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<h6 id="header">RMagick User's Guide and Reference</h6>
<div class="nav">
« <a href="draw.html">Prev</a> | <a href=
"index.html">Contents</a> | <a href=
"info.html">Next</a> »
</div>
<h1>Miscellaneous classes</h1>
<div id="toc">
<h2>Table of Contents</h2>
<h3><a href="#view">The Image::View class</a></h3>
<ul>
<li><a href="#view">Image::View</a></li>
</ul>
<h3><a href="#Geometry">The Geometry class</a></h3>
<ul>
<li><a href="#Geometry">Geometry</a></li>
</ul>
<h3><a href="#Pixel">The Pixel class</a></h3>
<ul>
<li><a href="#Pixel">Pixel</a></li>
</ul>
<h3><a href="#struct">Struct classes</a></h3>
<ul>
<li><a href="#AffineMatrix">AffineMatrix</a></li>
<li><a href="#Chromaticity">Chromaticity</a></li>
<li><a href="#Pixel">Pixel</a></li>
<li><a href="#Point">Point</a></li>
<li><a href="#Primary">Primary</a></li>
<li><a href="#Rectangle">Rectangle</a></li>
<li><a href="#Segment">Segment</a></li>
</ul>
<h3><a href="#fill">Fill classes</a></h3>
<ul>
<li><a href="#GradientFill">GradientFill</a></li>
<li><a href="#HatchFill">HatchFill</a></li>
<li><a href="#TextureFill">TextureFill</a></li>
</ul>
<h3><a href="#exception">Exception classes</a></h3>
<ul>
<li><a href="#MagickError">ImageMagickError</a></li>
</ul>
</div>
<div class="subhd">
<h2 id="view">The Image::View class</h2>
<div class="intro">
<h3>Introduction</h3>
<p>A view is a rectangle in an image. Within the view pixels
can be addressed by specifying their <code>[i][j]</code>
coordinates. The <span class="arg">i</span>, <span class=
"arg">j</span> index values can identify a single pixel or
multiple pixels. Pixels can be accessed or modified
individually or collectively. Pixel <em>channels</em> (that
is, the red, green, blue, and opacity components) can be
accessed or modified individually or collectively. The
<a href="#view_sync">sync</a> method stores modified pixels
back into the image.</p>
</div>
<h3>class Image::View <span class="superclass"><
Object</span></h3>
<div class="sig">
<h4>new</h4>
<p>Image::View.new(<span class="arg">img</span>, <span class=
"arg">x</span>, <span class="arg">y</span>, <span class=
"arg">width</span>, <span class="arg">height</span>) ->
aView</p>
</div>
<div class="desc">
<h5>Description</h5>
<p>The easiest way to use an <code>Image::View</code> object
is to create it with the <a href=
"image3.html#view">Image#view</a> method, which provides a
block-scoped view and automatic sync'ing. You probably won't
want to create a view by calling <code>new</code>.</p>
<h5>Arguments</h5>
<dl>
<dt>img</dt>
<dd>The image from which the view is taken.</dd>
<dt>x, y</dt>
<dd>The x- and y-offsets of the view relative to the
top-left corner of the image. Within the view, pixel
addresses are relative to the top-left corner of the
view.</dd>
<dt>width, height</dt>
<dd>The number of columns and the number of rows in the
view.</dd>
</dl>
<p>It is an error to specify a view that exceeds the
boundaries of the image.</p>
</div>
<div class="sig">
<h4>[][]</h4>
<p><span class="arg">view</span>[<span class=
"arg">i</span>][<span class="arg">j</span>] ->
<em>aPixel</em> or <em>anArray</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Return one or more pixels in the view. If i and j are each
