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<?xml version="1.0" standalone="no"?>
<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.1//EN"
"http://cvs.apache.org/viewcvs.cgi/*checkout*/xml-forrest/src/resources/schema/dtd/document-v11.dtd">
<document>
<header>
<title>FOP Graphics Formats</title>
</header>
<body>
<section id="support-overview">
<title>Overview of Graphics Support</title>
<p>
The table below summarizes the <em>theoretical</em> support for graphical formats within FOP. In other words, within the constraints of the limitations listed here, these formats <em>should</em> work. However, many of them have not been tested, and there may be limitations that have not yet been discovered or documented. The packages needed to support some formats are not included in the FOP distribution and must be installed separately. Follow the links in the "Support Thru" column for more details.
</p>
<table>
<tr>
<th>Format</th>
<th>Type</th>
<th>Support Thru</th>
</tr>
<tr>
<td>BMP (Microsoft Windows Bitmap)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link> or <link href="#jai">JAI</link></td>
</tr>
<tr>
<td>CUR</td>
<td>unknown</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td><link href="#eps">EPS</link> (Encapsulated PostScript)</td>
<td>metafile (both bitmap and vector), probably most frequently used for vector drawings</td>
<td><link href="#native">FOP native</link> (limited support)</td>
</tr>
<tr>
<td>GIF (Graphics Interchange Format)</td>
<td>bitmap</td>
<td><link href="#native">FOP native</link></td>
</tr>
<tr>
<td>FPX</td>
<td>unknown</td>
<td><link href="#jai">JAI</link></td>
</tr>
<tr>
<td>ICO (Sun Icon)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td><link href="#jpeg">JPEG</link> (Joint Photographic Experts Group)</td>
<td>bitmap</td>
<td><link href="#native">FOP native</link></td>
</tr>
<tr>
<td>PCX (PC Paintbrush)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td>PICT (Macintosh PICT)</td>
<td>metafile</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td>PNG (Portable Network Graphic)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link> or <link href="#jai">JAI</link></td>
</tr>
<tr>
<td>PNM (Portable aNyMap Utilities, part of the Portable Bitmap Utilies, aka pbmplus. PNM is a superset encompassing PBM or Portable Bitmap, PGM or Portable Grayscale, and PPM or Portable Pixmap.)</td>
<td>bitmap</td>
<td><link href="#jai">JAI</link></td>
</tr>
<tr>
<td>PSD (Adobe Photoshop)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td>RAS (Sunraster)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td><link href="#svg">SVG</link> (Scalable Vector Graphics)</td>
<td>vector (with embedded bitmaps)</td>
<td><link href="#batik">Batik</link></td>
</tr>
<tr>
<td>TGA (Targa)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td>TIFF (Tag Image Format File)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link> or <link href="#jai">JAI</link></td>
</tr>
<tr>
<td>XBM (X BitMap)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
<tr>
<td>XPM (X PixMap)</td>
<td>bitmap</td>
<td><link href="#jimi">JIMI</link></td>
</tr>
</table>
</section>
<section id="packages">
<title>Graphics Packages</title>
<section id="native">
<title>FOP Native</title>
<p>
FOP has native ability to handle some graphic file formats.
</p>
</section>
<section id="jimi">
<title>JIMI</title>
<p>
Because of licensing issues, the JIMI image library is not included in the FOP distribution. First, <fork href="http://java.sun.com/products/jimi">download</fork> and install it.
Then, copy the file "JimiProClasses.zip" from the archive to xml-fop/lib/jimi-1.0.jar. Please note that FOP binary distributions are compiled with JIMI support, so there is no need for you to build FOP to add the support. If jimi-1.0.jar is installed in the right place, it will automatically be used by FOP, otherwise it will not.
</p>
</section>
<section id="jai">
<title>JAI</title>
<p>
FOP has been compiled with JAI support, but JAI is not included in the FOP distribution.
To use it, simply install <link href="http://java.sun.com/products/java-media/jai">JAI</link>.
JAI is much faster than JIMI, but is not available for all platforms. See <link href="http://java.sun.com/products/java-media/jai/forDevelopers/jaifaq.html#platforms">What platforms are supported?</link> on the JAI FAQ page for more details.
