1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="https://www.w3.org/1999/xhtml">
<head>
<meta name="generator" content="HTML Tidy for Linux/x86 (vers 1 September 2005), see www.w3.org" />
<title>RMagick 0.0.0: RVG Reference: RVG Class</title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
<meta name="GENERATOR" content="Quanta Plus" />
<meta name="Copyright" content="Copyright (C) 2006 by Timothy P. Hunter" />
<link rel="stylesheet" type="text/css" href="css/doc.css" />
<script type="text/javascript" src="scripts/doc.js"></script>
<script type="text/javascript">
//<![CDATA[
//]]>
</script>
<style type="text/css">
/*<![CDATA[*/
}
/*]]>*/
</style>
</head>
<body>
<h6 id="header">RMagick 0.0.0 User's Guide and Reference</h6>
<div class="nav">« <a href="rvgtut.html">Prev</a> | <a href="index.html">Contents</a> | <a href="rvggroup.html">Next</a> »</div>
<h1>class RVG <span class="superclass">< Object</span></h1>
<div id="toc">
<h2>Table of Contents</h2>
<h3>class methods</h3>
<ul>
<li><a href="#RVG_new">new</a></li>
</ul>
<h3>attributes</h3>
<div class="toccol">
<ul>
<li><a href="#RVG_background_fill">background_fill=</a></li>
<li>
<a href="#RVG_background_fill_opacity">background_fill_opacity=</a>
</li>
<li><a href="#RVG_background_image">background_image=</a></li>
<li><a href="#RVG_background_pattern">background_pattern=</a></li>
<li><a href="#RVG_background_position">background_position=</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#RVG_canvas">canvas</a></li>
<li><a href="#RVG_desc">desc, desc=</a></li>
<li><a href="#RVG_height">height</a></li>
<li><a href="#RVG_metadata">metadata, metadata=</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#RVG_title">title, title=</a></li>
<li><a href="#RVG_width">width</a></li>
<li><a href="#RVG_x">x</a></li>
<li><a href="#RVG_y">y</a></li>
</ul>
</div>
<h3>instance methods</h3>
<div>
<div class="toccol">
<ul>
<li><a href="#RVG_draw">draw</a></li>
<li><a href="#RVG_g">g</a></li>
<li><a href="#RVG_image">image</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li>
<a href="#RVG_preserve_aspect_ratio">preserve_aspect_ratio</a>
</li>
<li><a href="#RVG_rvg">rvg</a></li>
<li><a href="#RVG_text">text</a></li>
</ul>
</div>
<div class="toccol">
<ul>
<li><a href="#RVG_use">use</a></li>
<li><a href="#RVG_viewbox">viewbox</a></li>
</ul>
</div>
</div>
<h3>shared methods</h3>
<p>
In addition to the methods listed above, <code>class RVG</code> also implements the <a href="rvgstyle.html">styles</a> method, the
<a href="rvgshape.html">shape methods</a> and the <a href="rvgxform.html">transform methods</a>.
</p>
<h3>Units</h3>
<div class="toccol">
<ul>
<li><a href="#units">Units conversion methods</a></li>
</ul>
</div>
</div>
<h2 class="methods">class methods</h2>
<div class="sig">
<h3 id="RVG_new">new</h3>
<p>
RVG.new(<span class="arg">width</span>=nil, <span class="arg">height</span>=nil) [ <span class="arg">{ |canvas| drawing method calls }</span> ] ->
<em>rvg</em>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Creates a container that can have its own coordinate system. Within the block, call drawing methods on <em>canvas</em> to render shapes, text, and
raster images in the container.
</p>
<p>
An RVG object is always the outermost container for a drawing. Call the
<a href="#RVG_draw">draw</a> method on the returned RVG object to produce the final image.
</p>
<h4>Arguments</h4>
<p>
If the RVG object is the outermost container,
<span class="arg">width</span> and <span class="arg">height</span> are required and specify the width and height of the final drawing in pixels. You can
call <a href="#units">conversion methods</a> to use units such as inches and millimeters instead of pixels.
