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## org.eclipse.jface.text
Interface ITextViewer

All Known Subinterfaces:
  ISourceViewer

All Known Implementing Classes:
  SourceViewer, TextViewer

public interface ITextViewer

A text viewer connects a text widget with an `IDocument`. The document is used as the widget's text model.

It supports the following kinds of listeners:

- view port listeners to inform about changes of the viewer's view port
- text listeners to inform about changes of the document and the subsequent viewer change
- text input listeners to inform about changes of the viewer's input document.

A text viewer supports a set of configuration options and plug-ins defining its behavior:

- undo manager
- double click behavior
- auto indentation
- text hover

Installed plug-ins are not automatically activated. Plug-ins must be activated with the `activatePlugins` call. Most plug-ins can be defined per content type. Content types are derived from a partitioning of the text viewer's input document. In case of documents that support multiple partitionings, the implementer is responsible for determining the partitioning to use.

A text viewer also provides the concept of event consumption. Events handled by the viewer can be filtered and processed by a dynamic event consumer. With `ITextViewerExtension`this mechanism has been replaced with the support for `VerifyKeyListener`.

A text viewer provides several text editing functions, some of them are configurable, through a text operation target interface. It also supports a presentation mode in which it only shows a specified section of its document. By calling `setVisibleRegion` clients define which section is visible. Clients can get access to this section by calling `getVisibleRegion`. The viewer's presentation mode does not affect any client of the viewer other than text listeners. With `ITextViewerExtension5`the visible region support has been reworked. With that extension interface, text viewers are allowed to show fractions of their input document. I.e. a widget selection of two visually neighboring characters is no longer guaranteed to be two neighboring characters in the viewer's input document. Thus, viewers implementing `ITextViewerExtension5`are potentially forced to change the fractions of the input document that are shown when clients ask for the visible region.

In order to provide backward compatibility for clients of `ITextViewer`, extension interfaces are used as a means of evolution. The following extension interfaces exist:

- `ITextViewerExtension`since version 2.0 replacing the event consumer mechanism and introducing the concept of rewrite targets and means to manage the viewer's redraw behavior
- `ITextViewerExtension2`since version 2.1 adding a way to invalidate a viewer's presentation and setters for hovers.
- `ITextViewerExtension3`since version 2.1 which itself was replaced by `ITextViewerExtension5`in version 3.0
- `ITextViewerExtension4`since version 3.0 introducing focus handling for widget token keepers and the concept of text presentation listeners.
- `ITextViewerExtension5`since version 3.0 extending the visible region concept with explicit handling and conversation of widget and model coordinates.

Clients may implement this interface and its extension interfaces or use the standard implementation `TextViewer`.

See Also:
  `ITextViewerExtension`, `ITextViewerExtension2`, `ITextViewerExtension3`, `ITextViewerExtension4`, `ITextViewerExtension5`, `IDocument`, `ITextInputListener`, `IViewportListener`, `ITextListener`, `IEventConsumer`

