org.opencms.jsp

Class CmsJspTagScaleImage

java.lang.Object

javax.servlet.jsp.tagext.TagSupport

javax.servlet.jsp.tagext.BodyTagSupport

org.opencms.jsp.CmsJspImageScalerTagSupport

org.opencms.jsp.CmsJspTagScaleImage

All Implemented Interfaces:

java.io.Serializable, javax.servlet.jsp.tagext.BodyTag, javax.servlet.jsp.tagext.IterationTag, javax.servlet.jsp.tagext.JspTag, javax.servlet.jsp.tagext.Tag

public class CmsJspTagScaleImage
extends CmsJspImageScalerTagSupport

This tag allows using the OpenCms native image scaling mechanism within JSP.

No output is generated by this tag! Instead the tag generates a CmsJspImageBean. This can be used to further process the selected image with the provided image scaling parameters.

The following image formats are supported: BMP, GIF, JPEG, PNG, PNM, TIFF.

Note: Picture scaling is by default only enabled for target size with width and height <=1500. The size can be changed in the image scaler configuration in the file opencms-vfs.xml in the body of the tag <loader>. Also other options for the image scaler are set there.

This tag is an alternative to the OpenCms standard tag cms:img, providing additional flexibility. This way you can use scaled images for:

• The standard HTML <img>-Tag.
• The HTML 5 <picture>-Tag with multiple sources (hi-DPI variants for retina displays) for responsive design.
• Further processing a scaled image anyway you want on your JSP.

Example for a simple JSP that uses this tag to obtain information about an image: <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="cms" uri="http://www.opencms.org/taglib/cms"%>

<cms:scaleImage var="imgBean" src="/.galleries/samples/09.jpg?__scale=h:385,w:961,cx:42,cy:32,ch:385,cw:961" />
srcUrl: <c:out value="${imgBean.srcUrl}" /><br>
vfsUri: <c:out value="${imgBean.vfsUri}" /><br>
scalerParams: <c:out value="${imgBean.scaler.requestParam}" /><br>
Width: <c:out value="${imgBean.width}" /><br>
Height: <c:out value="${imgBean.height}" /><br>
scaledWidth: <c:out value="${imgBean.scaler.width}" /><br>
scaledHeight: <c:out value="${imgBean.scaler.height}" /><br>
isScaled: <c:out value="${imgBean.scaled}" /><br>


See Also:

Serialized Form

Field Summary

Fields inherited from class org.opencms.jsp.CmsJspImageScalerTagSupport

m_scaler, m_src, SCALE_ATTR_HEIGHT, SCALE_ATTR_MAXHEIGHT, SCALE_ATTR_MAXWIDTH, SCALE_ATTR_POSITION, SCALE_ATTR_QUALITY, SCALE_ATTR_RENDERMODE, SCALE_ATTR_TYPE, SCALE_ATTR_WIDTH

Fields inherited from class javax.servlet.jsp.tagext.BodyTagSupport

bodyContent

Fields inherited from class javax.servlet.jsp.tagext.TagSupport

id, pageContext

Fields inherited from interface javax.servlet.jsp.tagext.BodyTag

EVAL_BODY_BUFFERED, EVAL_BODY_TAG

Fields inherited from interface javax.servlet.jsp.tagext.IterationTag

EVAL_BODY_AGAIN

Fields inherited from interface javax.servlet.jsp.tagext.Tag

EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE

Constructor Summary

Constructors

Constructor and Description
CmsJspTagScaleImage() Creates a new image scaling tag instance.