a single integer value, returns a single pixel. For any other
indexes, returns an array of one or more pixels. If any index
exceeds the boundaries of the view, raises
<code>IndexError</code>.</p>
<h5>Arguments</h5>
<p>The <span class="arg">i</span> index identifies a set of
rows in the view. The <span class="arg">j</span> index
identifies a set of columns in the view. The pixels that are
returned are the intersection of these two sets. The indexes
can be:</p>
<dl>
<dt>omitted</dt>
<dd>If <span class="arg">i</span> is omitted, all the rows
are used. If <code>j</code> is omitted, all the columns are
used.</dd>
<dt>an integer</dt>
<dd>or an object that can be converted to an integer. A
single integer identifies a single row or column. Identify
a single pixel by specifying integers for both indexes. If
the index is negative, counts from the bottom row or right
column of the view.</dd>
<dt>start, length</dt>
<dd>Identifies the set of <code>length</code> rows or
columns starting with <code>start</code>. If
<code>start</code> is negative, starts at the bottom row or
right column of the view.</dd>
<dt>an object that responds to <code>each</code></dt>
<dd>The index may be any object that responds to
<code>each</code> by returning a sequence of objects that
can be converted to integers. An array with integer values
or a range of integers are two examples.</dd>
</dl>
<h5>Examples</h5>
<pre>
# Get the 2nd pixel in the 4th row of the view.
pixel = view[3][1] # returns a pixel
# Returns an array with only one value
pixels = view[[3]][[1]]
# Get all the pixels in the 4th row
pixels = view[3][]
# Use arrays to specify a non-contiguous set of rows and columns
pixels = view[[1,3,5]][[2,4,6]]
# Use ranges to specify a contigous set of rows and columns
pixels = view[1..5][2..6]
</pre>
</div>
<div class="sig">
<h4>[][].red<br />
[][].green<br />
[][].blue<br />
[][].opacity</h4>
<p>[<span class="arg">i</span>][<span class=
"arg">j</span>].red -> <em>anInteger</em> or
<em>anArray</em><br />
[<span class="arg">i</span>][<span class=
"arg">j</span>].green -> <em>anInteger</em> or
<em>anArray</em><br />
[<span class="arg">i</span>][<span class="arg">j</span>].blue
-> <em>anInteger</em> or <em>anArray</em><br />
[<span class="arg">i</span>][<span class=
"arg">j</span>].opacity -> <em>anInteger</em> or
<em>anArray</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>If the indexes identify a single pixel, these methods
return the value of the red, green, blue, or opacity channel
of that pixel. If the indexes identify more than one pixel,
these methods return an array of values. See
<code>[][]</code> for a description of possible index
arguments.</p>
<h5>Examples</h5>
<pre>
# Get the value of the green channel of
# the top-left pixel in the view.
view[0][0] = Pixel(0,128,255)
g = view[0][0].green # returns 128
# Get the maximum value of the red channel
# for all the pixels in the top row of the view.
m = view[0][].red.max
</pre>
</div>
<div class="sig">
<h4>[][]=</h4>
<p><span class="arg">view</span>[<span class=
"arg">i</span>][<span class="arg">j</span>] = <em>rvalue</em>
-> <code>nil</code></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Replaces each pixel identified by the indexes with a
duplicate of <span class="arg">rvalue</span>. The rvalue is
either a <a href="#Pixel">Pixel</a> object or a <a href=
"imusage.html#color_name">color name</a>. If
<code>rvalue</code> is a color name, calls
<code>Pixel.from_color</code> to create a pixel.</p>
<h5>Arguments</h5>
<p>The indexes are the same as <code>[][]</code>, above.</p>
<dl>
<dt>rvalue</dt>
<dd>Either a pixel or a color name.</dd>
</dl>
</div>
<div class="sig">
<h4>[][].red=<br />
[][].green=<br />
[][].blue=<br />
[][].opacity=</h4>
<p>[<span class="arg">i</span>][<span class=
"arg">j</span>].red = <em>anInteger</em> ->
<code>nil</code><br />
[<span class="arg">i</span>][<span class=
"arg">j</span>].green = <em>anInteger</em> ->
<code>nil</code><br />
[<span class="arg">i</span>][<span class="arg">j</span>].blue
= <em>anInteger</em> -> <code>nil</code><br />
[<span class="arg">i</span>][<span class=
"arg">j</span>].opacity = <em>anInteger</em> ->
<code>nil</code></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Assigns <em>anInteger</em> to the red, green, blue, or
