[gs-cvs] gs/src

[Ray Johnston]

Update of /cvs/ghostscript/gs/src
In directory casper:/tmp/cvs-serv8741/src

Modified Files:
	zcolor2.c 
Log Message:
Fix: The addition of the function sampling logic for DeviceN tint
transforms (fix 474544) tripped over a bogus assumption in Adobe Procset
for DuoTones generated by (at least) Photoshop. The assumption was that if
the alternate color space of a DeviceN space was being used, that the
procedure would run when 'setcolor' was executed and that the stack would
be accessible during that procedure. This fixes several bug reports with
'/stackunderflow in pop' errors including SF #549307, 576577 and 582385
for Artifex customers. Thanks to Dan Coby for the analysis and fix.


Index: zcolor2.c
===================================================================
RCS file: /cvs/ghostscript/gs/src/zcolor2.c,v
retrieving revision 1.8
retrieving revision 1.9
diff -u -d -r1.8 -r1.9
--- zcolor2.c	16 Jun 2002 03:43:50 -0000	1.8
+++ zcolor2.c	31 Jul 2002 04:43:45 -0000	1.9
@@ -146,29 +146,6 @@
     return is_subset;   
 }
 
-/* Define a dummy cleanup function. */
-private int
-devicen_no_cleanup(i_ctx_t *i_ctx_p)
-{ 
-    return 0;
-}
-
-/* Discard the transformed color value. */
-private int
-devicen_setcolor_discard(i_ctx_t *i_ctx_p)
-{
-    gs_state *pgs = igs;
-    const gs_color_space *pcs = gs_currentcolorspace(pgs);  /* always DeviceN */
-    const gs_device_n_params *params = &pcs->params.device_n;
-    const gs_color_space *pacs = (const gs_color_space *)&params->alt_space;
-    int num_in = pcs->params.device_n.num_components; /* also on e-stack */
-    int num_out = gs_color_space_num_components(pacs);
-    
-    esp -= num_in + 2;		/* mark, count, tint values */
-    osp -= num_out;
-    return o_pop_estack;
-}
-
 /* <param1> ... <paramN> setcolor - */
 private int
 zsetcolor(i_ctx_t *i_ctx_p)
@@ -223,13 +200,25 @@
 	return code;
     if (pinst != 0)
 	istate->pattern = *op;
+    pop(n);
+    return code;
+}
+
+/*
+ * This operator will check if the current colorspace is DeviceN and the
+ * alternate colorspace is being used.  This strange function is part of a
+ * kludge to get around a spec violation in Adobe Photoshop 5+.  See
+ * comments in front of setcolor in lib/gs_ll3.ps for more info.
+ */
+private int
+zcheckdevicenaltused(i_ctx_t *i_ctx_p)        /* - .checkdevicenaltused <bool> */
+{
+    os_ptr op = osp;
+    const gs_color_space *pcs = gs_currentcolorspace(igs);
+    bool result = false;
+    int code;
+
     if(pcs->type->index == gs_color_space_index_DeviceN) {
-        /* 
-         * Duotone code generated by Adobe PhotoShop 5+ expects that setcolor
-         * (1) calls tint transform function (ttf). PLRM doesn't require this
-         * (2) permits ttf to change op stack as side effect. PLRM forbids this
-         * (3) assumes op stack is not changed when ttf is executed
-         */
         gs_color_space_type const *pcst = pcs->type;
         int num_comp    = pcst->num_components(pcs);
         gx_device const *dev  = gs_currentdevice(igs);
@@ -239,21 +228,32 @@
 
         code=device_color_idx(dev, idx_ink);
         if(code >= 0 && !is_subset_idx(idx_ink, num_ink, idx_comp, num_comp)) { 
-            int i;
-
-            check_estack(num_comp + 4);
-            for (i = 0; i < num_comp; ++i)
-	      *++esp = osp[i - num_comp + 1];
-            ++esp;
-            make_int(esp, num_comp);
-            push_mark_estack(es_for, devicen_no_cleanup);
-            push_op_estack(devicen_setcolor_discard);
-            *++esp = istate->colorspace.procs.special.device_n.tint_transform;
-            return o_push_estack;
+            result = true;
         }
     }
+    push(1);
+    make_bool(op, result ? 1 : 0);
+    return 0;
+}
+
+/*
+ * This operator will discard the components for a DeviceN alternate
+ * color space.  This strange function is part of a kludge to get around
+ * a spec violation in Adobe Photoshop 5+.  See comments in front of
+ * setcolor in lib/gs_ll3.ps for more info.
+ */
+private int
+zdiscardaltcolor(i_ctx_t *i_ctx_p) /* <param1> ... <paramN> .discardaltcolor - */
+{
+    os_ptr op = osp;
+    const gs_color_space *pcs = gs_currentcolorspace(igs);
+    int n = 0;
+
+    if(pcs->type->index == gs_color_space_index_DeviceN)
+      n = gs_color_space_num_components((gs_color_space *)
+                                      &pcs->params.device_n.alt_space);
     pop(n);
-    return code;
+    return 0;
 }
 
 /* <array> .setcolorspace - */
@@ -275,9 +275,10 @@
     op_def_begin_level2(),
     {"0currentcolor", zcurrentcolor},
     {"0.currentcolorspace", zcurrentcolorspace},
-    {"1setcolor", zsetcolor},
+    {"1.setcolor", zsetcolor},
     {"1.setcolorspace", zsetcolorspace},
-    {"0%.devicen_setcolor_discard", devicen_setcolor_discard},
+    {"0.checkdevicenaltused", zcheckdevicenaltused},
+    {"0.discardaltcolor", zdiscardaltcolor},
     op_def_end(0)
 };