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86530b38 AT |
1 | |
2 | package Ball; | |
3 | ||
4 | # Ball.pm, a class module that allows concurrent simulation (canvas) instances. | |
5 | # | |
6 | # This is simply a class module, nothing fancy like a derived widget or | |
7 | # composite widget. It has two virtual methods, new() and move_one_ball(). | |
8 | # There are two static methods, get_canvas_hash() and move_all_balls(). | |
9 | # | |
10 | # Essentially, move_all_balls() is invoked to move all of the balls in a | |
11 | # simulation's @BALLS list once - from their current to their new postion. | |
12 | # After moving one ball a call to DoOneEvent() is made to handle pending | |
13 | # XEvents. The *user* of this module, in this case bounce.pl, has their | |
14 | # own main loop which also calls DoOneEvent() and move_all_balls() to keep | |
15 | # the simulation active. | |
16 | # | |
17 | # Gurusamy Sarathy (gsar@engin.umich.edu) | |
18 | # Tidied up by SOL. | |
19 | ||
20 | use vars qw/$VERSION/; | |
21 | $VERSION = '3.009'; # $Id: //depot/Tk8/demos/demos/widget_lib/Ball.pm#9 $ | |
22 | ||
23 | use Tk::Canvas; | |
24 | use Tk::Widget; | |
25 | use Tk qw/DoOneEvent DONT_WAIT/; | |
26 | Construct Tk::Canvas 'Ball'; | |
27 | use strict; | |
28 | ||
29 | # Class Ball global variables. | |
30 | ||
31 | my %BALLS = (); # hold @BALLS list on a per canvas basis | |
32 | my (%DEFAULTS) = ( # Ball constructor option defaults | |
33 | -color => 'blue', | |
34 | -size => 20.0, | |
35 | -position => [12.0,12.0], | |
36 | -velocity => [6.0, 9.0], | |
37 | ); | |
38 | ||
39 | sub new { # Ball object constructor | |
40 | ||
41 | # Create a new Ball object, which just happens to be a Canvas item. | |
42 | # Fill-in values for defaulted parameters, create the oval item, and | |
43 | # store object-specific information in the ball's hash. | |
44 | # | |
45 | # Finally, update the class global %BALLS hash, indexed by a hashed canvas | |
46 | # reference, with the new ball. Note the special Tk::bind statement that | |
47 | # removes a canvas from the %BALLS hash when the canvas is destroyed, thus | |
48 | # keeping %BALLS trimmed and preventing a very slow memory leak. | |
49 | ||
50 | my($class, $canvas, %args) = @_; | |
51 | ||
52 | my @missing_args = grep ! defined $args{$_}, keys %DEFAULTS; | |
53 | @args{@missing_args} = @DEFAULTS{@missing_args}; | |
54 | my($color, $size, $pos, $vel) = @args{-color, -size, -position, -velocity}; | |
55 | ||
56 | my $ball = $canvas->create('oval', | |
57 | ($pos->[0] - ($size/2.0)), ($pos->[1] - ($size/2.0)), | |
58 | ($pos->[0] + ($size/2.0)), ($pos->[1] + ($size/2.0)), | |
59 | -fill => $color, | |
60 | ); | |
61 | $canvas->Tk::bind( | |
62 | '<Destroy>' => sub {delete $BALLS{Ball->get_canvas_hash($canvas)}} | |
63 | ); | |
64 | ||
65 | my $ball_obj = {'canvas_ID' => $ball, | |
66 | 'canvas' => $canvas, | |
67 | 'color' => $color, | |
68 | 'size' => $size, | |
69 | 'pos' => [@$pos], | |
70 | 'vel' => [@$vel], | |
71 | }; | |
72 | ||
73 | push @{$BALLS{Ball->get_canvas_hash($canvas)}->{'BALLS'}}, $ball_obj; | |
74 | return bless $ball_obj, $class; | |
75 | ||
76 | } # end new, Ball constructor | |
77 | ||
78 | sub get_canvas_hash { | |
79 | ||
80 | # Hash a canvas reference to a key for indexing into the %BALLS hash. | |
81 | # For now, just use the string-ified widget reference. If this trick | |
82 | # were ever to fail in the future then only this code needs to be fixed | |
83 | # and the Ball class would be up and running in short oder. | |
84 | ||
85 | my($class, $canvas) = @_; | |
86 | ||
87 | return $canvas | |
88 | ||
89 | } # end get_canvas_hash | |
90 | ||
91 | sub move_one_ball { | |
92 | ||
93 | # Move one ball, belonging to one simulation, one clock tick. | |
94 | ||
95 | my ($ball_obj, $speed_ratio) = @_; | |
96 | ||
97 | my($ball, $canv, $minx, $miny, $maxx, $maxy); | |
98 | my($ballx, $bally, $deltax, $deltay); | |
99 | ||
100 | $speed_ratio = 1.0 unless defined $speed_ratio; | |
101 | $ball = $ball_obj->{'canvas_ID'}; | |
102 | $canv = $ball_obj->{'canvas'}; | |
103 | $ballx = $ball_obj->{'pos'}[0]; | |
104 | $bally = $ball_obj->{'pos'}[1]; | |
105 | ||
106 | $minx = $ball_obj->{'size'} / 2.0; | |
107 | $maxx = $ball_obj->{'canvas'}->cget(-width) - $minx; | |
108 | ||
109 | $miny = $ball_obj->{'size'} / 2.0; | |
110 | $maxy = $ball_obj->{'canvas'}->cget(-height) - $miny; | |
111 | ||
112 | if ($ballx > $maxx || $ballx < $minx) { | |
113 | $ball_obj->{'vel'}[0] = -1.0 * $ball_obj->{'vel'}[0]; | |
114 | } | |
115 | if ($bally > $maxy || $bally < $miny) { | |
116 | $ball_obj->{'vel'}[1] = -1.0 * $ball_obj->{'vel'}[1]; | |
117 | } | |
118 | ||
119 | $deltax = $ball_obj->{'vel'}[0] * $speed_ratio; | |
120 | $deltay = $ball_obj->{'vel'}[1] * $speed_ratio; | |
121 | ||
122 | $canv->move($ball, $deltax, $deltay); | |
123 | $ball_obj->{'pos'}[0] = $ballx + $deltax; | |
124 | $ball_obj->{'pos'}[1] = $bally + $deltay; | |
125 | ||
126 | return $ball_obj; | |
127 | ||
128 | } # end move_one_ball | |
129 | ||
130 | sub move_all_balls { | |
131 | ||
132 | # Move all the balls belong to one simulation instance one clock tick. | |
133 | ||
134 | my($class, $canvas, $speed_ratio) = @_; | |
135 | ||
136 | foreach (@{$BALLS{Ball->get_canvas_hash($canvas)}->{'BALLS'}}) { | |
137 | $_->move_one_ball($speed_ratio); | |
138 | DoOneEvent(DONT_WAIT); # be kind and process XEvents if they arise | |
139 | } | |
140 | ||
141 | } # end move_all_balls | |
142 | ||
143 | 1; |