bitbake: taskexp_ncurses: ncurses version of taskexp.py

* Create an ncurses version of the GTK app "taskexp.py".
* Add these additional features:
  - Sort tasks in recipes by their dependency order
  - Print individual and/or recipe-wide dependencies to a file
  - Add a wild card filter
  - Show the target recipes on BOLD
* Provide a GUI self test
* Provide a non-ncurses self test for ptest

(Bitbake rev: f49bec66ad51c8cddeceafbbe2445c46e396ee8b)

Signed-off-by: David Reyna <David.Reyna@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 1511 insertions, 0 deletions

diff --git a/bitbake/lib/bb/ui/taskexp_ncurses.py b/bitbake/lib/bb/ui/taskexp_ncurses.py
new file mode 100755
index 0000000000..dd91d26bc3
--- /dev/null
+++ b/bitbake/lib/bb/ui/taskexp_ncurses.py
@@ -0,0 +1,1511 @@
+#
+# BitBake Graphical ncurses-based Dependency Explorer
+#   * Based on the GTK implementation
+#   * Intended to run on any Linux host
+#
+# Copyright (C) 2007        Ross Burton
+# Copyright (C) 2007 - 2008 Richard Purdie
+# Copyright (C) 2022 - 2024 David Reyna
+#
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+#
+# Execution example:
+#   $ bitbake -g -u taskexp_ncurses.py acl zlib
+#
+# Self-test example (executes a script of GUI actions):
+#   $ TASK_EXP_UNIT_TEST=1 bitbake -g -u taskexp_ncurses zlib acl
+#   ...
+#   $ echo $?
+#   0
+#   $ TASK_EXP_UNIT_TEST=1 bitbake -g -u taskexp_ncurses zlib acl foo
+#   ERROR: Nothing PROVIDES 'foo'. Close matches:
+#   ofono
+#   $ echo $?
+#   1
+#
+# Self-test with no terminal example (only tests dependency fetch from bitbake):
+#   $ TASK_EXP_UNIT_TEST_NOTERM=1 bitbake -g -u taskexp_ncurses quilt
+#   $ echo $?
+#   0
+#
+# Features:
+# * Ncurses is used for the presentation layer. Only the 'curses'
+#   library is used (none of the extension libraries), plus only
+#   one main screen is used (no sub-windows)
+# * Uses the 'generateDepTreeEvent' bitbake event to fetch the
+#   dynamic dependency data based on passed recipes
+# * Computes and provides reverse dependencies
+# * Supports task sorting on:
+#   (a) Task dependency order within each recipe
+#   (b) Pure alphabetical order
+#   (c) Provisions for third sort order (bitbake order?)
+# * The 'Filter' does a "*string*" wildcard filter on tasks in the
+#   main window, dynamically re-ordering and re-centering the content
+# * A 'Print' function exports the selected task or its whole recipe
+#   task set to the default file "taskdep.txt"
+# * Supports a progress bar for bitbake loads and file printing
+# * Line art for box drawing supported, ASCII art an alernative
+# * No horizontal scrolling support. Selected task's full name
+#   shown in bottom bar
+# * Dynamically catches terminals that are (or become) too small
+# * Exception to insure return to normal terminal on errors
+# * Debugging support, self test option
+#
+
+import sys
+import traceback
+import curses
+import re
+import time
+
+# Bitbake server support
+import threading
+from xmlrpc import client
+import bb
+import bb.event
+
+# Dependency indexes (depends_model)
+(TYPE_DEP, TYPE_RDEP) = (0, 1)
+DEPENDS_TYPE = 0
+DEPENDS_TASK = 1
+DEPENDS_DEPS = 2
+# Task indexes (task_list)
+TASK_NAME = 0
+TASK_PRIMARY = 1
+TASK_SORT_ALPHA = 2
+TASK_SORT_DEPS = 3
+TASK_SORT_BITBAKE = 4
+# Sort options (default is SORT_DEPS)
+SORT_ALPHA = 0
+SORT_DEPS = 1
+SORT_BITBAKE_ENABLE = False # NOTE: future sort
+SORT_BITBAKE = 2
+sort_model = SORT_DEPS
+# Print options
+PRINT_MODEL_1 = 0
+PRINT_MODEL_2 = 1
+print_model = PRINT_MODEL_2
+print_file_name = "taskdep_print.log"
+print_file_backup_name = "taskdep_print_backup.log"
+is_printed = False
+is_filter = False
+
+# Standard (and backup) key mappings
+CHAR_NUL = 0            # Used as self-test nop char
+CHAR_BS_H = 8           # Alternate backspace key
+CHAR_TAB = 9
+CHAR_RETURN = 10
+CHAR_ESCAPE = 27
+CHAR_UP = ord('{')      # Used as self-test ASCII char
+CHAR_DOWN = ord('}')    # Used as self-test ASCII char
+
+# Color_pair IDs
+CURSES_NORMAL = 0
+CURSES_HIGHLIGHT = 1
+CURSES_WARNING = 2
+
+
+#################################################
+### Debugging support
+###
+
+verbose = False
+
+# Debug: message display slow-step through display update issues
+def alert(msg,screen):
+    if msg:
+        screen.addstr(0, 10, '[%-4s]' % msg)
+        screen.refresh();
+        curses.napms(2000)
+    else:
+        if do_line_art:
+            for i in range(10, 24):
+                screen.addch(0, i, curses.ACS_HLINE)
+        else:
+            screen.addstr(0, 10, '-' * 14)
+        screen.refresh();
+
+# Debug: display edge conditions on frame movements
+def debug_frame(nbox_ojb):
+    if verbose:
+        nbox_ojb.screen.addstr(0, 50, '[I=%2d,O=%2d,S=%3s,H=%2d,M=%4d]' % (
+            nbox_ojb.cursor_index,
+            nbox_ojb.cursor_offset,
+            nbox_ojb.scroll_offset,
+            nbox_ojb.inside_height,
+            len(nbox_ojb.task_list),
+        ))
+        nbox_ojb.screen.refresh();
+
+#
+# Unit test (assumes that 'quilt-native' is always present)
+#
+
+unit_test = os.environ.get('TASK_EXP_UNIT_TEST')
+unit_test_cmnds=[
+    '# Default selected task in primary box',
+    'tst_selected=<TASK>.do_recipe_qa',
+    '# Default selected task in deps',
+    'tst_entry=<TAB>',
+    'tst_selected=',
+    '# Default selected task in rdeps',
+    'tst_entry=<TAB>',
+    'tst_selected=<TASK>.do_fetch',
+    "# Test 'select' back to primary box",
+    'tst_entry=<CR>',
+    '#tst_entry=<DOWN>',  # optional injected error
+    'tst_selected=<TASK>.do_fetch',
+    '# Check filter',
+    'tst_entry=/uilt-nativ/',
+    'tst_selected=quilt-native.do_recipe_qa',
+    '# Check print',
+    'tst_entry=p',
+    'tst_printed=quilt-native.do_fetch',
+    '#tst_printed=quilt-foo.do_nothing',  # optional injected error
+    '# Done!',
+    'tst_entry=q',
+]
+unit_test_idx=0
+unit_test_command_chars=''
+unit_test_results=[]
+def unit_test_action(active_package):
+    global unit_test_idx
+    global unit_test_command_chars
+    global unit_test_results
+    ret = CHAR_NUL
+    if unit_test_command_chars:
+        ch = unit_test_command_chars[0]
+        unit_test_command_chars = unit_test_command_chars[1:]
+        time.sleep(0.5)
+        ret = ord(ch)
+    else:
+        line = unit_test_cmnds[unit_test_idx]
+        unit_test_idx += 1
+        line = re.sub('#.*', '', line).strip()
+        line = line.replace('<TASK>',active_package.primary[0])
+        line = line.replace('<TAB>','\t').replace('<CR>','\n')
+        line = line.replace('<UP>','{').replace('<DOWN>','}')
+        if not line: line = 'nop=nop'
+        cmnd,value = line.split('=')
+        if cmnd == 'tst_entry':
+            unit_test_command_chars = value
+        elif cmnd == 'tst_selected':
+            active_selected = active_package.get_selected()
+            if active_selected != value:
+                unit_test_results.append("ERROR:SELFTEST:expected '%s' but got '%s' (NOTE:bitbake may have changed)" % (value,active_selected))
+                ret = ord('Q')
+            else:
+                unit_test_results.append("Pass:SELFTEST:found '%s'" % (value))
+        elif cmnd == 'tst_printed':
+            result = os.system('grep %s %s' % (value,print_file_name))
+            if result:
+                unit_test_results.append("ERROR:PRINTTEST:expected '%s' in '%s'" % (value,print_file_name))
