operationjai.html

Geotools是一个开源的Java GIS工具包,可利用它来开发符合标准的地理信息系统。Geotools提供了OGC(Open Geospatial Consortium)规范的一个实现来作为他们的

<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=1><FONT SIZE="+2">
<B>Field Detail</B></FONT></TD>
</TR>
</TABLE>

<A NAME="operation"><!-- --></A><H3>
operation</H3>
<PRE>
protected final <A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/OperationDescriptor.html" title="class or interface in javax.media.jai">OperationDescriptor</A> <B>operation</B></PRE>
<DL>
<DD>The JAI's operation descriptor.
<P>
<DL>
</DL>
</DL>

<!-- ========= CONSTRUCTOR DETAIL ======== -->

<A NAME="constructor_detail"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=1><FONT SIZE="+2">
<B>Constructor Detail</B></FONT></TD>
</TR>
</TABLE>

<A NAME="OperationJAI(java.lang.String)"><!-- --></A><H3>
OperationJAI</H3>
<PRE>
public <B>OperationJAI</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;operation)
             throws OperationNotFoundException</PRE>
<DL>
<DD>Constructs a grid coverage operation from a JAI operation name. This convenience
 constructor fetch the <A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/OperationDescriptor.html" title="class or interface in javax.media.jai"><CODE>OperationDescriptor</CODE></A> from the specified operation
 name using the default <A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/JAI.html" title="class or interface in javax.media.jai"><CODE>JAI</CODE></A> instance.
<P>
<DT><B>Parameters:</B><DD><CODE>operation</CODE> - JAI operation name (e.g. ).
<DT><B>Throws:</B>
<DD><CODE>OperationNotFoundException</CODE> - if no JAI descriptor was found for the given name.</DL>
<HR>

<A NAME="OperationJAI(javax.media.jai.OperationDescriptor)"><!-- --></A><H3>
OperationJAI</H3>
<PRE>
public <B>OperationJAI</B>(<A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/OperationDescriptor.html" title="class or interface in javax.media.jai">OperationDescriptor</A>&nbsp;operation)</PRE>
<DL>
<DD>Constructs a grid coverage operation backed by a JAI operation. The operation descriptor
 must supports the  mode (which is the case for most JAI operations).
<P>
<DT><B>Parameters:</B><DD><CODE>operation</CODE> - The JAI operation descriptor.</DL>
<HR>

<A NAME="OperationJAI(javax.media.jai.OperationDescriptor, org.opengis.parameter.ParameterDescriptorGroup)"><!-- --></A><H3>
OperationJAI</H3>
<PRE>
protected <B>OperationJAI</B>(<A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/OperationDescriptor.html" title="class or interface in javax.media.jai">OperationDescriptor</A>&nbsp;operation,
                       ParameterDescriptorGroup&nbsp;descriptor)</PRE>
<DL>
<DD>Constructs a grid coverage operation backed by a JAI operation. The operation descriptor
 must supports the  mode (which is the case for most JAI operations).
<P>
<DT><B>Parameters:</B><DD><CODE>operation</CODE> - The JAI operation descriptor.<DD><CODE>descriptor</CODE> - The OGC parameters descriptor.</DL>

<!-- ============ METHOD DETAIL ========== -->

<A NAME="method_detail"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TD COLSPAN=1><FONT SIZE="+2">
<B>Method Detail</B></FONT></TD>
</TR>
</TABLE>

<A NAME="getOperationDescriptor(java.lang.String)"><!-- --></A><H3>
getOperationDescriptor</H3>
<PRE>
protected static final <A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/OperationDescriptor.html" title="class or interface in javax.media.jai">OperationDescriptor</A> <B>getOperationDescriptor</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;name)
                                                           throws OperationNotFoundException</PRE>
<DL>
<DD>Returns the operation descriptor for the specified JAI operation name. This method
 uses the default <A HREF="http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/JAI.html" title="class or interface in javax.media.jai"><CODE>JAI</CODE></A> instance and looks for the  mode.
 <p>
 Should be inlined in the constructor if only Sun was to fix RFE #4093999
 ("Relax constraint on placement of this()/super() call in constructors").
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>name</CODE> - The operation name.
<DT><B>Returns:</B><DD>The operation descriptor for the given name.
<DT><B>Throws:</B>
<DD><CODE>OperationNotFoundException</CODE> - if no JAI descriptor was found for the given name.</DL>
</DD>
</DL>
<HR>

