X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~yarrgweb/git?p=ypp-sc-tools.db-live.git;a=blobdiff_plain;f=pctb%2Fpages.c;h=fcee3d5845eaae1c47f97aa2d965bf623b820ca0;hp=66c3ad8d8c59f1f850e5dffea6b5df94ba873efd;hb=309781e46dba727aed5fa6fe725da2d60d368057;hpb=024dcba9bc55d02e5c05100ed65f8d64a1eb3bbf

diff --git a/pctb/pages.c b/pctb/pages.c
index 66c3ad8..fcee3d5 100644
--- a/pctb/pages.c
+++ b/pctb/pages.c
@@ -1,220 +1,732 @@
 /*
-  */
+ * Interaction with the YPP client via X11
+ */
+/*
+ *  This is part of ypp-sc-tools, a set of third-party tools for assisting
+ *  players of Yohoho Puzzle Pirates.
+ * 
+ *  Copyright (C) 2009 Ian Jackson <ijackson@chiark.greenend.org.uk>
+ * 
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ * 
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ * 
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ *  Yohoho and Puzzle Pirates are probably trademarks of Three Rings and
+ *  are used without permission.  This program is not endorsed or
+ *  sponsored by Three Rings.
+ */
+
+/*
+ * Only this file #includes the X11 headers, as they're quite
+ * pollutant of the namespace.
+ */
 
-#include "ocr.h"
+#include "structure.h"
 
 #include <X11/Xlib.h>
 #include <X11/extensions/XTest.h>
 #include <X11/keysym.h>
+#include <X11/Xutil.h>
+
+#include <X11/extensions/XShm.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
 
 CanonImage *page_images[MAX_PAGES];
 int npages;
 
+const char *ocean, *pirate;
+
+static XWindowAttributes attr;
 static Window id;
 static Display *disp;
 static struct timeval tv_startup;
+static unsigned wwidth, wheight;
+static int max_relevant_y= -1;
+
+static XImage *shmim;
+static XShmSegmentInfo shminfo;
+
+DEBUG_DEFINE_DEBUGF(pages)
+
+#define xassert(what)					\
+  ((what) ? (void)0 :					\
+   fatal("X11 operation unexpectedly failed."		\
+	 " %s:%d: %s\n", __FILE__,__LINE__,#what))
 
 static KeyCode keycode(KeySym sym) {
   return XKeysymToKeycode(disp,sym);
 }
 
-static CanonImage *screenshot_now(void) {
-  char *cmd;
-  CanonImage *ci;
-  int r;
-  
-  r= asprintf(&cmd, "xwd -silent -id 0x%lx | xwdtopnm", (unsigned long)id);
-  eassert(r>=0);
-  FILE *f= popen(cmd,"r");  eassert(f);
-  ci= file_read_image(f);
-  r= fgetc(f);  eassert(r==EOF);  eassert(feof(f));
-  r= pclose(f);  eassert(r>=0);  eassert(WIFEXITED(r) && !WEXITSTATUS(r));
-  free(cmd);
-  return ci;
+void screenshot_startup(void) {
+  progress("starting...");
+  disp= XOpenDisplay(0);
+  if (!disp) fatal("Unable to open X11 display.");
+  sysassert(! gettimeofday(&tv_startup,0) );
 }
 
-static void screenshot_startup(void) {
-  int r;
-  disp= XOpenDisplay(0);  eassert(disp);
-  r= gettimeofday(&tv_startup,0);  eassert(!r);
-}
+/*---------- pager ----------*/
 
-#if 0
-static CanonImage *single_page(void) {
-  int r;
-  r= XRaiseWindow(disp, id);  eassert(r);
-  r= XSync(disp, False);  eassert(r);
-  return screenshot_now();
-}
-#endif
+typedef RgbImage Snapshot;
 
