extend.py

import nuke,os
IMPULSE_FILTER_ENUM = 0
__version__ = (0,0,1)

def grow():
    """
    Will make a Crop node that crops the frame to the union of the animated BBox of the nude currently selected.
    For example, if you have a Tracker node that stabilizes an image this function will  grow your bounding box
    to include the whole stabilized image
    """
    sel = nuke.selectedNode()
    xmin = 0
    xmax = 0
    ymin = 0
    ymax = 0
    # The trick is that we need to execute() some node every time we go to a next frame, to
    # update the context.
    # not any node can be executed(). Now, for Nuke 6.2+ you can feed the knobs an input context
    # to evaluate the knobs at specific frames BUT bbox is not a knob, it's the node's property.
    # So we create a CurveTool that we can execute() on every frame.
    c = nuke.nodes.CurveTool()
    f = nuke.frame()
    
    # Python ranges are NOT inclusive therefore +1
    for i in range(nuke.root().firstFrame(), nuke.root().lastFrame() + 1):
        nuke.execute(c, i, i) # Workaround to update the tree
        bbox = sel.bbox()
        rx = bbox.x() + bbox.w()
        ry = bbox.y() + bbox.h()
        if xmin > bbox.x():
            xmin = bbox.x()
        if xmax < rx:
            xmax = rx
        if ymin > bbox.y():
            ymin = bbox.y()
        if ymax < ry:
            ymax = ry
    
    nuke.delete(c)
    
    c = nuke.nodes.Crop(name="GrowCrop",reformat=True)
    c["box"].setValue((xmin, ymin, xmax, ymax))
    c.setInput(0, sel)
    
    # Generate a node that "uncrops" to match the old placement in the canvas
    t = nuke.nodes.Transform(name="UndoReformat")
    t["filter"].setValue(IMPULSE_FILTER_ENUM)
    t["translate"].setValue((xmin, ymin))
    t.setInput(0, c)
    t["ypos"].setValue(t["ypos"].getValue() - 20) # Leave some room
    
    # Return the frame to it's old position
    nuke.frame(f)