About Fonts Extension
Formerly used font definitions relied on font files available on the machine.
In this case, when defining how a piece of text should look like, one had to take care about the following possible issues:
- The needed font library might not be available to the JVM at runtime
because the font file is not installed on the system.
- When a font library is not available, the local JVM will replace it with some default fonts, and this could lead to
various side effects, such as totally different text appearance or truncated pieces of text.
It's obviously that running a report in this kind of approach becomes completely dependent on the local environment, and one
have to ensure that required font files are installed on the machine where the report is run. If they aren't, they should be installed first.
And that's what should be done on every machine running the report. Quite a little bit embarrassing, isn't it.
Therefore, this is not the best way to control fonts in JasperReports. A much better one is due to the extension points support,
available in JasperReports. Font files can be
provided as library extensions. In a very simple manner, making a font extension consists in putting various True Type Font files
in a JAR file together with a properties file describing the content of the JAR, and an XML file defining relationships between fonts
and locales.
Font Extensions Step By Step
Let's take a look into the /demo/fonts directory. It contains the DejaVu font extension available as default font for all
samples shipped with the JasperReports project distribution package.
As known from extensions support, any JasperReports extension provides a jasperreports_extension.properties file in its root
package, required by the JasperReports extension mechanism. This file is used to describe the content of the extension JAR file and consists in
the following lines:
net.sf.jasperreports.extension.registry.factory.simple.font.families=net.sf.jasperreports.engine.fonts.SimpleFontExtensionsRegistryFactory
net.sf.jasperreports.extension.simple.font.families.dejavu=net/sf/jasperreports/fonts/fonts.xml
The SimpleFontExtensionsRegistryFactory class represents
an implementation of the ExtensionsRegistryFactory interface, used to
instantiate a font extension registry.
The extension registry obtained from the factory is able to return a list of actual extension point implementations based on extension point class type.
The second line provides the path to the XML file describing the actual font extension. The XML file in this case is named fonts.xml.
The main unit in the fonts.xml file is the <fontFamily/> element. A font family is an object instance which
extends the FontFamily public interface. This is the point where
font extensions can be connected with the JasperReports engine.
Font families described in the fonts.xml file consist in up to 4 font faces: normal, bold, italic and bolditalic.
A font face is described by the FontFace interface.
In order to completely describe a font family extension, one have to indicate the mapping between the font faces and font files,
the pdfEncoding and pdfEmbedded attributes, equivalent font face names available for dedicated exporters,
such as the HTML exporter) and a list of supported locales, because font files usually support only certain languages.
The fonts.xml file includes 3 different font families:
DejaVu SansDejaVu SerifDejaVu Sans Mono
and some mappings for logical JVM fonts available for HTML exporters:
SansSerifSerifMonospaced
Let's take a look at the DejaVu Sans family. All the font family settings already discussed can be found in the example below:
net/sf/jasperreports/fonts/dejavu/DejaVuSans.ttf
net/sf/jasperreports/fonts/dejavu/DejaVuSans-Bold.ttf
net/sf/jasperreports/fonts/dejavu/DejaVuSans-Oblique.ttf
net/sf/jasperreports/fonts/dejavu/DejaVuSans-BoldOblique.ttf
Identity-H
true
'DejaVu Sans', Arial, Helvetica, sans-serif
'DejaVu Sans', Arial, Helvetica, sans-serif
]]>
The name attribute and the <normal/> font face represent required elements in a font family definition,
while all the others are optional.
The name of the font family will be used as the fontName attribute of the text element or style in the report
template. The fontName together with the isBold and isItalic attributes of the
text field or style in the report help to locate and load the appropriate font face from the family. If a particular font
face is not present or declared in the family, then the normal font face will be used instead.
In the example above we can see the mappings for the bold, italic and bolditalic font styles are also present.
The <exportFonts/> tag instructs the HTML exporters
to correlate this font family with other HTML supported font families, such as Arial, Helvetica, sans-serif.
The <locales/> contains a list of supported locales. This block being commented, the engine will try to apply this font family
for any locale, without taking into account if the font file really provides support for that locale. If a particular locale is not supported, errors might
occur at runtime and characters might be misrepresented.
However, if a given font family needs to be represented for locales supported by different font files, one can define separate font families in the XML file,
having the same name but with differing <locales/> tag. This feature is very useful when the same report has to be run in both
Japanese and Chinese, because there is no TTF file that simultaneously supports these two languages.
The <pdfEncoding/> and <pdfEmbedded/> are used to specify the PDF encoding attribute and the PDF embedding flag, and
people are strongly encouraged to use them instead of deprecated pdfEncoding and pdfEmbedded attributes available in the JRXML
<font/> tag.
Now, let's take a look at logical JVM fonts mappings:
'DejaVu Sans', Arial, Helvetica, sans-serif
'DejaVu Sans', Arial, Helvetica, sans-serif
'DejaVu Serif', 'Times New Roman', Times, serif
'DejaVu Serif', 'Times New Roman', Times, serif
'DejaVu Sans Mono', 'Courier New', Courier, monospace
'DejaVu Sans Mono', 'Courier New', Courier, monospace
]]>
Here the DejaVu font families are added to the font families list available for HTML at export time.
Once you have the TTF files, the jasperreports_extension.properties and fonts.xml files,
you can pack them together in a JAR file, and then put the JAR in your application's classpath,
in order to make the new fonts available to your reports, wherever the application might run.
For more details about deploying fonts as extensions, you can take a look at the
Fonts sample provided with the JasperReports project distribution
package, which adds one more font extension for another open source font called Gentium. Running the
sample using the > ant clean javac compile fontsXml command will generate in the
demo/samples/fonts/build/reports a font extension xml file named fonts.xml. This file contains all font families
available in the already installed font extensions.