</p>
<p>
Otherwise, <span class="arg">width</span> and <span class="arg">height</span> specify the area of the viewbox. If the RVG object will be used as an
argument to the <a href="rvguse.html#use">use</a> method, then <span class="arg">width</span> and <span class="arg">height</span> may be omitted here,
then specified as arguments to <code>use</code>.
</p>
<h4>Returns</h4>
<p>An RVG object</p>
<h4>Example</h4>
<p>
See the <a href="rvgtut.html">tutorial</a> for a simple example. The image below demonstrates an advanced use of <code>RVG.new</code>. This example
creates an RVG object that draws an orange-and-green target. The <span class="arg">width</span> and <span class="arg">height</span> arguments are
omitted in the <code>RVG.new</code> call. Instead, the viewport width and height are specified as arguments to 4 invocations of
<a href="rvguse.html#use">use</a>. Each <code>use</code> specifies a different viewport size, so the same RVG object draws 4 different-sized targets.
</p>
<p>Click the image to see the example script.</p>
<p>
<a href="javascript:popup('nested_rvg.rb.html')"><img src="ex/nested_rvg.gif" title="Click to see the example script" alt="nested RVG example" /></a>
</p>
<h4>See also</h4>
<p><a href="rvggroup.html">Group</a></p>
</div>
<h2 class="methods">attributes</h2>
<div class="sig">
<h3 id="RVG_background_fill">background_fill=</h3>
<p>
<span class="arg">canvas</span>.background_fill =
<span class="arg">value</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Specify a background fill color. The attribute value may be either a
<a href="struct.html#Pixel">pixel</a> or a <a href="imusage.html#color_names">color name.</a> The default fill color is "#00000000". This color is
usually called "none". This attribute has no effect on nested RVG objects.
</p>
<h4>Example</h4>
<pre>
canvas.background_fill = 'white'
</pre
>
<h4>Returns</h4>
<span class="arg">value</span>
</div>
<div class="sig">
<h3 id="RVG_background_fill_opacity">background_fill_opacity=</h3>
<p>
<span class="arg">canvas</span>.background_fill_opacity =
<span class="arg">value</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Specify the opacity of the background fill color when the
<a href="#RVG_background_fill">background fill</a> is not the default. The value is a number between 0.0 (fully transparent) and 1.0 (fully opaque). The
default is 1.0. The attribute is ignored unless <code>background_fill</code> is specified. This attribute has no effect on nested RVG objects.
</p>
<h4>Example</h4>
<pre>
canvas.background_fill = 'white'
canvas.background_fill_opacity = 0.50
</pre
>
<h4>Returns</h4>
<span class="arg">value</span>
</div>
<div class="sig">
<h3 id="RVG_background_image">background_image=</h3>
<p>
<span class="arg">canvas</span>.background_image =
<span class="arg">image</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Specify an image to be used as the canvas background. The value is an
<a href="image1.html#new">Image</a> object. This attribute has no effect on nested RVG objects.
</p>
<h4>Example</h4>
<pre>
canvas.background_image = Magick::Image.read('myBackground.gif').first
</pre
>
<h4>Returns</h4>
<span class="arg">image</span>
<h4>See also</h4>
<p><a href="#RVG_background_position">background_position=</a></p>
</div>
<div class="sig">
<h3 id="RVG_background_pattern">background_pattern=</h3>
<p>
<span class="arg">canvas</span>.background_pattern =
<span class="arg">fill</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Specify an <a href="struct.html#fill">Fill object</a> to fill the canvas background. This attribute has no effect on nested RVG objects.</p>
<h4>Example</h4>
<pre>
canvas.background_pattern = Magick::GradientFill.new(0, 0, 0, 100, "#900", "#000")
</pre
>
<h4>Returns</h4>
<p>a Fill object</p>
</div>
<div class="sig">
<h3 id="RVG_background_position">background_position=</h3>
<p>
<span class="arg">canvas</span>.background_position =
<span class="arg">pos</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
If the dimensions of the image specified by
<a href="#RVG_background_image">background_image</a> do not exactly match the canvas dimensions, this attribute specifies how to position the image on
the background. This attribute has no effect on nested RVG objects.