+                ret = ord('Q')
+            else:
+                unit_test_results.append("Pass:PRINTTEST:found '%s'" % (value))
+    # Return the action (CHAR_NUL for no action til next round)
+    return(ret)
+
+# Unit test without an interative terminal (e.g. ptest)
+unit_test_noterm = os.environ.get('TASK_EXP_UNIT_TEST_NOTERM')
+
+
+#################################################
+### Window frame rendering
+###
+### By default, use the normal line art. Since
+###  these extended characters are not ASCII, one
+###  must use the ncursus API to render them
+### The alternate ASCII line art set is optionally
+###  available via the 'do_line_art' flag
+
+# By default, render frames using line art
+do_line_art = True
+
+# ASCII render set option
+CHAR_HBAR = '-'
+CHAR_VBAR = '|'
+CHAR_UL_CORNER = '/'
+CHAR_UR_CORNER = '\\'
+CHAR_LL_CORNER = '\\'
+CHAR_LR_CORNER = '/'
+
+# Box frame drawing with line-art
+def line_art_frame(box):
+    x = box.base_x
+    y = box.base_y
+    w = box.width
+    h = box.height + 1
+
+    if do_line_art:
+        for i in range(1, w - 1):
+            box.screen.addch(y, x + i, curses.ACS_HLINE, box.color)
+            box.screen.addch(y + h - 1, x + i, curses.ACS_HLINE, box.color)
+        body_line = "%s" % (' ' * (w - 2))
+        for i in range(1, h - 1):
+            box.screen.addch(y + i, x, curses.ACS_VLINE, box.color)
+            box.screen.addstr(y + i, x + 1, body_line, box.color)
+            box.screen.addch(y + i, x + w - 1, curses.ACS_VLINE, box.color)
+        box.screen.addch(y, x, curses.ACS_ULCORNER, box.color)
+        box.screen.addch(y, x + w - 1, curses.ACS_URCORNER, box.color)
+        box.screen.addch(y + h - 1, x, curses.ACS_LLCORNER, box.color)
+        box.screen.addch(y + h - 1, x + w - 1, curses.ACS_LRCORNER, box.color)
+    else:
+        top_line  = "%s%s%s" % (CHAR_UL_CORNER,CHAR_HBAR * (w - 2),CHAR_UR_CORNER)
+        body_line = "%s%s%s" % (CHAR_VBAR,' ' * (w - 2),CHAR_VBAR)
+        bot_line  = "%s%s%s" % (CHAR_UR_CORNER,CHAR_HBAR * (w - 2),CHAR_UL_CORNER)
+        tag_line  = "%s%s%s" % ('[',CHAR_HBAR * (w - 2),']')
+        # Top bar
+        box.screen.addstr(y, x, top_line)
+        # Middle frame
+        for i in range(1, (h - 1)):
+            box.screen.addstr(y+i, x, body_line)
+        # Bottom bar
+        box.screen.addstr(y + (h - 1), x, bot_line)
+
+# Connect the separate boxes
+def line_art_fixup(box):
+    if do_line_art:
+        box.screen.addch(box.base_y+2, box.base_x, curses.ACS_LTEE, box.color)
+        box.screen.addch(box.base_y+2, box.base_x+box.width-1, curses.ACS_RTEE, box.color)
+
+
+#################################################
+### Ncurses box object : box frame object to display
+### and manage a sub-window's display elements
+### using basic ncurses
+###
+### Supports:
+###   * Frame drawing, content (re)drawing
+###   * Content scrolling via ArrowUp, ArrowDn, PgUp, PgDN,
+###   * Highlighting for active selected item
+###   * Content sorting based on selected sort model
+###
+
+class NBox():
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        # Box description
+        self.screen = screen
+        self.label = label
+        self.primary = primary
+        self.color = curses.color_pair(CURSES_NORMAL) if screen else None
+        # Box boundaries
+        self.base_x = base_x
+        self.base_y = base_y
+        self.width = width
+        self.height = height
+        # Cursor/scroll management
+        self.cursor_enable = False
+        self.cursor_index = 0   # Absolute offset
+        self.cursor_offset = 0  # Frame centric offset
+        self.scroll_offset = 0  # Frame centric offset
+        # Box specific content
+        # Format of each entry is [package_name,is_primary_recipe,alpha_sort_key,deps_sort_key]
+        self.task_list = []
+
+    @property
+    def inside_width(self):
+        return(self.width-2)
+
+    @property
+    def inside_height(self):
+        return(self.height-2)
+
+    # Populate the box's content, include the sort mappings and is_primary flag
+    def task_list_append(self,task_name,dep):
+        task_sort_alpha = task_name
+        task_sort_deps = dep.get_dep_sort(task_name)
+        is_primary = False
+        for primary in self.primary:
+            if task_name.startswith(primary+'.'):
+                is_primary = True
+        if SORT_BITBAKE_ENABLE:
+            task_sort_bitbake = dep.get_bb_sort(task_name)
+            self.task_list.append([task_name,is_primary,task_sort_alpha,task_sort_deps,task_sort_bitbake])
+        else:
+            self.task_list.append([task_name,is_primary,task_sort_alpha,task_sort_deps])
+
+    def reset(self):
+        self.task_list = []
+        self.cursor_index = 0   # Absolute offset
+        self.cursor_offset = 0  # Frame centric offset
+        self.scroll_offset = 0  # Frame centric offset
+
+    # Sort the box's content based on the current sort model
+    def sort(self):
+        if SORT_ALPHA == sort_model:
+            self.task_list.sort(key = lambda x: x[TASK_SORT_ALPHA])
+        elif SORT_DEPS == sort_model:
+            self.task_list.sort(key = lambda x: x[TASK_SORT_DEPS])
+        elif SORT_BITBAKE == sort_model:
+            self.task_list.sort(key = lambda x: x[TASK_SORT_BITBAKE])
+
+    # The target package list (to hightlight), from the command line
+    def set_primary(self,primary):
+        self.primary = primary
+
+    # Draw the box's outside frame
+    def draw_frame(self):
+        line_art_frame(self)
+        # Title
+        self.screen.addstr(self.base_y,
+            (self.base_x + (self.width//2))-((len(self.label)+2)//2),
+            '['+self.label+']')
+        self.screen.refresh()
+
+    # Draw the box's inside text content
+    def redraw(self):
+        task_list_len = len(self.task_list)
+        # Middle frame
+        body_line = "%s" % (' ' * (self.inside_width-1) )
+        for i in range(0,self.inside_height+1):
+            if i < (task_list_len + self.scroll_offset):
+                str_ctl = "%%-%ss" % (self.width-3)
+                # Safety assert
+                if (i + self.scroll_offset) >= task_list_len:
+                    alert("REDRAW:%2d,%4d,%4d" % (i,self.scroll_offset,task_list_len),self.screen)
+                    break
+
+                task_obj = self.task_list[i + self.scroll_offset]
+                task = task_obj[TASK_NAME][:self.inside_width-1]
+                task_primary = task_obj[TASK_PRIMARY]
+
+                if task_primary:
+                    line = str_ctl % task[:self.inside_width-1]
+                    self.screen.addstr(self.base_y+1+i, self.base_x+2, line, curses.A_BOLD)
+                else:
+                    line = str_ctl % task[:self.inside_width-1]
+                    self.screen.addstr(self.base_y+1+i, self.base_x+2, line)
+            else:
+                line = "%s" % (' ' * (self.inside_width-1) )
+                self.screen.addstr(self.base_y+1+i, self.base_x+2, line)
+        self.screen.refresh()
+
+    # Show the current selected task over the bottom of the frame
+    def show_selected(self,selected_task):
+        if not selected_task:
+            selected_task = self.get_selected()
+        tag_line   = "%s%s%s" % ('[',CHAR_HBAR * (self.width-2),']')
