composition.py

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from .base import LottieObject, Index, LottieProp
from .layers import Layer
 
 
## @ingroup Lottie
class Composition(LottieObject):
    """!
    Base class for layer holders
    """
    _props = [
        LottieProp("layers", "layers", Layer, True),
    ]
 
    def __init__(self):
        super().__init__()
        ## List of Composition Layers
        self.layerslayers = [] # ShapeLayer, SolidLayer, CompLayer, ImageLayer, NullLayer, TextLayer
 
        self._index_gen_index_gen = Index()
 
    def layer(self, index):
        for layer in self.layerslayers:
            if layer.index == index:
                return layer
        raise IndexError("No layer %s" % index)
 
    def add_layer(self, layer: Layer):
        """!
        @brief Appends a layer to the composition
        @see insert_layer
        """
        return self.insert_layerinsert_layer(len(self.layerslayers), layer)
 
    @classmethod
    def load(cls, lottiedict):
        obj = super().load(lottiedict)
        obj._fixup()
        return obj
 
    def _fixup(self):
        for layer in self.layerslayers:
            layer.composition = self
 
    def insert_layer(self, index, layer: Layer):
        """!
        @brief Inserts a layer to the composition
        @note Layers added first will be rendered on top of later layers
        """
        self.layerslayers.insert(index, layer)
        self.prepare_layerprepare_layer(layer)
        return layer
 
    def prepare_layer(self, layer: Layer):
        layer.composition = self
        if layer.index is None:
            layer.index = next(self._index_gen_index_gen)
        self._on_prepare_layer_on_prepare_layer(layer)
 
    def _on_prepare_layer(self, layer):
        raise NotImplementedError
 
    def clone(self):
        c = super().clone()
        c._index_gen._i = self._index_gen_index_gen._i
        return c
 
    def remove_layer(self, layer: Layer):
        """!
        @brief Removes a layer (and all of its children) from this composition
        @param layer    Layer to be removed
        """
        if layer.composition is not self:
            return
 
        children = list(layer.children)
 
        layer.composition = None
        self.layerslayers.remove(layer)
 
        for c in children:
            self.remove_layerremove_layer(c)