Initial Commit

lottie/objects/easing.py

@@ -0,0 +1,114 @@
+import math
+from .base import LottieObject, LottieProp, PseudoList, PseudoBool
+
+
+## @ingroup Lottie
+class KeyframeBezierHandle(LottieObject):
+    """!
+    Bezier handle for keyframe interpolation
+    """
+    _props = [
+        LottieProp("x", "x", list=PseudoList),
+        LottieProp("y", "y", list=PseudoList),
+    ]
+
+    def __init__(self, x=0, y=0):
+        ## x position of the handle.
+        ## This represents the change in time of the keyframe
+        self.x = x
+        ## y position of the handle.
+        ## This represents the change in value of the keyframe
+        self.y = y
+
+
+class Linear:
+    """!
+    Linear easing, the value will change from start to end in a straight line
+    """
+    def __call__(self, keyframe):
+        keyframe.out_value = KeyframeBezierHandle(
+            0,
+            0
+        )
+        keyframe.in_value = KeyframeBezierHandle(
+            1,
+            1
+        )
+
+
+class EaseIn:
+    """!
+    The value lingers near the start before accelerating towards the end
+    """
+    def __init__(self, delay=1/3):
+        self.delay = delay
+
+    def __call__(self, keyframe):
+        keyframe.out_value = KeyframeBezierHandle(
+            self.delay,
+            0
+        )
+        keyframe.in_value = KeyframeBezierHandle(
+            1,
+            1
+        )
+
+
+class EaseOut:
+    """!
+    The value starts fast before decelerating towards the end
+    """
+    def __init__(self, delay=1/3):
+        self.delay = delay
+
+    def __call__(self, keyframe):
+        keyframe.out_value = KeyframeBezierHandle(
+            0,
+            0
+        )
+        keyframe.in_value = KeyframeBezierHandle(
+            1-self.delay,
+            1
+        )
+
+
+class Jump:
+    """!
+    Jumps to the end value at the end of the keyframe
+    """
+    def __call__(self, keyframe):
+        keyframe.jump = True
+
+
+class Sigmoid:
+    """!
+    Combines the effects of EaseIn and EaseOut
+    """
+    def __init__(self, delay=1/3):
+        self.delay = delay
+
+    def __call__(self, keyframe):
+        keyframe.out_value = KeyframeBezierHandle(
+            self.delay,
+            0
+        )
+        keyframe.in_value = KeyframeBezierHandle(
+            1 - self.delay,
+            1
+        )
+
+
+class Split:
+    """
+    Uses different easing methods for in/out
+    """
+
+    def __init__(self, out_ease, in_ease):
+        self.out_ease = out_ease
+        self.in_ease = in_ease
+
+    def __call__(self, keyframe):
+        self.out_ease(keyframe)
+        t = keyframe.out_value
+        self.in_ease(keyframe)
+        keyframe.out_value = t