Method Summary

Modifier and Type	Method and Description
int	doEndTag() Does some cleanup before returning EVAL_PAGE
int	doStartTag() Handles the Start tag, checks some parameters, uses the CmsImageScaler to create a scaled version of the image (and hi-DPI variants if necessary), stores all information in a image bean and stores it as a request attribute (the name for this attribute is given with the tag attribute "var").
static CmsJspImageBean	imageTagAction(CmsObject cms, java.lang.String imageUri, CmsImageScaler targetScaler, java.util.List<java.lang.String> hiDpiVariantList) Internal action method to create the scaled image bean.
void	release() Does some cleanup before the tag is released to the tag pool
void	setHiDpiVariants(java.lang.String value) Sets the String containing a comma separated list of hi-DPI variants to produce line "1.3x,1.5x,2x,3x".
void	setVar(java.lang.String value) Sets the name of the variable used for storing the resulting bean.

Methods inherited from class org.opencms.jsp.CmsJspImageScalerTagSupport

getHeight, getMaxHeight, getMaxWidth, getScaleColor, getScaleFilter, getScalePosition, getScaleQuality, getScaleRendermode, getScaleType, getSrc, getWidth, setHeight, setMaxHeight, setMaxWidth, setScaleColor, setScaleFilter, setScalePosition, setScaleQuality, setScaleRendermode, setScaleType, setSrc, setWidth

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

doAfterBody, doInitBody, getBodyContent, getPreviousOut, setBodyContent

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

findAncestorWithClass, getId, getParent, getValue, getValues, removeValue, setId, setPageContext, setParent, setValue

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.servlet.jsp.tagext.Tag

getParent, setPageContext, setParent

Constructor Detail

CmsJspTagScaleImage

public CmsJspTagScaleImage()

Creates a new image scaling tag instance.

Method Detail

imageTagAction

public static CmsJspImageBean imageTagAction(CmsObject cms,
                                             java.lang.String imageUri,
                                             CmsImageScaler targetScaler,
                                             java.util.List<java.lang.String> hiDpiVariantList)
                                      throws CmsException

Internal action method to create the scaled image bean.

Parameters:

cms - the cms context

imageUri - the image URI

targetScaler - the target image scaler

hiDpiVariantList - optional list of hi-DPI variant sizes to produce, e.g. 1.3x, 1.5x, 2x, 3x

Returns:

the created ScaledImageBean bean

Throws:

CmsException - in case something goes wrong

doEndTag

public int doEndTag()
             throws javax.servlet.jsp.JspException

Does some cleanup before returning EVAL_PAGE

Specified by:

doEndTag in interface javax.servlet.jsp.tagext.Tag

Overrides:

doEndTag in class javax.servlet.jsp.tagext.BodyTagSupport

Throws:

javax.servlet.jsp.JspException

See Also:

Tag.doEndTag()

doStartTag

public int doStartTag()

Handles the Start tag, checks some parameters, uses the CmsImageScaler to create a scaled version of the image (and hi-DPI variants if necessary), stores all information in a image bean and stores it as a request attribute (the name for this attribute is given with the tag attribute "var").

Specified by:

doStartTag in interface javax.servlet.jsp.tagext.Tag

Overrides:

doStartTag in class javax.servlet.jsp.tagext.BodyTagSupport

Returns:

EVAL_BODY_INCLUDE or SKIP_BODY in case of an unexpected Exception (please consult the OpenCms log file if that happens)

release

public void release()

Does some cleanup before the tag is released to the tag pool

Specified by:

release in interface javax.servlet.jsp.tagext.Tag

Overrides:

release in class CmsJspImageScalerTagSupport

See Also:

Tag.release()

setHiDpiVariants

public void setHiDpiVariants(java.lang.String value)

Sets the String containing a comma separated list of hi-DPI variants to produce line "1.3x,1.5x,2x,3x".

Currently in most cases "2x" should suffice to generate an additiona image for retina screens. Please note that since 11.0 the variants are created by lazy initialization, so there is usually no need to use this.

Parameters:

value - comma separated list of hi-DPI variants to produce, e.g. "1.3x,1.5x,2x,3x"

setVar

public void setVar(java.lang.String value)

Sets the name of the variable used for storing the resulting bean.

Parameters:

value - name of the resulting CmsJspScaledImage bean