+        self.screen.addstr(self.base_y + self.height, self.base_x, tag_line)
+        self.screen.addstr(self.base_y + self.height,
+            (self.base_x + (self.width//2))-((len(selected_task)+2)//2),
+            '['+selected_task+']')
+        self.screen.refresh()
+
+    # Load box with new table of content
+    def update_content(self,task_list):
+        self.task_list = task_list
+        if self.cursor_enable:
+            cursor_update(turn_on=False)
+        self.cursor_index = 0
+        self.cursor_offset = 0
+        self.scroll_offset = 0
+        self.redraw()
+        if self.cursor_enable:
+            cursor_update(turn_on=True)
+
+    # Manage the box's highlighted task and blinking cursor character
+    def cursor_on(self,is_on):
+        self.cursor_enable = is_on
+        self.cursor_update(is_on)
+
+    # High-light the current pointed package, normal for released packages
+    def cursor_update(self,turn_on=True):
+        str_ctl = "%%-%ss" % (self.inside_width-1)
+        try:
+            if len(self.task_list):
+                task_obj = self.task_list[self.cursor_index]
+                task = task_obj[TASK_NAME][:self.inside_width-1]
+                task_primary = task_obj[TASK_PRIMARY]
+                task_font = curses.A_BOLD if task_primary else 0
+            else:
+                task = ''
+                task_font = 0
+        except Exception as e:
+            alert("CURSOR_UPDATE:%s" % (e),self.screen)
+            return
+        if turn_on:
+            self.screen.addstr(self.base_y+1+self.cursor_offset,self.base_x+1,">", curses.color_pair(CURSES_HIGHLIGHT) | curses.A_BLINK)
+            self.screen.addstr(self.base_y+1+self.cursor_offset,self.base_x+2,str_ctl % task, curses.color_pair(CURSES_HIGHLIGHT) | task_font)
+        else:
+            self.screen.addstr(self.base_y+1+self.cursor_offset,self.base_x+1," ")
+            self.screen.addstr(self.base_y+1+self.cursor_offset,self.base_x+2,str_ctl % task, task_font)
+
+    # Down arrow
+    def line_down(self):
+        if len(self.task_list) <= (self.cursor_index+1):
+            return
+        self.cursor_update(turn_on=False)
+        self.cursor_index += 1
+        self.cursor_offset += 1
+        if self.cursor_offset > (self.inside_height):
+            self.cursor_offset -= 1
+            self.scroll_offset += 1
+            self.redraw()
+        self.cursor_update(turn_on=True)
+        debug_frame(self)
+
+    # Up arrow
+    def line_up(self):
+        if 0 > (self.cursor_index-1):
+            return
+        self.cursor_update(turn_on=False)
+        self.cursor_index -= 1
+        self.cursor_offset -= 1
+        if self.cursor_offset < 0:
+            self.cursor_offset += 1
+            self.scroll_offset -= 1
+            self.redraw()
+        self.cursor_update(turn_on=True)
+        debug_frame(self)
+
+    # Page down
+    def page_down(self):
+        max_task = len(self.task_list)-1
+        if max_task < self.inside_height:
+            return
+        self.cursor_update(turn_on=False)
+        self.cursor_index += 10
+        self.cursor_index = min(self.cursor_index,max_task)
+        self.cursor_offset = min(self.inside_height,self.cursor_index)
+        self.scroll_offset = self.cursor_index - self.cursor_offset
+        self.redraw()
+        self.cursor_update(turn_on=True)
+        debug_frame(self)
+
+    # Page up
+    def page_up(self):
+        max_task = len(self.task_list)-1
+        if max_task < self.inside_height:
+            return
+        self.cursor_update(turn_on=False)
+        self.cursor_index -= 10
+        self.cursor_index = max(self.cursor_index,0)
+        self.cursor_offset = max(0, self.inside_height - (max_task - self.cursor_index))
+        self.scroll_offset = self.cursor_index - self.cursor_offset
+        self.redraw()
+        self.cursor_update(turn_on=True)
+        debug_frame(self)
+
+    # Return the currently selected task name for this box
+    def get_selected(self):
+        if self.task_list:
+            return(self.task_list[self.cursor_index][TASK_NAME])
+        else:
+            return('')
+
+#################################################
+### The helper sub-windows
+###
+
+# Show persistent help at the top of the screen
+class HelpBarView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(HelpBarView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+
+    def show_help(self,show):
+        self.screen.addstr(self.base_y,self.base_x, "%s" % (' ' * self.inside_width))
+        if show:
+            help = "Help='?' Filter='/' NextBox=<Tab> Select=<Enter> Print='p','P' Quit='q'"
+            bar_size = self.inside_width - 5 - len(help)
+            self.screen.addstr(self.base_y,self.base_x+((self.inside_width-len(help))//2), help)
+        self.screen.refresh()
+
+# Pop up a detailed Help box
+class HelpBoxView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height, dep):
+        super(HelpBoxView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+        self.x_pos = 0
+        self.y_pos = 0
+        self.dep = dep
+
+    # Instantial the pop-up help box
+    def show_help(self,show):
+        self.x_pos = self.base_x + 4
+        self.y_pos = self.base_y + 2
+
+        def add_line(line):
+            if line:
+                self.screen.addstr(self.y_pos,self.x_pos,line)
+            self.y_pos += 1
+
+        # Gather some statisics
+        dep_count = 0
+        rdep_count = 0
+        for task_obj in self.dep.depends_model:
+            if TYPE_DEP == task_obj[DEPENDS_TYPE]:
+                dep_count += 1
+            elif TYPE_RDEP == task_obj[DEPENDS_TYPE]:
+                rdep_count += 1
+
+        self.draw_frame()
+        line_art_fixup(self.dep)
+        add_line("Quit                : 'q' ")
+        add_line("Filter task names   : '/'")
+        add_line("Tab to next box     : <Tab>")
+        add_line("Select a task       : <Enter>")
+        add_line("Print task's deps   : 'p'")
+        add_line("Print recipe's deps : 'P'")
+        add_line(" -> '%s'" % print_file_name)
+        add_line("Sort toggle         : 's'")
+        add_line(" %s Recipe inner-depends order" % ('->' if (SORT_DEPS == sort_model) else '- '))
+        add_line(" %s Alpha-numeric order" % ('->' if (SORT_ALPHA == sort_model) else '- '))
+        if SORT_BITBAKE_ENABLE:
+            add_line(" %s Bitbake order" % ('->' if (TASK_SORT_BITBAKE == sort_model) else '- '))
+        add_line("Alternate backspace : <CTRL-H>")
+        add_line("")
+        add_line("Primary recipes = %s"  % ','.join(self.primary))
+        add_line("Task  count     = %4d" % len(self.dep.pkg_model))
+        add_line("Deps  count     = %4d" % dep_count)
+        add_line("RDeps count     = %4d" % rdep_count)
+        add_line("")
+        self.screen.addstr(self.y_pos,self.x_pos+7,"<Press any key>", curses.color_pair(CURSES_HIGHLIGHT))
+        self.screen.refresh()
+        c = self.screen.getch()
+
+# Show a progress bar
+class ProgressView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(ProgressView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+
+    def progress(self,title,current,max):
+        if title:
+            self.label = title
+        else:
+            title = self.label
+        if max <=0: max = 10
