Add all the A tasks

Task/Animation/C/animation.c

@@ -0,0 +1,72 @@
+#include <stdlib.h>
+#include <string.h>
+#include <gtk/gtk.h>
+
+const gchar *hello = "Hello World! ";
+gint direction = -1;
+gint cx=0;
+gint slen=0;
+
+GtkLabel *label;
+
+void change_dir(GtkLayout *o, gpointer d)
+{
+  direction = -direction;
+}
+
+gchar *rotateby(const gchar *t, gint q, gint l)
+{
+  gint i, cl = l, j;
+  gchar *r = malloc(l+1);
+  for(i=q, j=0; cl > 0; cl--, i = (i + 1)%l, j++)
+    r[j] = t[i];
+  r[l] = 0;
+  return r;
+}
+
+gboolean scroll_it(gpointer data)
+{
+  if ( direction > 0 )
+    cx = (cx + 1) % slen;
+  else
+    cx = (cx + slen - 1 ) % slen;
+  gchar *scrolled = rotateby(hello, cx, slen);
+  gtk_label_set_text(label, scrolled);
+  free(scrolled);
+  return TRUE;
+}
+
+
+int main(int argc, char **argv)
+{
+  GtkWidget *win;
+  GtkButton *button;
+  PangoFontDescription *pd;
+
+  gtk_init(&argc, &argv);
+  win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title(GTK_WINDOW(win), "Basic Animation");
+  g_signal_connect(G_OBJECT(win), "delete-event", gtk_main_quit, NULL);
+
+  label = (GtkLabel *)gtk_label_new(hello);
+
+  // since we shift a whole character per time, it's better to use
+  // a monospace font, so that the shifting seems done at the same pace
+  pd = pango_font_description_new();
+  pango_font_description_set_family(pd, "monospace");
+  gtk_widget_modify_font(GTK_WIDGET(label), pd);
+
+  button = (GtkButton *)gtk_button_new();
+  gtk_container_add(GTK_CONTAINER(button), GTK_WIDGET(label));
+
+  gtk_container_add(GTK_CONTAINER(win), GTK_WIDGET(button));
+  g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(change_dir), NULL);
+
+  slen = strlen(hello);
+
+  g_timeout_add(125, scroll_it, NULL);
+
+  gtk_widget_show_all(GTK_WIDGET(win));
+  gtk_main();
+  return 0;
+}