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Overview

Javadoc

Please see the

Javadoc

for further details; of greatest interest will be the documentation
for

NbDocument.


Contents



Overview

Typical use scenario


Accessing an Open Document

Getting the document object for a data object
Common operations on resulting document


Advanced Editor Automation

Using guard blocks
Using annotations


Loader Interactions with Guard Blocks

Implementing a Custom Editor

Creating editor kit
Creating styled document
Handling guards
Lines and elements
Handling annotations
Printing
Locking
Biases
Scrolling to display
Presentable actions
Undo/redo support
Customization
Installing







Editor API


This document describes the NetBeans Editor API, attempting to give a
summary of what you need to know about it for different purposes.




The Open APIs only cover certain aspects of working with the
editor. For example, you can open documents, modify them, add
annotations, register editor kits you built from scratch, and so on.
Some more specific capabilities that are frequently requested are
not guaranteed by the Open APIs but may be possible
using NetBeans modules which may have differing standards of API
design, documentation, and compatibility from release to release. Here
are some resources that may also be of interest:



    
The NetBeans editor module
is the typical editor implementation. It is possible to use base
classes in this module as a starting point for defining your own
editor kits: syntax coloring, code completion, etc. for new languages
and file formats. As of this writing, the details of how to add new
editor kits from a NetBeans module are virtually undocumented, and
compatibility is likely to be broken in future NetBeans releases, so
do so at your own risk.

The lexer module

is planned to make creation of new editor kits easier.






Overview

The Editor API may be used at a first cut for two purposes: accessing
editor-related functionality from within NetBeans for use by other
modules; and implementing a custom editor that
can be inserted into NetBeans as a module, replacing or supplementing
the NetBeans-supplied one.



Typical use scenario

Here is an example sequence of events describing how an editor is used
with Java source code and cooperates with the Form Editor.



The user either opens an existing form, or creates a new form (say
for a JFrame) from template - in either case, there is a
new .java file in the user's
repository containing Java source, together with a .form
file.

A "data object" is created for the form, using the "form" data loader; in this case
there is a standard NetBeans module
for the Form Editor. This module includes the
implementation of the Form Editor; but it is invoked only through a
loader, which recognizes a .form file associated with a
.java file;
when it finds them, it:



Creates nodes for the
form, including a top-level node, a node for the form itself (with
children corresponding to the AWT component structure), and a node for
the class (with children corresponding to methods, variables, etc.).

Opens the form (.form) file in the Form Editor.

Asks to open the .java file in an editor.



If the .java file was already open in some editor
window or pane, then this window/pane is reused and just given
focus (i.e. a new

JEditorPane

is created, but using the same

EditorKit

and

StyledDocument).

If not, a new JEditorPane is

asked

to create an editor for the Java source content type (typically
text/x-java). Now, the Form Editor's data loader is an
extension of the Java Source data loader; the Java loader specially treats the request to load its content
into an editor: it inserts most of the text straight into the
StyledDocument just as you would expect, but also checks
for special comments looking something like //GEN-BEGIN:
in the source code, which are the markers used to indicate guarded
areas in saved source code. When it finds one, rather than inserting
the marker into the document, it uses

NbDocument.insertGuarded(...)

to insert the enclosed text area, making it read-only to the user.

The JEditorPane now has a StyledDocument
suited to Java source code loaded into it. This document may be
implemented by the standard NetBeans Editor, or it may be a custom editor. The user may edit non-guarded
parts of the document; attempted actions (like typing) that would
affect guarded areas are prevented by the editor in use.

The user may make modifications to the form in the Form
Editor. This form is of course linked to the open document, allowing
the document to reflect needed code changes. The form editor does not
actually need to read the document at all; whenever something is
modified on the form, the form editor just replaces an existing
guarded block with new, regenerated contents, or it deletes an
existing block, or adds a new block just after an existing one. So if
the user had foolishly made edits to a guarded area while the source
file was on disk, those edits would simply be discarded upon being
loaded into the Form Editor.

Note that the Form Editor directly or indirectly calls

Document.insertString(...)

(or

NbDocument.insertGuarded(...))

and

Document.remove(...)

to do this work, so it is itself unaffected by guard blocks.