Method Summary
`void` | `activatePlugins()` Activates the installed plug-ins.
`void` | `addTextInputListener(ITextInputListener listener)` Adds a text input listener to this viewer.
`void` | `addTextListener(ITextListener listener)` Adds a text listener to this viewer.
`void` | `addViewportListener(IViewportListener listener)` Adds the given view port listener to this viewer.
`void` | `changeTextPresentation(TextPresentation presentation, boolean controlRedraw)` Applies the color information encoded in the given text presentation.
`int` | `getBottomIndex()` Returns the visible line with the highest line number.
`int` | `getBottomIndexEndOffset()` Returns the document offset of the lower right corner of this viewer's view port.
`IDocument` | `getDocument()` Returns the text viewer's input document.
`IFindReplaceTarget` | `getFindReplaceTarget()` Returns the find/replace operation target of this viewer.
`Point` | `getSelectedRange()` Returns the range of the current selection in coordinates of this viewer's document.
`ISelectionProvider` | `getSelectionProvider()` Returns a selection provider dedicated to this viewer.
`ITextOperationTarget` | `getTextOperationTarget()` Returns the text operation target of this viewer.
`StyledText` | `getTextWidget()` Returns this viewer's SWT control, `null` if the control is disposed.
`int` | `getTopIndex()` Returns the visible line with the smallest line number.
`int` | `getTopIndexStartOffset()` Returns the document offset of the upper left corner of this viewer's view port.
`int` | `getTopInset()` Returns the vertical offset of the first visible line.
`IRegion` | `getVisibleRegion()` Returns the current visible region of this viewer's document.
`void` | `invalidateTextPresentation()` Marks the currently applied text presentation as invalid.
`boolean` | `isEditable()` Returns whether the shown text can be manipulated.
`boolean` | `overlapsWithVisibleRegion(int offset, int length)` Returns whether a given range overlaps with the visible region of this viewer's document.
`void` | `removeTextInputListener(ITextInputListener listener)` Removes the given listener from this viewer's set of text input listeners.
`void` | `removeTextListener(ITextListener listener)` Removes the given listener from this viewer's set of text listeners.
`void` | `removeViewportListener(IViewportListener listener)` Removes the given listener from this viewer's set of view port listeners.
`void` | `resetPlugins()` Resets the installed plug-ins.
`void` | `resetVisibleRegion()` Resets the region of this viewer's document which is visible in the presentation.
`void` | `revealRange(int offset, int length)` Ensures that the given range is visible.
`void` | `setAutoIndentStrategy(IAutoIndentStrategy strategy, String contentType)` Sets this viewer's auto indent strategy for the given content type.
`void` | `setDefaultPrefixes(String[] defaultPrefixes, String contentType)` Sets the string that is used as prefix when lines of the given content type are prefixed by the prefix text operation.
`void` | `setDocument(IDocument document)` Sets the given document as the text viewer's model and updates the presentation accordingly.
`void` | `setDocument(IDocument document, int modelRangeOffset, int modelRangeLength)` Sets the given document as this viewer's model and exposes the specified region.
`void` | `setEditable(boolean editable)` Sets the editable state.
`void` | `setEventConsumer(IEventConsumer consumer)` Registers an event consumer with this viewer.
`void` | `setIndentPrefixes(String[] indentPrefixes, String contentType)` Sets the strings that are used as prefixes when lines of the given content type are shifted using the shift text operation.
`void` | `setSelectedRange(int offset, int length)` Sets the selection to the specified range.
`void` | `setTextColor(Color color)` Applies the given color as text foreground color to this viewer's selection.
`void` | `setTextColor(Color color, int offset, int length, boolean controlRedraw)` Applies the given color as text foreground color to the specified section of this viewer.
`void` | `setTextDoubleClickStrategy(ITextDoubleClickStrategy strategy, String contentType)` Sets this viewer's text double click strategy for the given content type.
`void` | `setTextHover(ITextHover textViewerHover, String contentType)` Sets this viewer's text hover for the given content type.
`void` | `setTopIndex(int index)` Scrolls the widget so the the given index is the line with the smallest line number of all visible lines.
`void` | `setUndoManager(IUndoManager undoManager)` Sets this viewer's undo manager.
`void` | `setVisibleRegion(int offset, int length)` Defines and sets the region of this viewer's document which will be visible in the presentation.

Method Detail

### getTextWidget

    public StyledText getTextWidget()

  Returns this viewer's SWT control, `null` if the control is disposed.

  Returns:
    the SWT control or `null`

### setUndoManager

    public void setUndoManager(IUndoManager undoManager)

  Sets this viewer's undo manager.

  Parameters:
    `undoManager` - the new undo manager. `null` is a valid argument.

### setTextDoubleClickStrategy

    public void setTextDoubleClickStrategy(ITextDoubleClickStrategy strategy,
                                           String contentType)

  Sets this viewer's text double click strategy for the given content type.

  Parameters:
    `strategy` - the new double click strategy. `null` is a valid argument.
    `contentType` - the type for which the strategy is registered

### setAutoIndentStrategy

    public void setAutoIndentStrategy(IAutoIndentStrategy strategy,
                                      String contentType)

  Sets this viewer's auto indent strategy for the given content type. If the given strategy is `null` any installed strategy for the content type is removed. This method has been replaced by `ITextViewerExtension2.prependAutoEditStrategy(IAutoEditStrategy, String)` and `ITextViewerExtension2.removeAutoEditStrategy(IAutoEditStrategy, String)`. It is now equivalent to

          ITextViewerExtension2 extension= (ITextViewerExtension2) viewer;
          extension.removeAutoEditStrategy(oldStrategy, contentType);
          extension.prependAutoEditStrategy(strategy, contentType);

  Parameters:
    `strategy` - the new auto indent strategy. `null` is a valid argument.
    `contentType` - the type for which the strategy is registered

### setTextHover

    public void setTextHover(ITextHover textViewerHover,
                             String contentType)

  Sets this viewer's text hover for the given content type.

