'''BlendedWarps.py

Warp an image, blending the effects of multiple
line-segment pairs that are controlling the warp.
Blending is based on the Beier-Neely method of weighting
the displacements according to a point's distance from
each control segment.

'''
from MorphMapper import MorphMapper
import SetOfSegmentPairs
#from JythonPixelMathInterface import pmGetPixel, pmSetPixel,\
#    pmGetImageWidth, pmGetImageHeight


def warp(methodToGetAPixel, methodToPutAPixel, w, h, ssp):
    # Use one line segment set to warp the source image.
    # w is the width of the images.
    # h is the height of the images.
    # First create a mapper for each line segment pair.
    mappers = [MorphMapper(lsp.dSeg.P, lsp.dSeg.Q, lsp.sSeg.P, lsp.sSeg.Q) for lsp in ssp.pairs]
    # Iterate to generate all the pixels of the target image.
    for yd in range(h):
        for xd in range(w):
            sum_x_displ = 0.0
            sum_y_displ = 0.0
            sum_weights = 0.0
            for m in mappers:
                (xs,ys,dist,weight)=m(xd,yd)
                sum_x_displ += weight*(xs - xd)
                sum_y_displ += weight*(ys - yd)
                sum_weights += weight
            if sum_weights==0: sum_weights = 1
            net_x_displ = sum_x_displ / sum_weights
            net_y_displ = sum_y_displ / sum_weights
            net_xs = int(xd + net_x_displ)
            net_ys = int(yd + net_y_displ)
            # Now fetch the source pixel data and insert in dest.
            if net_xs >= 0 and net_xs < w and net_ys >= 0 and net_ys < h:
                px = methodToGetAPixel(net_xs, net_ys)
            else:
                px = (127,127,127) # default value for out of range coords.
            methodToPutAPixel(xd, yd, px[0], px[1], px[2])
    #return new_win