+        bar_size = self.width - 7 - len(title)
+        bar_done = int( (float(current)/float(max)) * float(bar_size) )
+        self.screen.addstr(self.base_y,self.base_x, " %s:[%s%s]" % (title,'*' * bar_done,' ' * (bar_size-bar_done)))
+        self.screen.refresh()
+        return(current+1)
+
+    def clear(self):
+        self.screen.addstr(self.base_y,self.base_x, "%s" % (' ' * self.width))
+        self.screen.refresh()
+
+# Implement a task filter bar
+class FilterView(NBox):
+    SEARCH_NOP = 0
+    SEARCH_GO = 1
+    SEARCH_CANCEL = 2
+
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(FilterView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+        self.do_show = False
+        self.filter_str = ""
+
+    def clear(self,enable_show=True):
+        self.filter_str = ""
+
+    def show(self,enable_show=True):
+        self.do_show = enable_show
+        if self.do_show:
+            self.screen.addstr(self.base_y,self.base_x, "[ Filter: %-25s ]      '/'=cancel, format='abc'       " % self.filter_str[0:25])
+        else:
+            self.screen.addstr(self.base_y,self.base_x, "%s" % (' ' * self.width))
+        self.screen.refresh()
+
+    def show_prompt(self):
+        self.screen.addstr(self.base_y,self.base_x + 10 + len(self.filter_str), " ")
+        self.screen.addstr(self.base_y,self.base_x + 10 + len(self.filter_str), "")
+
+    # Keys specific to the filter box (start/stop filter keys are in the main loop)
+    def input(self,c,ch):
+        ret = self.SEARCH_GO
+        if c in (curses.KEY_BACKSPACE,CHAR_BS_H):
+            #  Backspace
+            if self.filter_str:
+                self.filter_str = self.filter_str[0:-1]
+                self.show()
+        elif ((ch >= 'a') and (ch <= 'z')) or ((ch >= 'A') and (ch <= 'Z')) or ((ch >= '0') and (ch <= '9')) or (ch in (' ','_','.','-')):
+            # The isalnum() acts strangly with keypad(True), so explicit bounds
+            self.filter_str += ch
+            self.show()
+        else:
+            ret = self.SEARCH_NOP
+        return(ret)
+
+
+#################################################
+### The primary dependency windows
+###
+
+# The main list of package tasks
+class PackageView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(PackageView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+
+    # Find and verticaly center a selected task (from filter or from dependent box)
+    # The 'task_filter_str' can be a full or a partial (filter) task name
+    def find(self,task_filter_str):
+        found = False
+        max = self.height-2
+        if not task_filter_str:
+            return(found)
+        for i,task_obj in enumerate(self.task_list):
+            task = task_obj[TASK_NAME]
+            if task.startswith(task_filter_str):
+                self.cursor_on(False)
+                self.cursor_index = i
+
+                # Position selected at vertical center
+                vcenter = self.inside_height // 2
+                if self.cursor_index <= vcenter:
+                    self.scroll_offset = 0
+                    self.cursor_offset = self.cursor_index
+                elif self.cursor_index >= (len(self.task_list) - vcenter - 1):
+                    self.cursor_offset = self.inside_height-1
+                    self.scroll_offset = self.cursor_index - self.cursor_offset
+                else:
+                    self.cursor_offset = vcenter
+                    self.scroll_offset = self.cursor_index - self.cursor_offset
+
+                self.redraw()
+                self.cursor_on(True)
+                found = True
+                break
+        return(found)
+
+# The view of dependent packages
+class PackageDepView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(PackageDepView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+
+# The view of reverse-dependent packages
+class PackageReverseDepView(NBox):
+    def __init__(self, screen, label, primary, base_x, base_y, width, height):
+        super(PackageReverseDepView, self).__init__(screen, label, primary, base_x, base_y, width, height)
+
+
+#################################################
+### DepExplorer : The parent frame and object
+###
+
+class DepExplorer(NBox):
+    def __init__(self,screen):
+        title = "Task Dependency Explorer"
+        super(DepExplorer, self).__init__(screen, 'Task Dependency Explorer','',0,0,80,23)
+
+        self.screen = screen
+        self.pkg_model = []
+        self.depends_model = []
+        self.dep_sort_map = {}
+        self.bb_sort_map = {}
+        self.filter_str = ''
+        self.filter_prev = 'deadbeef'
+
+        if self.screen:
+            self.help_bar_view = HelpBarView(screen, "Help",'',1,1,79,1)
+            self.help_box_view = HelpBoxView(screen, "Help",'',0,2,40,20,self)
+            self.progress_view = ProgressView(screen, "Progress",'',2,1,76,1)
+            self.filter_view = FilterView(screen, "Filter",'',2,1,76,1)
+            self.package_view = PackageView(screen, "Package",'alpha', 0,2,40,20)
+            self.dep_view = PackageDepView(screen, "Dependencies",'beta',40,2,40,10)
+            self.reverse_view = PackageReverseDepView(screen, "Dependent Tasks",'gamma',40,13,40,9)
+            self.draw_frames()
+
+    # Draw this main window's frame and all sub-windows
+    def draw_frames(self):
+        self.draw_frame()
+        self.package_view.draw_frame()
+        self.dep_view.draw_frame()
+        self.reverse_view.draw_frame()
+        if is_filter:
+            self.filter_view.show(True)
+            self.filter_view.show_prompt()
+        else:
+            self.help_bar_view.show_help(True)
+        self.package_view.redraw()
+        self.dep_view.redraw()
+        self.reverse_view.redraw()
+        self.show_selected(self.package_view.get_selected())
+        line_art_fixup(self)
+
+    # Parse the bitbake dependency event object
+    def parse(self, depgraph):
+        for task in depgraph["tdepends"]:
+            self.pkg_model.insert(0, task)
+            for depend in depgraph["tdepends"][task]:
+                self.depends_model.insert (0, (TYPE_DEP, task, depend))
+                self.depends_model.insert (0, (TYPE_RDEP, depend, task))
+        if self.screen:
+            self.dep_sort_prep()
+
+    # Prepare the dependency sort order keys
+    # This method creates sort keys per recipe tasks in
+    # the order of each recipe's internal dependecies
+    # Method:
+    #   Filter the tasks in dep order in dep_sort_map = {}
+    #   (a) Find a task that has no dependecies
+    #       Ignore non-recipe specific tasks
+    #   (b) Add it to the sort mapping dict with
+    #       key of "<task_group>_<order>"
+    #   (c) Remove it as a dependency from the other tasks
+    #   (d) Repeat till all tasks are mapped
+    # Use placeholders to insure each sub-dict is instantiated
+    def dep_sort_prep(self):
+        self.progress_view.progress('DepSort',0,4)
+        # Init the task base entries
+        self.progress_view.progress('DepSort',1,4)
+        dep_table = {}
+        bb_index = 0
+        for task in self.pkg_model:
+            # First define the incoming bitbake sort order
+            self.bb_sort_map[task] = "%04d" % (bb_index)
+            bb_index += 1
+            task_group = task[0:task.find('.')]
