].rgb;
  return 0;
}


/** Check if this is a valid animation with more than one frame.

 The \c is_animated() method is just a convenience method for testing the valid
 flag and the frame count beeing greater 1.

 \return true if the animation is valid and has multiple frames.
 */
bool Fl_Anim_GIF_Image::is_animated() const {
  return valid_ && fi_->frames_size > 1;
}


/*static*/
bool Fl_GIF_Image::is_animated(const char *name) {
  return Fl_Anim_GIF_Image::frame_count(name) > 1;
}


/** Load an animation from a file or from a memory block.

 The load() method is either used from the constructor to load the image from
 the given file, or to re-load an existing animation from another file.

 \param[in] name      path and name of GIF file in the file system, or the image
                      name when reading from memory
 \param[in] imgdata   pointer to the start of the GIF image in memory, or
                      \c NULL to read from a file
 \param[in] imglength length of the GIF image in memory, or \c 0
 \return true if the animation loaded correctly
 */
bool Fl_Anim_GIF_Image::load(const char *name, const unsigned char *imgdata /* =NULL */, size_t imglength /* =0 */) {
  DEBUG(("\nFl_Anim_GIF_Image::load '%s'\n", name));
  clear_frames();
  if (name_ != name) {
    if (name_) {
      ::free(name_);
    }
    if (name) {
      name_ = fl_strdup(name);
    } else {
      name_  = NULL;
    }
  }

  // as load() can be called multiple times
  // we have to replicate the actions of the pixmap destructor here
  uncache();
  if (alloc_data) {
    for (int i = 0; i < count(); i ++) delete[] (char *)data()[i];
    delete[] (char **)data();
  }
  alloc_data = 0;
  w(0);
  h(0);

  if (name_ || imgdata) {
    fi_->load(name, imgdata, imglength);
  }

  frame_ = fi_->frames_size - 1;
  valid_ = fi_->valid;

  if (!valid_) {
    Fl::error("Fl_Anim_GIF_Image: %s has invalid format.\n", name_);
    ld(ERR_FORMAT);
  }
  return valid_;
} // load


/** Return the name of the played file as specified in the constructor.

 If read from a memory block, this returns the name of the animation.

 \return pointer to a C string
 */
const char *Fl_Anim_GIF_Image::name() const {
  return name_;
}


bool Fl_Anim_GIF_Image::next_frame() {
  int frame(frame_);
  frame++;
  if (frame >= fi_->frames_size)  {
    fi_->loop++;
    if (Fl_Anim_GIF_Image::loop && fi_->loop_count > 0 && fi_->loop > fi_->loop_count) {
      DEBUG(("loop count %d reached - stopped!\n", fi_->loop_count));
      stop();
    }
    else
      frame = 0;
  }
  if (frame >= fi_->frames_size)
    return false;
  set_frame(frame);
  double delay = fi_->frames[frame].delay;
  if (min_delay && delay < min_delay) {
    DEBUG(("#%d: correct delay %f => %f\n", frame, delay, min_delay));
    delay = min_delay;
  }
  if (is_animated() && delay > 0 && speed_ > 0) {  // normal GIF has no delay
    delay /= speed_;
    Fl::add_timeout(delay, cb_animate, this);
  }
  return true;
}


/*virtual*/
void Fl_Anim_GIF_Image::on_frame_data(Fl_GIF_Image::GIF_FRAME &gf) {
  fi_->on_frame_data(gf);
}


/*virtual*/
void Fl_Anim_GIF_Image::on_extension_data(Fl_GIF_Image::GIF_FRAME &gf) {
  fi_->on_extension_data(gf);
}


/** Resizes the image to the specified size, replacing the current image.

 If \ref DONT_RESIZE_CANVAS is not set, the canvas widget will also be resized.

 \param[in] w, h new size of teh naimtion frames
 */
Fl_Anim_GIF_Image& Fl_Anim_GIF_Image::resize(int w, int h) {
  int W(w);
  int H(h);
  if (canvas_ && !W && !H) {
    W = canvas_->w();
    H = canvas_->h();
  }
  if (!W || !H || ((W == this->w() && H == this->h()))) {
    return *this;
  }
  fi_->resize(W, H);
  scale_frame(); // scale current frame now
  this->w(fi_->canvas_w);
  this->h(fi_->canvas_h);
  if (canvas_ && !(flags_ & DONT_RESIZE_CANVAS)) {
    canvas_->size(this->w(), this->h());
  }
  return *this;
}


/** Resizes the image to the specified size, replacing the current image.