The user may explore the Java parse hierarchy as presented in the
Explorer when expanding the class node for the form; from here,
methods, variables, and so on in the code may be seen as attributed
objects. If the user modifies one of these attributes, or uses a more
complex JavaBean view of the class, the document is asked to make the
corresponding update in the source; but in this case, the

guarded attribute

is checked, since the user should not be able to arbitrarily
rename or otherwise affect members used by the Form Editor without its
consent! NetBeans actions implementing such modifications will use

NbDocument.WriteLockable.runAtomicAsUser(...)

to make sure that the guard blocks are properly honored.

When the user is done with the form, he may close it; then he will
be prompted to save to disk. If a save action is performed, the Java
Data Object is responsible for looking for guard blocks in the editor
and converting these back into comments like //GEN-BEGIN:
before the text is written to file.







Accessing an Open Document

Starting from other APIs, it is not difficult to make use of the
Editor API to get access to an editor window displaying a particular
file.

Getting the document object for a data object

Here is an example of how to find a file by name stored in some
filesystem in the Repository; get its data object (assuming you do not
already have its data object, or a node representing the data object);
and get the Swing document to edit it, opening a new Editor window
with that document if necessary. Naturally this example is somewhat
long, because it demonstrates how to do all of this from
scratch. Also, exception handling is not illustrated here.

File f = new File("/home/me/sources/my/pkg/MyFile.java");
FileObject fo = FileUtil.fromFile(f)[0];
DataObject d = DataObject.find(fo);
EditorCookie ec = (EditorCookie)d.getCookie(EditorCookie.class);
ec.open();
StyledDocument doc = ec.openDocument();


Common operations on resulting document

You can check such things as whether or not the file is modified in the Editor:

if (ec.isModified()) ...


Then see what the current contents of line 26 are (zero-based):

int start=NbDocument.findLineOffset(doc, 25);
int end=NbDocument.findLineOffset(doc, 26);
String contents=doc.getText(start, end-start);


And display this line in the Editor window:

ec.getLineSet().getCurrent(25).show(Line.SHOW_TRY_SHOW);


Now insert a new line here after it:

final BadLocationException[] exc = new BadLocationException[] {null};
NbDocument.runAtomicAsUser(doc, new Runnable() {
    public void run() {
        try {
            doc.insertString(NbDocument.findLineOffset(doc, 26),
                             "// New text.\n",
                             SimpleAttributeSet.EMPTY);
        } catch (BadLocationException e) {
            exc[0] = e;
        }
    }
});
if (exc[0] != null) throw exc[0];


All done! Prompt to save the file, and close the editor window:

ec.close();


Advanced Editor Automation

For advanced modules on a level with the Form Editor or the
Compiler and Debugger, it is necessary to take more complete control
over the actions and content of an editor.

Using guard blocks

Manipulating guarded blocks should not be very difficult, if your
application requires it. They are used by the FormEditor, but any
module which needs to prevent the user from editing certain portions
of a text document (typically because they will be mechanically
recreated by other means), can do so.



To create a guard block over an existing area of text, you may use

NbDocument.markGuarded(...);

the guard block may subsequently be removed using

NbDocument.unmarkGuarded(...).

Typically you will want to remember the positions of the guard
blocks you added using a position, so that user edits in the vicinity
of the guard block will be taken into consideration. You may create
such a position using

NbDocument.createPosition(...),

and retrieve its current offset when needed using

Position.getOffset().

To insert a new guarded block of text, you may use

NbDocument.insertGuarded(...).

To change the contents of part of the document, without regard to
the presence of guard blocks (this assumes you know what you are doing
and what the guard blocks are being used for), you may use the
standard Swing

Document.insertString(...)

and

Document.remove(...).

You probably want to use

NbDocument.runAtomic(...)

to prevent errors in threaded code.

To do the same sort of thing while preventing yourself from
accidentally touching a guard block, i.e. if your module was not the
creator of the guard block (or you are not even sure if there any in
the document), please use

NbDocument.runAtomicAsUser(...)

instead.



Using annotations

In order to provide richer interactions between the editor and
other modules, the APIs provide for a system of annotations
which are used for things like debugger breakpoints, erroneous lines,
and so on. From an API perspective, anyone can create annotations and
attach them to a document; the editor implementation should attempt to
display these annotations as it sees fit, taking hints from the
annotation provider.

