Minimize bad cases CU-86c3mbjx8

vectorizing/solvers/color/ColorSolver.py

@@ -35,7 +35,7 @@ def solve(self):
         self.timer.end_timer()
 
         self.timer.start_timer("Polygon Clipping")
-        compound_paths = remove_layering(traced_bitmaps)
+        compound_paths = remove_layering(traced_bitmaps, self.img)
         self.timer.end_timer()
 
         return [compound_paths, colors, self.img.size[0], self.img.size[1]]

vectorizing/solvers/color/clip.py

@@ -1,23 +1,70 @@
-from pathops import op, PathOp
+from pathops import op, PathOp, Path
 from vectorizing.geometry.potrace import potrace_path_to_compound_path
 
-def remove_layering(traced_bitmaps):
+def create_background_rect(img, padding):
+    """
+    Creates a rectangle that matches the image dimensions plus
+    some padding.
+
+        Parameters:
+            img: A Pillow image instance.
+
+        Returns:
+            The rectangle.
+    """
+    rect = Path()
+    rect.moveTo(-padding, -padding)
+    rect.lineTo(img.width + padding, -padding)
+    rect.lineTo(img.width + padding, img.height + padding)
+    rect.lineTo(-padding, img.height + padding)
+    rect.close()
+    return rect
+
+def remove_layering(traced_bitmaps, img):
     """
     Performs boolean operations on a list of traced bitmaps
     to ensure that they are all disjoint.
 
-            Parameters:
-                traced_bitmaps: The list of traced bitmaps (potrace paths).
+    This function uses a technique devised to try to minimize
+    the holes created / outright failures of SKPath boolean operations.
+    Even so, a failure can still happen (and often does), particularly
+    for very intricate paths (usually coming from real world photographs).
+    In such cases, the routine fallbacks to a mixture of disjoint paths
+    (the ones for which the boolean operations didn't fail), and layered paths.
+
+        Parameters:
+            traced_bitmaps: The list of traced bitmaps (potrace paths).
+            img: A Pillow image.
 
-            Returns:
-                The processed list of compound paths.
+        Returns:
+            The processed list of compound paths.
     """
     compound_paths = [
         potrace_path_to_compound_path(traced) for traced in traced_bitmaps
     ]
 
+    disjoint_paths = []
     for x in range(len(compound_paths) - 1):
-        next = compound_paths[x + 1]
-        compound_paths[x] = op(compound_paths[x], next, PathOp.DIFFERENCE)
+        # Each base path has bigger padding to reduce
+        # the amount of overlapping borders.
+        base = create_background_rect(img, (x + 1) * 10)
+
+        to_subtract = Path()
+        for y in range(0, x):
+            to_subtract.addPath(disjoint_paths[y])
+        to_subtract.addPath(compound_paths[x + 1])
+
+        try:
+            result = op(base, to_subtract, PathOp.DIFFERENCE)
+        except:
+            break
+        disjoint_paths.append(result)
+
+    for x in range(len(disjoint_paths)):
+        try:
+            disjoint_paths[x] = op(disjoint_paths[x], create_background_rect(img, 0), PathOp.INTERSECTION)
+        except:
+            return compound_paths
 
-    return compound_paths
+    disjoint_paths = disjoint_paths + compound_paths[len(disjoint_paths) : len(compound_paths)]
+    return disjoint_paths