org.ditchnet.jsp.taglib.twod.handler
Class CanvasTag

java.lang.Object
  javax.servlet.jsp.tagext.SimpleTagSupport
      org.ditchnet.jsp.taglib.twod.handler.CanvasTag

All Implemented Interfaces:

javax.servlet.jsp.tagext.JspTag, javax.servlet.jsp.tagext.SimpleTag

public class CanvasTag

extends javax.servlet.jsp.tagext.SimpleTagSupport

Since:

0.1 TODO -- refactor this monolithic class into smaller classes with separate responsibilities.

Version:

0.1

Author:

Todd Ditchendorf

Constructor Summary

CanvasTag()

Method Summary

protected void	addJavaObjectsToJsRuntime(org.mozilla.javascript.Context ctx, org.mozilla.javascript.Scriptable scope) Add the graphics object and the app/session/request/page scope objects to the global scope of the Rhino JavaScript runtime.
protected void	assertImageTypeSupported() Assert that the given image format (e.g. jpg, png) is supported by this JVM.
protected void	createGraphics() Instantiate this object's BufferedImage and Graphics2D instance fields.
void	doTag() Retrieve the JavaScript code in this tag's body.
protected void	evalJs() Embed the Rhino JavaScript interpreter to evaluate the script body of this tag.
java.lang.String	getAlt()
java.lang.String	getBorder()
java.lang.String	getCache()
protected java.lang.String	getFileName() Determine the image's file name by concatinating this object's id property and the appropriate file extension.
java.lang.String	getHeight()
java.lang.String	getId()
protected java.lang.String	getImageDirPath() Get the string representation of the image dir's path.
java.lang.String	getImageFormat()
protected java.lang.String	getJsCode() Retrieve the JavaScript code in this tag's body.
java.lang.String	getStyle()
java.lang.String	getStyleClass()
java.lang.String	getWidth()
protected boolean	imageIsOutOfDate() Returns true if the JSP in which this tag handler was invoked has been edited since the last time it's associated image was generated.
void	setAlt(java.lang.String alt)
void	setBorder(java.lang.String border)
void	setCache(java.lang.String cache)
void	setHeight(java.lang.String height)
void	setId(java.lang.String id)
void	setImageFormat(java.lang.String imageFormat)
void	setStyle(java.lang.String style)
void	setStyleClass(java.lang.String styleClass)
void	setWidth(java.lang.String width)
protected void	writeFileToDir() Write the image to the image directory.
protected void	writeResponse() Render the XHTML response consisting of an <img> tag with the appropriate attributes.

Methods inherited from class javax.servlet.jsp.tagext.SimpleTagSupport

findAncestorWithClass, getJspBody, getJspContext, getParent, setJspBody, setJspContext, setParent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CanvasTag

public CanvasTag()

Method Detail

getId

public java.lang.String getId()

setId

public void setId(java.lang.String id)

getCache

public java.lang.String getCache()

setCache

public void setCache(java.lang.String cache)

getBorder

public java.lang.String getBorder()

setBorder

public void setBorder(java.lang.String border)

getStyle

public java.lang.String getStyle()

setStyle

public void setStyle(java.lang.String style)

getStyleClass

public java.lang.String getStyleClass()

setStyleClass

public void setStyleClass(java.lang.String styleClass)

getAlt

public java.lang.String getAlt()

setAlt

public void setAlt(java.lang.String alt)

getWidth

public java.lang.String getWidth()

setWidth

public void setWidth(java.lang.String width)

getHeight

public java.lang.String getHeight()

setHeight

public void setHeight(java.lang.String height)

getImageFormat

public java.lang.String getImageFormat()

setImageFormat

public void setImageFormat(java.lang.String imageFormat)

getJsCode

protected java.lang.String getJsCode()
                              throws java.io.IOException,
                                     javax.servlet.jsp.JspException

Retrieve the JavaScript code in this tag's body.

Throws:

java.io.IOException

javax.servlet.jsp.JspException

createGraphics

protected void createGraphics()

Instantiate this object's BufferedImage and Graphics2D instance fields.

getImageDirPath

protected java.lang.String getImageDirPath()

Get the string representation of the image dir's path.

writeFileToDir

protected void writeFileToDir()
                       throws java.io.IOException

Write the image to the image directory.

Throws:

java.io.IOException

getFileName

protected java.lang.String getFileName()

Determine the image's file name by concatinating this object's id property and the appropriate file extension.

assertImageTypeSupported

protected void assertImageTypeSupported()
                                 throws javax.servlet.jsp.JspException

Assert that the given image format (e.g. jpg, png) is supported by this JVM.

Throws:

javax.servlet.jsp.JspException

doTag

public void doTag()
           throws java.io.IOException,
                  javax.servlet.jsp.JspException

Retrieve the JavaScript code in this tag's body.

Throws:

java.io.IOException

javax.servlet.jsp.JspException

imageIsOutOfDate

protected boolean imageIsOutOfDate()

Returns true if the JSP in which this tag handler was invoked has been edited since the last time it's associated image was generated. This allows caching of the image.

evalJs

protected void evalJs()
               throws javax.servlet.jsp.JspException

Embed the Rhino JavaScript interpreter to evaluate the script body of this tag. A (@link java.awt.Graphics2D} object will be available as a globally scoped variable named g.

Throws:

javax.servlet.jsp.JspException

addJavaObjectsToJsRuntime

protected void addJavaObjectsToJsRuntime(org.mozilla.javascript.Context ctx,
                                         org.mozilla.javascript.Scriptable scope)

Add the graphics object and the app/session/request/page scope objects to the global scope of the Rhino JavaScript runtime. This will allow their use in this tag's JS body.

writeResponse

protected void writeResponse()
                      throws java.io.IOException,
                             javax.servlet.jsp.JspException

Render the XHTML response consisting of an <img> tag with the appropriate attributes.

Throws:

java.io.IOException

javax.servlet.jsp.JspException