# Method Image.GIF._render_block()

Method _render_block

  `string _render_block(int x, int y, int xsize, int ysize, int bpp, string indices, 0|string colortable, int interlace)`

Description

  Advanced (!) method for writing renderblocks for placement in a GIF file. This method only applies LZW encoding on the indices and makes the correct headers.

Parameter `x`
Parameter `y`

  Position of this image.

Parameter `xsize`
Parameter `ysize`

  Size of the image. Length if the `indices` string must be xsize*ysize.

Parameter `bpp`

  Bits per pixels in the indices. Valid range 1..8.

Parameter `indices`

  The image indices as an 8bit indices.

Parameter `colortable`

  Colortable with colors to write as palette. If this argument is zero, no local colortable is written. Colortable string len must be 1<<bpp.

Parameter `interlace`

  Interlace index data and set interlace bit. The given string should _not_ be pre-interlaced.

Note

  This is in the very advanced sector of the GIF support; please read about how GIF files works.

See also

  encode, _encode, header_block, end_block