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"""This module defines classes for creating and drawing effects on a series
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of drawings (as in a Flipbook).
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Effect classes are arranged in a (currently) simple hierarchy:
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from libtovid.render.drawing import Drawing
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from libtovid.render.animation import Keyframe, Tween
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from random import randint
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"""A "special effect" created by keyframing a Cairo drawing command
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along the given frame interval."""
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def __init__(self, start, end):
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"""Create an effect lasting from start frame to end frame."""
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self.keyframes = [Keyframe(self.start, 0), Keyframe(self.end, 0)]
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self.tween = Tween(self.keyframes)
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self._parent_flipbook = None
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self._parent_layer = None
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def _init_parent_flipbook(self, fb):
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self._parent_flipbook = fb
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def _init_parent_layer(self, layer):
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self._parent_layer = layer
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def pre_draw(self, drawing, frame):
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"""Set up effect elements that must be applied before drawing a Layer.
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drawing: The Drawing to apply effects to
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frame: The frame for which to render the effect
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Extend this function in derived classes.
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def post_draw(self, drawing, frame):
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"""Finalize effect elements after a Layer is drawn.
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drawing: The Drawing to apply effects to
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frame: The frame for which to render the effect
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Extend this function in derived classes.
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# ============================================================================
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# Copy and paste this code to create your own Effect
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# ============================================================================
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# The first line defines your effect's name. (Effect) means it inherits from
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# the base Effect class, and shares some properties with it.
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class MyEffect (Effect):
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"""Modify this documentation string to describe what your effect does.
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# The __init__ function is called whenever a MyEffect is created.
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# Make sure your __init__ takes start and end arguments; additional
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# arguments (such as start_val and end_val below) allow someone using
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# your effect class to customize its behavior in some way. See the
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# other effects below for examples.
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def __init__(self, start, end, start_val, end_val):
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"""Create a MyEffect lasting from start to end frame.
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# Be sure to call this first-thing:
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Effect.__init__(self, start, end)
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# It initializes the base Effect class with start and end frames.
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# Next, define any keyframes your effect needs to use. This
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# effect just varies something from start_val to end_val:
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Keyframe(start, start_val),
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Keyframe(end, end_val)
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# Call this afterwards, to calculate the values at all frames
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self.tween = Tween(self.keyframes)
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def draw(self, drawing, frame):
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# Example function that can be called when drawing a layer.
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# The Layer must know that his particular effect requires the
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# calling of this function, or to add special parameters, or to
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# draw between items in the layer.
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# First, it's good to make sure we really have a Drawing class
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assert isinstance(drawing, Drawing)
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# This effect varies the stroke width across a sequence of frames.
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# Replace 'stroke_width' with your own drawing function(s)
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drawing.stroke_width(self.tween[frame])
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# Effect rendering occurs in two phases: pre_draw and post_draw.
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# These functions are already defined in the Effect base class; extend
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# them to do your effect rendering.
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def pre_draw(self, drawing, frame):
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"""Do preliminary effect rendering."""
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# Always call the base class pre_draw first:
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Effect.pre_draw(self, drawing, frame)
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# This effect varies the stroke width across a sequence of frames.
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# Replace 'stroke_width' with your own drawing function(s)
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drawing.stroke_width(self.tween[frame])
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# Extend post_draw to do any post-rendering cleanup you need to do. Most
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# of the time, you won't need to extend this, but if you do, be sure to
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# call the base class post_draw at the end:
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def post_draw(self, drawing, frame):
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"""Do post-drawing cleanup."""
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# Post-drawing cleanup here
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Effect.post_draw(self, drawing, frame)
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# That's it! Your effect is ready to use.
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# See libtovid/flipbook.py for examples on how to use effects
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# ============================================================================
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# End of new effect template
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# ============================================================================
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class Movement (Effect):
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"""A movement effect, from one point to another."""
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def __init__(self, start, end, (x0, y0), (x1, y1)):
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"""Move from start (x0, y0) to end (x1, y1)."""