</p>
</section>
<section id="batik">
<title>Batik</title>
<p>Current FOP distributions include a distribution of the Apache Software Foundation's <jump href="http://xml.apache.org/batik">Batik</jump> version 1.5beta4. No installation is required. Because Batik's API changes frequently, it is highly recommended that you use this version with FOP.</p>
</section>
</section>
<section id="eps">
<title>EPS</title>
<p>FOP provides support for two output targets:</p>
<ul>
<li>PostScript (full support).</li>
<li>PDF (partial support). FOP embeds the EPS file into the PDF, but currently does not do so completely correctly. PostScript devices (including ghostscript) will render the EPS correctly, but Acrobat Reader will not currently display it.</li>
</ul>
</section>
<section id="jpeg">
<title>JPEG</title>
<p>Not all variants of JPEG are supported, especially those containing unusual color lookup tables and color profiles. If you have trouble with a JPEG image in FOP, try opening it with an image processing program (such as Photoshop or Gimp) and then saving it. Specifying 24-bit color output may also help.
</p>
</section>
<section id="svg">
<title>SVG</title>
<section id="svg-intro">
<title>Introduction</title>
<p>
FOP uses <link href="#batik">Batik</link> for SVG support.
This format can be handled as an <code>fo:instream-foreign-object</code> or in a separate
file referenced with <code>fo:external-graphic</code>. Either way the SVG document will be
read in and converted into a DOM in Batik. This DOM will then be used by the renderer to
create the graphical image.
</p>
<p>
The AWT and Print renderers simply use batik to draw the SVG into a graphic.
</p>
<p>
In the case of the PDF renderer there is a PDFGraphics2D class that Batik uses
to render the image into. This class converts the drawing instructions into
PDF markup which is placed into the current PDF document.
</p>
</section>
<section id="svg-pdf-conversion">
<title>Converting SVG to a PDF Document</title>
<p>
It is possible to convert a standalone SVG document directly into a simple page PDF document.
This is possible through the use of Batik's transcoder mechanism.<br/>
<code>java org.apache.batik.apps.rasterizer.Main -m application/pdf document.svg</code>
<br/>
This will output the svg document as "document.pdf" containing a PDF rendering of
the SVG file.
</p>
<p>
It is also possible to specify the width and/or height of the PDF document on the command line with -w and -h or if you are using the transcoder api you can use the transcoding hints.
</p>
<p>
Currently the SVG image is drawn at the SVG document size and simply scaled in PDF to the new size. So the result may not be the best possible. For example if you have any images or effects it will draw them at the original resolution of the svg document. When this is viewed in the pdf it will have an incorrect resolution for the size of the pdf.
</p>
<p>
The size of the pdf file will also remain the same regardless of what size the page is.
</p>
<p>
For more information see <link href="http://xml.apache.org/batik/">Batik</link> for
how transcoders work.
</p>
</section>
<section id="svg-pdf-graphics">
<title>Placing SVG Graphics into PDF</title>
<p>
The svg is inserted into PDF by using PDF commands to draw and fill
lines and curves. This means that the graphical objects created with
this remain as vector graphics.
</p>
<p>
There are a number of SVG things that cannot be converted directly into
PDF. Parts of the graphic such as effects, patterns and images are inserted
into the PDF as a raster graphic. The resolution of this graphic may not
be ideal depending on the FOP dpi (72dpi) and the scaling for that graphic.
This needs to be improved.</p>
<p>
Currently transparency is not supported in PDF so many svg images that
contain effects or graphics with transparent areas will not be displayed
correctly.
</p>
</section>
<section id="svg-pdf-text">
<title>Placing SVG Text into PDF</title>
<p>If possible, Batik will use normal PDF text when inserting text. It does
this by checking if the text can be drawn normally and the font is
supported. This example svg <link href="dev/svg/text.svg">text.svg</link> /
<link href="dev/svg/text.pdf">text.pdf</link>
shows how various types and effects with text are handled.
Note that tspan and outlined text are not yet implemented.</p>
<p>
Otherwise, text is converted and drawn as a set of shapes by batik, using the stroking text painter.
This means that a typical character will
have about 10 curves (each curve consists of at least 20 characters).
This can make the pdf files large and when the pdf is viewed the
viewer does not normally draw those fine curves very well (turning on
Smooth Line Art in the Acrobat preferences will fix this).
If the text is inserted into the PDF using the inbuilt text commands
for PDF it will use a single character.