 If \ref DONT_RESIZE_CANVAS is not set, the canvas widget will also be resized.

 \param[in] scale rescale factor in relation to current size
 */
Fl_Anim_GIF_Image& Fl_Anim_GIF_Image::resize(double scale) {
  return resize((int)round((double)w() * scale), (int)round((double)h() * scale));
}


void Fl_Anim_GIF_Image::scale_frame() {
  int i(frame_);
  if (i < 0)
    return;
  fi_->scale_frame(i);
}


void Fl_Anim_GIF_Image::set_frame() {
  int i(frame_);
  if (i < 0)
    return;
  fi_->set_frame(i);
}


void Fl_Anim_GIF_Image::set_frame(int frame) {
//  int last_frame = frame_;
  frame_ = frame;
  // NOTE: uncaching decreases performance, but saves a lot of memory
  if (uncache_ && this->image())
    this->image()->uncache();

  fi_->set_frame(frame_);

  Fl_Widget* cv = canvas();
  if (cv) {
    Fl_Group* parent = cv->parent();
    bool no_bg = !Fl::box_bg(cv->box());
    bool outside = (!(cv->align() & FL_ALIGN_INSIDE) && !((cv->align() & FL_ALIGN_POSITION_MASK)==FL_ALIGN_CENTER));
    // bool dispose =    (fi_->frames[last_frame].dispose == FrameInfo::DISPOSE_BACKGROUND)
    //                || (fi_->frames[last_frame].dispose == FrameInfo::DISPOSE_PREVIOUS);
    if (parent && (no_bg || outside))
      parent->redraw();
    else
      cv->redraw();

    // Note: the code below did not animate labels with a pixmap outside of the canvas.
    // Todo: Replace 'canvas()->box() == FL_NO_BOX' with '!Fl::box_bg(canvas()->box())'
    //       if the code below is ever uncommented again. Maybe this would fix it?
    //
    // canvas()->parent() &&
    //   (frame_ == 0 || (last_frame >= 0 && (fi_->frames[last_frame].dispose == FrameInfo::DISPOSE_BACKGROUND  ||
    //                                        fi_->frames[last_frame].dispose == FrameInfo::DISPOSE_PREVIOUS))) &&
    //     (canvas()->box() == FL_NO_BOX || (canvas()->align() && !(canvas()->align() & FL_ALIGN_INSIDE)))      ?
    //   canvas()->parent()->redraw() : canvas()->redraw();

  }
}


/** Get the animation speed factor.
 \return the current speed factor
 */
double Fl_Anim_GIF_Image::speed() const {
  return speed_;
}


/** Set the animation speed factor.

 The speed() method changes the playing speed to \p speed x original speed.
 E.g. to play at half speed call it with 0.5, for double speed with 2.

 \param[in] speed floating point speed factor
 */
void Fl_Anim_GIF_Image::speed(double speed) {
  speed_ = speed;
}


/** The start() method (re-)starts the playing of the frames.
 \return true if the animation has frames
 */
bool Fl_Anim_GIF_Image::start() {
  Fl::remove_timeout(cb_animate, this);
  if (fi_->frames_size) {
    next_frame();
  }
  return fi_->frames_size != 0;
}


/** The stop() method stops the playing of the frames.
 \return true if the animation has frames
 */
bool Fl_Anim_GIF_Image::stop() {
  Fl::remove_timeout(cb_animate, this);
  return fi_->frames_size != 0;
}


/** Show the next frame if the animation is stopped.
 \return true if the animation has frames
 */
bool Fl_Anim_GIF_Image::next() {
  if (fi_->frames_size && !(Fl::has_timeout(cb_animate, this))) {
    int f = frame() + 1;
    if (f >= frames()) f = 0;
    frame(f);
  }
  return fi_->frames_size != 0;
}


/** Uncache all cached image data now.
 Re-implemented from Fl_Pixmap.
 */
void Fl_Anim_GIF_Image::uncache() /*  */ {
  Fl_GIF_Image::uncache();
  for (int i=0; i < fi_->frames_size; i++) {
    if (fi_->frames[i].rgb) fi_->frames[i].rgb->uncache();
  }
}


/** Check if animation is valid.
 \return true if the class has successfully loaded and the image has at least
         one frame.
 */
bool Fl_Anim_GIF_Image::valid() const {
  return valid_;
}