Using annotations on a document need not be difficult. Everything
you need to do is to define the visual appearance of your annotation
and to provide a class which will represent it programmatically. For
example, if you are writing a module which interacts with an open
document containing some sort of program code, and the user has made a
syntax error in the code which you were able to detect and want to
point out, you may want to mark the line or part of the line as
"erroneous". To achieve this you must:



Describe the appearance of your annotation. This is the so-called
annotation type which consist of attributes like colors and
so on. After you have defined the annotation type you will be able to
create document annotations which will reference this annotation type.
Definition of an annotation type involves creation of an XML file with
the format specified by a

standard DTD.

This XML file must be registered in your module installation layer in
the folder Editors/AnnotationTypes. Here is an example
XML file
Editors/AnnotationTypes/org-nb-modules-foo-some-annotation.xml
(the file name within this folder is arbitrary but should be
distinctive to prevent collisions between modules):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE type PUBLIC
          "-//NetBeans//DTD annotation type 1.0//EN"
          "http://www.netbeans.org/dtds/annotation-type-1_0.dtd">
<type name="org-nb-modules-foo-some-annotation"
      description_key="LBL_some-annotation"
      localizing_bundle="org.nb.modules.foo.Bundle"
      visible="true" 
      glyph="nbresloc:/org/nb/modules/foo/some-annotation-glyph.gif"
      highlight="#FFFF00"
      type="line"/>


As you can see the definition of the annotation type consists of the highlight
color; the glyph icon which could be shown in the left margin of the editing
area - the glyph gutter; the localized name; and so on. For more details
about each field in the DTD see

below.

Extend the

Annotation

abstract class and define your own annotation. You must specify the
type - which matches the code name given in the XML
description - and a short description, which can form tool-tip text for
the annotation. For example:

public final class SomeAnnotation extends Annotation {
    private final String error;
    public SomeAnnotation(String error) {
        this.error = error;
    }
    public String getAnnotationType() {
        return "org-nb-modules-foo-some-annotation";
    }
    public String getShortDescription() {
        // Localize this with NbBundle:
        return "The error was: " + error;
    }
}


Note that you can return the tooltip text asynchronously, on demand,
or dynamically: you may return null for no tooltip, and
you may later return a new or changed tooltip - just use:

firePropertyChange(PROP_SHORT_DESCRIPTION, null, null);


to inform the editor of the change. The tooltip should be refreshed
on-screen.

Finally, attach an annotation instance you make to some

Annotatable

object. Normally this will be a

Line

representing a whole line of text, or a

Line.Part

representing a section of a line. For example:

// Given error output like: "pkg/Name.java:123: You made a mistake"
FileObject fileWithError = fs.findResource("pkg/Name.java");
DataObject objWithError = DataObject.find(fileWithError);
LineCookie cookie = (LineCookie)objWithError.getCookie(LineCookie.class);
Line.Set lineSet = cookie.getLineSet();
final Line line = lineSet.getOriginal(123);
final Annotation ann = new SomeAnnotation("You made a mistake");
ann.attach(line);








In this example the user may correct the erroneous line, or at
least do something to it - in this case we assume that the annotation
is no longer needed, and should be removed. It is a simple call to do
this; of course you need to know when it is appropriate, so for
example:

line.addPropertyChangeListener(new PropertyChangeListener() {
    public void propertyChange(PropertyChangeEvent ev) {
        String type = ev.getPropertyName();
        if (type == null || type == Annotatable.PROP_TEXT) {
            // User edited the line, assume error should be cleared.
            ann.detach();
            line.removePropertyChangeListener(this);
        }
    }
});








It is possible that there might be more than one annotation on the
same line. In this case it depends on the capabilities of the editor
how the annotations will be displayed. The simplest scenario is that
only one annotation is visible at time and the user can cycle through
them. If this is the case it may be helpful to force the editor to
move your annotation in front of any others:

ann.moveToFront();


NetBeans presents GUI settings to the user in which it is possible to
customize the attributes of annotation types - for example, foreground
and background color. Remember however that some editor implementations
may find it difficult or impossible to accurately display all of these
settings (for example display of arbitrary glyphs may be infeasible).

