# Plot a series of continuous functions on a Perl/Tk Canvas.
#
# This program is described in the Perl/Tk column from Volume 1, Issue 1 of
# The Perl Journal (http://tpj.com/tpj), and is included in the Perl/Tk
# distribution with permission. It has been modified slightly to conform
# to the widget demo standard.
#!/usr/local/bin/perl -w
#
# plot_program - plot a series of continuous functions on a Perl/Tk Canvas.
#
# Stephen O. Lidie, Lehigh University Computing Center, lusol@Lehigh.EDU
# 96/01/27.
#
# Copyright (C) 1996 - 1998 Stephen O. Lidie. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify it under
# the same terms as Perl itself.
require 5.002;
use strict;
use Tk;
use Tk::Dialog;
use Tk::LabEntry;
eval {require "plop.fnc";}; # user supplied math functions
# Predeclare global subroutines and variables.
sub collect_errors;
sub display_coordinates;
sub initialize_canvas;
sub initialize_dialogs;
sub initialize_functions;
sub initialize_menus;
sub make_menubutton;
sub plot_functions;
sub update_functions;
my $VERSION = '1.0';
# The default sample functions and limits, each in a different color.
my (@FUNCTIONS) = ('sin($x)', 'cos($x)', 'exp($x)', '$x', 'int($x)');
my (@COLORS) = qw(red green blue orange olivedrab magenta black salmon purple);
my $NUM_COLORS = scalar @COLORS;
my ($X_MIN, $X_MAX, $Y_MIN, $Y_MAX) = (-5, 5, -5, 5);
my ($DX, $DY) = ($X_MAX - $X_MIN, $Y_MAX - $Y_MIN);
# Declare constants that configure the plotting area: a square approximately
# 500 pixels on a side, with left/right and top/bottom margins of 80 pixles
# where we can paint axes labels. With this layout there is a 340x340 area
# available for graphs.
my $MIN_PXL = 0; # minimum Canvas pixel coordinate
my $MAX_PXL = 300; # maximum Canvas pixel coordinate
my $MARGIN = 80; # margin size, in pixels
my $ALEN = $MAX_PXL - 2 * $MARGIN; # X/Y axes length, in pixels
# Declare Perl/Tk widgets and other data.
my $CANV; # Canvas widget used for plotting functions
my $DIALOG_ABOUT; # Dialog widget showing "About" information
my $DIALOG_USAGE; # Dialog widget describing plot usage
my $MBF; # Menubutton frame
my $MW = MainWindow->new; # program's main window
my $ORIGINAL_CURSOR = ($MW->configure(-cursor))[3]; # restore this cursor
my $TEXT; # Text widget showing function definitions
# %ERRORS is a hash to collect eval() and -w errors. The keys are the error
# messages themselves and the values are the number of times a particular
# error was detected.
my %ERRORS;
# Begin main.
initialize_dialogs;
initialize_menus;
initialize_canvas;
initialize_functions;
# End main.
sub collect_errors {
# Update the hash %ERRORS with the latest eval() error message. Remove
# the eval() line number (it's useless to us) to maintain a compact hash.
my($error) = @_;
$error =~ s/eval\s+(\d+)/eval/;
$ERRORS{$error}++;
} # end collect_errors
sub display_coordinates {
# Print Canvas and Plot coordinates.
my($canvas) = @_;
my $e = $canvas->XEvent;
my($canv_x, $canv_y) = ($e->x, $e->y);
my($x, $y);
$x = $X_MIN + $DX * (($canv_x - $MARGIN) / $ALEN);
$y = $Y_MAX - $DY * (($canv_y - $MARGIN) / $ALEN);
print STDOUT "\nCanvas x = $canv_x, Canvas y = $canv_y.\n";
print STDOUT "Plot x = $x, Plot y = $y.\n";
} # end display_coordinates
sub initialize_canvas {
# Create the Canvas widget and draw axes and labels.
my($label_offset, $tick_length) = (20, 5);
$CANV = $MW->Canvas(
-width => $MAX_PXL + $MARGIN * 2,
-height => $MAX_PXL,
-relief => 'sunken',
);
$CANV->pack;
$CANV->Tk::bind('<Button-1>' => \&display_coordinates);
$CANV->create('text',
225, 25,
-text => 'Plot Continuous Functions Of The Form y=f($x)',
-fill => 'blue',
);