opacity channel of the pixel or pixels identified by the
indexes.</p>
<h5>Examples</h5>
<pre>
# Set the red channel of all the pixels in the 2nd
# row of the view to MaxRGB
view[1][].red = MaxRGB
# Set the green channel of the pixel at [20][30] to
# half that of its left-hand neighbor.
view[20][30].green = view[20][29].green * 0.5
</pre>
</div>
<div id="view_sync" class="sig">
<h4>sync</h4>
<p><span class="arg">view</span>.sync(<span class=
"arg">force</span>=<code>false</code>) ->
<code>true</code> or <code>false</code></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>If any of the pixels in the view have been modified, this
method stores them in the image. If no pixels have been
modified, this method has no effect.</p>
<h5>Arguments</h5>
<dl>
<dt>force</dt>
<dd>If <code>true</code>, forces the view pixels to be
stored in the image even if none have been modified.</dd>
</dl>
<h5>Returns</h5>Returns <code>true</code> if the pixels were
stored in the image either because the <code>dirty</code>
flag was <code>true</code> or <code>force</code> was
<code>true</code>, <code>false</code> otherwise.
</div>
<div class="sig">
<h4>dirty<br />
dirty=</h4>
<p>view.dirty -> <code>true</code> or
<code>false</code><br />
view.dirty = <code>true</code> or <code>false</code></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Any modification to a pixel in the view causes the
<code>dirty</code> attribute to be set to <code>true</code>.
You can (although normally you don't need to) set
<code>dirty=true</code> to force <code>sync</code> to store
the pixels in the image, or set <code>dirty=false</code> to
keep <code>sync</code> from storing the pixels.</p>
</div>
<div class="sig">
<h4>x<br />
y<br />
width<br />
height</h4>
<p>x -> anInteger<br />
y -> anInteger<br />
width -> anInteger<br />
height -> anInteger</p>
</div>
<div class="desc">
<h5>Description</h5>
<p>The <span class="arg">x</span>, <span class=
"arg">y</span>, <span class="arg">width</span>, and
<span class="arg">height</span> arguments specified when the
view was created.</p>
</div>
</div>
<div class="subhd" id="Geometry">
<h2>The Geometry class</h2>
<div class="intro">
<h3>Introduction</h3>
<p>The Geometry class contains the same information as an
×Magick <a href="imusage.html#geometry">geometry
string</a>. Geometry objects are interchangable with geometry
strings.</p>
</div>
<h3>class Geometry <span class="superclass"><
Object</span></h3>
<div class="sig">
<h4>new</h4>
<p>Geometry.<span class="arg">new</span>(<span class=
"arg">width</span>=nil, <span class="arg">height</span>=nil,
<span class="arg">x</span>=nil, <span class=
"arg">y</span>=nil, <span class="arg">flag</span>=nil) ->
<em>aGeometry</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Constructs a new <code>Geometry</code> object.</p>
<h5>Attributes</h5>
<p>A geometry string has the general form
"WxH+x+y[!@%<>]. In a <code>Geometry</code> object,</p>
<dl>
<dt>width</dt>
<dd>specifies the W value</dd>
<dt>height</dt>
<dd>specifies the H value</dd>
<dt>x, y</dt>
<dd>specify the x and y values, respectively</dd>
<dt>flag</dt>
<dd>one of the constants shown in this table:</dd>
</dl>
<table summary="geometry flag constants" class=
"simple_table">
<caption>
<strong>Geometry flag constants</strong>
</caption>
<tr>
<td align="center"><strong>Constant<br />
name</strong></td>
<td align="center"><strong>Geometry<br />
string flag</strong></td>
<td align="center"><strong>Explanation</strong></td>
</tr>
