git-gui: Support starting gitk from Gui Blame

Add a context menu command to load commits
that are within a certain time range from the
selected commit into gitk.

It can be useful for understanding of the code,
especially if the repository is imported from
a VCS that does not support atomic commits.

Signed-off-by: Alexander Gavrilov <angavrilov@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -668,6 +668,7 @@ set default_config(gui.pruneduringfetch) false
 set default_config(gui.trustmtime) false
 set default_config(gui.fastcopyblame) false
 set default_config(gui.copyblamethreshold) 40
+set default_config(gui.blamehistoryctx) 7
 set default_config(gui.diffcontext) 5
 set default_config(gui.commitmsgwidth) 75
 set default_config(gui.newbranchtemplate) {}

lib/blame.tcl

@@ -259,6 +259,9 @@ constructor new {i_commit i_path} {
 	$w.ctxm add command \
 		-label [mc "Do Full Copy Detection"] \
 		-command [cb _fullcopyblame]
+	$w.ctxm add command \
+		-label [mc "Show History Context"] \
+		-command [cb _gitkcommit]
 
 	foreach i $w_columns {
 		for {set g 0} {$g < [llength $group_colors]} {incr g} {
@@ -905,10 +908,14 @@ method _showcommit {cur_w lno} {
 	}
 }
 
-method _copycommit {} {
+method _get_click_amov_info {} {
 	set pos @$::cursorX,$::cursorY
 	set lno [lindex [split [$::cursorW index $pos] .] 0]
-	set dat [lindex $amov_data $lno]
+	return [lindex $amov_data $lno]
+}
+
+method _copycommit {} {
+	set dat [_get_click_amov_info $this]
 	if {$dat ne {}} {
 		clipboard clear
 		clipboard append \
@@ -918,6 +925,50 @@ method _copycommit {} {
 	}
 }
 
+method _format_offset_date {base offset} {
+	set exval [expr {$base + $offset*24*60*60}]
+	return [clock format $exval -format {%Y-%m-%d}]
+}
+
+method _gitkcommit {} {
+	set dat [_get_click_amov_info $this]
+	if {$dat ne {}} {
+		set cmit [lindex $dat 0]
+		set radius [get_config gui.blamehistoryctx]
+		set cmdline [list --select-commit=$cmit]
+
+                if {$radius > 0} {
+			set author_time {}
+			set committer_time {}
+
+			catch {set author_time $header($cmit,author-time)}
+			catch {set committer_time $header($cmit,committer-time)}
+
+			if {$committer_time eq {}} {
+				set committer_time $author_time
+			}
+
+			set after_time [_format_offset_date $this $committer_time [expr {-$radius}]]
+			set before_time [_format_offset_date $this $committer_time $radius]
+
+			lappend cmdline --after=$after_time --before=$before_time
+		}
+
+		lappend cmdline $cmit
+
+		set base_rev "HEAD"
+		if {$commit ne {}} {
+			set base_rev $commit
+		}
+
+		if {$base_rev ne $cmit} {
+			lappend cmdline $base_rev
+		}
+
+		do_gitk $cmdline
+	}
+}
+
 method _show_tooltip {cur_w pos} {
 	if {$tooltip_wm ne {}} {
 		_open_tooltip $this $cur_w

lib/option.tcl

@@ -125,6 +125,7 @@ proc do_options {} {
 		{b gui.matchtrackingbranch {mc "Match Tracking Branches"}}
 		{b gui.fastcopyblame {mc "Blame Copy Only On Changed Files"}}
 		{i-20..200 gui.copyblamethreshold {mc "Minimum Letters To Blame Copy On"}}
+		{i-0..300 gui.blamehistoryctx {mc "Blame History Context Radius (days)"}}
 		{i-0..99 gui.diffcontext {mc "Number of Diff Context Lines"}}
 		{i-0..99 gui.commitmsgwidth {mc "Commit Message Text Width"}}
 		{t gui.newbranchtemplate {mc "New Branch Name Template"}}