  This method has been replaced by `ITextViewerExtension2.setTextHover(ITextHover, String, int)`. It is now equivalent to

          ITextViewerExtension2 extension= (ITextViewerExtension2) document;
          extension.setTextHover(textViewerHover, contentType, ITextViewerExtension2#DEFAULT_HOVER_STATE_MASK);

  Parameters:
    `textViewerHover` - the new hover. `null` is a valid argument.
    `contentType` - the type for which the hover is registered

### activatePlugins

    public void activatePlugins()

  Activates the installed plug-ins. If the plug-ins are already activated this call has no effect.

### resetPlugins

    public void resetPlugins()

  Resets the installed plug-ins. If plug-ins change their state or behavior over the course of time, this method causes them to be set back to their initial state and behavior. E.g., if an `IUndoManager` has been installed on this text viewer, the manager's list of remembered text editing operations is removed.

### addViewportListener

    public void addViewportListener(IViewportListener listener)

  Adds the given view port listener to this viewer. The listener is informed about all changes to the visible area of this viewer. If the listener is already registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be added

### removeViewportListener

    public void removeViewportListener(IViewportListener listener)

  Removes the given listener from this viewer's set of view port listeners. If the listener is not registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be removed

### addTextListener

    public void addTextListener(ITextListener listener)

  Adds a text listener to this viewer. If the listener is already registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be added

### removeTextListener

    public void removeTextListener(ITextListener listener)

  Removes the given listener from this viewer's set of text listeners. If the listener is not registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be removed

### addTextInputListener

    public void addTextInputListener(ITextInputListener listener)

  Adds a text input listener to this viewer. If the listener is already registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be added

### removeTextInputListener

    public void removeTextInputListener(ITextInputListener listener)

  Removes the given listener from this viewer's set of text input listeners. If the listener is not registered with this viewer, this call has no effect.

  Parameters:
    `listener` - the listener to be removed

### setDocument

    public void setDocument(IDocument document)

  Sets the given document as the text viewer's model and updates the presentation accordingly. An appropriate `TextEvent` is issued. This text event does not carry a related document event.

  Parameters:
    `document` - the viewer's new input document

### getDocument

    public IDocument getDocument()

  Returns the text viewer's input document.

  Returns:
    the viewer's input document

### setEventConsumer

    public void setEventConsumer(IEventConsumer consumer)

  Registers an event consumer with this viewer. This method has been replaces with the `VerifyKeyListener` management methods in `ITextViewerExtension`.

  Parameters:
    `consumer` - the viewer's event consumer. `null` is a valid argument.

### setEditable

    public void setEditable(boolean editable)

  Sets the editable state.

  Parameters:
    `editable` - the editable state

### isEditable

    public boolean isEditable()

  Returns whether the shown text can be manipulated.

  Returns:
    the viewer's editable state

### setDocument

    public void setDocument(IDocument document,
                            int modelRangeOffset,
                            int modelRangeLength)

  Sets the given document as this viewer's model and exposes the specified region. An appropriate `TextEvent` is issued. The text event does not carry a related document event. This method is a convenience method for `setDocument(document);setVisibleRegion(offset, length)`.

  Parameters:
    `document` - the new input document
    `modelRangeOffset` - the offset of the model range
    `modelRangeLength` - the length of the model range

### setVisibleRegion

    public void setVisibleRegion(int offset,
                                 int length)

  Defines and sets the region of this viewer's document which will be visible in the presentation. Every character inside the specified region is supposed to be visible in the viewer's widget after that call.

  Parameters:
    `offset` - the offset of the visible region
    `length` - the length of the visible region

### resetVisibleRegion

    public void resetVisibleRegion()

  Resets the region of this viewer's document which is visible in the presentation. Afterwards, the whole input document is visible.

### getVisibleRegion

    public IRegion getVisibleRegion()

  Returns the current visible region of this viewer's document. The result may differ from the argument passed to `setVisibleRegion` if the document has been modified since then. The visible region is supposed to be a consecutive region in viewer's input document and every character inside that region is supposed to visible in the viewer's widget.

  Viewers implementing `ITextViewerExtension5` may be forced to change the fractions of the input document that are shown, in order to fulfill this contract.

  Returns:
    this viewer's current visible region

### overlapsWithVisibleRegion

    public boolean overlapsWithVisibleRegion(int offset,
                                             int length)

  Returns whether a given range overlaps with the visible region of this viewer's document.

  Viewers implementing `ITextViewerExtension5`may be forced to change the fractions of the input document that are shown in order to fulfill this request. This is because the overlap is supposed to be without gaps.

  Parameters:
    `offset` - the offset
    `length` - the length
  Returns:
    `true` if the specified range overlaps with the visible region

### changeTextPresentation

    public void changeTextPresentation(TextPresentation presentation,
                                       boolean controlRedraw)

  Applies the color information encoded in the given text presentation. `controlRedraw` tells this viewer whether it should take care of redraw management or not. If, e.g., this call is one in a sequence of multiple presentation calls, it is more appropriate to explicitly control redrawing at the beginning and the end of the sequence.