<tr>
<td>PercentGeometry</td>
<td align="center">%</td>
<td>Normally the attributes are treated as pixels. Use
this flag when the <code>width</code> and
<code>height</code> attributes represent
<em>percentages</em>. For example, 125x75 means 125% of
the height and 75% of the width. The <code>x</code> and
<code>y</code> attributes are not affected by this
flag.</td>
</tr>
<tr>
<td>AspectGeometry</td>
<td align="center">!</td>
<td>Use this flag when you want to force the new image to
have exactly the size specified by the the
<code>width</code> and <code>height</code>
attributes.</td>
</tr>
<tr>
<td>LessGeometry</td>
<td align="center"><</td>
<td>Use this flag when you want to change the size of the
image only if both its width and height are smaller the
values specified by those attributes. The image size is
changed proportionally.</td>
</tr>
<tr>
<td>GreaterGeometry</td>
<td align="center">></td>
<td>Use this flag when you want to change the size of the
image if either its width and height exceed the values
specified by those attributes. The image size is changed
proportionally.</td>
</tr>
<tr>
<td>AreaGeometry</td>
<td align="center">@</td>
<td>This flag is useful only with a single
<code>width</code> attribute. When present, it means the
<code>width</code> attribute represents the total area of
the image in pixels.</td>
</tr>
</table>
<p>If any attribute is omitted the default is nil or 0.</p>
<h5>Example</h5>
<pre>
g = Magick::Geometry.new(100,200,nil,nil,Magick::AspectGeometry)
</pre>
</div>
</div>
<div class="sig">
<h4>from_s</h4>
<p>Geometry.<span class="arg">from_s</span>(<span class=
"arg">string</span>) -> <em>aGeometry</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Constructs a new <code>Geometry</code> object from a
<a href="imusage.html#geometry">geometry string</a>.</p>
</div>
<div class="sig">
<h4>to_s</h4>
<p><span class="arg">geometry.</span>to_s() ->
<em>aString</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Returns the string equivalent of the <code>Geometry</code>
object..</p>
</div>
<div class="subhd" id="Pixel">
<h2>The Pixel class</h2>
<div class="intro">
<h3>Introduction</h3>
<p>A pixel describes the smallest individually addressable
part of an image. In the RBG <a href=
"constants.html#ColorspaceType">colorspace</a>, a pixel's
color is described by its intensity in the red, green, and
blue channels. Its opacity is described by its intensity in
the opacity (also called alpha, or matte) channel. In the
CMYK colorspace a pixel's color is described by its intensity
in the cyan, magenta, yellow and black (K) channels.
Intensity is a value between 0 and <a href=
"constants.html#MaxRGB">MaxRGB</a>.</p>
<p>Usually, RMagick methods operate on entire images or on
groups of pixels that have been selected by their position or
color. Some methods, such as <a href=
"image2.html#pixel_color">pixel_color</a> and <a href=
"image3.html#view">view</a>, operate on individual pixels or
even on the RGBA (or CMYK) components thereof.</p>
</div>
<h3>class Pixel <span class="superclass"><
Object</span><br />
<span class="mixin">mixes in Comparable, Observable</span></h3>
<div class="sig">
<h4>new</h4>
<p>Pixel.<span class="arg">new</span>(<span class=
"arg">red</span>, <span class="arg">green</span>,
<span class="arg">blue</span>, <span class=
"arg">opacity</span>) -> <em>aPixel</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Constructs a pixel object from the specified red, green,
