Add object type specific device halftones to the graphics state.

PostScript 'sethalftone' has an optional parameter "ObjectType" that allows
one of the three object specific types to be set: Vector, Image or Text.

Also add a new PostScript operator to set the current halftone (dev_ht,
set by sethalftone) as the device halftone to be used for an object type:
path, image and text.

For non-PostScript clients, the gs_halftone structure adds a 'objtype'
element (enum) that can be set prior to calling gs_sethalftone.

The gs_gstate_s dev_ht is now an array of HT_OBJTYPE_COUNT elements,
indexed by the gs_HT_objtype_t enum, with HT_OBJTYPE_DEFAULT (value 0)
used for prior sethalftone/setscreen/setcolorscreen operations.

NOTE: adding object types beyond the default+3 entries will require modification
of gx_select_dev_ht since it only uses 3 bits of the 'tag' to get the index
for the dev_ht[] array.

For code style, change to use != NULL instead of != 0 in most places that
this commit touched (but we may want a general cleanup of this everywhere).

TBD: Command line options for all PDL's will need a method to take a
halftone specification -- most likely a file that may be "PS-lite" syntax
and may be limited to a threshold array. Discussions are in progress.

1 files changed, 1 insertions, 0 deletions

diff --git a/pcl/pl/plht.c b/pcl/pl/plht.c
index 50730f35f..22a856dc4 100644
--- a/pcl/pl/plht.c
+++ b/pcl/pl/plht.c
@@ -40,6 +40,7 @@ pl_set_pcl_halftone(gs_gstate * pgs, gs_mapping_proc transfer_proc,
     if (code < 0)
         return code;
     ht.type = ht_type_threshold;
+    ht.objtype = HT_OBJTYPE_DEFAULT;
     ht.params.threshold.width = width;
     ht.params.threshold.height = height;
     ht.params.threshold.thresholds.data = threshold_data.data;