ImageEffect can have invisible_if_nill_clip_path option

Author: leejjoon

mpl_visual_context/image_box.py

@@ -202,11 +202,12 @@ def __init__(self, extent=None, bbox=None, coords="data", axes=None,
                  blend_color=None, **im_kw):
         self.coords = coords
         self.bbox_orig = self._get_bbox_orig(extent, bbox)
+        if "interpolation" not in im_kw:
+            im_kw["interpolation"] = "none"
         BboxImage.__init__(
             self,
             Bbox([[0, 0], [0, 0]]),
             origin="lower",
-            interpolation="none",
             transform=IdentityTransform(),
             **im_kw,
         )

mpl_visual_context/patheffects_image_effect.py

@@ -138,11 +138,15 @@ def get_rendered_image(self):
 
 
 class ImageEffect(AbstractPathEffect, ImageEffectBase):
-    def __init__(self, image_effect, clip_path_getter=None):
+    def __init__(self, image_effect, clip_path_getter=None,
+                 invisible_if_nill_clip_path=True):
         """
 
         clip_path_getter: set the clip_path of the resulting image. Need to be a callable
         or an object with get_clip_path method, which returns a path and a transform.
+
+        invisible_if_nill_clip_path: if clip_path_getter is used and if it retune a
+        nil path of length 0, do not draw the image. Default is True.
         """
         if clip_path_getter is None or hasattr(clip_path_getter, "get_clip_path") or callable(clip_path_getter):
             self._clip_path_getter = clip_path_getter
@@ -153,6 +157,7 @@ def __init__(self, image_effect, clip_path_getter=None):
 
         self._image_effect = image_effect
         self._path_effect = None
+        self._invisible_if_nill_clip_path = invisible_if_nill_clip_path
 
     def __ror__(self, other: AbstractPathEffect):
         e = ImageEffect(self._image_effect)
@@ -190,6 +195,10 @@ def draw_path(self, renderer, gc, tpath, affine, rgbFace):
             else:
                 raise ValueError("clip_path_getter need to be a callable or an object with get_clip_path method.")
 
+            if self._invisible_if_nill_clip_path and len(clip_path) == 0:
+                self.clear()
+                return
+
             pp = TransformedPath(clip_path, affine)
 
             gc.set_clip_path(pp)