python Sketcher utility class

samples/python2/common.py

 import numpy as np
-import cv2
+import cv2, cv
 import os
 
 image_extensions = ['.bmp', '.jpg', '.jpeg', '.png', '.tif', '.tiff', '.pbm', '.pgm', '.ppm']
@@ -57,3 +57,29 @@ def mtx2rvec(R):
 def draw_str(dst, (x, y), s):
     cv2.putText(dst, s, (x+1, y+1), cv2.FONT_HERSHEY_PLAIN, 1.0, (0, 0, 0), thickness = 2, linetype=cv2.CV_AA)
     cv2.putText(dst, s, (x, y), cv2.FONT_HERSHEY_PLAIN, 1.0, (255, 255, 255), linetype=cv2.CV_AA)
+
+class Sketcher:
+    def __init__(self, windowname, dests, colors_func):
+        self.prev_pt = None
+        self.windowname = windowname
+        self.dests = dests
+        self.colors_func = colors_func
+        self.dirty = False
+        self.show()
+        cv2.setMouseCallback(self.windowname, self.on_mouse)
+
+    def show(self):
+        cv2.imshow(self.windowname, self.dests[0])
+
+    def on_mouse(self, event, x, y, flags, param):
+        pt = (x, y)
+        if event == cv.CV_EVENT_LBUTTONDOWN:
+            self.prev_pt = pt
+        if self.prev_pt and flags & cv.CV_EVENT_FLAG_LBUTTON:
+            for dst, color in zip(self.dests, self.colors_func()):
+                cv.Line(dst, self.prev_pt, pt, color, 5)
+            self.dirty = True
+            self.prev_pt = pt
+            self.show()
+        else:
+            self.prev_pt = None

samples/python2/watershed.py

 import numpy as np
 import cv2, cv
+from common import Sketcher
 
 help_message = '''
   USAGE: watershed.py [<image>]
@@ -21,34 +22,17 @@ class App:
         self.cur_marker = 1
         self.colors = np.int32( list(np.ndindex(2, 2, 2)) ) * 255
 
-        cv2.imshow('img', self.markers_vis)
-
-        self.prev_pt = None
-        self.need_update = False
         self.auto_update = True
-        cv2.setMouseCallback('img', self.onmouse)
-
-
-    def onmouse(self, event, x, y, flags, param):
-        pt = (x, y)
-        if event == cv.CV_EVENT_LBUTTONDOWN:
-            self.prev_pt = pt
-        if self.prev_pt and flags & cv.CV_EVENT_FLAG_LBUTTON:
-            color = map(int, self.colors[self.cur_marker])
-            cv.Line(self.markers, self.prev_pt, pt, self.cur_marker, 5)
-            cv.Line(self.markers_vis, self.prev_pt, pt, color, 5)
-            self.need_update = True
-            self.prev_pt = pt
-            cv2.imshow('img', self.markers_vis)
-        else:
-            self.prev_pt = None
+        self.sketch = Sketcher('img', [self.markers_vis, self.markers], self.get_colors)
+        
+    def get_colors(self):
+        return map(int, self.colors[self.cur_marker]), self.cur_marker
 
     def watershed(self):
         m = self.markers.copy()
         cv2.watershed(self.img, m)
         vis = np.uint8( (self.img + self.colors[np.maximum(m, 0)]) / 2 )
         cv2.imshow('watershed', vis)
-        self.need_update = False
 
     def run(self):
         while True:
@@ -58,15 +42,16 @@ class App:
             if ch >= ord('1') and ch <= ord('7'):
                 self.cur_marker = ch - ord('0')
                 print 'marker: ', self.cur_marker
-            if ch == ord(' ') or (self.need_update and self.auto_update):
+            if ch == ord(' ') or (self.sketch.dirty and self.auto_update):
                 self.watershed()
+                self.sketch.dirty = False
             if ch in [ord('a'), ord('A')]:
                 self.auto_update = not self.auto_update
                 print 'auto_update if', ['off', 'on'][self.auto_update]
             if ch in [ord('r'), ord('R')]:
-                self.markers = np.zeros(self.img.shape[:2], np.int32)
-                self.markers_vis = self.img.copy()
-                cv2.imshow('img', self.markers_vis)
+                self.markers[:] = 0
+                self.markers_vis[:] = self.img
+                self.sketch.show()
                 cv2.destroyWindow('watershed')