png.py 文件源码

def write(self, outfile, rows):
        """Write a PNG image to the output file.  `rows` should be
        an iterable that yields each row in boxed row flat pixel format.
        The rows should be the rows of the original image, so there
        should be ``self.height`` rows of ``self.width * self.planes`` values.
        If `interlace` is specified (when creating the instance), then
        an interlaced PNG file will be written.  Supply the rows in the
        normal image order; the interlacing is carried out internally.

        .. note ::

          Interlacing will require the entire image to be in working memory.
        """

        if self.interlace:
            fmt = 'BH'[self.bitdepth > 8]
            a = array(fmt, itertools.chain(*rows))
            return self.write_array(outfile, a)
        else:
            nrows = self.write_passes(outfile, rows)
            if nrows != self.height:
                raise ValueError(
                  "rows supplied (%d) does not match height (%d)" %
                  (nrows, self.height))