Detailed description of annotation XML files

Attributes of the <type> element are:



name

Unique non-localized name of the annotation type. Should match the
result of Annotation.getAnnotationType().

description_key

Bundle key for the localized name of the annotation type. This
name is shown in annotation settings as the name of the annotation
type.

localizing_bundle

Name of the bundle (dot-separated and sans extension or locale
suffix) which contains the localized annotation name under the
description_key.

visible

Whether the annotation type is visible or not.

glyph

URL of the glyph icon. Typically this would use the
nbresloc protocol to access module resources and
automatically localize them. A 16x16 GIF is common.

highlight

RGB value of the highlight color.

foreground

RGB value of the foreground color. If the color is not specified,
the line's normal text color is inherited.

type

Style of annotation. Currently two styles are permitted:
line (full-line annotation) and linepart
(may be applied to a column range within a line).

actions

The name of a subfolder (rooted from
Editors/AnnotationTypes/) in which actions for
this annotation type may be specified. The editor may present these
actions to the user when the annotation glyph is right-clicked, for
example. The actions may be defined by

listing instances:

<folder name="YourAnnotationTypeActions">
  <file name="org-foo-BarAction.instance"/>
</folder>



severity

Severity of this annotation. Allowed values are error,
warning, ok and none. Annotations with severity
other then none will be shown in the Error Stripe using default color
or color specified in custom_sidebar_color. Default value is none.


custom_sidebar_color

A color which should be used when showing this annotation in the Error Stripe.
Specify this color if the default color derived from the severity is
not feasible. Note that this setting has no effect if severity
is set to none.


browseable

Whether this annotation should be "browseable" using action like Show Next Error.
Valid values are true and false, default is false.


priority

Priority of this annotation with respect to other annotations with the same severity.
Valid values are integer numbers. Default is 0.




The annotation <type> may also contain the
<combinations> element - a definition of annotation
combinations. If two or more annotations from the same module (or
otherwise mutually known) are on the same line it might make sense to
combine them into one annotation visually. For example, if a debugger
module attached a breakpoint to a line and the current program counter
reached the same line, it is more pleasant to show a combination of
these two annotations rather than two separate annotations. This can
be accomplished using a combination definition. A combined annotation
type is otherwise normal (it may have a glyph icon and colors), but it
also contains the definition of annotation types which are subsumed by
this type. For example the combination of program counter with
breakpoint could be defined as follows:

<combinations tiptext_key="PC_BREAKPOINT_COMBINATION_TOOLTIP_TEXT">
  <combine annotationtype="NameOfTheBreakpointAnnotationType"/>
  <combine annotationtype="NameOfTheCurrentPCAnnotationType"/>
</combinations>


It is the responsibility of the editor to display combinations
where the criteria for combinations as defined in available annotation
types are met.

Attributes of the <combinations> element
are:



tiptext_key

Bundle key for the localized tooltip text of the combining
annotation. The same bundle is used as was specified in
description_key on <type>. Since
multiple annotation types are being combined, each of which might have
its own tooltip, the combined annotation has just a static tooltip
which might explain that several annotations are combined in it.

order

If necessary, the order in which the combinations should be
processed can be specified. This might be useful for more complicated
combinations. If the value is not specified, the combination is added
to the end of the list.

min_optionals

This is related to the attribute optional of the
<combine/> element. The combination is defined as a
list of annotation types to be combined. To make creation of the
combination more flexible, some annotation types can be optional
(optional attribute on <combine/>).
min_optionals is then used to specify the minimum number
of optional annotation types which must be found to make the
combination valid. For example, you may have have a conditional
breakpoint and disabled breakpoint and wish to combine either of them
with the current program counter. You can define it as follows:

<combinations tiptext_key="COMBINATION_TOOLTIP_TEXT" min_optionals="1">
  <combine annotationtype="debugger-disabledbreakpoint" optional="true"/>
  <combine annotationtype="debugger-conditionalbreakpoint" optional="true"/>
  <combine annotationtype="debugger-currentpc"/>
</combinations>


This way you specify that both breakpoints are optional, but that at
least one must be found to make the combination succeed.



The <combinations> element can contain only
<combine/> elements (one for each annotation type)
and they can have these attributes:



annotationtype

Name of the annotation which is subsumed by this combination;
matches name on <type>.

absorb_all

Whether all occurrences of this annotation type should be absorbed
by this combination or only one. This might be useful in case there
are for example multiple breakpoints on the same line.

optional

Whether this annotation type is optional for the combination or
not.

min

Minimum count of annotations of this annotation type which must be
on the line for the combination to match with this type. This can be
used to define combinations such as collapsed multiple
breakpoints.



