1 files changed, 109 insertions, 0 deletions
diff --git a/draw_points.py b/draw_points.py
new file mode 100644
index 0000000..1d9921d
--- /dev/null
+++ b/draw_points.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python
+# Copyright (C) 2011, One Laptop Per Child
+# Author, Gonzalo Odiard <gonzalo@laptop.org>
+
+from gi.repository import Gtk
+from gi.repository import Gdk
+from gi.repository import Pango, PangoCairo
+import math
+import logging
+
+t1 = "[(130.0, 58.0), (111, 77), (84, 115), (73, 137), (64, 172), (55, 195), (51, 230), (53, 273), (61, 284), (107, 305), (130, 305), (171, 300), (189, 291), (214, 279), (241, 249), (284, 202), (308, 181), (333, 156), (355, 141), (391, 126), (409, 113), (447, 101), (468, 100), (499, 101), (508, 107), (519, 133), (522, 132)]"
+
+
+class ShowPoints(Gtk.DrawingArea):
+
+    def __init__(self):
+        self.points = []
+        self._mark_next = False
+        self._last_crossproduct = 0
+        super(ShowPoints, self).__init__()
+        self.connect('draw', self.__draw_cb)
+
+    def __draw_cb(self, widget, ctx):
+        i = 0
+        EPS = 100
+        for point in self.points:
+            if self._mark_next:
+                ctx.set_source_rgba(1, 0, 0, 0.7)
+            else:
+                ctx.set_source_rgba(0.3, 0.3, 0.3, 0.7)
+            self._mark_next = False
+
+            crossproduct = 0
+            if i < len(self.points) - 3:
+                # X_ab, Y_ab - coordinates of vector B-A.
+                X_ab = float(self.points[i +1][0] - self.points[i][0])
+                Y_ab = float(self.points[i +1][1] - self.points[i][1])
+
+                # X_ac, Y_ac - coordinates of vector C-A.
+                X_ac = float(self.points[i +2][0] - self.points[i][0])
+                Y_ac = float(self.points[i +2][1] - self.points[i][1])
+
+                crossproduct = Y_ab * X_ac - X_ab * Y_ac
+                if abs(crossproduct) < EPS:  # if crossprudct == 0
+                    # on the same line.
+                    innerproduct = X_ab * X_ac + Y_ab * Y_ac;
+                    logging.error('innerproduct %f', innerproduct)
+                    if innerproduct > 0:
+                        self._mark_next = True
+            i = i + 1
+
+            ctx.save()
+            x, y = point[0], point[1]
+            logging.error('point %d %d', point[0], point[1])
+            ctx.arc(x, y, 5, 0., 2 * math.pi)
+            ctx.fill()
+
+            pango_layout = PangoCairo.create_layout(ctx)
+            fd = Pango.FontDescription('Sans 10')
+            pango_layout.set_font_description(fd)
+            label = str(self._last_crossproduct)
+            pango_layout.set_text(unicode(label), len(unicode(label)))
+            ctx.move_to(x + 20, y + 20)
+            PangoCairo.show_layout(ctx, pango_layout)
+            ctx.stroke()
+            ctx.restore()
+            self._last_crossproduct = crossproduct
+
+
+class SPWin(Gtk.Window):
+
+    def __init__(self):
+        super(Gtk.Window, self).__init__(   )
+        vbox = Gtk.VBox()
+        self.add(vbox)
+        self.show_points = ShowPoints()
+        vbox.add(self.show_points)
+        self.entry = Gtk.Entry()
+        self.entry.set_text(t1)
+        vbox.add(self.entry)
+        self.entry.connect('activate', self.show_points_from_entry)
+        self.connect("destroy", Gtk.main_quit)
+        self.show_all()
+        self.maximize()
+
+    def show_points_from_entry(self, entry):
+        self.show_points.points = self.parse_points(entry.get_text())
+        self.show_points.queue_draw()
+
+    def parse_points(self, text):
+        points_list = []
+        pairs = text.split('),')
+        for pair in pairs:
+            parts = pair.split(',')
+            xs = parts[0].replace('[','').replace('(','').replace(')','').replace(']','')
+            ys = parts[1].replace('[','').replace('(','').replace(')','').replace(']','')
+            x, y = int(float(xs)), int(float(ys))
+            points_list.append((x, y))
+        return points_list
+
+    #def update_points(entry):
+
+
+def main():
+    window = SPWin()
+    Gtk.main()
+
+if __name__ == "__main__":
+    main()