</p>
<h4>Argument</h4>
The value of <span class="arg">pos</span> can be any one of the following symbols :
<dl>
<dt>:scaled</dt>
<dd>The image is scaled to fit. The image proportions are not retained.</dd>
<dt>:tiled</dt>
<dd>The image is tiled across the background.</dd>
<dt>:fit</dt>
<dd>
The image is scaled to fit. The image proportions are retained. Any part of the background that is not covered by the image is colored with the
<a href="#RVG_background_color">background color</a>.
</dd>
</dl>
<h4>Example</h4>
<pre>
canvas.background_image = Magick::Image.read('myBackground.gif').first
canvas.background_position = :scaled
</pre
>
<h4>Returns</h4>
<span class="arg">pos</span>
</div>
<div class="sig">
<h3 id="RVG_canvas">canvas</h3>
<p><span class="arg">rvg</span>.canvas -> image</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
After the <a href="#RVG_draw">draw</a> method has been used, returns the rendered image. This is the same image that
<a href="#RVG_draw">draw</a> returns.
</p>
<h4>Returns</h4>
<p>An image</p>
</div>
<div class="sig">
<h3 id="RVG_desc">desc, desc=</h3>
<p>
<span class="arg">rvg</span>.desc -> <span class="arg">string</span><br />
<span class="arg">rvg</span>.desc = <span class="arg">string</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
Use the <code>desc</code> attribute to assign a text description to the drawing. The description will be assigned to the "desc" property of the resulting
image. This attribute has no effect on nested RVG objects.
</div>
<div class="sig">
<h3 id="RVG_height">height</h3>
<p>
<span class="arg">rvg</span>.height ->
<span class="arg">height</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>The height of the RVG object in user coordinates.</p>
<h4>See also</h4>
<p><a href="#RVG_width">width</a></p>
</div>
<div class="sig">
<h3 id="RVG_metadata">metadata, metadata=</h3>
<p>
<span class="arg">rvg</span>.metadata -> <span class="arg">string</span><br />
<span class="arg">rvg</span>.metadata = <span class="arg">string</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
Use the <code>metadata</code> attribute to assign additional metadata to the drawing. The metadata string will be assigned to the "metadata" property of
the resulting image. This attribute has no effect on nested RVG objects.
</div>
<div class="sig">
<h3 id="RVG_title">title, title=</h3>
<p>
<span class="arg">rvg</span>.title -> <span class="arg">string</span><br />
<span class="arg">rvg</span>.title = <span class="arg">string</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
Use the <code>title</code> attribute to assign a title to the drawing. The title will be assigned to the "title" property of the resulting image. This
attribute has no effect on nested RVG objects.
</div>
<div class="sig">
<h3 id="RVG_width">width</h3>
<p><span class="arg">rvg</span>.width -> <span class="arg">width</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>The width of the RVG object in user coordinates.</p>
<h4>See also</h4>
<p><a href="#RVG_height">height</a></p>
</div>
<div class="sig">
<h3 id="RVG_x">x</h3>
<p><span class="arg">rvg</span>.x -> <span class="arg">x-offset</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
If this RVG object is nested within another RVG object, returns the x-offset in user coordinates from the upper-left corner of the enclosing RVG object.
</p>
<h4>See also</h4>
<p><a href="#RVG_y">y</a></p>
</div>
<div class="sig">
<h3 id="RVG_y">y</h3>
<p><span class="arg">rvg</span>.y -> <span class="arg">y-offset</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
If this RVG object is nested within another RVG object, returns the y-offset in user coordinates from the upper-left corner of the enclosing RVG object.