Loader Interactions with Guard Blocks

The NetBeans-supplied

data object

for Java source code automatically sets up guard blocks in the source
documents it opens, if they contain the magic tokens in comments which
delimit guard blocks on disk. So, if you are working with Java
sources, you need do nothing special to load and save guarded
documents; you may set guard blocks on them in memory, and this will
be retained; or you may add the special tokens to them on disk,
triggering guard block creation when the file is opened.

If you would like to add something akin to guard blocks to a custom
file type handled by your module, you will need to insert the
appropriate hooks. The best thing to do is to subclass

EditorSupport,

and use this subclass to implement cookies such as

EditorCookie.

Now just provide appropriate implementations of

CloneableEditorSupport.loadFromStreamToKit(...)

(to interpret special markings in the saved file and convert them into document attributes); and

CloneableEditorSupport.saveFromKitToStream(...)

(to translate these attributes back into ASCII markings).



Implementing a Custom Editor

It is possible to integrate a custom editor (presumably for textual
content types) into NetBeans, in place of the default
editor. The basic requirement is that it conform to the Swing
EditorKit conventions. The Swing Text system is rather complex, so if
you are not familiar with it you should look at Using
the Swing Text Package.

Beyond being a generic EditorKit, there are two significant pieces of
functionality used by NetBeans which the editor should support if at
all possible:



Be able to mark NetBeans-supplied blocks of text as read-only, and
prevent the user from editing or removing these blocks.

Be able to mark certain lines of the document (or parts of lines)
with NetBeans-supplied annotations, e.g. background color, gutter
glyphs, or as much as feasible, and change these display markings upon
request.



Creating editor kit

You should not need to do anything special to create the editor kit
beyond what is normally required by Swing.

Creating styled document

You will need to create an implementation of

javax.swing.text.StyledDocument

to hold the content of the buffer being edited.

Actually, you could get away with a plain

Document

if you really wanted, but you would be unable to support guard blocks
and would have a harder time supporting annotations and line numbering; while this would probably
suffice for an editor that was not to be used on Java source code, in
general it is very much recommended that StyledDocument
be used instead.

Handling guards

This is really the central problem in creating a compliant editor. If
you want to completely skip this step, it is possible to return a
plain Document from the registered editor kit; however
this will not support guards (or NetBeans attributes either), and so if the
user edits what should have been a guarded block, they may cause
errors in the code, and their edits may be overwritten by NetBeans. If
you implement StyledDocument, it is assumed you are
handling guard blocks, but again it is up to you to actually do so
correctly - NetBeans cannot determine this.

There is very little to the way NetBeans indicates
guarding. Essentially, it is just a character attribute, NbDocument.GUARDED,
which will be set to Boolean.TRUE for guarded characters,
and Boolean.FALSE (or unset) for others; it is typically
placed on the document by means of the

NbDocument.markGuarded(...)

and

NbDocument.unmarkGuarded(...)

methods, which just call

StyledDocument.setCharacterAttributes(...).

Very likely you will want to override this method, calling its
superclass method but first checking to see if the attribute setting
mentions GUARDED, whether setting it to TRUE
or FALSE, and if so keeping track in another data
structure of which ranges of characters are currently guarded or not;
or you might already have a good way of keeping track of attributes in
general and would rather just query this attribute when it is
needed. If overriding setCharacterAttributes for this
purpose, also remember to check the attributes on

insertString,

etc.

Note that currently guarded areas always consist of entire lines or
sets of lines, so if you make this assumption your editor will be
acceptable - but please handle sub-line granularity of guard blocks if
you can do so easily, in case this situation changes. Along the same
lines, you should make sure that users may only insert a newline
immediately before a guarded block, and not any other character, for
otherwise a half-guarded line would be created.

It is important to understand that the guarded attribute applies
only to user modifications, i.e. those undertaken in the
context of a user-initiated Swing action, or by

NbDocument.runAtomicAsUser(...).

Internal NetBeans module code may freely insert or remove text (typically using

NbDocument.insertGuarded(...)

and Document.remove(...)). For example, this would be
done by the Form Editor component while adding a new event
handler. The editor implementation should permit such programmatic
inserts and removes, while corresponding user actions must be
forbidden.

