PCStitch (not the pattern viewer) can be used for any project that uses a "grid" pattern. This does include some crochet (such as fillet crochet). I don't know about double-crochet because those stitches are elongated but you can define your "blocks" to be other than square.
The key is how you interpret each square of the grid. Depending on the craft, it can be a cross-stitch, a latch hook knot, a bead, a crochet stitch - anything that can be represented in a grid pattern.
I want to make a chart for line picture crocheting (using single and double crochets). Is pcstitch able to make a chart for this purpose?
You can use XStitch Patterns to make graph afghans. Each square equals a stitch, so you wouldn't want too many stitches or your project will be too large. Single Stitch or Afghan Stitch is perfect for using Cross Stitch Charts. You can also crochet your entire piece (i.e. afghan or blanket) and work a cross stitch over each stitch. The Single Stitch makes the design at a slight angle but not distort too bad where the Tunisian/ Afghan Stitch are straight like the squares on graph paper. Double crochet could be used, but your stitches will be taller which might effect your design.