Animated GIF support (Fl_Anim_GIF_Image class) (#375)

1 files changed, 237 insertions, 0 deletions

diff --git a/examples/animgifimage-play.cxx b/examples/animgifimage-play.cxx
new file mode 100644
index 000000000..4a319f842
--- /dev/null
+++ b/examples/animgifimage-play.cxx
@@ -0,0 +1,237 @@
+//
+//  Demonstrates how to play an animated GIF file
+//  under application control frame by frame if
+//  this is needed.
+//  Also demonstrates how to use a single animation
+//  object to load multiple animations.
+//
+//  animgifimage <file> [-r] [-s speed_factor]
+//
+//  Multiple files can be specified e.g. testsuite/*
+//
+//  Use keys '+'/'-'/Enter to change speed, ' ' to pause.
+//  Right key changes to next frame in paused mode.
+//  'n' changes to next file, 'r' toggles reverse play.
+//
+#include <FL/Fl_Anim_GIF_Image.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl.H>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+static double speed_factor = 1.; // slow down/speed up playback by factor
+static bool reverse = false;  // true = play animation backwards
+static bool paused = false;  // flag for paused animation
+static bool frame_info = false; // flag to update current frame info in title
+static Fl_Anim_GIF_Image animgif; // the animation object
+static char **Argv = 0; // copy of main() argv[]
+static int Argc = 0;    // copy of main() argc
+static int current_arg = 0; // current index in argv[]
+
+static int next_arg() {
+  while (1) {
+    current_arg++;
+    if (current_arg >= Argc) {
+      current_arg = 1;
+    }
+    if (Argv[current_arg]) break;
+  }
+  return current_arg;
+}
+
+static const char *next_file() {
+  while (Argv[next_arg()][0] == '-') ;
+  return Argv[current_arg];
+}
+
+static void set_title() {
+  char buf[200];
+  char fi[50];
+  if (frame_info)
+    snprintf(fi, sizeof(fi), "frame %d/%d", animgif.frame() + 1, animgif.frames());
+  else
+    snprintf(fi, sizeof(fi), "%d frames", animgif.frames());
+  snprintf(buf, sizeof(buf), "%s (%s) x %3.2f %s%s",
+    Argv[current_arg], fi,
+    speed_factor, reverse ? "reverse" : "",
+    paused ? " PAUSED" : "");
+
+  Fl::first_window()->copy_label(buf);
+}
+
+static void cb_anim(void *d_) {
+  Fl_Anim_GIF_Image *animgif = (Fl_Anim_GIF_Image *)d_;
+  int frame(animgif->frame());
+
+  // switch to next/previous frame
+  if (reverse) {
+    animgif->canvas()->window()->redraw();
+    frame--;
+    if (frame < 0) {
+      frame = animgif->frames() - 1;
+    }
+  }
+  else {
+    frame++;
+    if (frame >= animgif->frames()) {
+      frame = 0;
+    }
+  }
+  // set the frame (and update canvas)
+  animgif->frame(frame);
+
+  // setup timer for next frame
+  if (!paused && animgif->delay(frame)) {
+    Fl::repeat_timeout(animgif->delay(frame) / speed_factor, cb_anim, d_);
+  }
+  if (frame_info)
+    set_title();
+}
+
+static void next_frame() {
+  cb_anim(&animgif);
+}
+
+static void toggle_pause() {
+  paused = !paused;
+  set_title();
+  if (paused)
+    Fl::remove_timeout(cb_anim, &animgif);
+  else
+    next_frame();
+  set_title();
+}
+
+static void toggle_info() {
+  frame_info = !frame_info;
+  set_title();
+}
+
+static void toggle_reverse() {
+  reverse = !reverse;
+  set_title();
+}
+
+static void zoom(bool out) {
+  int W = animgif.w();
+  int H = animgif.h();
+  // Note: deliberately no range check (use key 'N' to reset)
+  static const double f = 1.05;
+  if (out)
+    animgif.resize((double)W/f, (double)H/f);
+  else
+    animgif.resize(f*W, f*H);
+}
+
+static void change_speed(int dir_) {
+  if (dir_> 0) {
+    speed_factor += (speed_factor < 1) ? 0.01 : 0.1;
+    if (speed_factor > 100)
+      speed_factor = 100.;
+  }
+  else if (dir_ < 0) {
+    speed_factor -= (speed_factor > 1) ? 0.1 : 0.01;
+    if (speed_factor < 0.01)
+      speed_factor = 0.01;
+  }
+  else {
+    speed_factor = 1.;
+  }
+  set_title();
+}
+
+static void load_next() {
+  Fl::remove_timeout(cb_anim, &animgif);
+  paused = false;
+  animgif.load(next_file());
+  animgif.canvas()->window()->redraw();
+  // check if loading succeeded
+  printf("valid: %d frames: %d\n", animgif.valid(), animgif.frames());
+  if (animgif.valid()) {
+    printf("play '%s'%s with %3.2f x speed\n", animgif.name(),
+       (reverse ? " reverse" : ""), speed_factor);
+    animgif.frame(reverse ? animgif.frames() - 1 : 0);
+    // setup first timeout, but check for zero-delay (normal GIF)!
