Bug 704639 Avoid writing halftones into clist

If the target device is a contone device there is no
need to write and read halftone data into and out of
the clist.

4 files changed, 19 insertions, 3 deletions

diff --git a/base/gdevdflt.c b/base/gdevdflt.c
index 638b66eab..413bb1444 100644
--- a/base/gdevdflt.c
+++ b/base/gdevdflt.c
@@ -376,6 +376,15 @@ set_linear_color_bits_mask_shift(gx_device * dev)
 /* Determine if a number is a power of two.  Works only for integers. */
 #define is_power_of_two(x) ((((x) - 1) & (x)) == 0)
 
+/* A brutish way to check if we are a HT device */
+bool
+device_is_contone(gx_device* pdev)
+{
+    if ((float)pdev->color_info.depth / (float)pdev->color_info.num_components >= 8)
+        return true;
+    return false;
+}
+
 /*
  * This routine attempts to determine if a device's encode_color procedure
  * produces gx_color_index values which are 'separable'.  A 'separable' value
diff --git a/base/gsht.c b/base/gsht.c
index 76838723c..e9ad49a17 100644
--- a/base/gsht.c
+++ b/base/gsht.c
@@ -1305,7 +1305,10 @@ gx_gstate_set_effective_xfer(gs_gstate * pgs)
         }
     }
 
-    if (pdht) { /* might not be initialized yet */
+    /* HT may not be initialized yet.  Only do if the target is a halftone device.
+       Per the spec, the HT is a self-contained description of a halftoning process.
+       We don't use any xfer function from the HT if we are not halftoning */
+    if (pdht && !device_is_contone(pgs->device)) {
 
         /* Since the transfer function is pickled into the threshold array (if any)*/
         /*  we need to free it so it can be reconstructed with the current transfer */
diff --git a/base/gxclimag.c b/base/gxclimag.c
index 37421198b..5bb179e33 100644
--- a/base/gxclimag.c
+++ b/base/gxclimag.c
@@ -1588,8 +1588,8 @@ cmd_put_color_mapping(gx_device_clist_writer * cldev,
     int code;
     const gx_device_halftone *pdht = gx_select_dev_ht(pgs);
 
-    /* Put out the halftone, if present. */
-    if (pdht && pdht->id != cldev->device_halftone_id) {
+    /* Put out the halftone, if present, and target is not contone. */
+    if (pdht && pdht->id != cldev->device_halftone_id && !device_is_contone(cldev->target)) {
         code = cmd_put_halftone(cldev, pdht);
         if (code < 0)
             return code;
diff --git a/base/gxdevice.h b/base/gxdevice.h
index 55c0a045c..c01950e9d 100644
--- a/base/gxdevice.h
+++ b/base/gxdevice.h
@@ -434,6 +434,10 @@ void gx_device_forward_color_procs(gx_device_forward *);
  */
 void check_device_separable(gx_device * dev);
 /*
+ * Is this a contone device?
+ */
+bool device_is_contone(gx_device* pdev);
+/*
  * Check if the device's encode_color routine uses a pdf14 compatible
  * encoding.  For more info see the routine's header.
  */