detect straight lines more readily

.gitignore

@@ -0,0 +1,26 @@
+*.o
+Makefile
+*.a
+src/xournal
+stamp*
+*.Po
+*.gmo
+compile
+autom4te.cache/
+*.log
+*.guess
+ar-lib
+*.status
+
+# specific files
+config.h
+config.sub
+configure
+po/Makefile.in
+po/Makefile.in.in
+po/POTFILES
+src/Makefile.in
+src/ttsubset/Makefile.in
+Makefile.in
+aclocal.m4
+

README.org

@@ -0,0 +1,133 @@
+#+STARTUP: showall
+
+* This is a testing repository for new features of Xournal
+
+This is a mirror of the git repository of Xournal
+(http://xournal.sourceforge.net) and contains experimental code that
+is not yet in the official repo. Its purpose is to help in the
+development of new features
+
+It should *not be used* for code intended for further distribution.
+
+* Xournal
+
+Xournal is hosted in sourceforge at [[http://sourceforge.net/projects/xournal/][http://xournal.sourceforge.net/]]
+with a mailing list located at sourceforge too
+[[http://sourceforge.net/p/xournal/mailman/]]
+
+The latest official version of xournal can always be found at
+[[http://xournal.sourceforge.net/]]
+
+* Where to find the code
+
+** Official Repository
+
+The official repository of xournal is managed under git. It can be
+found in sourceforge at: [[git://git.code.sf.net/p/xournal/code%20xournal-code][git://git.code.sf.net/p/xournal/code
+xournal-code]]
+
+For compatibility reasons a CVS repo is still maintained and it mirrors the
+git repository, but its use is deprecated.
+
+** Experimental repository
+
+The Xournal development team has an experimental repository where new
+features of Xournal are tested before they are incorporated into the
+official version. These features are not considered to be
+stable enough for wider distributions and should be considered as
+unstable and prone to crash.
+
+The experimental repository is hosted at github in the
+following repository [[https://github.com/dmgerman/xournal]]
+
+Currently this repository contains the following [[https://github.com/dmgerman/xournal/branches][branches]]:
+
+1. [[https://github.com/dmgerman/xournal][Master]]. *DO NOT* use this branch as the basis of your code.
+1. [[https://github.com/dmgerman/xournal/tree/upstream][upstream]]. Its purpose is to mirror the official repository. Use
+   this branch as the basis to develop your new features.
+2. for-denis. This branch is expected to be merged into the official
+   repository. It contains features that are ready to be included in
+   his repository.
+3. [[https://github.com/dmgerman/xournal/tree/next][next]]. This branch is for integration of several features that have
+   been considered solid, but not yet incorporated into the official
+   repository.
+4. [[https://github.com/dmgerman/xournal/tree/gtk3][gtk3]]. It is an advanced effort towards porting xournal to
+   gtk3+. Currently Xournal uses gtk2+
+5. Other experimental branches. They will contain features that are
+   being tested before they are deployed to a wider audience.
+
+The repository is likely to contain other branches with other
+experimental features.
+
+** Summary of experimental branches
+
+These branches are reliable and do not break compatibility with Xournal:
+
+| Name                   | Purpose                                                                             | Rebased to head  | Integrated into next |
+|------------------------+-------------------------------------------------------------------------------------+------------------+----------------------|
+| Master                 | Identical to upstream except for this file                                          | <2016-04-20 Wed> | yes                  |
+| Upstream               | Identical to Denis repo                                                             | <2016-04-20 Wed> | yes                  |
+|------------------------+-------------------------------------------------------------------------------------+------------------+----------------------|
+| fix-update-width       | Fixes annoyance: when rest the width of selected strokes, keep their variable width | <2016-04-20 Wed> | yes                  |
+| glade                  | Uses XML glade interface for configuration files                                    | <2016-04-20 Wed> | yes                  |
+| horizontal-scroll-lock | Option to Lock the scroll horizontally                                              | <2016-04-20 Wed> | yes                  |