blue, and opacity intensities. The intensity is a number
between 0 and <a href=
"constants.html#Miscellaneous_constants">MaxRGB</a>.</p>
<h5>Attributes</h5>
<dl>
<dt>red, green, blue</dt>
<dd>The red, green, and blue intensities of the pixel,
respectively. If the colorspace is <a href=
"constants.html#ColorspaceType">CMYKColorspace</a>, these
attributes are interpreted as the cyan, magenta, and yellow
intensities.</dd>
<dt>opacity</dt>
<dd>The opacity level. Higher intensities are more
transparent. If the colorspace is CMYKColorspace, this
attribute is interpreted as the black intensity.</dd>
<dt>cyan, magenta, yellow, black</dt>
<dd>These attributes are aliases for <code>red</code>,
<code>green</code>, <code>blue</code>, and
<code>opacity</code>, respectively.</dd>
</dl>
</div>
<div class="sig">
<h4>from_color</h4>
<p>Pixel.<span class="arg">from_color</span>(<span class=
"arg">color_name</span>) -> <em>aPixel</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Constructs a new Pixel object from the <a href=
"imusage.html#color_names">color name</a>. Raises
ArgumentError if the name is unknown.</p>
</div>
<div class="sig">
<h4>from_HSL</h4>
<p>Pixel.<span class="arg">from_HSL</span>(<span class=
"arg">[hue, saturation, luminosity]</span>) ->
<em>aPixel</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Constructs a pixel object from the specified array of 3
values: hue, saturation, and luminosity.</p>
</div>
<div class="sig">
<h4 id="spaceship"><=></h4>
<p><span class="arg">pixel1</span> <=> <span class=
"arg">pixel2</span> -> -1, 0, <em>or</em> 1</p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Returns -1, 0, or 1 depending on if <span class=
"arg">pixel1</span> is "less than," equal, or "greater than"
the <span class="arg">pixel2</span>.</p>
<p>Since there is no way to rank order pixels, and thus
determine if one pixel is "greater than" or "less than"
another, this method uses an arbitrary algorithm that ensures
these two conditions:</p>
<ol>
<li>pixels with equal RGBA (or CMYK) values compare equal,
and</li>
<li>comparing the same two unequal pixels always returns
the same result.</li>
</ol>
<h5>Returns</h5>
<p>-1, 0, or 1</p>
<h5>See also</h5>
<p><a href="#fcmp">fcmp</a></p>
</div>
<div class="sig">
<h4 id="fcmp">fcmp</h4>
<p><span class="arg">pixel</span>.fcmp(<span class=
"arg">aPixel</span>, <span class="arg">fuzz</span>=0.0,
<span class="arg">colorspace</span>=RGBColorspace) ->
<code>true</code> <em>or</em> <code>false</code></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Returns true if the argument is the same color as
<span class="arg">pixel</span>.</p>
<h5>Arguments</h5>
<dl>
<dt>pixel</dt>
<dd>The pixel to which the receiver is compared.</dd>
<dt>fuzz</dt>
<dd>The amount of fuzz to allow before the colors are
considered to be different.</dd>
<dt>colorspace</dt>
<dd>If the pixels are in the CMYK colorspace, specify
<a href=
"constants.html#ColorspaceType">Magick::CMYKColorspace</a>.</dd>
</dl>
<h5>Returns</h5>
<p><code>true</code> or <code>false</code></p>
<h5>See also</h5>
<p><a href="#spaceship"><=></a></p>
</div>
<div class="sig">
<h4>intensity</h4>
<p><span class="arg">pixel</span>.intensity() ->
anInteger</p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Returns the intensity of the pixel. The intensity is
computed as 0.299*R+0.587*G+0.114*B.</p>
</div>
<div class="sig">
<h4>to_color</h4>
<p><span class="arg">pixel</span>.to_color(<span class=
"arg">compliance</span>=AllCompliance, <span class=