-static void raise_and_set_focus(void) {
-  int r;
-  XWindowAttributes attr;
-  int xpos,ypos, evbase,errbase,majver,minver;
-  unsigned width,height,bd,depth;
-  Window dummy;
-  
-  fprintf(stderr,"PAGING raise_and_set_focus\n");
+static double last_input;
+static const double min_update_allowance= 0.25;
 
-  r= XTestQueryExtension(disp, &evbase,&errbase,&majver,&minver);
-  eassert(r==True);
+static double timestamp(void) {
+  struct timeval tv;
+  
+  sysassert(! gettimeofday(&tv,0) );
+  double t= (tv.tv_sec - tv_startup.tv_sec) +
+            (tv.tv_usec - tv_startup.tv_usec) * 1e-6;
+  debugf("PAGING %f\n",t);
+  return t;
+}
+static void delay(double need_sleep) {
+  debugf("PAGING     delay %f\n",need_sleep);
+  sysassert(! usleep(need_sleep * 1e6) );
+}
 
-  r= XRaiseWindow(disp, id);  eassert(r);
+static void sync_after_input(void) {
+  xassert( XSync(disp, False) );
+  last_input= timestamp();
+}
 
-  r= XGetWindowAttributes(disp, id, &attr);  eassert(r);
-  r= XGetGeometry(disp,id, &attr.root,&xpos,&ypos,&width,&height, &bd,&depth);
-  eassert(r);
+static void translate_coords_toroot(int wx, int wy, int *rx, int *ry) {
+  Window dummy;
+  xassert( XTranslateCoordinates(disp, id,attr.root, wx,wy, rx,ry, &dummy) );
+}
 
-  r= XTranslateCoordinates(disp, id,attr.root, 160,160, &xpos,&ypos,
-			   &dummy);
-  eassert(r);
+static void check_client_window_all_on_screen(void) {
+  Rect onroot;
+  unsigned rwidth, rheight;
+  Window dummy;
+  unsigned bd, depth;
+  int rxpos, rypos;
 
-  int screen= XScreenNumberOfScreen(attr.screen);
-  XTestFakeMotionEvent(disp,screen, xpos, ypos, 0);
+  xassert( XGetGeometry(disp,attr.root, &dummy, &rxpos,&rypos,
+			&rwidth, &rheight,
+			&bd,&depth) );
+  
+  translate_coords_toroot(0,0, &onroot.tl.x,&onroot.tl.y);
+  translate_coords_toroot(wwidth-1,wheight-1, &onroot.br.x,&onroot.br.y);
+  if (!(onroot.tl.x >= 0 &&
+	onroot.tl.y >= 0 &&
+	onroot.br.x < rwidth &&
+	onroot.br.y < rheight))
+    fatal("YPP client window is not entirely on the screen.");
+}
 
-  XTestFakeButtonEvent(disp,1,1, 50);
-  XTestFakeButtonEvent(disp,1,0, 50);
-  r= XSync(disp, False);  eassert(r);
+static void check_not_disturbed(void) {
+  XEvent ev;
+  int r;
+  
+  for (;;) {
+    r= XCheckMaskEvent(disp, ~0, &ev);
+    if (r==False) return;
 
-  fprintf(stderr,"PAGING raise_and_set_focus done.\n");
-}
+    switch (ev.type) {
+    case VisibilityNotify:
+      if (ev.xvisibility.state != VisibilityUnobscured)
+	fatal("YPP client window has become obscured.");
+      break;
+    case ConfigureNotify:
+      check_client_window_all_on_screen();
+      break;
+    case FocusOut:
+      fatal("Focus left YPP client window.");
+      break;
+    case FocusIn:
+      warning("focus entered YPP client window ?!");
+      break;
+    default:
+      fatal("Received unexpected X11 event (type code %d)!", ev.type);
+    }
+  }
+}      
 