+| layers                 | Option to see layers above the current one                                          | <2016-04-20 Wed> | yes                  |
+| message                | Add a pop up warning that you are using my code (used by next, useless stand alone) | <2016-04-20 Wed> | yes                  |
+| mru                    | Update the Most-Recently-Used list with the currently opened page                   | <2016-04-20 Wed> | yes                  |
+| popupmenu              | Add a menu to right click on next/prev page to improve stylus navigation            | <2016-04-20 Wed> | yes                  |
+| snap-to-grid           | Defines a grid to which any annotation is snapped to.                               | <2016-04-20 Wed> | yes                  |
+| quick-zoom             | Quickly zoom-in/zoom-out to a predefined zoom factor                                | <2016-04-20 Wed> | yes                  |
+|------------------------+-------------------------------------------------------------------------------------+------------------+----------------------|
+| next                   | This branch integrates all the branches above plus current xournal code             | <2016-04-20 Wed> |                      |
+|------------------------+-------------------------------------------------------------------------------------+------------------+----------------------|
+| cl-options             | Command line options management                                                     | <2016-04-20 Wed> | NO                   |
+| snap-to-grid           | Any annotation snaps to grid                                                        | <2016-04-20 Wed> | NO                   |
+
+Some experimental branches, they are incomplete or break compatibility:
+
+| Name            | Purpose                                                 | Todo                     |
+|-----------------+---------------------------------------------------------+--------------------------|
+| bookmarks       | Tries to implement bookmarks                            | Code is a bit outdated   |
+| cmake           | Replaces autogen/automake with cmake                    | Problems detecting glade |
+| dot-paper-style | Implements dotted paper style, breaks XOJ compatibility | Fully implemented        |
+| gtk3            | Attempts to replace gtk2 with gtk3                      | Performance issues       |
+
+
+** 
+
+** How to contribute
+
+One of the features that characterizes Xournal is its
+robustness. Features that make it to the official repository should be
+rock-solid and error-free (to the extent that this is feasible).  In
+order to guarantee this we propose the following workflow:
+
+1. New ideas should be posted as a short proposal to the mailing list
+   (xournal-devel@lists.sourceforge.net, you can subscribe here
+   http://sourceforge.net/p/xournal/mailman/). Xournal developers will
+   be able to comment whether the idea fits within the vision of
+   xournal. They might also provide valuable comments and advice, and
+   direct to existing code (such as experimental branches).
+2. Make a clone of the *upstream* branch of the github repo
+   https://github.com/dmgerman/xournal/tree/upstream
+3. Develop your feature, test it.
+4. When it is ready, submit a pull-request to Daniel (github user
+   dmgerman). Make sure your commits are rebased to the upstream
+   branch to facilitate integration. Submit only one feature per
+   request.
+5. If the feature aligns with the short and long term goals of
+   Xournal, Daniel will incorporate your changes as a branch, where
+   they will be tested by others. At this point it becomes an
+   experimental feature. The name of the branch will reflect the
+   feature. Ideally each independent feature should be incorporated
+   into a separate branch. That will facilitate testing and code
+   review. Daniel will make sure the feature is continuously rebased
+   to the front of official.
+6. Daniel will evaluate the feature for inclusion into next, where it
+   can be used along many other features not yet in official (and
+   further tested).
+7. Simultaneously, Denis will evaluate the feature for inclusion in
+   official. If he accepts the feature, it will be submitted to him
+   via the for-denis branch.
+8. Once the feature is merged into official (and hence into next) the
+   branch is removed.

