Eclipse Plug-in Developer Guide (Galileo) - TextLayout (Eclipse Platform API Specification)

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Eclipse Platform
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org.eclipse.swt.graphics
Class TextLayout


java.lang.Object
  

org.eclipse.swt.graphics.Resource
      
org.eclipse.swt.graphics.TextLayout

public final class TextLayout
extends Resource
extends Resource

TextLayout is a graphic object that represents styled text.

Instances of this class provide support for drawing, cursor navigation, hit testing, text wrapping, alignment, tab expansion line breaking, etc. These are aspects required for rendering internationalized text.

Application code must explicitly invoke the TextLayout#dispose() method to release the operating system resources managed by each instance when those instances are no longer required.

Since:: 3.0
See Also:: TextLayout, TextStyle snippets, SWT Example: CustomControlExample, StyledText tab, Sample code and further information

Constructor Summary

TextLayout ( Device device)
          Constructs a new instance of this class on the given device.

Method Summary

void draw ( GC gc, int x, int y)
          Draws the receiver's text using the specified GC at the specified point.

void draw ( GC gc, int x, int y, int selectionStart, int selectionEnd, Color selectionForeground, Color selectionBackground)
          Draws the receiver's text using the specified GC at the specified point.

void draw ( GC gc, int x, int y, int selectionStart, int selectionEnd, Color selectionForeground, Color selectionBackground, int flags)
          Draws the receiver's text using the specified GC at the specified point.

int getAlignment ()
          Returns the receiver's horizontal text alignment, which will be one of SWT.LEFT, SWT.CENTER or SWT.RIGHT.

int getAscent ()
          Returns the ascent of the receiver.

Rectangle getBounds ()
          Returns the bounds of the receiver.

Rectangle getBounds (int start, int end)
          Returns the bounds for the specified range of characters.

int getDescent ()
          Returns the descent of the receiver.

Font getFont ()
          Returns the default font currently being used by the receiver to draw and measure text.

int getIndent ()
          Returns the receiver's indent.

boolean getJustify ()
          Returns the receiver's justification.

int getLevel (int offset)
          Returns the embedding level for the specified character offset.

Rectangle getLineBounds (int lineIndex)
          Returns the bounds of the line for the specified line index.

int getLineCount ()
          Returns the receiver's line count.

int getLineIndex (int offset)
          Returns the index of the line that contains the specified character offset.

FontMetrics getLineMetrics (int lineIndex)
          Returns the font metrics for the specified line index.

int[] getLineOffsets ()
          Returns the line offsets.

Point getLocation (int offset, boolean trailing)
          Returns the location for the specified character offset.

int getNextOffset (int offset, int movement)
          Returns the next offset for the specified offset and movement type.

int getOffset (int x, int y, int[] trailing)
          Returns the character offset for the specified point.

int getOffset ( Point point, int[] trailing)
          Returns the character offset for the specified point.

int getOrientation ()
          Returns the orientation of the receiver.

int getPreviousOffset (int offset, int movement)
          Returns the previous offset for the specified offset and movement type.

int[] getRanges ()
          Gets the ranges of text that are associated with a TextStyle.

int[] getSegments ()
          Returns the text segments offsets of the receiver.

int getSpacing ()
          Returns the line spacing of the receiver.

TextStyle getStyle (int offset)
          Gets the style of the receiver at the specified character offset.

TextStyle[] getStyles ()
          Gets all styles of the receiver.

int[] getTabs ()
          Returns the tab list of the receiver.

String getText ()
          Gets the receiver's text, which will be an empty string if it has never been set.

int getWidth ()
          Returns the width of the receiver.

boolean isDisposed ()
          Returns true if the text layout has been disposed, and false otherwise.

void setAlignment (int alignment)
          Sets the text alignment for the receiver.

void setAscent (int ascent)
          Sets the ascent of the receiver.

void setDescent (int descent)
          Sets the descent of the receiver.

void setFont ( Font font)
          Sets the default font which will be used by the receiver to draw and measure text.

void setIndent (int indent)
          Sets the indent of the receiver.

void setJustify (boolean justify)
          Sets the justification of the receiver.