 static void send_key(KeySym sym) {
-  int r;
+  check_not_disturbed();
   XTestFakeKeyEvent(disp, keycode(sym),1, 10);
   XTestFakeKeyEvent(disp, keycode(sym),0, 10);
-  r= XSync(disp, False);  eassert(r);
+}
+static void mouse_1_updown_here(void) {
+  check_not_disturbed();
+  XTestFakeButtonEvent(disp,1,1, 50);
+  XTestFakeButtonEvent(disp,1,0, 50);
+}
+static void mouse_1_updown(int x, int y) {
+  check_not_disturbed();
+  int screen= XScreenNumberOfScreen(attr.screen);
+  int xpos, ypos;
+  translate_coords_toroot(x,y, &xpos,&ypos);
+  XTestFakeMotionEvent(disp, screen, xpos,ypos, 0);
+  mouse_1_updown_here();
 }
 
-static void send_pgup(void) {
-  fprintf(stderr,"PAGING   PageUp\n");
-  send_key(XK_Prior);
+static int pgupdown;
+
+static void send_pgup_many(void) {
+  int i;
+  for (i=0; i<25; i++) {
+    send_key(XK_Prior);
+    pgupdown--;
+  }
+  debugf("PAGING   PageUp x %d\n",i);
+  sync_after_input();
 }
 static void send_pgdown(void) {
-  fprintf(stderr,"PAGING   PageDown\n");
   send_key(XK_Next);
+  pgupdown++;
+  debugf("PAGING   PageDown\n");
+  sync_after_input();
+}
+static void send_pgdown_torestore(void) {
+  debugf("PAGING   PageDown x %d\n", -pgupdown);
+  while (pgupdown < 0) {
+    send_key(XK_Next);
+    pgupdown++;
+  }
+  sync_after_input();
 }
 
-static double timestamp(void) {
-  struct timeval tv;
-  int r;
-  
-  r= gettimeofday(&tv,0);  eassert(!r);
-  return (tv.tv_sec - tv_startup.tv_sec) +
-         (tv.tv_usec - tv_startup.tv_usec) * 1e-6;
+static void free_snapshot(Snapshot **io) {
+  free(*io);
+  *io= 0;
 }
 
-static double worst_snapshot= 0.050, worst_stabilise= 0.100;
+#define SAMPLEMASK 0xfful
+
+typedef struct {
+  int lshift, rshift;
+} ShMask;
 
-static void snapshot(CanonImage **output) {
-  free(*output);
-  double a= timestamp();
-  *output= screenshot_now();
-  fprintf(stderr,"PAGING   snapshot\n");
-  double b= timestamp();
-  double it_took= b-a;
-  fprintf(stderr,"PAGING   snapshot took=%f\n",it_took);
-  if (it_took > worst_snapshot)
-    worst_snapshot= it_took;
+static void compute_shift_mask(ShMask *sm, unsigned long ximage_mask) {
+  sm->lshift= 0;
+  sm->rshift= 0;
+  
+  for (;;) {
+    if (ximage_mask <= (SAMPLEMASK>>1)) {
+      sm->lshift++;  ximage_mask <<= 1;
+    } else if (ximage_mask > SAMPLEMASK) {
+      sm->rshift++;  ximage_mask >>= 1;
+    } else {
+      break;
+    }
+    assert(!(sm->lshift && sm->rshift));
+  }
+  assert(sm->lshift < LONG_BIT);
+  assert(sm->rshift < LONG_BIT);
 }
 