"arg">matte</span>=<code>false</code>, <span class=
"arg">depth</span>=<code>QuantumDepth</code>) ->
<em>aString</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Returns the <a href="imusage.html#color_names">color
name</a> corresponding the the pixel values. If there is no
such named color in the specified color standard, returns a
string in the form "#RRGGBBOO" or, if the depth is 16,
"#RRRRGGGGBBBBOOOO".</p>
<h5>Arguments</h5>
<dl>
<dt>compliance</dt>
<dd>A <a href=
"constants.html#ComplianceType">ComplianceType</a>
constant. The default value of AllCompliance causes
<code>to_color</code> to search for a color name in any of
the 3 defined color standards.</dd>
<dt>matte</dt>
<dd>If false, the pixel's opacity attribute is
ignored.</dd>
<dt>depth</dt>
<dd>An image depth. The default is the quantum depth used
when ×Magick was compiled. The values 16 and 32 can
be used only when ×Magick was compiled with the
appropriate QuantumDepth.</dd>
</dl>
<h5>See also</h5>
<p>Compare this method to <a href=
"image3.html#to_color">Image#to_color</a>, in which the
<span class="arg">matte</span> and <span class=
"arg">depth</span> values are taken from an image.</p>
</div>
<div class="sig">
<h4>to_HSL</h4>
<p><span class="arg">pixel</span>.to_HSL ->
<em>anArray</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Converts the RGB representation of the pixel to hue,
saturation, and luminosity values.</p>
<h5>Returns</h5>
<p>An array of the form <code>[hue, saturation,
luminosity]</code>.</p>
</div>
</div>
<div class="subhd">
<h2 id="struct">Struct classes</h2>
<div class="intro">
<h3>Introduction</h3>
<p>These classes are created by the Struct class and are used
to create objects used as attribute and argument values in
other RMagick classes. Like all the classes created by
Struct, these classes define both getter and setter methods
for their attributes. That is, for an attribute <em>x</em>
both the <code>x</code> and <code>x=</code> methods are
defined.</p>
<p>The <code>Pixel</code> and <code>Geometry</code> classes
define additional constructors and conversion methods.</p>
</div>
<h3 id="AffineMatrix">class AffineMatrix <span class=
"superclass">< Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>AffineMatrix.<span class="arg">new</span>(<span class=
"arg">sx</span>, <span class="arg">rx</span>, <span class=
"arg">ry</span>, <span class="arg">sy</span>, <span class=
"arg">tx</span>, <span class="arg">ty</span>) ->
<em>anAffineMatrix</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>An AffineMatrix object describes a coordinate
transformation. This object is used as an argument to the
<a href=
"image1.html#affine_transform">Image#affine_transform</a>,
<a href=
"image1.html#composite_affine">Image#composite_affine</a>,
and <a href="draw.html#affine_eq">Draw#affine</a>
methods.</p>
<h5>Attributes</h5>
<dl>
<dt>sx, sy</dt>
<dd>The amount of scaling on the x- and y- axes.</dd>
<dt>rx, ry</dt>
<dd>The amount of rotation on the x- and y-axes, in
radians.</dd>
<dt>tx, ty</dt>
<dd>The amount of translation on the x- and y-axes, in
pixels.</dd>
</dl>
</div>
<h3 id="Chromaticity">class Chromaticity <span class=
"superclass">< Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>Chromaticity.<span class="arg">new</span>(<span class=
"arg">red_primary</span>, <span class=
"arg">green_primary</span>, <span class=
"arg">blue_primary</span>, <span class=
