Add tests for 'slide_out' transition

moviepy/video/compositing/transitions.py

@@ -51,7 +51,7 @@ def slide_in(clip, duration, side):
 
     side : str
       Side of the screen where the clip comes from. One of
-      'top' | 'bottom' | 'left' | 'right'
+      'top', 'bottom', 'left' or 'right'.
 
     Examples
     --------
@@ -91,26 +91,30 @@ def slide_out(clip, duration, side):
     Parameters
     ----------
 
-    clip
+    clip : moviepy.Clip.Clip
       A video clip.
 
-    duration
+    duration : float
       Time taken for the clip to fully disappear.
 
-    side
+    side : str
       Side of the screen where the clip goes. One of
-      'top' | 'bottom' | 'left' | 'right'
+      'top', 'bottom', 'left' or 'right'.
 
     Examples
     --------
 
-    >>> from moviepy import *
     >>> clips = [... make a list of clips]
-    >>> slided_clips = [CompositeVideoClip([
-                            clip.fx(transfx.slide_out, duration=1, side='left')])
-                        for clip in clips]
-    >>> final_clip = concatenate_videoclips( slided_clips, padding=-1)
-
+    >>> slided_clips = [
+    ...     CompositeVideoClip([clip.fx(transfx.slide_out, 1, "left")])
+    ...     for clip in clips
+    ... ]
+    >>> final_clip = concatenate_videoclips(slided_clips, padding=-1)
+    >>>
+    >>> clip = ColorClip(
+    ...     color=(255, 0, 0), duration=1, size=(300, 300)
+    ... ).with_fps(60)
+    >>> final_clip = CompositeVideoClip([transfx.slide_out(clip, 1, "right")])
     """
     w, h = clip.size
     ts = clip.duration - duration  # start time of the effect.

tests/test_compositing.py

@@ -8,7 +8,7 @@
 from moviepy.utils import close_all_clips
 from moviepy.video.compositing.CompositeVideoClip import CompositeVideoClip, clips_array
 from moviepy.video.compositing.concatenate import concatenate_videoclips
-from moviepy.video.compositing.transitions import slide_in
+from moviepy.video.compositing.transitions import slide_in, slide_out
 from moviepy.video.fx.resize import resize
 from moviepy.video.io.VideoFileClip import VideoFileClip
 from moviepy.video.VideoClip import BitmapClip, ColorClip
@@ -171,5 +171,57 @@ def test_slide_in():
             assert n_reds == n_reds_expected
 
 
+def test_slide_out():
+    duration = 0.1
+    size = (11, 1)
+    fps = 10
+    color = (255, 0, 0)
+
+    # left and right sides
+    clip = ColorClip(
+        color=color,
+        duration=duration,
+        size=size,
+    ).with_fps(fps)
+
+    for side in ["left", "right"]:
+        new_clip = CompositeVideoClip([slide_out(clip, duration, side)])
+
+        for t in np.arange(0, duration, duration / fps):
+            n_reds, n_reds_expected = (0, round(11 - t * 100, 6))
+
+            if t:
+                assert n_reds_expected
+
+            for r, g, b in new_clip.get_frame(t)[0]:
+                if r == color[0] and g == color[1] and g == color[2]:
+                    n_reds += 1
+
+            assert n_reds == n_reds_expected
+
+    # top and bottom sides
+    clip = ColorClip(
+        color=color,
+        duration=duration,
+        size=(size[1], size[0]),
+    ).with_fps(fps)
+
+    for side in ["top", "bottom"]:
+        new_clip = CompositeVideoClip([slide_out(clip, duration, side)])
+        for t in np.arange(0, duration, duration / fps):
+            n_reds, n_reds_expected = (0, round(11 - t * 100, 6))
+
+            if t:
+                assert n_reds_expected
+
+            for row in new_clip.get_frame(t):
+                r, g, b = row[0]
+
+                if r == color[0] and g == color[1] and g == color[2]:
+                    n_reds += 1
+
+            assert n_reds == n_reds_expected
+
+
 if __name__ == "__main__":
     pytest.main()