1Prima::Drawable::CurvedUTseexrt(C3o)ntributed Perl DocumPernitmaat:i:oDnrawable::CurvedText(3)
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6 Prima::Drawable::CurvedText - fit text to path
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9 The module registers single function "curved_text_out" in
10 "Prima::Drawable" namespace. The function plots the line of text along
11 the path, which given as a set of points. Various options regulate
12 behavior of the function when glyphs collide with the path boundaries
13 and each other.
14
16 use Prima qw(Application Drawable::CurvedText);
17 my $spline = [qw(100 100 150 150 200 100)];
18 $::application-> begin_paint;
19 $::application-> spline($spline);
20 $::application-> curved_text_out( 'Hello, world!', $::application-> render_spline( $spline ));
21 curved_text_out $TEXT, $POLYLINE, %OPTIONS
23 $TEXT is a line of text, no special treatment is given to tab and
24 newline characters. The text is plotted over $POLYLINE path that
25 should be an array of coordinate numeric pairs, in the same format as
26 "Prima::Drawable::polyline" expects.
27 The text begins to plot by drawing the first glyphs at the first path
29 point, unless specified otherwise with the "offset" option. The glyph
30 is plotted with the angle perpendicular to the path segment; therefore
31 the path may contain floating point numbers if futher plotting angle
32 accuracy is desired.
33 When text cannot be fit along a single segment, it is plotted along the
35 next segment in the path. Depending on the "bevel" boolean option, the
36 next glyph is either simply drawn on the next segment with the angle
37 corresponding to the tangent of that segment (value 0), or is drawn
38 with the normal text concatenation offset, with the angle averaged
39 between tangents of the two segments it is plotted between (value 1).
40 The default value of "bevel" option is 1.
41 The glyph positioning rules differ depending on "collisions" integer
43 option. If 0 (default), the next glyph position always corresponds with
44 the glyph width as projected to the path. That means, that glyphs will
45 overlap when plotted inside segments forming an acute angle. Also, when
46 plotting along a reflex angle, the glyphs will be visually more distant
47 from each other that when plotted along the straight line.
48 Simple collision detection can be turned on with setting "collisions"
50 to 1 so that no two neighbour glyphs may overlap. Also, the glyphs will
51 be moved together to the minimal distance, when possible. With this
52 option set the function will behave slower. If detection of not only
53 neighbouring glyphs is required, "collisions" value can be set to 2, in
54 which case a glyph is guaranteedly will never overlap any other glyph.
55 This option may be needed when, for example, text is plotted inside an
56 acute angle and upper parts of glyphs plotted along one segment will
57 overlap with lower parts of glyphs plotted along the other one.
58 Setting "collisions" to 2 will slow the function even more.
59 The function internally creates an array of tuples where each contains
61 text, plotting angle, and horisontal and vertical coordinates for the
62 text to be plotted. In the array context the function returns this
63 array. In the scalar context the function returns the success flag that
64 is the result of last call to "text_out".
65 Options:
67 bevel BOOLEAN=true
69 If set, glyphs between two adjoining segments will be plotted with
70 bevelled angle. Otherwise glyphs will strictly follow the angles
71 of the segments in the path.
72 callback CODE($SELF, $POLYLINE, $CHUNKS)
74 If set, the callback is called with $CHUNKS after the calculations
75 were made but before the text is plotted. $CHUNKS is an array of
76 tuples where each consists of text, angle, x and y coordinates for
77 each text. The callback is free to modify the array.
78 collisions INTEGER=0
80 If 0, collision detection is disabled, glyphs plotted along the
81 path. If 1, no two neighbour glyphs may overlap, and no two
82 neighbour glyph will be situated further away from each other than
83 it is necessary. If 2, same functionality as with 1, and also two
84 glyphs (in all text) will overlap.
85 nodraw BOOLEAN=false
87 If set, calculate glyph positions but do not draw them.
88 offset INTEGER=0
90 Sets offset from the beginning of the path where the first glyph is
91 plotted. If offset is negative, it is calculated from the end of
92 the path.
93 skiptail BOOLEAN=false
95 If set, the remainder of the text that is left after the path is
96 completely traversed, is not shown. Otherwise (default), the tail
97 text is shown with the angle used to plot the last glyph (if
98 bevelling was requested) or the angle perpendicular to the last
99 path segment (otherwise).
100
102 Dmitry Karasik, <dmitry@karasik.eu.org>.
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105 Prima, Prima::Drawable
106perl v5.38.0 2023-07-21 Prima::Drawable::CurvedText(3)