</p>
<h4>See also</h4>
<p><a href="#RVG_x">x</a></p>
</div>
<h2 class="methods">instance methods</h2>
<div class="sig">
<h3 id="RVG_draw">draw</h3>
<p><span class="arg">rvg</span>.draw -> image</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Causes all the drawing objects that have been added to the canvas to be rendered.</p>
<p>
Regardless of the order in which methods were called,
<code>draw</code> executes the methods in this order:
</p>
<ol>
<li>transforms, in the order they were called.</li>
<li><code>viewbox</code> and <code>preserve_aspect_ratio</code></li>
<li>styles</li>
<li>nested groups, RVG objects, shapes, text, and images, in the order they were added to the containing object</li>
</ol>
<p>Nested groups and RVG objects also follow this sequence.</p>
<h4>Returns</h4>
<p>An image</p>
<h4>Example</h4>
<pre>
img = rvg.draw
img.write('myDrawing.jpg')
</pre
>
</div>
<div class="sig">
<h3 id="RVG_g">g</h3>
<p><span class="arg">rvg.</span>g [{|<span class="arg">grp</span>| ...}] -> <span class="arg">group</span></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Calls <a href="rvggroup.html#new">RVG::Group.new</a> to construct a group and adds it to the enclosing RVG object. Yields to a block if one is present,
passing the new group as an argument.
</p>
<h4>Returns</h4>
<p>Returns the new group, so <code>RVG::Group</code> methods can be chained to this method.</p>
</div>
<div class="sig">
<h3 id="RVG_image">image</h3>
<p>
<span class="arg">rvg.</span>image(<span class="arg">raster_image</span>, <span class="arg">width</span>=nil, <span class="arg">height</span>=nil,
<span class="arg">x</span>=0, <span class="arg">y</span>=0) -> <span class="arg">image</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Calls <a href="rvgimage.html#new">RVG::Image.new</a> to construct an image and adds it to the enclosing RVG object.</p>
<h4>Returns</h4>
<p>Returns the new image, so <code>RVG::Image</code> methods can be chained to this method.</p>
<h4>Notes</h4>
<p>An <code>RVG::Image</code> object is <em>not</em> the same as a <a href="image1.html">Magick::Image</a> object!</p>
</div>
<div class="sig">
<h3 id="RVG_preserve_aspect_ratio">preserve_aspect_ratio</h3>
<p>
<span class="arg">rvg</span>.preserve_aspect_ratio(<span class="arg">align</span>, <span class="arg">meet_or_slice</span>='meet') [{|<span class="arg"
>self</span
>| ...}] -> <span class="arg">self</span>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
If you use the <a href="#RVG_viewbox">viewbox</a> method and the user coordinate system does not scale uniformly to the default coordinate system (for
example, the width and height of the RVG object is 4x3 and the user coordinate system is 16x9), use the <code>preserve_aspect_ratio</code> method to
specify whether or not the content is stretched to fit. If not, you can specify how to fit the content into the space.
</p>
<p><code>Preserve_aspect_ratio</code> yields to a block if one is present, passing <span class="arg">self</span> as an argument.</p>
<h4>Arguments</h4>
<dl>
<dt>align</dt>
<dd>
When the value of the <code>meet_or_slice</code> argument is 'meet' or 'slice', this argument controls the placement of the content within the
viewport. The <code>align</code> argument is the concatenation of an <em>x</em>-alignment and a <em>y</em>-alignment. The values are shown in these
lists:
<h6><em>x</em>-alignment</h6>
<dl>
<dt>xMin</dt>
<dd>align the minimum <em>x</em> value of the content with the left corner of the viewport.</dd>
<dt>xMid</dt>
<dd>vertically center the content within the viewport.</dd>
<dt>xMax</dt>
<dd>align the maximum <em>x</em> value of the content with the right corner of the viewport.</dd>
</dl>
<h6><em>y</em>-alignment</h6>
<dl>
<dt>YMin</dt>
<dd>align the minimum <em>y</em> value of the content with the top of the viewport.</dd>
<dt>YMid</dt>
<dd>horizontally center the content within the viewport.</dd>
<dt>YMax</dt>
<dd>align the maximum <em>y</em> value of the content with the bottom of the viewport</dd>
</dl>
</dd>
<dt>meet_or_slice</dt>
<dd>
This argument can have one of these three values:
<dl>
<dt>'none'</dt>
<dd>The content is scaled as necessary so that it fits exactly within the viewport. The aspect ratio is <em>not</em> maintained.</dd>
<dt>'meet'</dt>
<dd>
The content is scaled as necessary so that the larger dimension exactly fits the viewport. There may be some unused space in the viewport. The
aspect ratio is maintained.