It is preferable, though optional, for the editor to visually mark
guarded areas, say with a special background color. It is your
responsibility to choose a color or another appearance for this
purpose, however. Possibly NetBeans will specify a

StyleConstants.ColorConstants.Background

attribute describing which color will actually be used, and make this
color settable in a control panel, but assume that you need to
colorize based on this attribute yourself.



The recommended way to handle guards

It is highly recommended that all of the Swing actions (such as those
returned by

EditorKit.getActions())

applicable to your editor kit be reviewed for the possibility that
they might attempt to change the content of the document (so, not only
character inserts but search-and-replace, block paste, etc.). Any that
do perform some kind of mutation should be reimplemented (or
a wrapper written for them) so that they check to make sure that a
guarded block is not being violated.

Even better, whenever possible an action should be disabled when it
can easily be determined in advance that it would be in violation if
performed at that time. As an example, if the user moves the caret
into the middle of a guarded block, it would be much preferable for
the editor to disable "Paste" (say, on a right-click context menu) for
the time being, rather than permitting a Paste action to be invoked
but then displaying an error dialog or beeping!

The cheap way to handle guards

If you think the recommended path is too much work, you can try a
cheaper trick - but this is not recommended, and we do not guarantee
that it is even possible to do satisfactorily. This applies only to
people who are trying to adapt an existing
StyledDocument, such as Swing's

DefaultStyledDocument,

which already has a full implementation of important things but no
recognition of guard blocks.

The idea is to first get a list of all

actions

which might involve buffer modification - or, to be conservative, just
all actions. For each of these, create a new action which calls the
original

actionPerformed,

but "dynamically binds" some special flag stored with the document to
true - dynamic binding here means that it should be restored (turned
back off) in a finally block, and also that its value
should be specific to the executing thread (and its children,
perhaps). This flag indicates that operations are currently being
performed from a user action.

Override the insertString(...) and remove
methods. They should check the flag just mentioned. If it is turned
off, just call the superclass method normally. If it is turned on,
check whether the requested insertion or removal is affecting a
guarded area (insertion within, or removal within or overlapping). If
not, again call the superclass method. If there is an attempted
violation, you might do one or more of the following:



 Not perform the insertion/removal, and just silently return.

 Throw a

javax.swing.text.BadLocationException

and see what happens. Since the original action cannot ignore this
exception (since actionPerformed does not have any
throws), it must do something - currently, it seems the Swing actions
simply beep.

Try to run a beep action to alert the user (using

Toolkit.beep()).

This would probably need to be done with

SwingUtilities.invokeLater(...).



Now bind all invocation objects (such as keymaps) to the new "wrapper" actions.
Note that just returning them from the editor kit may not suffice.

If you go to the trouble of identifying specifically which actions
could cause a violation, and under what circumstances they would or
would not do so, then you could make specific wrappers that could
disable actions, or safely invoke them only when possible, calling the
original action if all is well - this is just one way to do the
recommended implementation.

Testing guard blocks

If you are not able to test live in NetBeans, try doing something like this:


SimpleAttributeSet sas=new SimpleAttributeSet();

sas.addAttribute(NbDocument.GUARDED, Boolean.TRUE);

doc.setCharacterAttributes(0, 100, sas, false);


Now verify that modification attempts in this block are disabled.



Lines and elements

You should make sure that lines in the editor are separated by
exactly one text character - a newline. The APIs may rely on this to
count character positions during parsing, so that this functionality
may be efficient.

Furthermore you should ensure that the

default root element

of the document has child elements corresponding to all text lines;
and if using StyledDocument, that

"paragraph" elements

again correspond to text lines. Proper use of elements corresponding
to lines will enable the APIs to accurately translate between buffer
offsets and line numbers. It is fine to have additional element
structures not corresponding to lines so long as the two conditions
above are met.

Handling annotations

An editor must do two things to support annotations:



Implement the NbDocument.Annotatable interface.

Implement parsing of annotation type XML files.



NbDocument.Annotatable

This

interface

has two methods. One adds an annotation to the document:

public void addAnnotation(Position startPos, int length, Annotation annotation);


The method is called with a Position in the document; the
length of the annotation (if the annotation is of the whole-line type,
the length will be -1); and the annotation instance. Now
it is the responsibility of editor to collect all annotations for the
document and to display them properly. It may be helpful to take
advantage of StyledDocument for changing the style of the
line (or part of the line). As for the glyph icon, it is fully up to
the editor how to represent it (if at all). The NetBeans standard
editor displays it in the left gutter.

