1Prima::RubberBand(3)  User Contributed Perl Documentation Prima::RubberBand(3)
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4

NAME

6       Prima::RubberBand - draw rubberbands
7

DESCRIPTION

9       The motivation for this module was that I was tired to see corrupted
10       screens on Windows 7 when dragging rubberbands in Prima code. Even
11       though MS somewhere warned of not doing any specific hacks to
12       circumvent the bug, I decided to give it a go anyway.
13
14       This module thus is a "Prima::Widget/rect_focus" with a safeguard. The
15       only thing it can do is to draw a static rubberband - but also remember
16       the last coordinates drawn, so cleaning comes for free.
17
18       The idea is that a rubberband object is meant to be a short-lived one:
19       as soon as it get instantiated it draws itself on the screen. When it
20       is destroyed, the rubberband is erased too.
21

SYNOPSIS

23               use strict;
24               use Prima qw(Application RubberBand);
25
26               sub xordraw
27               {
28                       my ($self, @new_rect) = @_;
29                       $::application-> rubberband( @new_rect ?
30                               ( rect => \@new_rect ) :
31                               ( destroy => 1 )
32                       );
33               }
34
35               Prima::MainWindow-> create(
36                       onMouseDown => sub {
37                               my ( $self, $btn, $mod, $x, $y) = @_;
38                               $self-> {anchor} = [$self-> client_to_screen( $x, $y)];
39                               xordraw( $self, @{$self-> {anchor}}, $self-> client_to_screen( $x, $y));
40                               $self-> capture(1);
41                       },
42                       onMouseMove => sub {
43                               my ( $self, $mod, $x, $y) = @_;
44                               xordraw( $self, @{$self-> {anchor}}, $self-> client_to_screen( $x, $y)) if $self-> {anchor};
45                       },
46                       onMouseUp => sub {
47                               my ( $self, $btn, $mod, $x, $y) = @_;
48                               xordraw if delete $self-> {anchor};
49                               $self-> capture(0);
50                       },
51               );
52
53               run Prima;
54

API

56       new %properties
57           Creates a new RubberBand instance. See description of properties
58           below.
59
60   Properties
61       breadth INTEGER = 1
62           Defines rubberband breadth, in pixels.
63
64       canvas = $::application
65           Sets the painting surface, and also the widget (it must be a
66           widget) used for drawing.
67
68       clipRect X1, Y1, X2, Y2
69           Defines the clipping rectangle, in inclusive-inclusive coordinates.
70           If set to [-1,-1,-1,-1], means no clipping is done.
71
72       rect X1, Y1, X2, Y2
73           Defines the band geometry, in inclusive-inclusive coordinates. The
74           band is drawn so that its body is always inside these coordinates,
75           no matter what breadth is.
76
77   Methods
78       hide
79           Hides the band, if drawn
80
81       has_clip_rect
82           Checks whether clipRect contains an actual clippring rectange or it
83           is empty.
84
85       set %profile
86           Applies all properties
87
88       left, right, top, bottom, width, height, origin, size
89           Same shortcuts as in "Prima::Widget", but read-only.
90
91       show
92           Show the band, if invisible
93

Prima::Widget interface

95       The module adds a single method to "Prima::Widget" namespace,
96       "rubberband" (see example of use in the synopsis).
97
98       rubberband(%profile)
99           Instantiates a "Prima::RubberBand" with %profile, also sets
100           "canvas" to $self unless "canvas" is set explicitly.
101
102       rubberband()
103           Returns the existing "Prima::RubberBand" object
104
105       rubberband(destroy => 1)
106           Destroys the existing "Prima::RubberBand" object
107

AUTHOR

109       Dmitry Karasik, <dmitry@karasik.eu.org>.
110

SEE ALSO

112       "rect_focus" in Prima::Widget, "grip.pl" in examples
113
114   Windows 7 Aero mode
115       Quote from
116       <http://blogs.msdn.com/b/greg_schechter/archive/2006/05/02/588934.aspx>
117       :
118
119       "One particularly dangerous practice is writing to the screen, either
120       through the use of GetDC(NULL) and writing to that, or attempting to do
121       XOR rubber-band lines, etc  ...  Since the UCE doesn't know about it,
122       it may get cleared in the next frame refresh, or it may persist for a
123       very long time, depending on what else needs to be updated on the
124       screen.  (We really don't allow direct writing to the primary anyhow,
125       for that very reason... if you try to access the DirectDraw primary,
126       for instance, the DWM will turn off until the accessing application
127       exits)"
128
129       This quote seems to explain the effect why screen sometimes gets badly
130       corrupted when using a normal xor rubberband. UCE ( Update
131       Compatibility Evaluator ?? ) seems to be hacky enough to recognize some
132       situations, but not all.
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136perl v5.32.1                      2021-01-27              Prima::RubberBand(3)