void setOrientation (int orientation)
          Sets the orientation of the receiver, which must be one of SWT.LEFT_TO_RIGHT or SWT.RIGHT_TO_LEFT.

void setSegments (int[] segments)
          Sets the offsets of the receiver's text segments.

void setSpacing (int spacing)
          Sets the line spacing of the receiver.

void setStyle ( TextStyle style, int start, int end)
          Sets the style of the receiver for the specified range.

void setTabs (int[] tabs)
          Sets the receiver's tab list.

void setText ( String text)
          Sets the receiver's text.

void setWidth (int width)
          Sets the line width of the receiver, which determines how text should be wrapped and aligned.

String toString ()
          Returns a string containing a concise, human-readable description of the receiver.

Methods inherited from class org.eclipse.swt.graphics. Resource

dispose, getDevice

Methods inherited from class java.lang. Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

TextLayout

public TextLayout(
Device device)

Constructs a new instance of this class on the given device.

You must dispose the text layout when it is no longer required.

Parameters:

device - the device on which to allocate the text layout

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if device is null and there is no current device

See Also:

Resource.dispose()

Method Detail

draw

public void draw(
GC gc,
                 int x,
                 int y)

Draws the receiver's text using the specified GC at the specified point.

Parameters:

gc - the GC to draw

x - the x coordinate of the top left corner of the rectangular area where the text is to be drawn

y - the y coordinate of the top left corner of the rectangular area where the text is to be drawn

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the gc is null

draw

public void draw(
GC gc,
                 int x,
                 int y,
                 int selectionStart,
                 int selectionEnd,
                 
Color selectionForeground,
                 
Color selectionBackground)

Draws the receiver's text using the specified GC at the specified point.

Parameters:

gc - the GC to draw

x - the x coordinate of the top left corner of the rectangular area where the text is to be drawn

y - the y coordinate of the top left corner of the rectangular area where the text is to be drawn

selectionStart - the offset where the selections starts, or -1 indicating no selection

selectionEnd - the offset where the selections ends, or -1 indicating no selection

selectionForeground - selection foreground, or NULL to use the system default color

selectionBackground - selection background, or NULL to use the system default color

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the gc is null

draw

public void draw(
GC gc,
                 int x,
                 int y,
                 int selectionStart,
                 int selectionEnd,
                 
Color selectionForeground,
                 
Color selectionBackground,
                 int flags)

Draws the receiver's text using the specified GC at the specified point.

The parameter flags can include one of SWT.DELIMITER_SELECTION or SWT.FULL_SELECTION to specify the selection behavior on all lines except for the last line, and can also include SWT.LAST_LINE_SELECTION to extend the specified selection behavior to the last line.

Parameters:

gc - the GC to draw

x - the x coordinate of the top left corner of the rectangular area where the text is to be drawn

y - the y coordinate of the top left corner of the rectangular area where the text is to be drawn

selectionStart - the offset where the selections starts, or -1 indicating no selection

selectionEnd - the offset where the selections ends, or -1 indicating no selection

selectionForeground - selection foreground, or NULL to use the system default color

selectionBackground - selection background, or NULL to use the system default color

flags - drawing options

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the gc is null

Since:

3.3

getAlignment

public int getAlignment()

Returns the receiver's horizontal text alignment, which will be one of SWT.LEFT, SWT.CENTER or SWT.RIGHT.

Returns:

the alignment used to positioned text horizontally

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getAscent

public int getAscent()

Returns the ascent of the receiver.

Returns:

the ascent

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getBounds

public 
Rectangle getBounds()

Returns the bounds of the receiver. The width returned is either the width of the longest line or the width set using setWidth(int). To obtain the text bounds of a line use getLineBounds(int).

Returns:

the bounds of the receiver

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

setWidth(int), getLineBounds(int)

getBounds

public 
Rectangle getBounds(int start,
                           int end)

Returns the bounds for the specified range of characters. The bounds is the smallest rectangle that encompasses all characters in the range. The start and end offsets are inclusive and will be clamped if out of range.

Parameters:

start - the start offset

end - the end offset

Returns:

the bounds of the character range

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getDescent

public int getDescent()

Returns the descent of the receiver.