</dd>
<dt>'slice'</dt>
<dd>
The content is scaled as necessary so that the smaller dimension exactly fits the viewport. Some of the content in the larger dimension may be cut
off. The aspect ratio is maintained.
</dd>
</dl>
</dd>
</dl>
<h4>Example</h4>
<p>
<a href="javascript:popup('preserve_aspect_ratio.rb.html')"
><img src="ex/preserve_aspect_ratio.gif" title="Click to see the example script" alt="preserve_aspect_ratio example"
/></a>
</p>
<h4>Returns</h4>
<p><span class="arg">Self</span>, so other <code>RVG</code> methods can be chained to this method.</p>
<h4>See Also</h4>
<p><a href="#RVG_viewbox">viewbox</a></p>
</div>
<div class="sig">
<h3 id="RVG_rvg">rvg</h3>
<p>
<span class="arg">rvg</span>.rvg(<span class="arg">width</span>, <span class="arg">height</span>, <span class="arg">x</span>=0,
<span class="arg">y</span>=0) [{|<span class="arg">new_rvg</span>| ...}] -> <em>self</em>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
This method constructs a new RVG object and adds it to the enclosing RVG object. Each nested RVG object can use the
<a href="#RVG_viewbox">viewbox</a> method to define its own coordinate system. The <code>rvg</code> method yields to a block, passing the nested RVG
object as an argument. Within the block, any drawing objects added to the nested RVG object are rendered within the nested RVG object's viewport.
</p>
<h4>Arguments</h4>
<dl>
<dt>width, height</dt>
<dd>Specifies the viewport width and height. The units are in the user coordinate system of the parent container.</dd>
<dt>x, y</dt>
<dd>The x- and y-axis offsets of the viewport upper-left corner. The units are in the user coordinate system of the parent container.</dd>
</dl>
<h4>Example</h4>
<p>
See the example for
<a href="#RVG_preserve_aspect_ratio">preserve_aspect_ratio</a>.
</p>
<h4>Returns</h4>
<p>The <code>RVG</code> object, so other <code>RVG</code> methods can be chained to this method.</p>
</div>
<div class="sig">
<h3 id="RVG_text">text</h3>
<p>
<span class="arg">rvg.</span>text(<span class="arg">x</span>=0, <span class="arg">y</span>=0, <span class="arg">text</span>=nil) [{|<span class="arg"
>text</span
>| ...}] -> <em>text</em>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
Calls <a href="rvgtext.html#new">RVG::Text.new</a> to construct a text object and adds it to the enclosing RVG object. Yields to a block if one is
present, passing the new text object as an argument.
</p>
<h4>Returns</h4>
<p>The <code>RVG::Text</code> object, so other <code>RVG::Text</code> methods can be chained to this method.</p>
</div>
<div class="sig">
<h3 id="RVG_use">use</h3>
<p>
<span class="arg">rvg</span>.use(<span class="arg">obj</span>, <span class="arg">x</span>=0, <span class="arg">y</span>=0,
<span class="arg">width</span>=nil, <span class="arg">height</span>=nil) -> <em>use</em>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Calls <a href="rvguse.html#new">RVG::Use.new</a> to construct a <code>use</code> object and adds it to the RVG object.</p>
<p>
When the referenced argument is another RVG object,
<span class="arg">width</span> and <span class="arg">height</span> can be used to specify the width and height of the viewport. If present and non-nil,
these arguments override any width and height specified when the RVG object was created. You must specify the viewport size either when creating the RVG
object or when referencing it with <code>use</code>.
</p>
<h4>Examples</h4>
<p>See <a href="rvguse.html#new">RVG::Use.new</a></p>
<h4>Returns</h4>
<p>The <code>RVG::Use</code> object, so other <code>RVG::Use</code> methods can be chained to this method.</p>
</div>
<div class="sig">
<h3 id="RVG_viewbox">viewbox</h3>
<p>
<span class="arg">rvg</span>.viewbox(<span class="arg">min_x</span>, <span class="arg">min_y</span>, <span class="arg">width</span>,
<span class="arg">height</span>) [{|<span class="arg">self</span>| ...}] -> <em>self</em>
</p>
</div>
<div class="desc">
<h4>Description</h4>
<p>
The area of the RVG object is called the <em>viewport</em>. By default the origin of the coordinate system for an RVG object is (0,0). The user
coordinates are pixels and the width and height are established by the <span class="arg">width</span> and <span class="arg">height</span> arguments to
<code>RVG.new</code>.
