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  <h6 id="header">RMagick 0.0.0 User's Guide and Reference</h6>

  <div class="nav">
    &laquo;&nbsp;<a href="rvgtut.html">Prev</a> | <a href=
    "index.html">Contents</a> | <a href=
    "rvggroup.html">Next</a>&nbsp;&raquo;
  </div>

  <h1>class RVG <span class="superclass">&lt; 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> ] -&gt; <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 -&gt; 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 -&gt; <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 -&gt; <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 -&gt; <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 -&gt; <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 -&gt; <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 -&gt; <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 -&gt; <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 -&gt; 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>| ...}] -&gt; <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) -&gt;
    <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>| ...}] -&gt; <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('PreserveAspectRatio.rb.html')"><img src=
    "ex/PreserveAspectRatio.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>| ...}] -&gt;
    <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>| ...}]
    -&gt; <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) -&gt; <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>| ...}]
    -&gt; <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('ViewBox.rb.html')"><img src=
    "ex/ViewBox_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('ViewBox.rb.html')"><img src=
    "ex/ViewBox_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 Fixnum 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  # =&gt; 900 pixels
</pre>

    <p>If the dpi is defined, the following methods are added to
    <code>Float</code> and <code>Fixnum</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) -&gt;
      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>

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