+            if task_group not in dep_table:
+                dep_table[task_group] = {}
+                dep_table[task_group]['-'] = {}         # Placeholder
+            if task not in dep_table[task_group]:
+                dep_table[task_group][task] = {}
+                dep_table[task_group][task]['-'] = {}   # Placeholder
+        # Add the task dependecy entries
+        self.progress_view.progress('DepSort',2,4)
+        for task_obj in self.depends_model:
+            if task_obj[DEPENDS_TYPE] != TYPE_DEP:
+                continue
+            task = task_obj[DEPENDS_TASK]
+            task_dep = task_obj[DEPENDS_DEPS]
+            task_group = task[0:task.find('.')]
+            # Only track depends within same group
+            if task_dep.startswith(task_group+'.'):
+                dep_table[task_group][task][task_dep] = 1
+        self.progress_view.progress('DepSort',3,4)
+        for task_group in dep_table:
+            dep_index = 0
+            # Whittle down the tasks of each group
+            this_pass = 1
+            do_loop = True
+            while (len(dep_table[task_group]) > 1) and do_loop:
+                this_pass += 1
+                is_change = False
+                delete_list = []
+                for task in dep_table[task_group]:
+                    if '-' == task:
+                        continue
+                    if 1 == len(dep_table[task_group][task]):
+                        is_change = True
+                        # No more deps, so collect this task...
+                        self.dep_sort_map[task] = "%s_%04d" % (task_group,dep_index)
+                        dep_index += 1
+                        # ... remove it from other lists as resolved ...
+                        for dep_task in dep_table[task_group]:
+                            if task in dep_table[task_group][dep_task]:
+                                del dep_table[task_group][dep_task][task]
+                        # ... and remove it from from the task group
+                        delete_list.append(task)
+                for task in delete_list:
+                    del dep_table[task_group][task]
+                if not is_change:
+                    alert("ERROR:DEP_SIEVE_NO_CHANGE:%s" % task_group,self.screen)
+                    do_loop = False
+                    continue
+        self.progress_view.progress('',4,4)
+        self.progress_view.clear()
+        self.help_bar_view.show_help(True)
+        if len(self.dep_sort_map) != len(self.pkg_model):
+            alert("ErrorDepSort:%d/%d" % (len(self.dep_sort_map),len(self.pkg_model)),self.screen)
+
+    # Look up a dep sort order key
+    def get_dep_sort(self,key):
+        if key in self.dep_sort_map:
+            return(self.dep_sort_map[key])
+        else:
+            return(key)
+
+    # Look up a bitbake sort order key
+    def get_bb_sort(self,key):
+        if key in self.bb_sort_map:
+            return(self.bb_sort_map[key])
+        else:
+            return(key)
+
+    # Find the selected package in the main frame, update the dependency frames content accordingly
+    def select(self, package_name, only_update_dependents=False):
+        if not package_name:
+            package_name = self.package_view.get_selected()
+        # alert("SELECT:%s:" % package_name,self.screen)
+
+        if self.filter_str != self.filter_prev:
+            self.package_view.cursor_on(False)
+            # Fill of the main package task list using new filter
+            self.package_view.task_list = []
+            for package in self.pkg_model:
+                if self.filter_str:
+                    if self.filter_str in package:
+                        self.package_view.task_list_append(package,self)
+                else:
+                    self.package_view.task_list_append(package,self)
+            self.package_view.sort()
+            self.filter_prev = self.filter_str
+
+            # Old position is lost, assert new position of previous task (if still filtered in)
+            self.package_view.cursor_index = 0
+            self.package_view.cursor_offset = 0
+            self.package_view.scroll_offset = 0
+            self.package_view.redraw()
+            self.package_view.cursor_on(True)
+
+        # Make sure the selected package is in view, with implicit redraw()
+        if (not only_update_dependents):
+            self.package_view.find(package_name)
+        # In case selected name change (i.e. filter removed previous)
+        package_name = self.package_view.get_selected()
+
+        # Filter the package's dependent list to the dependent view
+        self.dep_view.reset()
+        for package_def in self.depends_model:
+            if (package_def[DEPENDS_TYPE] == TYPE_DEP) and (package_def[DEPENDS_TASK] == package_name):
+                self.dep_view.task_list_append(package_def[DEPENDS_DEPS],self)
+        self.dep_view.sort()
+        self.dep_view.redraw()
+        # Filter the package's dependent list to the reverse dependent view
+        self.reverse_view.reset()
+        for package_def in self.depends_model:
+            if (package_def[DEPENDS_TYPE] == TYPE_RDEP) and (package_def[DEPENDS_TASK] == package_name):
+                self.reverse_view.task_list_append(package_def[DEPENDS_DEPS],self)
+        self.reverse_view.sort()
+        self.reverse_view.redraw()
+        self.show_selected(package_name)
+        self.screen.refresh()
+
+    # The print-to-file method
+    def print_deps(self,whole_group=False):
+        global is_printed
+        # Print the selected deptree(s) to a file
+        if not is_printed:
+            try:
+                # Move to backup any exiting file before first write
+                if os.path.isfile(print_file_name):
+                    os.system('mv -f %s %s' % (print_file_name,print_file_backup_name))
+            except Exception as e:
+                alert(e,self.screen)
+                alert('',self.screen)
+        print_list = []
+        selected_task = self.package_view.get_selected()
+        if not selected_task:
+            return
+        if not whole_group:
+            print_list.append(selected_task)
+        else:
+            # Use the presorted task_group order from 'package_view'
+            task_group = selected_task[0:selected_task.find('.')+1]
+            for task_obj in self.package_view.task_list:
+                task = task_obj[TASK_NAME]
+                if task.startswith(task_group):
+                    print_list.append(task)
+        with open(print_file_name, "a") as fd:
+            print_max = len(print_list)
+            print_count = 1
+            self.progress_view.progress('Write "%s"' % print_file_name,0,print_max)
+            for task in print_list:
+                print_count = self.progress_view.progress('',print_count,print_max)
+                self.select(task)
+                self.screen.refresh();
+                # Utilize the current print output model
+                if print_model == PRINT_MODEL_1:
+                    print("=== Dependendency Snapshot ===",file=fd)
+                    print(" = Package =",file=fd)
+                    print('   '+task,file=fd)
+                    # Fill in the matching dependencies
+                    print(" = Dependencies =",file=fd)
+                    for task_obj in self.dep_view.task_list:
+                        print('   '+ task_obj[TASK_NAME],file=fd)
+                    print(" = Dependent Tasks =",file=fd)
+                    for task_obj in self.reverse_view.task_list:
+                        print('   '+ task_obj[TASK_NAME],file=fd)
+                if print_model == PRINT_MODEL_2:
+                    print("=== Dependendency Snapshot ===",file=fd)
+                    dep_count = len(self.dep_view.task_list) - 1
+                    for i,task_obj in enumerate(self.dep_view.task_list):
+                        print('%s%s' % ("Dep    =" if (i==dep_count) else "        ",task_obj[TASK_NAME]),file=fd)
+                    if not self.dep_view.task_list:
+                        print('Dep    =',file=fd)
+                    print("Package=%s" % task,file=fd)
+                    for i,task_obj in enumerate(self.reverse_view.task_list):
+                        print('%s%s' % ("RDep   =" if (i==0) else "        ",task_obj[TASK_NAME]),file=fd)
+                    if not self.reverse_view.task_list:
+                        print('RDep   =',file=fd)
+                curses.napms(2000)
+                self.progress_view.clear()
+                self.help_bar_view.show_help(True)
+            print('',file=fd)
+        # Restore display to original selected task
+        self.select(selected_task)
+        is_printed = True
+
+#################################################
+### Load bitbake data
+###
+
+def bitbake_load(server, eventHandler, params, dep, curses_off, screen):
+    global bar_len_old
+    bar_len_old = 0
+
+    # Support no screen
+    def progress(msg,count,max):
+        global bar_len_old
+        if screen:
+            dep.progress_view.progress(msg,count,max)
+        else:
+            if msg:
+                if bar_len_old:
+                    bar_len_old = 0
+                    print("\n")
+                print(f"{msg}: ({count} of {max})")
+            else:
+                bar_len = int((count*40)/max)
+                if bar_len_old != bar_len:
+                    print(f"{'*' * (bar_len-bar_len_old)}",end='',flush=True)
+                bar_len_old = bar_len
+    def clear():
+        if screen:
+            dep.progress_view.clear()
+    def clear_curses(screen):
+        if screen:
+            curses_off(screen)
+
+    #
+    # Trigger bitbake "generateDepTreeEvent"
+    #
+
+    cmdline = ''
+    try:
+        params.updateToServer(server, os.environ.copy())
+        params.updateFromServer(server)
+        cmdline = params.parseActions()
+        if not cmdline:
+            clear_curses(screen)
+            print("ERROR: nothing to do.  Use 'bitbake world' to build everything, or run 'bitbake --help' for usage information.")
+            return 1,cmdline
+        if 'msg' in cmdline and cmdline['msg']:
+            clear_curses(screen)
+            print('ERROR: ' + cmdline['msg'])
+            return 1,cmdline
+        cmdline = cmdline['action']
+        if not cmdline or cmdline[0] != "generateDotGraph":
+            clear_curses(screen)
+            print("ERROR: This UI requires the -g option")
+            return 1,cmdline
+        ret, error = server.runCommand(["generateDepTreeEvent", cmdline[1], cmdline[2]])
+        if error:
+            clear_curses(screen)
+            print("ERROR: running command '%s': %s" % (cmdline, error))
+            return 1,cmdline
+        elif not ret:
+            clear_curses(screen)
+            print("ERROR: running command '%s': returned %s" % (cmdline, ret))
+            return 1,cmdline
+    except client.Fault as x:
+        clear_curses(screen)
+        print("ERROR: XMLRPC Fault getting commandline:\n %s" % x)
+        return 1,cmdline
+    except Exception as e:
+        clear_curses(screen)
+        print("ERROR: in startup:\n %s" % traceback.format_exc())
+        return 1,cmdline
+
+    #
+    # Receive data from bitbake
+    #
+
+    progress_total = 0
+    load_bitbake = True
+    quit = False
+    try:
+        while load_bitbake:
+            try:
+                event = eventHandler.waitEvent(0.25)
+                if quit:
+                    _, error = server.runCommand(["stateForceShutdown"])
+                    clear_curses(screen)
+                    if error:
+                        print('Unable to cleanly stop: %s' % error)
+                    break
+
+                if event is None:
+                    continue
+
+                if isinstance(event, bb.event.CacheLoadStarted):
+                    progress_total = event.total
+                    progress('Loading Cache',0,progress_total)
+                    continue
+
+                if isinstance(event, bb.event.CacheLoadProgress):
+                    x = event.current
+                    progress('',x,progress_total)
+                    continue
+
+                if isinstance(event, bb.event.CacheLoadCompleted):
+                    clear()
+                    progress('Bitbake... ',1,2)
+                    continue
+
+                if isinstance(event, bb.event.ParseStarted):
+                    progress_total = event.total
+                    progress('Processing recipes',0,progress_total)
+                    if progress_total == 0:
+                        continue
+
+                if isinstance(event, bb.event.ParseProgress):
+                    x = event.current
+                    progress('',x,progress_total)
+                    continue
+
+                if isinstance(event, bb.event.ParseCompleted):
+                    progress('Generating dependency tree',0,3)
+                    continue
+
+                if isinstance(event, bb.event.DepTreeGenerated):
+                    progress('Generating dependency tree',1,3)
+                    dep.parse(event._depgraph)
+                    progress('Generating dependency tree',2,3)
+
+                if isinstance(event, bb.command.CommandCompleted):
+                    load_bitbake = False
+                    progress('Generating dependency tree',3,3)
+                    clear()
+                    if screen:
+                        dep.help_bar_view.show_help(True)
+                    continue
+
+                if isinstance(event, bb.event.NoProvider):
+                    clear_curses(screen)
+                    print('ERROR: %s' % event)
+
+                    _, error = server.runCommand(["stateShutdown"])
+                    if error:
+                        print('ERROR: Unable to cleanly shutdown: %s' % error)
+                    return 1,cmdline
+
+                if isinstance(event, bb.command.CommandFailed):
+                    clear_curses(screen)
+                    print('ERROR: ' + str(event))
+                    return event.exitcode,cmdline
+
+                if isinstance(event, bb.command.CommandExit):
+                    clear_curses(screen)
+                    return event.exitcode,cmdline
+
+                if isinstance(event, bb.cooker.CookerExit):
+                    break
+
+                continue
+            except EnvironmentError as ioerror:
+                # ignore interrupted io
+                if ioerror.args[0] == 4:
+                    pass
+            except KeyboardInterrupt:
+                if shutdown == 2:
+                    clear_curses(screen)
+                    print("\nThird Keyboard Interrupt, exit.\n")
+                    break
+                if shutdown == 1:
+                    clear_curses(screen)
+                    print("\nSecond Keyboard Interrupt, stopping...\n")
+                    _, error = server.runCommand(["stateForceShutdown"])
+                    if error:
+                        print('Unable to cleanly stop: %s' % error)
+                if shutdown == 0:
+                    clear_curses(screen)
+                    print("\nKeyboard Interrupt, closing down...\n")
+                    _, error = server.runCommand(["stateShutdown"])
+                    if error:
+                        print('Unable to cleanly shutdown: %s' % error)
+                shutdown = shutdown + 1
+                pass
+    except Exception as e:
+        # Safe exit on error
+        clear_curses(screen)
+        print("Exception : %s" % e)
+        print("Exception in startup:\n %s" % traceback.format_exc())
+
+    return 0,cmdline
+
+#################################################
+### main
+###
+
+SCREEN_COL_MIN = 83
+SCREEN_ROW_MIN = 26
+
+def main(server, eventHandler, params):
+    global verbose
+    global sort_model
+    global print_model
+    global is_printed
+    global is_filter
+    global screen_too_small
+
+    shutdown = 0
+    screen_too_small = False
+    quit = False
+
+    # Unit test with no terminal?