The second method removed an annotation previously added:

public void removeAnnotation(Annotation annotation);


This method will be called when the annotation is programmatically
detached, or the document is about to be closed.

The editor should combine annotation types where requested if this
behavior is supported.

Annotation type XML files

As for visual attributes of annotations, the editor should parse
the XML files in the Editors/AnnotationTypes/ directory.
The NetBeans standard editor can serve as a source of examples for how to do this.
In the future there may be shared parsing support.

Printing

If you want your editor to support printing of its contents,
you might just provide no special support. In this case,
printing should be able to work with plain text. If you have a styled
document, it is possible that NetBeans will be able to run through the
entire contents of the document; for each paragraph, retrieve its
Style, and for each character, its attribute set; and
then attempt to convert these (Swing) formatting specifications into
(AWT) attributed character descriptions, for purposes of printing.

However, this process could be rather slow; is not terribly exact;
and may not be implemented. To better support printing, it is
desirable for the StyledDocument to implement

org.openide.text.NbDocument.Printable,

which will allow it to specify exactly how it wants to be printed. The
method

NbDocument.Printable.createPrintIterators(...)

should return a list of

java.text.AttributedCharacterIterators,

providing attributes taken from

java.awt.font.TextAttribute.

Also, if your document supports either

java.awt.print.Printable

or

java.awt.print.Pageable,

then these interfaces will be used to perform the printing
directly. You should only need to do this if attributed characters do
not satisfactorily capture everything that you are interested in
printing - for example, if your editor is working on HTML and it is
desired to print embedded images.

Locking

It is desirable for your StyledDocument implementation to
be able to lock the document against write access, as this will make
certain operations (performed by NetBeans, not in response to user
events) more reliable and safer. In order to do this, please
implement

org.openide.text.NbDocument.WriteLockable

and its

runAtomic(...)

method. The Runnable passed in this way should be
executed with all other write actions (and reads) disabled,
i.e. blocked.

If you are extending

javax.swing.text.AbstractDocument,

please note that just enclosing the Runnable block in
calls to

writeLock()

and

writeUnlock()

will not do the trick - these calls do take out exclusive locks,
however they specifically do not nest. This means that you cannot
lock and then enter a runnable this way, because any modifications
attempted within the runnable will throw an illegal state
exception.  Also, the locking methods are final and cannot be
advised to nest.  So you must find some other way to implement
this, e.g. your own locks.

You must also implement

NbDocument.WriteLockable.runAtomicAsUser(...),

which is very similar but is invoked on behalf of user actions
unrelated to whatever component created the guard blocks - e.g., this
would be used to rename a method from the Explorer, in which case the
rename ought to check that the renamed method is not guarded due to
being used by the Form Editor. Thus, it should attempt to make
modifications requested by the Runnable, locking out
other modifications, but ensure that guard blocks are not violated.
Any attempted violation should be prevented (or rolled back at the end
of the runnable), and after the end of the runnable an appropriate
exception should be thrown.

Note that while both methods in this interface ought to provide a
transactional interface if at all possible - i.e., either succeed at
executing the entire Runnable, or fail and leave the
document untouched - the transactional aspect is much more important to
implement properly for runAtomicAsUser. This is because
it is quite possible for an innocent user action (e.g. attempting to
rename a JavaBean property) to interfere with a guard block, and the
document should not be left half-modified after such a
mistake. On the other hand, a failure in the block of
runAtomic is more likely to be an bug in some module,
and not the user's fault; so perfect recovery is of course less
important, as the bug should be fixed anyway.

There is currently no default convenience implementation of
runAtomicAsUser, as any implementation may well be
closely tied to how guard blocks are implemented in that particular
editor - e.g. in Emacs there will be a quite idiosyncratic
implementation.

Biases

Please consider implementing

org.openide.text.NbDocument.PositionBiasable

and its

createPosition(...)

method, to create a position marker which not only moves freely with
insertions and deletions in nearby text, but also specifies the
direction the marker will move to when text is inserted at that
position.

If this is not done, NetBeans creates its own replacement.

Scrolling to display

NetBeans sometimes asks the editor to scroll the display so that a
given line will be displayed. You should not need to do anything
special to support this;

Caret.setDot()

will be called and ought to perform the scrolling appropriately.