# Create the line to represent the X axis and label it. Then label the
# minimum and maximum X values and draw tick marks to indicate where they
# fall. The axis limits are LabEntry widgets embedded in Canvas windows.
$CANV->create('line',
$MIN_PXL + $MARGIN, $MAX_PXL - $MARGIN,
$MAX_PXL - $MARGIN, $MAX_PXL - $MARGIN,
);
$CANV->create('window',
$MIN_PXL + $MARGIN, $MAX_PXL - $label_offset,
-window => $MW->LabEntry(
-textvariable => \$X_MIN,
-label => 'X Minimum',
-width => 5,
),
);
$CANV->create('line',
$MIN_PXL + $MARGIN, $MAX_PXL - $MARGIN - $tick_length,
$MIN_PXL + $MARGIN, $MAX_PXL - $MARGIN + $tick_length,
);
$CANV->create('window',
$MAX_PXL - $MARGIN, $MAX_PXL - $label_offset,
-window => $MW->LabEntry(
-textvariable => \$X_MAX,
-label => 'X Maximum',
-width => 5,
),
);
$CANV->create('line',
$MAX_PXL - $MARGIN, $MAX_PXL - $MARGIN - $tick_length,
$MAX_PXL - $MARGIN, $MAX_PXL - $MARGIN + $tick_length,
);
# Create the line to represent the Y axis and label it. Then label the
# minimum and maximum Y values and draw tick marks to indicate where they
# fall. The axis limits are LabEntry widgets embedded in Canvas windows.
$CANV->create('line',
$MAX_PXL - $MARGIN, $MIN_PXL + $MARGIN,
$MAX_PXL - $MARGIN, $MAX_PXL - $MARGIN,
);
$CANV->create('window',
$MAX_PXL + $label_offset, $MIN_PXL + $MARGIN,
-window => $MW->LabEntry(
-textvariable => \$Y_MAX,
-label => 'Y Maximum',
-width => 5,
),
);
$CANV->create('line',
$MAX_PXL - $MARGIN - $tick_length, $MIN_PXL + $MARGIN,
$MAX_PXL - $MARGIN + $tick_length, $MIN_PXL + $MARGIN,
);
$CANV->create('window',
$MAX_PXL + $label_offset, $MAX_PXL - $MARGIN,
-window => $MW->LabEntry(
-textvariable => \$Y_MIN,
-label => 'Y Minimum',
-width => 5,
),
);
$CANV->create('line',
$MAX_PXL - $MARGIN - $tick_length, $MAX_PXL - $MARGIN,
$MAX_PXL - $MARGIN + $tick_length, $MAX_PXL - $MARGIN,
);
} # end initialize_canvas
sub initialize_dialogs {
# Create all application Dialog objects.
$DIALOG_ABOUT = $MW->Dialog(
-title => 'About',
-text =>
"plot_program $VERSION\n\n95/12/04\n\nThis program is described in the Perl/Tk column from Volume 1, Issue 1 of The Perl Journal (http://tpj.com/tpj), and is included in the Perl/Tk distribution with permission.",
-bitmap => 'info',
-buttons => ['Dismiss'],
);
$DIALOG_ABOUT->configure(-wraplength => '6i');
$DIALOG_USAGE = $MW->Dialog(
-title => 'Usage',
-buttons => ['Dismiss'],
);
$DIALOG_USAGE->Subwidget('message')->configure(
-wraplength => '4i',
-text => "plot_program iterates over the range of values X Minimum to X Maximum, setting the variable \$x to each value in turn, then evaluates each f(\$x) and paints a point on the Y axis. The X axis increment is (Xmax - Xmin) / $ALEN.\n\nJust enter your functions in the Text widget and click the Plot button.\n\nYou can define a file named \"plop.fnc\" that contains additional private math functions, which is automatically \"require\"d by plot_program. In this file are your private functions that you can plot.\n\nPressing button one on the pointing device displays on standard output the current canvas and plot X and Y coordinates.",
);
