Fix problems with pngalpha and deep color transparency filling.

The pngalpha device is created with a depth of 32, with 3 color
components; this was confusing pdf14 into thinking that more
than 8 bits per color were being used, and so deep color buffers
were required.

To fix this we update the logic to be smarter; in cases where we
don't have a clear determination based on bits alone, we look
at the max_color and max_gray values. Because this code is now
more complex than before, we pull it into a shared function.

1 files changed, 1 insertions, 4 deletions

diff --git a/base/gsptype1.c b/base/gsptype1.c
index da96e8b9c..f81a63c10 100644
--- a/base/gsptype1.c
+++ b/base/gsptype1.c
@@ -2047,10 +2047,7 @@ gx_dc_pattern_read(
     int code, l;
     tile_trans_clist_info_t trans_info = { { { 0 } } };
     int cache_space_needed;
-    bool has_tags = device_encodes_tags(dev);
-    int bits_per_comp = ((dev->color_info.depth - has_tags*8) /
-                         dev->color_info.num_components);
-    bool deep = bits_per_comp > 8;
+    bool deep = device_is_deep(dev);
 
     if (offset == 0) {
         pdevc->mask.id = gx_no_bitmap_id;