+    if (animgif.delay(animgif.frame())) {
+      Fl::add_timeout(animgif.delay(animgif.frame()) / speed_factor, cb_anim, &animgif);
+    }
+  }
+  set_title();
+}
+
+static int events(int event_) {
+  if (event_ == FL_SHORTCUT && Fl::first_window()) {
+    switch (Fl::event_key()) {
+      case '+': change_speed(1); break;
+      case '-': change_speed(-1); break;
+      case FL_Enter: change_speed(0); break;
+      case 'n': load_next(); break;
+      case 'z': zoom(Fl::event_shift()); break;
+      case 'i': toggle_info(); break; // Note: this can raise cpu usage considerably!
+      case 'r': toggle_reverse(); break;
+      case ' ': toggle_pause(); break;
+      case FL_Right:
+        if (paused && Fl::get_key(FL_Right)) next_frame();
+        break;
+      default:
+        return 0;
+    }
+    Fl::first_window()->redraw();
+    return 1;
+  }
+  return 0;
+}
+
+int main(int argc, char *argv[]) {
+  // setup play parameters from args
+  Argv = argv;
+  Argc = argc;
+  int n = 0;
+  for (int i = 1; i < argc; i++) {
+    if (!strcmp(argv[i], "-r"))
+      reverse = !reverse;
+    else if (!strcmp(argv[i], "-s") && i + 1 < argc) {
+      i++;
+      speed_factor = atof(argv[i]);
+      argv[i] = 0;
+    }
+    else if (argv[i][0] != '-') {
+      n++;
+      continue;
+    }
+    else {
+      printf("Invalid argument: '%s'\n", argv[i]);
+      exit(1);
+    }
+  }
+  if (!n) {
+     fprintf(stderr, "Test program for application controlled GIF animation.\n");
+     fprintf(stderr, "Please specify one or more image files!\n");
+     exit(0);
+  }
+  if (speed_factor < 0.01 || speed_factor > 100)
+    speed_factor = 1.;
+
+  Fl_Double_Window win(800, 600);
+
+  // prepare a canvas for the animation
+  // (we want to show it in the center of the window)
+  Fl_Box canvas(0, 0, win.w(), win.h());
+  Fl_Box help(0, win.h()-20, win.w(), 20, "Keys: N=next file, I=toggle info, R=play reverse, +/-/Enter/Space=change speed, Z=Zoom");
+  win.resizable(win);
+
+  win.end();
+  win.show();
+  Fl::add_handler(events);
+
+  // use the 'DONT_RESIZE_CANVAS' flag to tell the animation
+  // not to change the canvas size (which is the default).
+  unsigned short flags = Fl_Anim_GIF_Image::DONT_RESIZE_CANVAS;
+//  flags |= Fl_Anim_GIF_Image::DEBUG_FLAG|Fl_Anim_GIF_Image::LOG_FLAG;
+  animgif.canvas(&canvas, flags);
+
+  load_next();
+  return Fl::run();
+}