#!/usr/bin/env python

# test program for the "perspective" geometric tranform element

import cv

import gi
gi.require_version('Gst', '1.0')
from gi.repository import Gst
Gst.init(None)

from gi.repository import GObject
GObject.threads_init()


def calc_matrix():
    top_x_shift = 200

    width, height = 800, 480
    corners = [(0, 0), (width, 0), (width, height), (0, height)]
    target = [(top_x_shift, 0), (width - top_x_shift, 0), (width, height), (0, height)]

    mat = cv.CreateMat(3, 3, cv.CV_64F)
    cv.GetPerspectiveTransform(corners, target, mat)

    inv_mat = cv.CreateMat(3, 3, cv.CV_64F)
    cv.Invert(mat, inv_mat)

    matrix = [inv_mat[j, i] for j in range(mat.rows) for i in range(mat.cols)]
    return matrix


def main():
    pipeline = Gst.ElementFactory.make('pipeline', None)

    videosrc = Gst.ElementFactory.make('videotestsrc', None)
    pipeline.add(videosrc)

    # Test the perspective element
    perspective = Gst.ElementFactory.make("perspective", None)
    pipeline.add(perspective)

    print perspective.get_property("matrix")

    M = calc_matrix()
    perspective.set_property("matrix", M)
    print perspective.get_property("matrix")

    # This should fail!
    perspective.set_property("matrix", [0])
    print perspective.get_property("matrix")

    videoconvert = Gst.ElementFactory.make("autovideoconvert", None)
    pipeline.add(videoconvert)

    videosink = Gst.ElementFactory.make("autovideosink", None)
    pipeline.add(videosink)

    caps = Gst.caps_from_string(
        "video/x-raw,format=\"AYUV\",width=800,height=480")

    videosrc.link_filtered(perspective, caps)
    perspective.link(videoconvert)
    videoconvert.link(videosink)

    pipeline.set_state(Gst.State.PLAYING)

    loop = GObject.MainLoop()
    loop.run()


if __name__ == '__main__':
    main()