src/xo-shapes.c

@@ -540,6 +540,103 @@ gboolean try_closed_polygon(int nsides)
   return TRUE;
 }
 
+// this only checks lines, therefore can be slightly more generous in checking for deviations
+// it detects my own lines quite reliably.  I suck at drawing straight lines :-P
+gboolean check_line(struct Item *it) {
+/*  struct RecoSegment *rs;*/
+  GnomeCanvasPoints *points;
+  int num_points;
+  double *coords;
+  int n;
+  float x0, y0, xN, yN, xm, ym, a, b, l, invsqrt1plusbsquared, lastDistance;
+  float x, y, thisDistance, perpDistance;
+
+/*  printf("it->type %i\n", it->type);*/
+  points = it->path;
+  num_points = points->num_points;
+  coords = points->coords;
+  // what we will do is assume the line is between the first and last points
+  // since those points will tend to be well-defined by the person who is drawing them
+  // (I reckon; certainly they are for me; whereas the bits in between are all over the place :-P )
+  // then we measure the mean perpendicular squared loss, something like
+  // http://mathworld.wolfram.com/LeastSquaresFittingPerpendicularOffsets.html
+  // then we figure out how large this is compared to things like, how long is the line
+
+  if(num_points < 3) {
+    // not much point in doing anything with only 2 points...
+    return FALSE;
+  }
+
+  x0 = coords[0];
+  y0 = coords[1];
+  xN = coords[(num_points-1)*2];
+  yN = coords[(num_points-2)*2+1];
+
+  // get equation of a line, hope it's not vertical for now...
+  if(x0 == xN) {
+    // we dont handle vertical lines yet...
+    return FALSE;
+  }
+  // for y = a + xb
+  b = (yN - y0) / (xN - x0);
+  xm = (x0 + xN) / 2.0f; // mean point between lines
+  ym = (y0 + yN) / 2.0f;
+  a = ym - b * xm;
+
+  l = sqrt((yN-y0)*(yN-y0) + (xN-x0)*(xN-x0)); // line length
+
+  printf("%f,%f %f,%f  y = %f + %f x   l=%f\n",
+     x0, y0, xN, yN, a, b, l);
+
+  invsqrt1plusbsquared = 1.0f / sqrt(1 + b * b);
+  // if too big, we're vertical, just abort...
+  if(abs(invsqrt1plusbsquared > 1e8)) {
+/*    printf("too vertical\n");*/
+    return FALSE;
+  }
+  lastDistance = 0.0f;
+  for(n = 1; n < num_points; n++) {
+/*     printf("%.2f,%.2f\n", coords[i * 2], coords[i*2+1]);*/
+    x = coords[n*2];
+    y = coords[n*2+1];
+    // actually, we should check that distance from first point is always increasing
+    // if not, immediately return
+    thisDistance = sqrt((x-x0)*(x-x0) + (y-y0)*(y-y0));
+    if(thisDistance <= lastDistance) {
+/*      printf("backwards...\n");*/
+      return FALSE;
+    }
+    perpDistance = abs(y - (a + b * x)) * invsqrt1plusbsquared;
+/*    printf("%i/%i thisDistance %f perpdistance %f\n", n, num_points, thisDistance, perpDistance);*/
+    if(perpDistance > l / 10.0f) {
+/*      printf("too deviant\n");*/
+      return FALSE;
+    }
+  }
+  // its a line ... update it.. somehow
+/*  points->num_points = 2;*/
+/*  coords[2] = xN;*/
+/*  coords[3] = yN;*/
+
+/*  rs = recognizer_queue;*/
+
+  realloc_cur_path(2);
+  ui.cur_path.num_points = 2;
+  ui.cur_path.coords[0] = x0;
+  ui.cur_path.coords[1] = y0;
+  ui.cur_path.coords[2] = xN;
+  ui.cur_path.coords[3] = yN;
+  recognizer_queue[0].item = it;
+/*  remove_recognized_strokes(rs, 1);*/
+  remove_recognized_strokes(recognizer_queue, 1);
+  insert_recognized_curpath();
+
+  printf("updated :-)\n");
+  return TRUE;
+
+/*  return FALSE;*/
+}
+
 /* the main pattern recognition function, called after finalize_stroke() */
 void recognize_patterns(void)
 {
@@ -562,6 +659,10 @@ void recognize_patterns(void)
      s.mass, center_x(s), center_y(s), I_xx(s), I_yy(s), I_xy(s), I_rad(s), I_det(s));
 #endif
 
+  if(check_line(it)) {
+    return;
+  }
+
   // first see if it's a polygon
   n = find_polygonal(it->path->coords, 0, it->path->num_points-1, MAX_POLYGON_SIDES, brk, ss);
   if (n>0) {