NAME
Rivl_DirectSource - find the direct source of a signal if it exists
SYNOPSIS
#include <rivl.h>
Rivl_Signal
Rivl_DirectSource (interp, signal);
ARGUMENTS
- Tcl_Interp *interp (in)
-
The Tcl interpreter.
- Rivl_Signal outSignal (in)
-
Signal to find source of.
DESCRIPTION
Rivl_DirectSource determines if the contents of signal come directly
from a single leaf node. It does this by working backwards in the
graph til a leaf node is reached, making sure that the only
intervening nodes, if any, are those that do not affect the content of
the signal (such as Dup and Cache nodes). If
a direct source is found, its outgoing signal is returned. Otherwise,
NULL is returned.
This function is useful for detecting direct-transfer in write
commands. For example, if a signal that we are writing to JPEG has a
direct JPEG-read source with the right size and type, then we can copy
the JPEG file directly. See
Rivl_CreateFileFormat.