-static void snapshot_idle(void) {
-  int r;
-  r= usleep(worst_snapshot * 1e6 * 2);
-  /* spend no more than 1/3 of our time constantly snapshotting */
-  eassert(!r);
+static void rtimestamp(double *t, const char *wh) {
+  double n= timestamp();
+  debugf("PAGING                INTERVAL %f  %s\n", n-*t, wh);
+  *t= n;
+}
+
+static void snapshot(Snapshot **output) {
+  XImage *im_use, *im_free=0;
+
+  ShMask shiftmasks[3];
+
+  debugf("PAGING   snapshot\n");
+
+  double begin= timestamp();
+  if (shmim) {
+    rtimestamp(&begin, "XShmGetImage before");
+    xassert( XShmGetImage(disp,id,shmim, 0,0, AllPlanes) );
+    rtimestamp(&begin, "XShmGetImage");
+
+    size_t dsz= shmim->bytes_per_line * shmim->height;
+    im_use= im_free= mmalloc(sizeof(*im_use) + dsz);
+    *im_free= *shmim;
+    im_free->data= (void*)(im_free+1);
+    memcpy(im_free->data, shmim->data, dsz);
+    rtimestamp(&begin, "mmalloc/memcpy");
+  } else {
+    rtimestamp(&begin, "XGetImage before");
+    xassert( im_use= im_free=
+	     XGetImage(disp,id, 0,0, wwidth,wheight, AllPlanes, ZPixmap) );
+    rtimestamp(&begin, "XGetImage");
+  }
+
+#define COMPUTE_SHIFT_MASK(ix, rgb) \
+  compute_shift_mask(&shiftmasks[ix], im_use->rgb##_mask)
+  COMPUTE_SHIFT_MASK(0, red);
+  COMPUTE_SHIFT_MASK(1, green);
+  COMPUTE_SHIFT_MASK(2, blue);
+  
+  if (!*output)
+    *output= alloc_rgb_image(wwidth, wheight);
+
+  rtimestamp(&begin, "compute_shift_masks+alloc_rgb_image");
+
+  int x,y,i;
+  unsigned char *op= (*output)->data;
+  for (y=0; y<wheight; y++) {
+    for (x=0; x<wwidth; x++) {
+      long xrgb= XGetPixel(im_use,x,y);
+      for (i=0; i<3; i++) {
+	unsigned long sample=
+	  ((xrgb << shiftmasks[i].lshift) >> shiftmasks[i].rshift)
+	  & SAMPLEMASK;
+	*op++= sample;
+      }
+    }
+  }
+
+  rtimestamp(&begin,"w*h*XGetPixel");
+  if (im_free)
+    XDestroyImage(im_free);
+  
+  rtimestamp(&begin,"XDestroyImage");
+  check_not_disturbed();
+
+  debugf("PAGING   snapshot done.\n");
 }
 
-static int identical(const CanonImage *a, const CanonImage *b) {
-  return !(memcmp(a,    b,    sizeof(*a)) ||
-	   memcmp(a->d, b->d, a->w * a->h));
+static int identical(const Snapshot *a, const Snapshot *b) {
+  if (!(a->w == b->w &&
+	a->h == b->h))
+    return 0;
+
+  int compare_to= a->h;
+  if (max_relevant_y>=0 && compare_to > max_relevant_y)
+    compare_to= max_relevant_y;
+  
+  return !memcmp(a->data, b->data, a->w * 3 * compare_to);
 }
 
-static void wait_for_stability(CanonImage **output,
-			       const CanonImage *previously,
-			       void (*with_keypress)(void)) {
-  CanonImage *last=0;
+static void wait_for_stability(Snapshot **output,
+			       const Snapshot *previously,
+			       void (*with_keypress)(void),
+			       const char *fmt, ...)
+     FMT(4,5);
+
+static void wait_for_stability(Snapshot **output,
+			       const Snapshot *previously,
+			       void (*with_keypress)(void),
+			       const char *fmt, ...) {
+  va_list al;
+  va_start(al,fmt);
+
+  Snapshot *last=0;
+  int nidentical=0;
   /* waits longer if we're going to return an image identical to previously
    * if previously==0, all images are considered identical to it */
 
-  double when_started= timestamp();
-  double last_change= when_started;
-  double it_took= -1;
+  char *doing;
+  sysassert( vasprintf(&doing,fmt,al) >=0 );
 
-  fprintf(stderr,"PAGING  wait_for_stability"
-	  "  worst_snapshot=%f worst_stabilise=%f\n",
-	  worst_snapshot, worst_stabilise);
+  debugf("PAGING  wait_for_stability"
+	  "  last_input=%f previously=%p `%s'\n",
+	  last_input, previously, doing);
 
