Add option for StringMobject to only render one svg

manimlib/mobject/svg/string_mobject.py

@@ -9,6 +9,7 @@ from scipy.spatial.distance import cdist
 from manimlib.constants import WHITE
 from manimlib.logger import log
 from manimlib.mobject.svg.svg_mobject import SVGMobject
+from manimlib.mobject.types.vectorized_mobject import VMobject
 from manimlib.mobject.types.vectorized_mobject import VGroup
 from manimlib.utils.color import color_to_hex
 from manimlib.utils.color import hex_to_int
@@ -55,12 +56,17 @@ class StringMobject(SVGMobject, ABC):
         base_color: ManimColor = WHITE,
         isolate: Selector = (),
         protect: Selector = (),
+        # When set to true, only the labelled svg is
+        # rendered, and its contents are used directly
+        # for the body of this String Mobject
+        use_labelled_svg: bool = False,
         **kwargs
     ):
         self.string = string
         self.base_color = base_color or WHITE
         self.isolate = isolate
         self.protect = protect
+        self.use_labelled_svg = use_labelled_svg
 
         self.parse()
         super().__init__(
@@ -72,47 +78,34 @@ class StringMobject(SVGMobject, ABC):
         )
         self.labels = [submob.label for submob in self.submobjects]
 
-    def get_file_path(self) -> str:
-        original_content = self.get_content(is_labelled=False)
-        return self.get_file_path_by_content(original_content)
+    def get_file_path(self, is_labelled: bool = False) -> str:
+        is_labelled = is_labelled or self.use_labelled_svg
+        return self.get_file_path_by_content(self.get_content(is_labelled))
 
     @abstractmethod
     def get_file_path_by_content(self, content: str) -> str:
         return ""
 
-    def generate_mobject(self) -> None:
-        super().generate_mobject()
-
+    def assign_labels_by_color(self, mobjects: list[VMobject]) -> None:
+        """
+        Assuming each mobject in the list `mobjects` has a fill color
+        meant to represent a numerical label, this assigns those
+        those numerical labels to each mobject as an attribute
+        """
         labels_count = len(self.labelled_spans)
         if labels_count == 1:
-            for submob in self.submobjects:
-                submob.label = 0
+            for mob in mobjects:
+                mob.label = 0
             return
 
-        labelled_content = self.get_content(is_labelled=True)
-        file_path = self.get_file_path_by_content(labelled_content)
-        labelled_svg = SVGMobject(file_path)
-        if len(self.submobjects) != len(labelled_svg.submobjects):
-            log.warning(
-                "Cannot align submobjects of the labelled svg " + \
-                "to the original svg. Skip the labelling process."
-            )
-            for submob in self.submobjects:
-                submob.label = 0
-            return
-
-        self.rearrange_submobjects_by_positions(labelled_svg)
         unrecognizable_colors = []
-        for submob, labelled_svg_submob in zip(
-            self.submobjects, labelled_svg.submobjects
-        ):
-            label = hex_to_int(color_to_hex(
-                labelled_svg_submob.get_fill_color()
-            ))
+        for mob in mobjects:
+            label = hex_to_int(color_to_hex(mob.get_fill_color()))
             if label >= labels_count:
                 unrecognizable_colors.append(label)
                 label = 0
-            submob.label = label
+            mob.label = label
+
         if unrecognizable_colors:
             log.warning(
                 "Unrecognizable color labels detected (%s). " + \
@@ -123,26 +116,59 @@ class StringMobject(SVGMobject, ABC):
                 )
             )
 
+    def mobjects_from_file(self, file_path: str) -> list[VMobject]:
+        submobs = super().mobjects_from_file(file_path)
+
+        if self.use_labelled_svg:
+            # This means submobjects are colored according to spans
+            self.assign_labels_by_color(submobs)
+            return submobs
+
+        # Otherwise, submobs are not colored, so generate a new list
+        # of submobject which are and use those for labels
+        unlabelled_submobs = submobs
+        labelled_content = self.get_content(is_labelled=True)
+        labelled_file = self.get_file_path_by_content(labelled_content)
+        labelled_submobs = super().mobjects_from_file(labelled_file)
+        self.labelled_submobs = labelled_submobs
+        self.unlabelled_submobs = unlabelled_submobs
+
+        self.assign_labels_by_color(labelled_submobs)
+        self.rearrange_submobjects_by_positions(labelled_submobs, unlabelled_submobs)
+        for usm, lsm in zip(unlabelled_submobs, labelled_submobs):
+            usm.label = lsm.label
+
+        if len(unlabelled_submobs) != len(labelled_submobs):
+            log.warning(
+                "Cannot align submobjects of the labelled svg " + \
+                "to the original svg. Skip the labelling process."
+            )
+            for usm in unlabelled_submobs:
+                usm.label = 0
+            return unlabelled_submobs
+
+        return unlabelled_submobs
+
     def rearrange_submobjects_by_positions(
-        self, labelled_svg: SVGMobject
+        self, labelled_submobs: list[VMobject], unlabelled_submobs: list[VMobject],
     ) -> None:
-        # Rearrange submobjects of `labelled_svg` so that
-        # each submobject is labelled by the nearest one of `labelled_svg`.
-        # The correctness cannot be ensured, since the svg may
-        # change significantly after inserting color commands.
-        if not labelled_svg.submobjects:
+        """
+        Rearrange `labeleled_submobjects` so that each submobject
+        is labelled by the nearest one of `unlabelled_submobs`.
+        The correctness cannot be ensured, since the svg may
+        change significantly after inserting color commands.
+        """
+        if len(labelled_submobs) == 0:
             return
 
-        labelled_svg.replace(self)
+        labelled_svg = VGroup(*labelled_submobs)
+        labelled_svg.replace(VGroup(*unlabelled_submobs))
         distance_matrix = cdist(
-            [submob.get_center() for submob in self.submobjects],
-            [submob.get_center() for submob in labelled_svg.submobjects]
+            [submob.get_center() for submob in unlabelled_submobs],
+            [submob.get_center() for submob in labelled_submobs]
         )
         _, indices = linear_sum_assignment(distance_matrix)
-        labelled_svg.set_submobjects([
-            labelled_svg.submobjects[index]
-            for index in indices
-        ])
+        labelled_submobs[:] = [labelled_submobs[index] for index in indices]
 
     # Toolkits