diff options
| -rw-r--r-- | devices/gdevpng.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/devices/gdevpng.c b/devices/gdevpng.c index 26fc5a8ab..b41162be3 100644 --- a/devices/gdevpng.c +++ b/devices/gdevpng.c @@ -765,10 +765,28 @@ pngalpha_create_buf_device(gx_device **pbdev, gx_device *target, int y, const gx_render_plane_t *render_plane, gs_memory_t *mem, gx_color_usage_t *color_usage) { - gx_device_printer *ptarget = (gx_device_printer *)target; + gx_device_printer *ptarget; int code = gx_default_create_buf_device(pbdev, target, y, render_plane, mem, color_usage); /* Now set copy_alpha to one that handles RGBA */ + + /* this is really pretty nasty. The pngalpha device is going to replace + * the device methods in the memory rendering device with some of its own. + * To me this seems fraught with peril, its making a lot of assumptions + * about the compatibility of the devices! + * This, of course, totally breaks device chaining, but since the memory + * device wasn't going to pass on the intermediate method calls to the + * 'terminating' device, we can work around it here. We simply descend + * the chain of devices to the terminating device, and pull the methods + * we need directly from that device. I don't know why we are using + * 'orig_procs' either, but its safe to do so because this is only + * done here for the PNG device, and we know that this is a gx_device_prn + * based device. + */ + while (target->child != NULL) + target = target->child; + + ptarget= (gx_device_printer *)target; set_dev_proc(*pbdev, copy_alpha, ptarget->orig_procs.copy_alpha); set_dev_proc(*pbdev, fillpage, pngalpha_fillpage); return code; |