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Effect.__init__(self, start, end)
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Keyframe(start, (x0, y0)),
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Keyframe(end, (x1, y1))
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self.tween = Tween(self.keyframes)
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def pre_draw(self, drawing, frame):
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drawing.translate(*self.tween[frame])
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def post_draw(self, drawing, frame):
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class Translate (Movement):
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"""Translates the layer to some relative (x,y) coordinates"""
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def __init__(self, start, end, (dx, dy)):
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Movement.__init__(self, start, end, (0,0), (dx, dy))
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"""A generic fade effect, varying the opacity of a layer.
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def __init__(self, keyframes, method='linear'):
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"""Fade in from start, for fade_length frames; hold at full
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opacity, then fade out for fade_length frames before end.
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fade_length -- num of frames to fade-in from start, and num of
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frames to fade-out before end. Everything in-between
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keyframes -- a set of Keyframe() objects, determining the fading
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curve. Values of the Keyframe() must be floats ranging
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from 0.0 to 1.0 (setting opacity).
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method -- linear, cosine
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# A fill-opacity curve, something like:
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if isinstance(keyframes, list):
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if not isinstance(keyframes[0], Keyframe):
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raise ValueError, "Must be a list of Keyframe objects"
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self.keyframes = keyframes
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raise ValueError, "List of Keyframe objects required"
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self.tween = Tween(self.keyframes, method)
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def pre_draw(self, drawing, frame):
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"""Called before drawing on a layer"""
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def post_draw(self, drawing, frame):
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"""Called after drawing on a layer"""
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assert isinstance(drawing, Drawing)
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drawing.pop_group_to_source()
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drawing.paint_with_alpha(self.tween[frame])
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class FadeInOut(Fade):
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def __init__(self, start, end, fade_length=30):
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"""Fade in from start, for fade_length frames; hold at full
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opacity, then fade out for fade_length frames before end.
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fade_length -- num of frames to fade-in from start, and num of
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frames to fade-out before end. Everything in-between
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# A fill-opacity curve, something like:
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Keyframe(start, 0.0), # Start fading in
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Keyframe(start + fade_length, 1.0), # Fade-in done
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Keyframe(end - fade_length, 1.0), # Start fading out
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Keyframe(end, 0.0) # Fade-out done
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self.tween = Tween(self.keyframes)
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class Colorfade (Effect):
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"""A color-slide effect between an arbitrary number of RGB colors."""
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def __init__(self, start, end, (r0, g0, b0), (r1, g1, b1)):
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"""Fade between the given RGB colors."""
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Effect.__init__(self, start, end)
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Keyframe(start, (r0, g0, b0)),
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Keyframe(end, (r1, g1, b1))
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self.tween = Tween(self.keyframes)
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def pre_draw(self, drawing, frame):
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"""Set source color"""
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drawing.set_source(self.tween[frame])
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def post_draw(self, drawing, frame):
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class Spectrum (Effect):
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"""A full-spectrum color-fade effect between start and end frames."""
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def __init__(self, start, end):
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Effect.__init__(self, start, end)
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step = (end - start) / 6
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Keyframe(start, (1.0, 0, 0)),
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Keyframe(start + step, (1.0, 0, 1.0)),
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Keyframe(start + step*2, (0, 0, 1.0)),
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Keyframe(start + step*3, (0, 1.0, 1.0)),
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Keyframe(start + step*4, (0, 1.0, 0)),
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Keyframe(start + step*5, (1.0, 1.0, 0)),
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Keyframe(end, (1.0, 0, 0))
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self.tween = Tween(self.keyframes)
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def pre_draw(self, drawing, frame):
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drawing.set_source(self.tween[frame])
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def post_draw(self, drawing, frame):
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class Scale (Effect):
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"""A Scaling effect, from one size to another."""
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def __init__(self, start, end, (w0, h0), (w1, h1)):
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Effect.__init__(self, start, end)
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Keyframe(start, (w0, h0)),
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Keyframe(end, (w1, h1))
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self.tween = Tween(self.keyframes)
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def pre_draw(self, drawing, frame):
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drawing.scale(self.tween[frame])
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def post_draw(self, drawing, frame):
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"""Rotates an object a number of times.
