[PATCH v2 3/3] gitk: Allow displaying time zones from author and commit timestamps

[Anders Kaseorg <andersk@MIT.EDU>]

Now gitk can be configured to display author and commit dates in their
original timezone, by putting %z into datetimeformat in ~/.gitk.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 gitk |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/gitk b/gitk
index 8e15572..c77771e 100755
--- a/gitk
+++ b/gitk
@@ -11021,7 +11021,23 @@ proc prefsok {} {
 proc formatdate {d} {
     global datetimeformat
     if {$d ne {}} {
-	set d [clock format [lindex $d 0] -format $datetimeformat]
+	# If $datetimeformat includes a timezone, display in the
+	# timezone of the argument.  Otherwise, display in local time.
+	if {[string match {*%[zZ]*} $datetimeformat]} {
+	    if {[catch {set d [clock format [lindex $d 0] -timezone [lindex $d 1] -format $datetimeformat]}]} {
+		# Tcl < 8.5 does not support -timezone.  Emulate it by
+		# setting TZ=Unknown±NNNN.
+		global env
+		catch {set savedTZ $env(TZ)}
+		set zone [lindex $d 1]
+		set sign [string map {+ - - +} [string index $zone 0]]
+		set env(TZ) Unknown$sign[string range $zone 1 2]:[string range $zone 3 4]
+		set d [clock format [lindex $d 0] -format $datetimeformat]
+		if {[catch {set env(TZ) $savedTZ}]} {unset env(TZ)}
+	    }
+	} else {
+	    set d [clock format [lindex $d 0] -format $datetimeformat]
+	}
     }
     return $d
 }
-- 
1.7.5.3