Presentable actions

It is desirable for the editor to present actions to the user that may
be invoked on the document and may be accessed in various ways. For
example, if your editor provides an

action

for reindenting a section of text, it is best if this action can be
integrated into the rest of NetBeans consistently: a "Reindent" item
under the "Edit" menu on the main toolbar, active when your editor has
focus; a button with an icon representing reindentation placed onto
the NetBeans toolbar; a context menu item within the editor pane named
"Reindent"; a keyboard shortcut Ctrl-R; etc.

While it might be possible to add some of these things manually
into the NetBeans action containers (like the "Main Window" entry in the
Environment, visible in the Explorer), this is discouraged as that
makes it more difficult for NetBeans to manage actions added by various
modules.

Instead, you should use the Actions API to add

CallbackSystemActions

(e.g.) to your module.

Default toolbar

Although it is best to use the Actions API to specify in your module's
manifest file which actions to install where, NetBeans may
also create a toolbar attached to the editor window which will reflect
all displayable actions supported by your editor, automatically. This
may be better for less-commonly used actions which it would be
inappropriate to install into the main control window.

You do not need to do much to support this editor toolbar: in the

getActions()

method of your editor kit, if there are any actions which are also

SystemActions

implementing

Presenter.Toolbar,

then this interface will be used to get a

java.awt.Component

which will be displayed in the editor toolbar. You are free to make
this component be whatever you like, e.g. a button to run some
routine, or a checkbox to toggle an option; just add the appropriate
event listeners to it.

Standard actions

A few basic editing commands you do not need to explicitly
present to NetBeans; this will be done for you automatically. NetBeans
tests whether an editor kit provides (from its
EditorKit.getActions() method) any actions with certain
names. Default instances of these are also available in the
DefaultEditorKit class, but your actions will be
recognized based on a call to

getValue(Action.NAME):


Name
Static field in
DefaultEditorKit
copy-to-clipboard
copyAction
cut-to-clipboard
cutAction
paste-from-clipboard
pasteAction


There are a few more which unfortunately do not exist in the
DefaultEditorKit, and therefore have no standard
names. The following may be used:




Name
Description
find
Pop up dialog to find a string in the text.
replace
Pop up dialog to find &
replace a string in the text.
goto
Pop up dialog to go to some place in
the text, e.g. a specific line number.
delete
Delete the selection, without
affecting clipboard.
undo
Undo action. See package
javax.swing.undo for help. Currently not specially
supported, except to call your action.
redo
Redo action. Ditto.


The corresponding items in the NetBeans "Edit" menu, and other
standard invocations such as from the system toolbar, will
automatically invoke these actions on your document, if you supply
them. You should use

Action.isEnabled()

to indicate whether your action is ready, and thus whether or not the
corresponding UI elements should be grayed out.

Undo/redo support

It is desirable for your document's user-level edit actions to implement

UndoableEdit,

so that NetBeans can smoothly provide Undo/Redo support for the editor
from the standard places (e.g. in the Edit menu). Note that

AbstractDocument,

for example, already provides this support.

Customization

This API does not provide any special mechanism for allowing the user
to customize aspects of the editor's operation from the GUI; if you
want to do this, please use NbPreferences or similar.

Installing

It should be straightforward to install the new editor -
you will make a JAR file containing a manifest with attributes
recognized by NetBeans as constituting a module, and just call

javax.swing.JEditorPane.registerEditorKitForContentType(...),

and NetBeans should subsequently use it.

Implementing a module with editor support



It is possible that there will be special support in the Modules
API for registering editors. Although doing it manually in the
module's

installed()

method is not difficult, properly the module should also restore the
original editor kit for each content type upon an uninstall, and
ideally there would be a user-visible control panel permitting
selection of the editor for each content type from among those
claiming to support it.

This is not likely to be done unless it turns out to be popular to
have multiple editors installed, and conflicts become a problem.

In the meantime, please refer to the

Modules API

for instructions on creating a module to contain your editor.



Registering unusual MIME types

If your editor has support for an unusual MIME type that is not
currently recognized, you may wish to use the

MIME resolution

infrastructure in the Filesystems API to help your files be
recognized. Additionally,

CloneableEditorSupport.setMIMEType(String)

may be used to control the MIME type of an editor kit regardless of
the type of the underlying file.



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