<A NAME="computeOnGeophysicsValues(org.opengis.parameter.ParameterValueGroup)"><!-- --></A><H3>
computeOnGeophysicsValues</H3>
<PRE>
protected boolean <B>computeOnGeophysicsValues</B>(ParameterValueGroup&nbsp;parameters)</PRE>
<DL>
<DD>Returns  if grid coverage content should be converted from sample values
 to geophysics value before to apply an operation. This method is invoked automatically
 by <A HREF="../../../../org/geotools/coverage/processing/OperationJAI.html#doOperation(org.opengis.parameter.ParameterValueGroup, org.geotools.factory.Hints)"><CODE>doOperation</CODE></A>. If this method returns , then the
 computation will be performed on the <cite>geophysics</cite> view as returned by
 <code><A HREF="../../../../org/geotools/coverage/grid/GridCoverage2D.html#geophysics(boolean)">GridCoverage2D.geophysics</A>(true)</code>.
 If this method returns , then the view will <strong>not</strong> be changed
 before the operation is applied (i.e. the  method is not invoked at all).
 The default implementation always returns .
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>parameters</CODE> - The parameters supplied by the user to the  method.
<DT><B>Returns:</B><DD> if this operation should be applied on geophysics values.<DT><B>See Also:</B><DD><A HREF="../../../../org/geotools/coverage/grid/GridCoverage2D.html#geophysics(boolean)"><CODE>GridCoverage2D.geophysics(boolean)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="doOperation(org.opengis.parameter.ParameterValueGroup, org.geotools.factory.Hints)"><!-- --></A><H3>
doOperation</H3>
<PRE>
public Coverage <B>doOperation</B>(ParameterValueGroup&nbsp;parameters,
                            <A HREF="../../../../org/geotools/factory/Hints.html" title="class in org.geotools.factory">Hints</A>&nbsp;hints)
                                          throws <A HREF="../../../../org/geotools/coverage/processing/CoverageProcessingException.html" title="class in org.geotools.coverage.processing">CoverageProcessingException</A></PRE>
<DL>
<DD>Applies a process operation to a grid coverage.
 The default implementation performs the following steps:

 <ol>
   <li>Converts source grid coverages to their <cite>geophysics</cite> view using
       <code><A HREF="../../../../org/geotools/coverage/grid/GridCoverage2D.html#geophysics(boolean)">GridCoverage2D.geophysics</A>(true)</code>.
       This allow to performs all computation on geophysics values instead of encoded
       samples. <strong>Note:</strong> this step is disabled if
       <A HREF="../../../../org/geotools/coverage/processing/OperationJAI.html#computeOnGeophysicsValues(org.opengis.parameter.ParameterValueGroup)"><CODE>computeOnGeophysicsValues</CODE></A> returns
       .</li>

   <li>Ensures that every sources s use the same coordinate reference
       system (at least for the two-dimensional part) with the same
       <A HREF="../../../../org/geotools/coverage/grid/GridGeometry2D.html#getGridToCRS2D()"><CODE>gridToCRS</CODE></A> relationship.</li>

   <li>Invokes <A HREF="../../../../org/geotools/coverage/processing/OperationJAI.html#deriveGridCoverage(org.geotools.coverage.grid.GridCoverage2D[], org.geotools.coverage.processing.OperationJAI.Parameters)"><CODE>deriveGridCoverage(org.geotools.coverage.grid.GridCoverage2D[], org.geotools.coverage.processing.OperationJAI.Parameters)</CODE></A>.
       The sources in the  are <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/awt/image/RenderedImage.html" title="class or interface in java.awt.image"><CODE>RenderedImage</CODE></A> objects
       obtained from <A HREF="../../../../org/geotools/coverage/grid/GridCoverage2D.html#getRenderedImage()"><CODE>GridCoverage2D.getRenderedImage()</CODE></A>.</li>

   <li>If a changes from non-geophysics to geophysics view were performed at step 1,
       converts the result back to the original view using
       <code><A HREF="../../../../org/geotools/coverage/grid/GridCoverage2D.html#geophysics(boolean)">GridCoverage2D.geophysics</A>(false)</code>.
       </li>
 </ol>
<P>
<DD><DL>
<DT><B>Specified by:</B><DD><CODE><A HREF="../../../../org/geotools/coverage/processing/AbstractOperation.html#doOperation(org.opengis.parameter.ParameterValueGroup, org.geotools.factory.Hints)">doOperation</A></CODE> in class <CODE><A HREF="../../../../org/geotools/coverage/processing/AbstractOperation.html" title="class in org.geotools.coverage.processing">AbstractOperation</A></CODE></DL>
</DD>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>parameters</CODE> - List of name value pairs for the parameters required for the operation.<DD><CODE>hints</CODE> - A set of rendering hints, or  if none.
<DT><B>Returns:</B><DD>The result as a grid coverage.
<DT><B>Throws:</B>
<DD><CODE><A HREF="../../../../org/geotools/coverage/processing/CoverageProcessingException.html" title="class in org.geotools.coverage.processing">CoverageProcessingException</A></CODE> - if the operation can't be applied.<DT><B>See Also:</B><DD><A HREF="../../../../org/geotools/coverage/processing/OperationJAI.html#deriveGridCoverage(org.geotools.coverage.grid.GridCoverage2D[], org.geotools.coverage.processing.OperationJAI.Parameters)"><CODE>deriveGridCoverage(org.geotools.coverage.grid.GridCoverage2D[], org.geotools.coverage.processing.OperationJAI.Parameters)</CODE></A></DL>
</DD>