</p>
<p>
Use the <code>viewbox</code> method to superimpose a user coordinate system on the viewport. The <code>viewbox</code> method lets you set up a
coordinate system using the units of your choice.
</p>
<p>The <code>viewbox</code> method yields to a block if one is present, passing <code>self</code> as an argument.</p>
<h4>Arguments</h4>
<dl>
<dt>min_x, min_y</dt>
<dd>The minimum <em>x</em>-coordinate and <em>y</em>-coordinate of the user coordinate system.</dd>
<dt>width, height</dt>
<dd>The width and height of the user coordinate system.</dd>
</dl>
<h4>Example</h4>
<p>
In the following examples, because the <code>viewbox</code> method specifies the dimensions of the coordinate system, the dimensions specified for the
graphic objects can remain the same while the size of the canvas changes.
</p>
<p>
<strong>Rendered into a 300x200 viewport</strong
><a href="javascript:popup('view_box.rb.html')"
><img src="ex/view_box_300x200.gif" title="Click to see the example script" alt="viewbox 300x200 example"
/></a>
</p>
<p>
<strong>Rendered into a 150x200 viewport</strong
><a href="javascript:popup('view_box.rb.html')"
><img src="ex/view_box_150x200.gif" title="Click to see the example script" alt="viewbox 150x200 example"
/></a>
</p>
<h4>Returns</h4>
<p><span class="arg">Self</span>, so other <code>RVG</code> methods may be chained to <code>viewbox</code>.</p>
<h4>See Also</h4>
<p><a href="#RVG_preserve_aspect_ratio">preserve_aspect_ratio</a></p>
</div>
<h2 id="units" class="methods">Units</h2>
<div style="margin-left: 235px; margin-top: 1em">
<p>
RVG supports a subset of the unit identifiers defined by the SVG specification. In RVG, unit identifiers are methods in the Float and Integer classes.
The units are (for the most part) defined in terms of "dots per inch," accordingly, the unit identifier methods are added only if the value
</p>
<pre>
Magick::RVG.dpi = NN
</pre
>
<p>is defined, where NN is the number of "dots" (pixels) per inch you wish to use. (Hint: 90 is a good default.)</p>
<p>For example, to specify a length of 10 inches, you can use</p>
<pre>
Magick::RVG.dpi = 90
length = 10.in # => 900 pixels
</pre
>
<p>
If the dpi is defined, the following methods are added to
<code>Float</code> and <code>Integer</code>
</p>
<dl>
<dt>px</dt>
<dd>Pixel. The default unit of measurement.</dd>
<dt>in</dt>
<dd>Converts inches to pixels</dd>
<dt>mm</dt>
<dd>Converts millimeters to pixels</dd>
<dt>cm</dt>
<dd>Converts centimeters to pixels</dd>
<dt>pt</dt>
<dd>Converts points to pixels. There are 72 points to the inch.</dd>
<dt>pc</dt>
<dd>Converts picas to pixels. There are 12 points to the pica.</dd>
<dt>deg</dt>
<dd>Degrees. The default unit of rotation.</dd>
<dt>rad</dt>
<dd>Converts radians to degrees.</dd>
<dt>grad</dt>
<dd>Converts grads to degrees. There are 400 grads in a circle.</dd>
<dt>pct</dt>
<dd>This conversion takes an numeric argument and returns a percentage of the argument. For example 20.pct(150) -> 30</dd>
</dl>
<p>SVG also supports <em>em</em> and <em>ex</em>, which are measurements based on the font size. RVG does not.</p>
</div>
<p class="spacer"> </p>
<div class="nav">
« <a href="rvgtut.html">Prev</a> | <a href="index.html">Contents</a> | <a href="rvggroup.html">Next</a>
»
</div>
</body>
</html>
|
