Default text measurer implementation.
When a the contents of a text element do not fit
into the area given by the element width and height, the engine will either truncate the
text contents or, in the case of a text field that is allowed to stretch, increase the height of
the element to accommodate the contents. To do so, the JasperReports engine needs to
measure the text and calculate how much of it fits in the element area, or how much the
element needs to stretch in order to fit the entire text.
JasperReports does this, by default, by using standard Java AWT classes to layout and
measure the text with its style information given by the text font and by other style
attributes. This ensures that the result of the text layout calculation is exact according to
the JasperReports principle of pixel perfectness.
However, this comes at a price - the AWT text layout calls contribute to the overall
report fill performance. For this reason and possibly others, it might be desired in some
cases to implement a different text measuring mechanism. JasperReports allows users to
employ custom text measurer implementations by setting a value for the
The property can be set globally (in
or via the
report level or at element level (as an element property). The property value should be
either the name of a class that implements the
interface, or an
alias defined for such a text measurer factory class. To define an alias, one needs to
define a property having
as key and the factory
class name as value. Take the following examples of text measurer factory properties:
- in jasperreports.properties set a custom default text measurer factory:
- define an alias for a different text measurer factory:
- in a JRXML, use the fast text measurer for a static text:
<property name="net.sf.jasperreports.text.measurer.factory" value="fast"/>
The default text measurer factory used by JasperReports is
; the factory is also
registered under an alias named
The built-in text measurer supports a series of text truncation customizations. As a
reminder, text truncation occurs when a the contents of a static text element or of a text
field that is not set as stretchable do not fit the area reserved for the element in the report
template. Note that text truncation only refers to the truncation of the last line of a text
element, and not to the word wrapping of a text element that spans across multiple lines.
The default behavior is to use the standard AWT line break logic (as returned by the
method) to determine where to
truncate the text. This means that the last line of text will be truncated after the last word
that fits on the line, or after the last character when the first word on the line does not
This behavior can be changed by forcing the text to always get truncated at the last
character that fits the element area, and by appending one or more characters to the
truncated text to notify a report reader that the text has been truncated.
To force the text to be wrapped at the last character, the
property needs to be set to true
globally, at report level or at text element level. The levels at which the property can be
set are listed in a decreasing order of precedence, therefore an element level property
overrides the report level property, which in its turn overrides the global property. The
property can also be set to false at report or element level to override the true value of the
property set at a higher level.
To append a suffix to the truncated text, one needs to set the desired suffix as the value
property globally, at report level or at element level. For instance, to use a Unicode
horizontal ellipsis character (code point U+2026) as text truncation suffix, one would set
the property globally or at report level as following:
- globally in
- at report level:
<property name="net.sf.jasperreports.text.truncate.suffix" value="…"/>
Note that in the JRXML the ellipsis character was introduced via an XML numerical
character entity. If the JRXML file uses a Unicode XML encoding, the Unicode
character can also be directly written in the JRXML.
When using a truncation suffix, the truncate at character property is taken into
consideration in order to determine where to append the truncation suffix. If the
truncation at character property is set to false, the suffix is appended after the last word
that fits; if the property is set to true, the suffix is appended after the last text character
When used for a text element that produces styled text, the truncation suffix is placed
outside the styled text, that is, the truncation suffix will be displayed using the style
defined at element level.
Text truncation is desirable when producing reports for that are displayed on a screen or
printed on paper - in such scenarios the layout of the report is important. On the other
hand, some JasperReports exporters, such as the Excel or CSV ones, produce output
which in many cases is intended as data-centric. In such cases, it could be useful not to
truncate any text generated by the report, even if some texts would not fit when rendered
on a layout-sensitive media.
To inhibit the unconditional truncation of report texts, one would need to set the
property to true globally, at report level or at text element level. When the
property is set to true, the text is not truncated at fill time and the generated
report preserves the full text as produced by the text element.
Visual report exporters (such as the exporters used for PDF, HTML, RTF, printing or the
Java report viewer) would still truncate the rendered text, but the Excel and CSV data-centric
exporters would use the full text. Note that preserving the full text does not affect
the size of the text element, therefore the Excel exporter would display the full text
inside a cell that has the size of the truncated text.