added mouse drawing

ocv_drawline.py

@@ -0,0 +1,51 @@
+import cv2
+
+
+class DrawLineWidget(object):
+    def __init__(self):
+        self.original_image = cv2.imread('./data/1.jpg')
+        self.clone = self.original_image.copy()
+        self.work = self.original_image.copy()
+
+        cv2.namedWindow('image')
+        cv2.setMouseCallback('image', self.extract_coordinates)
+
+        # List to store start/end points
+        self.image_coordinates = []
+
+    def extract_coordinates(self, event, x, y, flags, parameters):
+        # Record starting (x,y) coordinates on left mouse button click
+        if event == cv2.EVENT_LBUTTONDOWN:
+            if len(self.image_coordinates) == 0:
+                self.image_coordinates = [(x, y)]
+        elif event == cv2.EVENT_MOUSEMOVE:
+            if len(self.image_coordinates) > 0:
+                self.work = self.clone.copy()
+                # Draw line
+                cv2.line(self.work, self.image_coordinates[0], (x, y), (36, 255, 12), 2)
+                cv2.imshow("image", self.work)
+
+        # Record ending (x,y) coordintes on left mouse bottom release
+        elif event == cv2.EVENT_LBUTTONUP:
+            self.clone = self.work.copy()
+            self.image_coordinates = []
+        # Clear drawing boxes on right mouse button click
+        elif event == cv2.EVENT_MBUTTONDOWN:
+            self.work = self.original_image.copy()
+            self.clone = self.original_image.copy()
+            cv2.imshow("image", self.work)
+
+    def show_image(self):
+        return self.work
+
+
+if __name__ == '__main__':
+    draw_line_widget = DrawLineWidget()
+    while True:
+        cv2.imshow('image', draw_line_widget.show_image())
+        key = cv2.waitKey(1)
+
+        # Close program with keyboard 'q'
+        if key == 27:
+            cv2.destroyAllWindows()
+            exit(1)