+  double min_interval= 25000; /*us*/
   for (;;) {
+    progress_spinner("%s",doing);
+    
+    double since_last_input= timestamp() - last_input;
+    double this_interval= min_interval - since_last_input;
+
+    if (this_interval >= 0)
+      usleep(this_interval);
+
     snapshot(output);
-    double right_now= timestamp();
 
-    if (!last || !identical(*output,last)) {
-      fprintf(stderr,"PAGING  wait_for_stability changed...\n");
-      last_change= right_now;
-      free(last); last=*output; *output=0;
-      it_took= -1;
+    if (!last) {
+      debugf("PAGING  wait_for_stability first...\n");
+      last=*output; *output=0;
+    } else if (!identical(*output,last)) {
+      debugf("PAGING  wait_for_stability changed...\n");
+      free_snapshot(&last); last=*output; *output=0;
+      nidentical=0;
+      if (!with_keypress) {
+	min_interval *= 3.0;
+	min_interval += 0.5;
+      }
     } else {
-      if (it_took<0)
-	it_took= right_now - when_started;
-
-      double threshold= (worst_stabilise + worst_snapshot) * 3;
-      if (!previously || identical(*output,previously))
-	threshold *= 2;  threshold += 1.5;
-
-      double stable_for= right_now - last_change;
-      fprintf(stderr,"PAGING  wait_for_stability"
-	      "  worst_snapshot=%f worst_stabilise=%f"
-	      "  stable for %f thresh %f...\n",
-	      worst_snapshot, worst_stabilise,
-	      stable_for, threshold);
-      
-      if (stable_for > threshold)
+      nidentical++;
+      int threshold=
+	!previously ? 3 :
+	identical(*output,previously) ? 5
+	: 1;
+      debugf("PAGING  wait_for_stability nidentical=%d threshold=%d\n",
+	      nidentical, threshold);
+      if (nidentical >= threshold)
 	break;
+
+      min_interval += 0.5;
+      min_interval *= 2.0;
     }
+
     if (with_keypress)
       with_keypress();
-    snapshot_idle();
   }
 
-  if (it_took > worst_stabilise)
-    worst_stabilise= it_took;
+  free_snapshot(&last);
+  free(doing);
+  debugf("PAGING  wait_for_stability done.\n");
+  va_end(al);
+}
+
+static void raise_and_get_details(void) {
+  int evbase,errbase,majver,minver;
+  int wxpos, wypos;
+  unsigned bd,depth;
+
+  progress("raising and checking YPP client window...");
+
+  debugf("PAGING raise_and_get_details\n");
+
+  int xtest= XTestQueryExtension(disp, &evbase,&errbase,&majver,&minver);
+  if (!xtest) fatal("X server does not support the XTEST extension.");
 
