From 6302a2b92d5bd13a6423d22956f9e3b3959512b3 Mon Sep 17 00:00:00 2001
From: Andrey Pohilko <apc4@ya.ru>
Date: Sat, 30 Sep 2017 22:13:45 +0300
Subject: [PATCH] preparing image manipulations

---
 examples/imgtracer.py | 92 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 70 insertions(+), 22 deletions(-)

diff --git a/examples/imgtracer.py b/examples/imgtracer.py
index c3c11dd..aa33e20 100644
--- a/examples/imgtracer.py
+++ b/examples/imgtracer.py
@@ -1,6 +1,5 @@
 import logging
 import matplotlib.pyplot as plt
-import time
 from threading import Thread
 
 import numpy
@@ -14,26 +13,72 @@ class Tracer(object):
         self.conv1 = self.orig.convert("1")
         self.src = numpy.asarray(self.conv1)
         self.dst = numpy.copy(self.src)
+        self.dst.fill(False)
+        self.mark = numpy.copy(self.dst)
+        # start in center
+        self.height, self.width = self.dst.shape
+        self.posy = self.height / 2
+        self.posx = self.width / 2
 
     def trace(self):
-        width, height = self.dst.shape
-        self.dst.fill(False)
-        mark = numpy.copy(self.dst)
+        while self._has_unchecked_pixels():
+            # go circles to find a pixel in src
+            self._spiral_till_pixel()
 
-        # start in center
-        posx = width / 2
-        posy = height / 2
+            # move until we find new pixels
+            self._move_while_you_can()
 
-        # go circles to find a pixel in src
+    def _has_unchecked_pixels(self):
+        ix, iy = numpy.where(self.mark == False)
+        return len(ix) or len(iy)
 
-        # move until we find new pixels
-        # repeat
+    def _spiral_till_pixel(self):
+        radius = 1
+        direction = 0
+        offset = 0
+        while self._has_unchecked_pixels():
+            in_lower = self.posy < self.height and self.posx < self.width
+            in_upper = self.posy >= 0 and self.posx >= 0
+            if in_lower and in_upper and not self.mark[self.posy][self.posx]:
+                if self.src[self.posy][self.posx]:
+                    return
 
-        for x in range(0, width):
-            for y in range(0, height):
-                time.sleep(0.01)
-                if (x + y) % 2 == 0:
-                    self.dst[x][y] = True
+                self.mark[self.posy][self.posx] = True
+
+            if direction == 0:
+                self.posx += 1
+                self.posy += 0
+            elif direction == 1:
+                self.posx += 0
+                self.posy += 1
+            elif direction == 2:
+                self.posx += -1
+                self.posy += 0
+            elif direction == 3:
+                self.posx += 0
+                self.posy += -1
+            else:
+                pass
+
+            offset += 1
+            if offset >= radius:
+                # time.sleep(0.01)
+                offset = 0
+                direction += 1
+                if direction > 3:
+                    direction = 0
+
+                if direction in (0, 2):
+                    radius += 1
+
+        raise KeyboardInterrupt("End of image")  # end of image
+
+    def _move_while_you_can(self):
+        logging.debug("%s %s", self.posy, self.posx)
+        self.mark[self.posy][self.posx] = True
+        self.dst[self.posy][self.posx] = True
+        # self.posx += 1
+        # self.posy += 1
 
 
 class TracerVisualizer(object):
@@ -45,18 +90,21 @@ class TracerVisualizer(object):
 
     def run(self):
         tracer = self.tracer
+
+        fig, ((ax1, ax2), (ax3, ax4)) = plt.subplots(nrows=2, ncols=2)
+        ax1.imshow(tracer.orig)
+        ax2.imshow(tracer.src)
+        plt.show(block=False)
+
         thr = Thread(target=tracer.trace)
         thr.setDaemon(True)
         thr.start()
 
-        fig, (ax1, ax2, ax3) = plt.subplots(nrows=1, ncols=3)
-        ax1.imshow(tracer.orig)
-        ax2.imshow(tracer.conv1)
-        plt.show(block=False)
-
         while plt.get_fignums():  # weird trick to react on close
-            ax3.imshow(tracer.dst, cmap='gray')
-            plt.pause(0.01)
+            ax3.set_title("%s:%s" % (tracer.posx, tracer.posy))
+            ax3.imshow(tracer.mark, cmap='gray')
+            ax4.imshow(tracer.dst, cmap='gray')
+            plt.pause(0.5)
 
 
 if __name__ == "__main__":