  Parameters:
    `presentation` - the presentation to be applied to this viewer
    `controlRedraw` - indicates whether this viewer should manage redraws

### invalidateTextPresentation

    public void invalidateTextPresentation()

  Marks the currently applied text presentation as invalid. It is the viewer's responsibility to take any action it can to repair the text presentation.

  See `ITextViewerExtension2.invalidateTextPresentation(int, int)` for a way to invalidate specific regions rather than the presentation as a whole.

  Since:
    2.0

### setTextColor

    public void setTextColor(Color color)

  Applies the given color as text foreground color to this viewer's selection.

  Parameters:
    `color` - the color to be applied

### setTextColor

    public void setTextColor(Color color,
                             int offset,
                             int length,
                             boolean controlRedraw)

  Applies the given color as text foreground color to the specified section of this viewer. `controlRedraw` tells this viewer whether it should take care of redraw management or not.

  Parameters:
    `color` - the color to be applied
    `offset` - the offset of the range to be changed
    `length` - the length of the range to be changed
    `controlRedraw` - indicates whether this viewer should manage redraws

### getTextOperationTarget

    public ITextOperationTarget getTextOperationTarget()

  Returns the text operation target of this viewer.

  Returns:
    the text operation target of this viewer

### getFindReplaceTarget

    public IFindReplaceTarget getFindReplaceTarget()

  Returns the find/replace operation target of this viewer.

  Returns:
    the find/replace operation target of this viewer

### setDefaultPrefixes

    public void setDefaultPrefixes(String[] defaultPrefixes,
                                   String contentType)

  Sets the string that is used as prefix when lines of the given content type are prefixed by the prefix text operation. Sets the strings that are used as prefixes when lines of the given content type are prefixed using the prefix text operation. The prefixes are considered equivalent. Inserting a prefix always inserts the defaultPrefixes[0]. Removing a prefix removes all of the specified prefixes.

  Parameters:
    `defaultPrefixes` - the prefixes to be used
    `contentType` - the content type for which the prefixes are specified
  Since:
    2.0

### setIndentPrefixes

    public void setIndentPrefixes(String[] indentPrefixes,
                                  String contentType)

  Sets the strings that are used as prefixes when lines of the given content type are shifted using the shift text operation. The prefixes are considered equivalent. Thus "\t" and " " can both be used as prefix characters. Shift right always inserts the indentPrefixes[0]. Shift left removes all of the specified prefixes.

  Parameters:
    `indentPrefixes` - the prefixes to be used
    `contentType` - the content type for which the prefixes are specified

### setSelectedRange

    public void setSelectedRange(int offset,
                                 int length)

  Sets the selection to the specified range.

  Parameters:
    `offset` - the offset of the selection range
    `length` - the length of the selection range

### getSelectedRange

    public Point getSelectedRange()

  Returns the range of the current selection in coordinates of this viewer's document.

  Returns:
    the current selection

### getSelectionProvider

    public ISelectionProvider getSelectionProvider()

  Returns a selection provider dedicated to this viewer. Subsequent calls to this method return always the same selection provider.

  Returns:
    this viewer's selection provider

### revealRange

    public void revealRange(int offset,
                            int length)

  Ensures that the given range is visible.

  Parameters:
    `offset` - the offset of the range to be revealed
    `length` - the length of the range to be revealed

### setTopIndex

    public void setTopIndex(int index)

  Scrolls the widget so the the given index is the line with the smallest line number of all visible lines.

  Parameters:
    `index` - the line which should become the top most line

### getTopIndex

    public int getTopIndex()

  Returns the visible line with the smallest line number.

  Returns:
    the number of the top most visible line

### getTopIndexStartOffset

    public int getTopIndexStartOffset()

  Returns the document offset of the upper left corner of this viewer's view port.

  Returns:
    the upper left corner offset

### getBottomIndex

    public int getBottomIndex()

  Returns the visible line with the highest line number.

  Returns:
    the number of the bottom most line

### getBottomIndexEndOffset

    public int getBottomIndexEndOffset()

  Returns the document offset of the lower right corner of this viewer's view port. This is the visible character with the highest character position. If the content of this viewer is shorter, the position of the last character of the content is returned.

  Returns:
    the lower right corner offset

### getTopInset

    public int getTopInset()

  Returns the vertical offset of the first visible line.

  Returns:
    the vertical offset of the first visible line

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