-  free(last);
-  fprintf(stderr,"PAGING  wait_for_stability done.\n");
+  xassert( XRaiseWindow(disp, id) );
+  /* in case VisibilityNotify triggers right away before we have had a
+   * change to raise; to avoid falsely detecting lowering in that case */
+  
+  xassert( XSelectInput(disp, id,
+			StructureNotifyMask|
+			VisibilityChangeMask
+			) );
+
+  xassert( XRaiseWindow(disp, id) );
+  /* in case the window was lowered between our Raise and our SelectInput;
+   * to avoid failing to detect that lowering */
+
+  xassert( XGetWindowAttributes(disp, id, &attr) );
+  xassert( XGetGeometry(disp,id, &attr.root,
+			&wxpos,&wypos, &wwidth,&wheight,
+			&bd,&depth) );
+
+  if (!(wwidth >= 320 && wheight >= 320))
+    fatal("YPP client window is implausibly small?");
+
+  if (attr.depth < 24)
+    fatal("Display is not 24bpp.");
+
+  check_client_window_all_on_screen();
+
+  Bool shmpixmaps=0;
+  int major=0,minor=0;
+  int shm= XShmQueryVersion(disp, &major,&minor,&shmpixmaps);
+  debugf("PAGING shm=%d %d.%d pixmaps=%d\n",shm,major,minor,shmpixmaps);
+  if (shm) {
+    xassert( shmim= XShmCreateImage(disp, attr.visual, attr.depth, ZPixmap,
+				    0,&shminfo, wwidth,wheight) );
+
+    sigset_t oldset, all;
+    sigfillset(&all);
+    sysassert(! sigprocmask(SIG_BLOCK,&all,&oldset) );
+
+    int pfd[2];
+    pid_t cleaner;
+    sysassert(! pipe(pfd) );
+    sysassert( (cleaner= fork()) != -1 );
+    if (!cleaner) {
+      sysassert(! close(pfd[1]) );
+      for (;;) {
+	int r= read(pfd[0], &shminfo.shmid, sizeof(shminfo.shmid));
+	if (!r) exit(0);
+	if (r==sizeof(shminfo.shmid)) break;
+	assert(r==-1 && errno==EINTR);
+      }
+      for (;;) {
+	char bc;
+	int r= read(pfd[0],&bc,1);
+	if (r>=0) break;
+	assert(r==-1 && errno==EINTR);
+      }
+      sysassert(! shmctl(shminfo.shmid,IPC_RMID,0) );
+      exit(0);
+    }
+    sysassert(! close(pfd[0]) );
+
+    sysassert(! sigprocmask(SIG_SETMASK,&oldset,0) );
+
+    assert(shmim->height == wheight);
+    sysassert( (shminfo.shmid=
+		shmget(IPC_PRIVATE, shmim->bytes_per_line * wheight,
+		       IPC_CREAT|0600)) >= 0 );
+
+    sysassert( write(pfd[1],&shminfo.shmid,sizeof(shminfo.shmid)) ==
+	       sizeof(shminfo.shmid) );
+    sysassert( shminfo.shmaddr= shmat(shminfo.shmid,0,0) );
+    shmim->data= shminfo.shmaddr;
+    shminfo.readOnly= False;
+    xassert( XShmAttach(disp,&shminfo) );
+
+    close(pfd[1]); /* causes IPC_RMID */
+  }
 }
 
-static void read_pages(void) {
-  CanonImage *current=0, *last;
+static void set_focus_commodity(void) {
+  int screen= XScreenNumberOfScreen(attr.screen);
+
+  progress("taking control of YPP client window...");
 
-  raise_and_set_focus();
+  debugf("PAGING set_focus\n");
 