"arg">white_point</span>) -> <em>aChromaticity</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>A Chromaticity object represents chromaticity values for
the <a href=
"imageattrs.html#chromaticity">Image#chromaticity</a>
attribute.</p>
<h5>Attributes</h5>
<p>The attribute values are <a href="#Primary">Primary</a>
objects.</p>
<dl>
<dt>red_primary</dt>
<dd>Red primary point (e.g. red_primary.x=0.64,
red_primary.y=0.33)</dd>
<dt>green_primary</dt>
<dd>Green primary point (e.g. green_primary.x=0.3,
green_primary.y=0.6)</dd>
<dt>blue_primary</dt>
<dd>Blue primary point (e.g. blue_primary.x=0.15,
blue_primary.y=0.06)</dd>
<dt>white_point</dt>
<dd>White point (e.g. white_point.x=0.3127,
white_point.y=0.329)</dd>
</dl>
</div>
<h3 id="Point">class Point <span class="superclass"><
Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>Point.new(<span class="arg">x</span>, <span class=
"arg">y</span>) -> <em>aPoint</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>The value of the <code>pixels_per_em</code> attribute in
the TypeMetric struct returned by <a href=
"draw.html#get_type_metrics">Draw#get_type_metrics</a> is a
<code>Point</code> object..</p>
<h5>Attributes</h5>
<dl>
<dt>x</dt>
<dd>Character width</dd>
<dt>y</dt>
<dd>Character height</dd>
</dl>
</div>
<h3 id="Primary">class Primary <span class="superclass"><
Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>Primary.new(<span class="arg">x</span>, <span class=
"arg">y</span>, <span class="arg">z</span>) ->
<em>aPrimary</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>See <a href="#Chromaticity">class Chromaticity</a>.</p>
<h5>Attributes</h5>
<dl>
<dt>x</dt>
<dd>X ordinate</dd>
<dt>y</dt>
<dd>Y ordinate</dd>
<dt>z</dt>
<dd>Z ordinate. This attribute is always ignored.</dd>
</dl>
</div>
<h3 id="Rectangle">class Rectangle <span class=
"superclass">< Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>Rectangle.new(<span class="arg">width</span>, <span class=
"arg">height</span>, <span class="arg">x</span>, <span class=
"arg">y</span>) -> <em>aRectangle</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>The value of the <a href=
"imageattrs.html#tile_info">Image#tile_info</a> and <a href=
"imageattrs.html#bounding_box">Image#bounding_box</a>
attributes.</p>
<h5>Attributes</h5>
<dl>
<dt>width</dt>
<dd>Rectangle width</dd>
<dt>height</dt>
<dd>Rectangle height</dd>
<dt>x</dt>
<dd>Offset from the left edge of the image</dd>
<dt>y</dt>
<dd>Offset from the top edge of the image</dd>
</dl>
</div>
<h3 id="Segment">class Segment <span class="superclass"><
Struct</span></h3>
<div class="sig">
<h4>new</h4>
<p>Segment.new(<span class="arg">x1</span>, <span class=
"arg">y1</span>, <span class="arg">x2</span>, <span class=
"arg">y2</span>) -> <em>aSegment</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>The value of the <code>bounds</code> attribute in the
<a href="draw.html#get_type_metrics">TypeMetric</a>
class.</p>
<h5>Attributes</h5>
<p><em>x1</em>, <em>y1</em>, <em>x2</em>, <em>y2</em></p>
</div>
</div>
<div class="subhd">
<h2 id="fill">Fill classes</h2>
<div class="intro">
<h3>Introduction</h3>
<p>The <a href="image.html#new">Image#new</a> and <a href=
"ilist.html#new_image">ImageList#new_image</a> methods accept
a <code>Fill</code> object as an optional third argument. A
<code>Fill</code> object is an instance of a <em>Fill
class</em>. Fill classes are designed to support custom
background fills. Each <code>Fill</code> class defines only
two methods, <code>initialize</code> and <code>fill</code>.