</p>
<p>
It is possible to make sure that all text is drawn into PDF using the
PDF text commands (instead of the graphical shapes), by adding the following to the user config:
</p>
<source><![CDATA[<entry>
<key>strokeSVGText</key>
<value>false</value>
</entry>]]></source>
<p>In a servlet environment, you can set it directly:</p>
<source>org.apache.fop.configuration.Configuration.put("strokeSVGText", Boolean.FALSE);</source>
<p>For information on using a configuration file in a servlet, see the <link href="faq.html#usercfg">FAQ</link> on that topic.</p>
<p>Note that this configuration setting works only for the PDF renderer.</p>
<p>
The drawback to forcing text to be rendered as text is that it will be confined to text that is
possible for PDF fonts (including embedded fonts) and implemented with
this workaround. The fonts available are the standard pdf fonts and any
fonts that you have embedded using FOP. The font sizes will be rounded
to an integer value. In future this will be improved.
</p>
<p>Note that because SVG text can be rendered as either text or a vector graphic, you may need to consider settings in your viewer for both.
The Acrobat viewer has both "smooth line art" and "smooth text" settings that may need to be set for SVG images to be displayed nicely on your screen (see Edit / Preferences / Display).
This setting will not affect the printing of your document, which should be OK in any case, but will only affect the quality of the screen display.</p>
</section>
<section id="svg-scaling">
<title>Scaling</title>
<p>Currently, SVG images are rendered with the dimensions specified <em>in the SVG file</em>, within the viewport specified in the fo:external-graphic element.
For everything to work properly, the two should be equal.
The SVG standard leaves this issue as an implementation detail.
FOP will probably implement a scaling mechanism in the future.</p>
</section>
<section id="svg-problems">
<title>Known Problems</title>
<ul>
<li>
soft mask transparency is combined with white so that it looks better
on pdf 1.3 viewers but this causes the soft mask to be slightly lighter
or darker on pdf 1.4 viewers
</li>
<li>
there is some problem with a gradient inside a pattern causing a pdf
error when viewed in acrobat 5
</li>
<li>
text is not always handled correctly, it may select the wrong font
especially if characters have multiple fonts in the font list
</li>
<li>
more pdf text handling could be implemented
It could draw the string using the attributed character iterator
to handle tspans and other simple changes of text.
</li>
<li>
JPEG images are not inserted directly into the pdf document
This area has not been implemented yet since the appropriate
method in batik is static
</li>
<li>
Uniform transparency for images and other svg elements that are converted
into a raster graphic are not drawn properly in PDF. The image is opaque.
</li>
</ul>
</section>
</section>
<section id="resolution">
<title>Graphics Resolution</title>
<p>Some bitmapped image file formats store a dots-per-inch (dpi) or other resolution value. Since PDF and most output formats do not have a concept of resolution, but only of absolute image units (i.e. pixels) FOP ignores the resolution values as well. Instead, FOP uses the dimensions of the image as specified in the fo:external-graphic element to render the image:</p>
<ul>
<li>If no dimensions are given, FOP uses a default value of 72 dpi to compute the graphic's dimensions. For example, suppose a graphic 300 pixels wide and 400 pixels high. FOP will render the graphic at 4.167 inches wide, 5.555 inches high, with an apparent resolution of 72 dpi.</li>
<li>If only one dimension is given, FOP by default uses the same aspect ratio to compute the other dimension (to avoid the appearance of stretching). For example, suppose a graphic 300 pixels wide and 400 pixels high, for which content-width = ".5in". FOP will compute the content-height = .667 inches, and will render the graphic at that size, with an apparent resolution of 600 dpi.</li>
<li>If both dimensions are given, FOP simply renders the image in that space. For example, suppose a graphic 300 pixels wide and 400 pixels high, for which content-width = "3in" and content-height = "4in". FOP will render the graphic at that size, with an apparent resolution of 100 dpi.</li>
</ul>
<p>If you need a higher apparent output resolution for bitmapped images, first make sure that at least one dimension of the image is defined in your XSL-FO input. Apart from that, resolution problems are in the image file itself, and must be corrected there: use or create a higher-resolution image file.</p>
<note>The explanation above describes only the basic default behavior. There are other attributes of the fo:external-graphic element that can affect the behavior described above.</note>
</section>
</body>
</document>
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