+  mouse_1_updown(160,160);
+  sync_after_input();
+
+  delay(0.5);
+  xassert( XSelectInput(disp, id,
+			StructureNotifyMask|
+			VisibilityChangeMask|
+			FocusChangeMask
+			) );
+
+  int xpos,ypos;
+  translate_coords_toroot(10,10, &xpos,&ypos);
+  XTestFakeMotionEvent(disp,screen, xpos,ypos, 0);
+
+  sync_after_input();
+
+  debugf("PAGING raise_and_set_focus done.\n");
+}
+
+static CanonImage *convert_page(Snapshot *sn) {
+  CanonImage *im;
+
+  fwrite_ppmraw(screenshot_file, sn);
+
+  unsigned char *pixel= sn->data;
+  CANONICALISE_IMAGE(im, sn->w, sn->h, {
+    rgb=
+      (pixel[0] << 16) |
+      (pixel[1] <<  8) |
+      (pixel[2]      );
+    pixel += 3;
+  });
+    
+  sysassert(!ferror(screenshot_file));
+  sysassert(!fflush(screenshot_file));
+
+  return im;
+}
+
+static void prepare_ypp_client(void) {
+  CanonImage *test;
+  Snapshot *current=0;
+  
+  /* find the window and check it's on the right kind of screen */
+  raise_and_get_details();
+  wait_for_stability(&current,0,0, "checking current YPP client screen...");
+
+  test= convert_page(current);
+  find_structure(test, &max_relevant_y);
+  check_correct_commodities();
+  Rect sunshine= find_sunshine_widget();
+
+  progress("poking client...");
+  mouse_1_updown((sunshine.tl.x   + sunshine.br.x) / 2,
+		 (sunshine.tl.y*9 + sunshine.br.y) / 10);
+
+  free(test);
+
+  wait_for_stability(&current,0,0, "checking basic YPP client screen...");
+  mouse_1_updown(250, wheight-10);
+  mouse_1_updown_here();
+  mouse_1_updown_here();
+  XSync(disp,False);
+  check_not_disturbed();
+  send_key(XK_slash);
+  send_key(XK_w);
+  send_key(XK_Return);
+  sync_after_input();
+
+  Snapshot *status=0;
+  wait_for_stability(&status,current,0, "awaiting status information...");
+  free_snapshot(&current);
+  free_snapshot(&status);
+}
+
+void take_screenshots(void) {
+  Snapshot *current=0, *last=0;
+
+  prepare_ypp_client();
+  
   /* page to the top - keep pressing page up until the image stops changing */
-  wait_for_stability(&current,0, send_pgup);
+  set_focus_commodity();
+  wait_for_stability(&current,0, send_pgup_many,
+		     "paging up to top of commodity list...");
 
   /* now to actually page down */
   for (;;) {
-    fprintf(stderr,"PAGING page %d\n",npages);
-    eassert(npages < MAX_PAGES);
-    page_images[npages++]= last= current;
-    send_pgdown();
-    wait_for_stability(&current,last, 0);
+    debugf("paging page %d\n",npages);
+
+    if (!(npages < MAX_PAGES))
+      fatal("Paging down seems to generate too many pages - max is %d.",
+	    MAX_PAGES);
+    
+    page_images[npages]= convert_page(current);
+    free_snapshot(&last); last=current; current=0;
+
+    debugf("PAGING page %d converted\n",npages);
+
+    wait_for_stability(&current,last, 0,
+		       "collecting screenshot of page %d...",
+		       npages+1);
+
     if (npages &&  /* first pagedown doesn't do much */
 	identical(current,last)) {
-      free(current);
+      free_snapshot(&current);
       break;
     }
+
+    send_pgdown();
+    npages++;
   }
-  fprintf(stderr,"PAGING all done.\n");
+  progress("finishing with the YPP client...");
+  send_pgdown_torestore();
+
+  debugf("PAGING all done.\n");
+  progress_log("collected %d screenshots.",npages);
 }    
 
-int main(int argc, char **argv) {
-  screenshot_startup();
+void take_one_screenshot(void) {
+  Snapshot *current=0;
 
-  id= strtoul(*++argv,0,0);
+  prepare_ypp_client();
+  wait_for_stability(&current,0,0, "taking screenshot...");
+  page_images[0]= convert_page(current);
+  npages= 1;
+  progress_log("collected single screenshot.");
+}
 
-  read_pages();
-  return 0;
+void set_yppclient_window(unsigned long wul) {
+  id= wul;
 }
 