+    if unit_test_noterm:
+        # Load bitbake, test that there is valid dependency data, then exit
+        screen = None
+        print("* UNIT TEST:START")
+        dep = DepExplorer(screen)
+        print("* UNIT TEST:BITBAKE FETCH")
+        ret,cmdline = bitbake_load(server, eventHandler, params, dep, None, screen)
+        if ret:
+            print("* UNIT TEST: BITBAKE FAILED")
+            return ret
+        # Test the acquired dependency data
+        quilt_native_deps = 0
+        quilt_native_rdeps = 0
+        quilt_deps = 0
+        quilt_rdeps = 0
+        for i,task_obj in enumerate(dep.depends_model):
+            if TYPE_DEP == task_obj[0]:
+                task = task_obj[1]
+                if task.startswith('quilt-native'):
+                    quilt_native_deps += 1
+                elif task.startswith('quilt'):
+                    quilt_deps += 1
+            elif TYPE_RDEP == task_obj[0]:
+                task = task_obj[1]
+                if task.startswith('quilt-native'):
+                    quilt_native_rdeps += 1
+                elif task.startswith('quilt'):
+                    quilt_rdeps += 1
+        # Print results
+        failed = False
+        if 0 < len(dep.depends_model):
+             print(f"Pass:Bitbake dependency count = {len(dep.depends_model)}")
+        else:
+            failed = True
+            print(f"FAIL:Bitbake dependency count = 0")
+        if quilt_native_deps:
+             print(f"Pass:Quilt-native depends count = {quilt_native_deps}")
+        else:
+            failed = True
+            print(f"FAIL:Quilt-native depends count = 0")
+        if quilt_native_rdeps:
+             print(f"Pass:Quilt-native rdepends count = {quilt_native_rdeps}")
+        else:
+            failed = True
+            print(f"FAIL:Quilt-native rdepends count = 0")
+        if quilt_deps:
+             print(f"Pass:Quilt depends count = {quilt_deps}")
+        else:
+            failed = True
+            print(f"FAIL:Quilt depends count = 0")
+        if quilt_rdeps:
+             print(f"Pass:Quilt rdepends count = {quilt_rdeps}")
+        else:
+            failed = True
+            print(f"FAIL:Quilt rdepends count = 0")
+        print("* UNIT TEST:STOP")
+        return failed
+
+    # Help method to dynamically test parent window too small
+    def check_screen_size(dep, active_package):
+        global screen_too_small
+        rows, cols = screen.getmaxyx()
+        if (rows >= SCREEN_ROW_MIN) and (cols >= SCREEN_COL_MIN):
+            if screen_too_small:
+                # Now big enough, remove error message and redraw screen
+                dep.draw_frames()
+                active_package.cursor_on(True)
+                screen_too_small = False
+            return True
+        # Test on App init
+        if not dep:
+            # Do not start this app if screen not big enough
+            curses.endwin()
+            print("")
+            print("ERROR(Taskexp_cli): Mininal screen size is %dx%d" % (SCREEN_COL_MIN,SCREEN_ROW_MIN))
+            print("Current screen is Cols=%s,Rows=%d" % (cols,rows))
+            return False
+        # First time window too small
+        if not screen_too_small:
+            active_package.cursor_on(False)
+            dep.screen.addstr(0,2,'[BIGGER WINDOW PLEASE]', curses.color_pair(CURSES_WARNING) | curses.A_BLINK)
+            screen_too_small = True
+        return False
+
+    # Helper method to turn off curses mode
+    def curses_off(screen):
+        if not screen: return
+        # Safe error exit
+        screen.keypad(False)
+        curses.echo()
+        curses.curs_set(1)
+        curses.endwin()
+
+        if unit_test_results:
+            print('\nUnit Test Results:')
+            for line in unit_test_results:
+                print(" %s" % line)
+
+    #
+    # Initialize the ncurse environment
+    #
+
+    screen = curses.initscr()
+    try:
+        if not check_screen_size(None, None):
+            exit(1)
+        try:
+            curses.start_color()
+            curses.use_default_colors();
+            curses.init_pair(0xFF, curses.COLOR_BLACK, curses.COLOR_WHITE);
+            curses.init_pair(CURSES_NORMAL, curses.COLOR_WHITE, curses.COLOR_BLACK)
+            curses.init_pair(CURSES_HIGHLIGHT, curses.COLOR_WHITE, curses.COLOR_BLUE)
+            curses.init_pair(CURSES_WARNING, curses.COLOR_WHITE, curses.COLOR_RED)
+        except:
+            curses.endwin()
+            print("")
+            print("ERROR(Taskexp_cli): Requires 256 colors. Please use this or the equivalent:")
+            print("  $ export TERM='xterm-256color'")
+            exit(1)
+
+        screen.keypad(True)
+        curses.noecho()
+        curses.curs_set(0)
+        screen.refresh();
+    except Exception as e:
+        # Safe error exit
+        curses_off(screen)
+        print("Exception : %s" % e)
+        print("Exception in startup:\n %s" % traceback.format_exc())
+        exit(1)
+
+    try:
+        #
+        # Instantiate the presentation layers
+        #
+
+        dep = DepExplorer(screen)
+
+        #
+        # Prepare bitbake
+        #
+
+        # Fetch bitbake dependecy data
+        ret,cmdline = bitbake_load(server, eventHandler, params, dep, curses_off, screen)
+        if ret: return ret
+
+        #
+        # Preset the views
+        #
+
+        # Cmdline example = ['generateDotGraph', ['acl', 'zlib'], 'build']
+        primary_packages = cmdline[1]
+        dep.package_view.set_primary(primary_packages)
+        dep.dep_view.set_primary(primary_packages)
+        dep.reverse_view.set_primary(primary_packages)
+        dep.help_box_view.set_primary(primary_packages)
+        dep.help_bar_view.show_help(True)
+        active_package = dep.package_view
+        active_package.cursor_on(True)
+        dep.select(primary_packages[0]+'.')
