#!/usr/bin/wish
# First, we will create the main window components, including a text widget, with an
# associated scrollbar, and a status widget, to display menu traversal and error messages.
# We arrange these widgets on the screen using the grid command.
# We will also create a new font named myFont.
# We will use the menu to manipulate the font attributes so that the text in the text
# widget will change its appearance.

wm title . "Menu demonstration"
wm iconname . "Menu demo"

# create the basic UI
scrollbar .yscroll -orient vertical -command ".text yview"
font create myfont -family Courier -size 10 -weight bold -slant italic \
    -underline 1 
text .text -height 10 -width 40 -bg white -yscrollcommand ".yscroll set" -font myfont
label .msg -relief sunken -bd 2 -textvariable message -anchor w -font "Helvetica 10"
.text insert end "Menu Demonstration!"

# manage the widgets using the grid geometry manager.
grid .text -row 0 -column 0  -sticky "news" 
grid .yscroll -row 0 -column 1 -sticky "ns"
grid .msg -row 1 -columnspan 2 -sticky "ew" 

grid columnconfigure . 0 -weight 1
grid rowconfigure . 0 -weight 1

# Next, we will develop callback functions, which will be associated with the menu entries.
# The SetBg procedure will change the background color of the text.
# ConfigureFont will change the attributes of myFont.
# InsertImage will insert the named bitmap into the text buffer.
# The InsertImage procedure has a side effect.
# If the named bitmap already exists in the text buffer, it will get deleted and a
# new bitmap will be inserted.
# The OpenFile procedure will prompt the user for a file and if the user selects a file,
# its contents will be displayed in the text widget.

# procedure to set text background color
proc SetBg {} {
    global background
    .text configure -bg $background
}

# procedure to configure the previously created font.

proc ConfigureFont {} {
    global bold italic underline
    expr {$bold ? [set weight bold]: [set weight normal]}
    expr {$italic? [set slant italic]: [set slant roman]}
    expr {$underline? [set underline 1]: [set underline 0]}
    font configure myfont -weight $weight -slant $slant -underline $underline
}

# Procedure to insert images in the text widget

proc InsertImage {image} {
    catch {destroy .text.$image}    
    label .text.$image -bitmap $image
    .text window create end -window .text.$image
}

# Callback for open menubutton

proc OpenFile {} {
    global message
    set file [tk_getOpenFile]
    if {$file == ""}  {
        set message "No file selected..."
        return;
    }
    .text delete 0.0 end
    set fd [open $file "r"] 
    while {[eof $fd] != 1} {
        gets $fd line
        .text insert end $line
        puts $line
        update idletasks
    }
    close $fd
}

# Next, we will focus on the menu widget and its components.
# First, we will create a menu that will become the menu bar for the toplevel window. 

# create toplevel menu

menu .menu -tearoff 0  -type menubar

# Create File menu

set m .menu.file

# We will add a File submenu with open and exit entries.
# The open entry will prompt the user with an open file dialog.
# If the user chooses a file, that file will be displayed in the text widget using
# the OpenFile procedure.
# The exit menu entry is used to exit the application.#
# As you can see, Tk does not create a default global binding for the menu entry just
# by using the -accelerator menu entry option.
# We have to explicitly create the binding in order for the accelerator to take effect.

menu $m -tearoff 0
.menu add cascade -label "File" -menu $m -underline 0
set modifier Meta
$m add command -label "Open..." -accelerator $modifier+o -command "OpenFile" -underline 0 -command OpenFile 
bind . <$modifier-o> "OpenFile"
$m add separator
$m add command -label "Exit..." -accelerator $modifier+x -command "exit" -underline 0
bind . <$modifier-x> "exit"

# We next add an Option submenu to the main menu.
# The Options submenu contains background and font cascade menus.
# A background cascaded menu contains a group of radio buttons to change the background
# color of the text widget.
# The Font cascade menu provides a group of check buttons to manipulate myfont menu attributes.

# Create options menu
set m .menu.options
menu $m -tearoff 1
.menu add cascade -label "Options" -menu $m -underline 0 
$m add cascade -label "Background" -menu .menu.options.bg -underline 0
$m add cascade -label "Font" -menu  .menu.options.font -underline 0

# create Radio button cascade menu
set m .menu.options.bg
menu $m -tearoff 0
$m add radio  -label "Red" -background red -variable background -value red \
    -command SetBg
$m add radio  -label "Yellow" -background yellow -variable background \
    -value yellow -command SetBg
$m add radio  -label "Blue" -background blue -variable background -value blue \
    -command SetBg
$m add radio  -label "White" -background white -variable background -value white \
    -command SetBg
$m invoke 3

# Insert option button cascade Menu
set m .menu.options.font
menu $m -tearoff 0
$m add check -label "Bold" -variable bold -command ConfigureFont
$m add check -label "Italic" -variable italic -command ConfigureFont
$m add check -label "underline" -variable underline -command ConfigureFont
$m invoke 3

# As you can see from the above code, the entries in a menu can be configured to have
# different backgrounds and foregrounds, as well as other standard widget options.

# Next, we will proceed to add yet another cascade entry to the main menu to insert
# bitmaps into the text widget. As explained earlier, these bitmap entry commands have
# a side effect-that only one instance of these bitmaps can be present in the text
# widget at any given time.

# Create insert menu option
set m .menu.insert
menu $m -tearoff 0
.menu add cascade -label "Insert" -menu $m -underline 0
foreach i {info questhead error} {
    $m add command -bitmap $i -command "puts {You invoked the $i bitmap}" -hidemargin 1 -command "InsertImage $i"
}
$m entryconfigure 2 -columnbreak 1

# One thing to observe from the above code snippet is that entries in a menu can be
# arranged in a tabular fashion using the entryconfigure command with the -columnbreak option.

# Finally, we will attach the menu to the toplevel widget to make it the default menu bar.
# We also make use of the <<MenuSelect>> virtual event, which gets fired when any menu or
# its entries are selected.
# The <<MenuSelect>> virtual event will display a message in the message label,
# which indicates that a particular entry has been selected.

# Attach the menu to the toplevel menu
. configure -menu .menu

#  Bind  global tags
bind Menu <<MenuSelect>> {
    global message
    if {[catch {%W entrycget active -label} label]} {
	set label "    "
    }
    set message "You have selected $label..."
}