+DEBUG_DEFINE_SOME_DEBUGF(findypp,debugfind)
+
+static int nfound;
+static Atom wm_name;
+static int screen;
+
+static void findypp_recurse(int depth, int targetdepth, Window w) {
+  unsigned int nchildren;
+  int i;
+  Window *children=0;
+  Window gotroot, gotparent;
+
+  static const char prefix[]= "Puzzle Pirates - ";
+  static const char onthe[]= " on the ";
+  static const char suffix[]= " ocean";
+#define S(x) ((int)sizeof((x))-1)
+
+  debugfind("FINDYPP %d/%d screen %d  %*s %lx",
+	    depth,targetdepth,screen,
+	    depth,"",(unsigned long)w);
+  
+  if (depth!=targetdepth) {
+    xassert( XQueryTree(disp,w,
+			&gotroot,&gotparent,
+			&children,&nchildren) );
+    debugfind(" nchildren=%d\n",nchildren);
+  
+    for (i=0; i<nchildren; i++) {
+      Window child= children[i];
+      findypp_recurse(depth+1, targetdepth, child);
+    }
+    XFree(children);
+    return;
+  }
+    
+
+  int gotfmt;
+  Atom gottype;
+  unsigned long len, gotbytesafter;
+  char *title;
+  unsigned char *gottitle=0;
+  xassert( !XGetWindowProperty(disp,w, wm_name,0,512, False,
+			       AnyPropertyType,&gottype, &gotfmt, &len,
+			       &gotbytesafter, &gottitle) );
+  title= (char*)gottitle;
+
+  if (DEBUGP(findypp)) {
+    debugfind(" gf=%d len=%lu gba=%lu \"", gotfmt,len,gotbytesafter);
+    char *p;
+    for (p=title; p < title+len; p++) {
+      char c= *p;
+      if (c>=' ' && c<=126) fputc(c,debug);
+      else fprintf(debug,"\\x%02x",c & 0xff);
+    }
+    fputs("\": ",debug);
+  }
+
+#define REQUIRE(pred)							\
+  if (!(pred)) { debugfind(" failed test  %s\n", #pred); return; }	\
+  else
+
+  REQUIRE( gottype!=None );
+  REQUIRE( len );
+  REQUIRE( gotfmt==8 );
+
+  REQUIRE( len >= S(prefix) + 1 + S(onthe) + 1 + S(suffix) );
+
+  char *spc1= strchr(  title        + S(prefix), ' ');  REQUIRE(spc1);
+  char *spc2= strrchr((title + len) - S(suffix), ' ');  REQUIRE(spc2);
+
+  REQUIRE( (title + len) - spc1  >= S(onthe)  + S(suffix) );
+  REQUIRE(  spc2         - title >= S(prefix) + S(onthe) );
+
+  REQUIRE( !memcmp(title,                   prefix, S(prefix)) );
+  REQUIRE( !memcmp(title + len - S(suffix), suffix, S(suffix))  );
+  REQUIRE( !memcmp(spc1,                    onthe,  S(onthe))  );
+
+#define ASSIGN(what, start, end)			\
+  what= masprintf("%.*s", (int)((end)-(start)), start);	\
+  if (o_##what) REQUIRE( !strcasecmp(o_##what, what) );	\
+  else
+
+  ASSIGN(ocean,  spc1 + S(onthe),   (title + len) - S(suffix));
+  ASSIGN(pirate, title + S(prefix),  spc1);
+
+  debugfind(" YES!\n");
+  id= w;
+  nfound++;
+  progress_log("found YPP client (0x%lx):"
+	       " %s ocean - %s.",
+	       (unsigned long)id, ocean, pirate);
+}
+
+void find_yppclient_window(void) {
+  int targetdepth;
+
+  nfound=0;
+  
+  if (id) return;
+  
+  progress("looking for YPP client window...");
+
+  xassert( (wm_name= XInternAtom(disp,"WM_NAME",True)) != None);
+
+  for (targetdepth=1; targetdepth<4; targetdepth++) {
+    for (screen=0; screen<ScreenCount(disp); screen++) {
+      debugfind("FINDYPP screen %d\n", screen);
+      findypp_recurse(0,targetdepth, RootWindow(disp,screen));
+    }
+    if (nfound) break;
+  }
+
+  if (nfound>1)
+    fatal("Found several possible YPP clients.   Close one,\n"
+	  " disambiguate with --pirate or --ocean,"
+	  " or specify --window-id.\n");
+  if (nfound<1)
+    fatal("Did not find %sYPP client."
+	  " Use --window-id and/or report this as a fault.\n",
+	  o_ocean || o_pirate ? "matching ": "");
+}