+        if unit_test:
+            alert('UNIT_TEST',screen)
+
+        # Help method to start/stop the filter feature
+        def filter_mode(new_filter_status):
+            global is_filter
+            if is_filter == new_filter_status:
+                # Ignore no changes
+                return
+            if not new_filter_status:
+                # Turn off
+                curses.curs_set(0)
+                #active_package.cursor_on(False)
+                active_package = dep.package_view
+                active_package.cursor_on(True)
+                is_filter = False
+                dep.help_bar_view.show_help(True)
+                dep.filter_str = ''
+                dep.select('')
+            else:
+                # Turn on
+                curses.curs_set(1)
+                dep.help_bar_view.show_help(False)
+                dep.filter_view.clear()
+                dep.filter_view.show(True)
+                dep.filter_view.show_prompt()
+                is_filter = True
+
+        #
+        # Main user loop
+        #
+
+        while not quit:
+            if is_filter:
+                dep.filter_view.show_prompt()
+            if unit_test:
+                c = unit_test_action(active_package)
+            else:
+                c = screen.getch()
+            ch = chr(c)
+
+            # Do not draw if window now too small
+            if not check_screen_size(dep,active_package):
+                continue
+
+            if verbose:
+                if c == CHAR_RETURN:
+                    screen.addstr(0, 4, "|%3d,CR |" % (c))
+                else:
+                    screen.addstr(0, 4, "|%3d,%3s|" % (c,chr(c)))
+
+            # pre-map alternate filter close keys
+            if is_filter and (c == CHAR_ESCAPE):
+                # Alternate exit from filter
+                ch = '/'
+                c = ord(ch)
+
+            # Filter and non-filter mode command keys
+            # https://docs.python.org/3/library/curses.html
+            if c in (curses.KEY_UP,CHAR_UP):
+                active_package.line_up()
+                if active_package == dep.package_view:
+                    dep.select('',only_update_dependents=True)
+            elif c in (curses.KEY_DOWN,CHAR_DOWN):
+                active_package.line_down()
+                if active_package == dep.package_view:
+                    dep.select('',only_update_dependents=True)
+            elif curses.KEY_PPAGE == c:
+                active_package.page_up()
+                if active_package == dep.package_view:
+                    dep.select('',only_update_dependents=True)
+            elif curses.KEY_NPAGE == c:
+                active_package.page_down()
+                if active_package == dep.package_view:
+                    dep.select('',only_update_dependents=True)
+            elif CHAR_TAB == c:
+                # Tab between boxes
+                active_package.cursor_on(False)
+                if active_package == dep.package_view:
+                    active_package = dep.dep_view
+                elif active_package == dep.dep_view:
+                    active_package = dep.reverse_view
+                else:
+                    active_package = dep.package_view
+                active_package.cursor_on(True)
+            elif curses.KEY_BTAB == c:
+                # Shift-Tab reverse between boxes
+                active_package.cursor_on(False)
+                if active_package == dep.package_view:
+                    active_package = dep.reverse_view
+                elif active_package == dep.reverse_view:
+                    active_package = dep.dep_view
+                else:
+                    active_package = dep.package_view
+                active_package.cursor_on(True)
+            elif (CHAR_RETURN == c):
+                # CR to select
+                selected = active_package.get_selected()
+                if selected:
+                    active_package.cursor_on(False)
+                    active_package = dep.package_view
+                    filter_mode(False)
+                    dep.select(selected)
+                else:
+                    filter_mode(False)
+                    dep.select(primary_packages[0]+'.')
+
+            elif '/' == ch: # Enter/exit dep.filter_view
+                if is_filter:
+                    filter_mode(False)
+                else:
+                    filter_mode(True)
+            elif is_filter:
+                # If in filter mode, re-direct all these other keys to the filter box
+                result = dep.filter_view.input(c,ch)
+                dep.filter_str = dep.filter_view.filter_str
+                dep.select('')
+
+            # Non-filter mode command keys
+            elif 'p' == ch:
+                dep.print_deps(whole_group=False)
+            elif 'P' == ch:
+                dep.print_deps(whole_group=True)
+            elif 'w' == ch:
+                # Toggle the print model
+                if print_model == PRINT_MODEL_1:
+                    print_model = PRINT_MODEL_2
+                else:
+                    print_model = PRINT_MODEL_1
+            elif 's' == ch:
+                # Toggle the sort model
+                if sort_model == SORT_DEPS:
+                    sort_model = SORT_ALPHA
+                elif sort_model == SORT_ALPHA:
+                    if SORT_BITBAKE_ENABLE:
+                        sort_model = TASK_SORT_BITBAKE
+                    else:
+                        sort_model = SORT_DEPS
+                else:
+                    sort_model = SORT_DEPS
+                active_package.cursor_on(False)
+                current_task = active_package.get_selected()
+                dep.package_view.sort()
+                dep.dep_view.sort()
+                dep.reverse_view.sort()
+                active_package = dep.package_view
+                active_package.cursor_on(True)
+                dep.select(current_task)
+                # Announce the new sort model
+                alert("SORT=%s" % ("ALPHA" if (sort_model == SORT_ALPHA) else "DEPS"),screen)
+                alert('',screen)
+
+            elif 'q' == ch:
+                quit = True
+            elif ch in ('h','?'):
+                dep.help_box_view.show_help(True)
+                dep.select(active_package.get_selected())
+
+            #
+            # Debugging commands
+            #
+
+            elif 'V' == ch:
+                verbose = not verbose
+                alert('Verbose=%s' % str(verbose),screen)
+                alert('',screen)
+            elif 'R' == ch:
+                screen.refresh()
+            elif 'B' == ch:
+                # Progress bar unit test
+                dep.progress_view.progress('Test',0,40)
+                curses.napms(1000)
+                dep.progress_view.progress('',10,40)
+                curses.napms(1000)
+                dep.progress_view.progress('',20,40)
+                curses.napms(1000)
+                dep.progress_view.progress('',30,40)
+                curses.napms(1000)
+                dep.progress_view.progress('',40,40)
+                curses.napms(1000)
+                dep.progress_view.clear()
+                dep.help_bar_view.show_help(True)
+            elif 'Q' == ch:
+                # Simulated error
+                curses_off(screen)
+                print('ERROR: simulated error exit')
+                return 1
+
+        # Safe exit
+        curses_off(screen)
+    except Exception as e:
+        # Safe exit on error
+        curses_off(screen)
+        print("Exception : %s" % e)
+        print("Exception in startup:\n %s" % traceback.format_exc())
+
+    # Reminder to pick up your printed results
+    if is_printed:
+        print("")
+        print("You have output ready!")
+        print("  * Your printed dependency file is: %s" % print_file_name)
+        print("  * Your previous results  saved in: %s" % print_file_backup_name)
+        print("")