The <code>initialize</code> method is called from the
application to create an instance of the fill class. It
accepts any arguments and does whatever is necessary to
create the fill. The <code>fill</code> method is called from
the initialize method of the new image object, after the
image is completely initialized. The <code>fill</code> method
gets the image as its only argument and sends whatever
methods are necessary to the image to fill the image's
background.</p>
<p>RMagick supplies three Fill classes,
<code><strong>HatchFill</strong></code>,
<code><strong>GradientFill</strong></code>, and
<code><strong>TextureFill</strong></code>. These classes are
explained below. The <code>HatchFill</code> class is intended
as an example of how to write a <code>Fill</code> class and
is written in pure Ruby. You can read it in RMagick.rb.</p>
</div>
<h3 id="GradientFill">class GradientFill <span class=
"superclass">< Object</span></h3>
<div class="sig">
<h4>new</h4>
<p><span class="arg">GradientFill.new(<em>x1</em>,
<em>y1</em>, <em>x2</em>, <em>y2</em>, <em>start_color</em>,
<em>end_color</em>) -></span> <em>aGradientFill</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Creates a gradient fill. The <span class="arg">x1</span>,
<span class="arg">y1</span>, and <span class="arg">x2</span>,
<span class="arg">y2</span> arguments describe either a line
or a point. If <span class="arg">x1</span> != <span class=
"arg">x2</span> or <span class="arg">y1</span> !=
<span class="arg">y2</span>, then the arguments describe the
starting line for the gradient. The gradient will start with
<span class="arg">start_color</span> at the starting line and
gradually transform to <span class="arg">end_color</span> as
the distance increases from the starting line.</p>
<p>If <span class="arg">x1</span> == <span class=
"arg">x2</span> and <span class="arg">y1</span> ==
<span class="arg">y2</span>, the gradient radiates from the
specified point, gradually transforming from <span class=
"arg">start_color</span> to <span class=
"arg">end_color</span>.</p>
<p>The line or point does not have to lie within the image
bounds.</p>
<h5>Arguments</h5>
<dl>
<dt>x1, y1</dt>
<dd>One of the starting line end-points.</dd>
<dt>x2, y2</dt>
<dd>The other end-point on the starting line.</dd>
<dt>start_color</dt>
<dd>The color at the starting line.</dd>
<dt>end_color</dt>
<dd>The color to which the gradient transforms.</dd>
</dl>
<h5>Example</h5>
<p><a href=
"javascript:popup('gradientfill.rb.html')"><img src=
"ex/gradientfill.gif" alt="GradientFill example" title=
"Click to see the example script" /></a></p>
</div>
<h3 id="HatchFill">class HatchFill <span class=
"superclass">< Object</span></h3>
<div class="sig">
<h4>new</h4>
<p>HatchFill.new(<span class="arg">background_color</span>,
<span class="arg">hatch_color</span>='white', <span class=
"arg">dist</span>=10) -> <em>aHatchFill</em></p>
</div>
<div class="desc">
<h4>Description</h4>
<p>Creates a cross-hatched fill.</p>
<h4>Arguments</h4>
<dl>
<dt>background_color</dt>
<dd>The image background color.</dd>
<dt>hatch_color</dt>
<dd>The color of the cross-hatch lines.</dd>
<dt>dist</dt>
<dd>The distance between cross-hatch lines, in pixels.</dd>
</dl>
<h4>Example</h4>
<p><a href="javascript:popup('hatchfill.rb.html')"><img src=
"ex/hatchfill.gif" alt="HatchFill example" title=
"Click to see the example script" /></a></p>
</div>
<h3 id="TextureFill">class TextureFill <span class=
"superclass">< Object</span></h3>
<div class="sig">
<h4>new</h4>
<p>TextureFill.new(<span class="arg">texture_image</span>)
-> <em>aTextureFill</em></p>
</div>
<div class="desc">
<h5>Description</h5>
<p>Creates a texture fill by tiling the <span class=
"arg">texture_image</span> to fill the image.</p>
<h5>Arguments</h5>
<p>The texture to be used as the background. May be an image
or imagelist. If <span class="arg">texture_image</span> is an
imagelist, uses the current image.</p>
<h5>Example</h5>
<p><a href=
"javascript:popup('texturefill.rb.html')"><img src="ex/texturefill.gif"
alt="TextureFill example" title=
"Click to see the example script" /></a></p>
</div>
</div>
<div class="subhd">
<h2 id="exception">Exception classes</h2>
<h3 id="MagickError">class ImageMagickError <span class=
"superclass">< StandardError</span></h3>
<div class="desc">
<h4>Description</h4>
<p>When an ×Magick function returns an error condition,
RMagick raises an <code>ImageMagickError</code>
exception.</p>
<h4>Attributes</h4>
<dl>
<dt>magick_location</dt>
<dd>With GraphicsMagick 1.1, this attribute contains a
string that indicates the source file (module), function
and line number in which GraphicsMagick raised the error.
The string is in the form <tt><function> at
<module>:<line></tt>. (Get-only.)</dd>
</dl>
</div>
</div>
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