Package 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:
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:

  • Constructor Details

  • Method Details

    • imageTagAction

      public static CmsJspImageBean imageTagAction(CmsObject cms, String imageUri, CmsImageScaler targetScaler, List<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(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(String value)
      Sets the name of the variable used for storing the resulting bean.
      Parameters:
      value - name of the resulting CmsJspScaledImage bean