} # end initialize_dialogs
sub initialize_functions {
# Pack a spacer Frame and then display instructions in a Label widget.
# $MW->Frame(-height => 10)->pack;
$MW->Label(
-text => 'Enter your functions here',
-foreground => 'blue',
)->pack;
# Create a Frame with a scrollable Text widget that displays the function
# list, and a Button to initiate plot activities.
my $functions_frame = $MW->Frame;
$functions_frame->pack;
$TEXT = $functions_frame->Text(-height => 3);
$TEXT->pack;
$functions_frame->AddScrollbars($TEXT);
$functions_frame->configure(-scrollbars => 'e');
update_functions;
my $buttons_frame = $MW->Frame;
$buttons_frame->pack(-padx => 10, -pady => 5, -expand => 1, -fill => 'x');
my @pack_attributes = qw(-side left -fill x -expand 1);
$buttons_frame->Button(
-text => 'Plot',
-command => \&plot_functions,
)->pack(@pack_attributes);
} # end initialize_functions
sub initialize_menus {
# Create the Menubuttons and their associated Menu items.
$MBF = $MW->Frame(-relief => 'raised', -borderwidth => 1);
$MBF->pack(-fill => 'x');
make_menubutton($MBF, 'File', 0, 'left',
[
['Quit', [$MW => 'bell'], 0],
],
);
make_menubutton($MBF, 'Help', 0, 'right',
[
['About', [$DIALOG_ABOUT => 'Show'], 0],
['', undef, 0],
['Usage', [$DIALOG_USAGE => 'Show'], 0],
],
);
} # end initialize_menus
sub make_menubutton {
# Make a Menubutton widget; note that the Menu is automatically created.
# If the label is '', make a separator.
my($mbf, $mb_label, $mb_label_underline, $pack, $mb_list_ref) = @_;
my $mb = $mbf->Menubutton(
-text => $mb_label,
-underline => $mb_label_underline,
);
my $mb_list;
foreach $mb_list (@{$mb_list_ref}) {
$mb_list->[0] eq '' ? $mb->separator :
$mb->command(
-label => $mb_list->[0],
-command => $mb_list->[1],
-underline => $mb_list->[2],
);
}
$mb->pack(-side => $pack);
} # end make_menubutton
sub plot_functions {
# Plot all the functions.
my($x, $y, $canv_x, $canv_y) = (0, 0, 0, 0);
$canv_x = $MIN_PXL + $MARGIN; # X minimum
$MW->configure(-cursor => 'watch');
$DX = $X_MAX - $X_MIN; # update delta X
$DY = $Y_MAX - $Y_MIN; # update delta Y
$CANV->delete('plot'); # erase all previous plots
# Fetch the newline-separated Text widget contents and update the function
# list @FUNCTIONS. Also update the Text widget with the new colors.
@FUNCTIONS = ();
foreach (split /\n/, $TEXT->get('0.0', 'end')) {
next if $_ eq '';
push @FUNCTIONS, $_;
}
update_functions;
$MW->idletasks;
%ERRORS = ();
local $SIG{'__WARN__'} = sub {collect_errors($_[0])};
ALL_X_VALUES:
for ($x = $X_MIN; $x <= $X_MAX; $x += ($X_MAX - $X_MIN) / $ALEN) {
ALL_FUNCTIONS:
foreach (0 .. $#FUNCTIONS) {
next if $FUNCTIONS[$_] =~ /^ERROR:/;
$y = eval $FUNCTIONS[$_];
if ($::EVAL_ERROR) {
collect_errors($::EVAL_ERROR);
next;
}
$canv_y = (($Y_MAX - $y) / $DY) * $ALEN + $MARGIN;
$CANV->create('text', $canv_x, $canv_y,
-fill => $COLORS[$_ % $NUM_COLORS],
-tags => ['plot'],
-text => '.',
) if $canv_y > $MIN_PXL + $MARGIN and
$canv_y < $MAX_PXL - $MARGIN;
} # forend ALL_FUNCTIONS
$canv_x++; # next X pixel
} # forend ALL_X_VALUES
$MW->configure(-cursor => $ORIGINAL_CURSOR);
$MW->idletasks;
# Print all the eval() errors to alert the user of malformed functions.
print STDOUT "\n" if %ERRORS;
foreach (keys %ERRORS) {
print STDOUT "$ERRORS{$_} occurrences of $_";
}
} # end plot_functions
sub update_functions {
# Insert the function list into the Text widget.
$TEXT->delete('0.0', 'end');
my $i = 0;
foreach (@FUNCTIONS) {
$TEXT->insert('end', "$_\n", [$i]);
$TEXT->tagConfigure($i,
-foreground => $COLORS[$i % $NUM_COLORS],
-font => 'fixed',
);
$i++;
}
$TEXT->yview('end');
} # end update_function_list