fix: issue with ImageMobject bounding box (#3340)

* fix: fix an issue with ImageMobject bounding box

A missing point resulted in smaller bounding box causing issues it to be
smaller when the object is rotated. Added the missing fourth point to
ImageMobject points and altered call from camera. Filled in docstring
that used to propagate from superclass, saying that ImageMobject has no
points.

* add a test to check that rotating an image to and from doesn't change it

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: Václav Blažej <[email protected]>
Co-authored-by: Naveen M K <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 4 people

manim/camera/camera.py

@@ -965,7 +965,7 @@ def display_image_mobject(
             The Pixel array to put the imagemobject in.
         """
         corner_coords = self.points_to_pixel_coords(image_mobject, image_mobject.points)
-        ul_coords, ur_coords, dl_coords = corner_coords
+        ul_coords, ur_coords, dl_coords, _ = corner_coords
         right_vect = ur_coords - ul_coords
         down_vect = dl_coords - ul_coords
         center_coords = ul_coords + (right_vect + down_vect) / 2

manim/mobject/types/image_mobject.py

@@ -86,12 +86,13 @@ def set_resampling_algorithm(self, resampling_algorithm: int):
         return self
 
     def reset_points(self):
-        # Corresponding corners of image are fixed to these 3 points
+        """Sets :attr:`points` to be the four image corners."""
         self.points = np.array(
             [
                 UP + LEFT,
                 UP + RIGHT,
                 DOWN + LEFT,
+                DOWN + RIGHT,
             ],
         )
         self.center()

tests/test_graphical_units/test_img_and_svg.py

@@ -284,3 +284,20 @@ def test_ImageInterpolation(scene):
     scene.add(img1, img2, img3, img4, img5)
     [s.shift(4 * LEFT + pos * 2 * RIGHT) for pos, s in enumerate(scene.mobjects)]
     scene.wait()
+
+
+def test_ImageMobject_points_length():
+    file_path = get_svg_resource("tree_img_640x351.png")
+    im1 = ImageMobject(file_path)
+    assert len(im1.points) == 4
+
+
+def test_ImageMobject_rotation():
+    # see https://github.com/ManimCommunity/manim/issues/3067
+    # rotating an image to and from the same angle should not change the image
+    file_path = get_svg_resource("tree_img_640x351.png")
+    im1 = ImageMobject(file_path)
+    im2 = im1.copy()
+    im1.rotate(PI / 2)
+    im1.rotate(-PI / 2)
+    np.testing.assert_array_equal(im1.points, im2.points)