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+#
+# Bindings for Menubuttons.
+#
+# Menubuttons have three interaction modes:
+#
+# Pulldown: Press menubutton, drag over menu, release to activate menu entry
+# Popdown: Click menubutton to post menu
+# Keyboard: <Key-space> or accelerator key to post menu
+#
+# (In addition, when menu system is active, "dropdown" -- menu posts
+# on mouse-over. Ttk menubuttons don't implement this).
+#
+# For keyboard and popdown mode, we hand off to tk_popup and let
+# the built-in Tk bindings handle the rest of the interaction.
+#
+# ON X11:
+#
+# Standard Tk menubuttons use a global grab on the menubutton.
+# This won't work for Ttk menubuttons in pulldown mode,
+# since we need to process the final <ButtonRelease> event,
+# and this might be delivered to the menu. So instead we
+# rely on the passive grab that occurs on <ButtonPress> events,
+# and transition to popdown mode when the mouse is released
+# or dragged outside the menubutton.
+#
+# ON WINDOWS:
+#
+# I'm not sure what the hell is going on here. [$menu post] apparently
+# sets up some kind of internal grab for native menus.
+# On this platform, just use [tk_popup] for all menu actions.
+#
+# ON MACOS:
+#
+# Same probably applies here.
+#
+
+namespace eval ttk {
+ namespace eval menubutton {
+ variable State
+ array set State {
+ pulldown 0
+ oldcursor {}
+ }
+ }
+}
+
+bind TMenubutton <Enter> { %W instate !disabled {%W state active } }
+bind TMenubutton <Leave> { %W state !active }
+bind TMenubutton <Key-space> { ttk::menubutton::Popdown %W }
+bind TMenubutton <<Invoke>> { ttk::menubutton::Popdown %W }
+
+if {[tk windowingsystem] eq "x11"} {
+ bind TMenubutton <ButtonPress-1> { ttk::menubutton::Pulldown %W }
+ bind TMenubutton <ButtonRelease-1> { ttk::menubutton::TransferGrab %W }
+ bind TMenubutton <B1-Leave> { ttk::menubutton::TransferGrab %W }
+} else {
+ bind TMenubutton <ButtonPress-1> \
+ { %W state pressed ; ttk::menubutton::Popdown %W }
+ bind TMenubutton <ButtonRelease-1> \
+ { %W state !pressed }
+}
+
+# PostPosition --
+# Returns the x and y coordinates where the menu
+# should be posted, based on the menubutton and menu size
+# and -direction option.
+#
+# TODO: adjust menu width to be at least as wide as the button
+# for -direction above, below.
+#
+proc ttk::menubutton::PostPosition {mb menu} {
+ set x [winfo rootx $mb]
+ set y [winfo rooty $mb]
+ set dir [$mb cget -direction]
+
+ set bw [winfo width $mb]
+ set bh [winfo height $mb]
+ set mw [winfo reqwidth $menu]
+ set mh [winfo reqheight $menu]
+ set sw [expr {[winfo screenwidth $menu] - $bw - $mw}]
+ set sh [expr {[winfo screenheight $menu] - $bh - $mh}]
+
+ switch -- $dir {
+ above { if {$y >= $mh} { incr y -$mh } { incr y $bh } }
+ below { if {$y <= $sh} { incr y $bh } { incr y -$mh } }
+ left { if {$x >= $mw} { incr x -$mw } { incr x $bw } }
+ right { if {$x <= $sw} { incr x $bw } { incr x -$mw } }
+ flush {
+ # post menu atop menubutton.
+ # If there's a menu entry whose label matches the
+ # menubutton -text, assume this is an optionmenu
+ # and place that entry over the menubutton.
+ set index [FindMenuEntry $menu [$mb cget -text]]
+ if {$index ne ""} {
+ incr y -[$menu yposition $index]
+ }
+ }
+ }
+
+ return [list $x $y]
+}
+
+# Popdown --
+# Post the menu and set a grab on the menu.
+#
+proc ttk::menubutton::Popdown {mb} {
+ if {[$mb instate disabled] || [set menu [$mb cget -menu]] eq ""} {
+ return
+ }
+ foreach {x y} [PostPosition $mb $menu] { break }
+ tk_popup $menu $x $y
+}
+
+# Pulldown (X11 only) --
+# Called when Button1 is pressed on a menubutton.
+# Posts the menu; a subsequent ButtonRelease
+# or Leave event will set a grab on the menu.
+#
+proc ttk::menubutton::Pulldown {mb} {
+ variable State
+ if {[$mb instate disabled] || [set menu [$mb cget -menu]] eq ""} {
+ return
+ }
+ foreach {x y} [PostPosition $mb $menu] { break }
+ set State(pulldown) 1
+ set State(oldcursor) [$mb cget -cursor]
+
+ $mb state pressed
+ $mb configure -cursor [$menu cget -cursor]
+ $menu post $x $y
+ tk_menuSetFocus $menu
+}
+
+# TransferGrab (X11 only) --
+# Switch from pulldown mode (menubutton has an implicit grab)
+# to popdown mode (menu has an explicit grab).
+#
+proc ttk::menubutton::TransferGrab {mb} {
+ variable State
+ if {$State(pulldown)} {
+ $mb configure -cursor $State(oldcursor)
+ $mb state {!pressed !active}
+ set State(pulldown) 0
+
+ set menu [$mb cget -menu]
+ tk_popup $menu [winfo rootx $menu] [winfo rooty $menu]
+ }
+}
+
+# FindMenuEntry --
+# Hack to support tk_optionMenus.
+# Returns the index of the menu entry with a matching -label,
+# -1 if not found.
+#
+proc ttk::menubutton::FindMenuEntry {menu s} {
+ set last [$menu index last]
+ if {$last eq "none"} {
+ return ""
+ }
+ for {set i 0} {$i <= $last} {incr i} {
+ if {![catch {$menu entrycget $i -label} label]
+ && ($label eq $s)} {
+ return $i
+ }
+ }
+ return ""
+}
+
+#*EOF*