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def __init__(self, keyframes, center=(0,0), method='linear', units='deg'):
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"""Create a Whirl effect
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method -- 'linear' or 'cosine', for passing from one angle to another
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Pass from one angle to another
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units -- 'deg' or 'rad', the unit used in the Keyframes
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if units != 'deg' and units != 'rad':
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raise ValueError, "units must be 'rad' (radians) or 'deg' (degrees)"
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if not isinstance(center, tuple):
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raise ValueError, "center must be a two-value tuple"
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self.keyframes = keyframes
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self.tween = Tween(self.keyframes, method)
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def pre_draw(self, drawing, frame):
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# how to center the thing ? so you give a rotation point ?
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drawing.translate(*self.center)
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if self.units is 'deg':
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drawing.rotate_deg(self.tween[frame])
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elif self.units is 'rad':
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drawing.rotate_rad(self.tween[frame])
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def post_draw(self, drawing, frame):
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drawing.translate(- self.center[0], - self.center[1])
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class PhotoZoom(Effect):
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"""Zoom in and create dynamism by moving a picture.
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Normally applies to an Image layer, but can be used with others.
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def __init__(self, keyframes, subject=(0,0), direction=None, movement=50, method='linear'):
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"""Create a PhotoZoom effect
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keyframes -- 0.0 for beginning of effect, and 1.0 to reach the end,
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intermediate values show the intermediate state of the
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subject -- Position of the subject of interest. That is the point where
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the zoom in/out will focus it's attention.
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If (0,0), the focus will be chosen randomly in the 2/3 of
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the center of the screen.
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direction -- 'in', 'out', None (random)
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movement -- 0 to 100, percentage of movement to create.
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method -- 'linear' or 'cosine'
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if direction != 'in' and direction != 'out' and direction != None:
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raise ValueError, "'direction' must be 'in', 'out' or None"
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if (direction == None):
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self.direction = randint(0,1) and 'in' or 'out'
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self.direction = direction
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print "Zoom in direction: %s" % self.direction
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self.subject = subject
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self.movement = movement
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self.keyframes = keyframes
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self.tween = Tween(self.keyframes, method)
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def pre_draw(self, drawing, frame):
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fb = self._parent_flipbook
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# Use subject, or randomize in the center 1/3 of the image.
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if (self.subject == (0,0)):
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self.subject = (randint(int(0.33 * fb.w),
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randint(int(0.33 * fb.h),
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# Max moving = 25% * pixels estimation * movement factor
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zoomfactor = 0.25 * (self.movement / 100.)
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inter = self.tween[frame]
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if (self.direction == 'in'):
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gozoom = 1.0 + (1.0 - inter) * zoomfactor
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gozoom = 1.0 + inter * zoomfactor
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#print "Values: zoomfactor %s inter %s gozoom %s fb %s" % (zoomfactor, inter, gozoom, fb)
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drawing.scale_centered(self.subject[0], self.subject[1],
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def post_draw(self, drawing, frame):
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class KeyFunction (Effect):
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"""A keyframed effect on an arbitrary Drawing function."""
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def __init__(self, draw_function, keyframes, method='linear'):
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"""Create an effect using the given Drawing function, with values
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determined by the given list of Keyframes. For example:
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KeyFunction(Drawing.stroke_width,
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[Keyframe(1, 1), Keyframe(30, 12)])
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This says to vary the stroke width from 1 (at frame 1) to 12 (at
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The 'method' argument defines an interpolation method to use between
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keyframes, and may be either 'linear' or 'cosine'.
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# Call base constructor with start and end frames
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Effect.__init__(self, keyframes[0].frame, keyframes[-1].frame)
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# TODO: Make sure a valid function name is given
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self.draw_function = draw_function
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self.keyframes = keyframes
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# Tween keyframes using the given interpolation method
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self.tween = Tween(self.keyframes, method)
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def pre_draw(self, drawing, frame):
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self.draw_function(drawing, self.tween[frame])
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def post_draw(self, drawing, frame):
added
removed
libtovid/render/effect.py
