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, 7 insertions, 7 deletions

diff --git a/base/gxicolor.c b/base/gxicolor.c
index 05820695b..4785ab4f0 100644
--- a/base/gxicolor.c
+++ b/base/gxicolor.c
@@ -108,7 +108,7 @@ color_halftone_init(gx_image_enum *penum)
     if (!gx_device_must_halftone(penum->dev))
         return NULL;
 
-    if (penum->pgs == NULL || penum->pgs->dev_ht == NULL)
+    if (penum->pgs == NULL || penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT] == NULL)
         return NULL;
     dda_ht = penum->dda.pixel0.x;
     if (penum->dxx > 0)
@@ -136,20 +136,20 @@ color_halftone_init(gx_image_enum *penum)
     if (cal_ht == NULL)
         goto fail;
 
-    for (k = 0; k < penum->pgs->dev_ht->num_comp; k++) {
-        d_order = &(penum->pgs->dev_ht->components[k].corder);
+    for (k = 0; k < penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->num_comp; k++) {
+        d_order = &(penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->components[k].corder);
         code = gx_ht_construct_threshold(d_order, penum->dev, penum->pgs, k);
         if (code < 0)
             goto fail;
         if (cal_halftone_add_screen(ctx,
                                     penum->memory->non_gc_memory,
                                     cal_ht,
-                                    penum->pgs->dev_ht->components[k].corder.threshold_inverted,
-                                    penum->pgs->dev_ht->components[k].corder.width,
-                                    penum->pgs->dev_ht->components[k].corder.full_height,
+                                    penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->components[k].corder.threshold_inverted,
+                                    penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->components[k].corder.width,
+                                    penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->components[k].corder.full_height,
                                     -penum->pgs->screen_phase[k].x,
                                     -penum->pgs->screen_phase[k].y,
-                                    penum->pgs->dev_ht->components[k].corder.threshold) < 0)
+                                    penum->pgs->dev_ht[HT_OBJTYPE_DEFAULT]->components[k].corder.threshold) < 0)
             goto fail;
     }