Returns:

the descent

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getFont

public 
Font getFont()

Returns the default font currently being used by the receiver to draw and measure text.

Returns:

the receiver's font

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getIndent

public int getIndent()

Returns the receiver's indent.

Returns:

the receiver's indent

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

getJustify

public boolean getJustify()

Returns the receiver's justification.

Returns:

the receiver's justification

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

getLevel

public int getLevel(int offset)

Returns the embedding level for the specified character offset. The embedding level is usually used to determine the directionality of a character in bidirectional text.

Parameters:

offset - the character offset

Returns:

the embedding level

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the character offset is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLineBounds

public 
Rectangle getLineBounds(int lineIndex)

Returns the bounds of the line for the specified line index.

Parameters:

lineIndex - the line index

Returns:

the line bounds

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the line index is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLineCount

public int getLineCount()

Returns the receiver's line count. This includes lines caused by wrapping.

Returns:

the line count

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLineIndex

public int getLineIndex(int offset)

Returns the index of the line that contains the specified character offset.

Parameters:

offset - the character offset

Returns:

the line index

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the character offset is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLineMetrics

public 
FontMetrics getLineMetrics(int lineIndex)

Returns the font metrics for the specified line index.

Parameters:

lineIndex - the line index

Returns:

the font metrics

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the line index is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLineOffsets

public int[] getLineOffsets()

Returns the line offsets. Each value in the array is the offset for the first character in a line except for the last value, which contains the length of the text.

Returns:

the line offsets

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getLocation

public 
Point getLocation(int offset,
                         boolean trailing)

Returns the location for the specified character offset. The trailing argument indicates whether the offset corresponds to the leading or trailing edge of the cluster.

Parameters:

offset - the character offset

trailing - the trailing flag

Returns:

the location of the character offset

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getNextOffset

public int getNextOffset(int offset,
                         int movement)

Returns the next offset for the specified offset and movement type. The movement is one of SWT.MOVEMENT_CHAR, SWT.MOVEMENT_CLUSTER, SWT.MOVEMENT_WORD, SWT.MOVEMENT_WORD_END or SWT.MOVEMENT_WORD_START.

Parameters:

offset - the start offset

movement - the movement type

Returns:

the next offset

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the offset is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

getPreviousOffset(int, int)

getOffset

public int getOffset(
Point point,
                     int[] trailing)

Returns the character offset for the specified point. For a typical character, the trailing argument will be filled in to indicate whether the point is closer to the leading edge (0) or the trailing edge (1). When the point is over a cluster composed of multiple characters, the trailing argument will be filled with the position of the character in the cluster that is closest to the point.

Parameters:

point - the point

trailing - the trailing buffer

Returns:

the character offset

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the trailing length is less than 1
ERROR_NULL_ARGUMENT - if the point is null


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

getLocation(int, boolean)

getOffset

public int getOffset(int x,
                     int y,
                     int[] trailing)

Parameters:

x - the x coordinate of the point

y - the y coordinate of the point

trailing - the trailing buffer

Returns:

the character offset

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the trailing length is less than 1


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

getLocation(int, boolean)

getOrientation

public int getOrientation()

Returns the orientation of the receiver.

Returns:

the orientation style

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getPreviousOffset

public int getPreviousOffset(int offset,
                             int movement)

Returns the previous offset for the specified offset and movement type. The movement is one of SWT.MOVEMENT_CHAR, SWT.MOVEMENT_CLUSTER or SWT.MOVEMENT_WORD, SWT.MOVEMENT_WORD_END or SWT.MOVEMENT_WORD_START.

Parameters:

offset - the start offset

movement - the movement type

Returns:

the previous offset

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the offset is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

getNextOffset(int, int)

getRanges

public int[] getRanges()

Gets the ranges of text that are associated with a TextStyle.

Returns:

the ranges, an array of offsets representing the start and end of each text style.

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

See Also:

getStyles()

getSegments

public int[] getSegments()

Returns the text segments offsets of the receiver.

Returns:

the text segments offsets

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getSpacing

public int getSpacing()

Returns the line spacing of the receiver.

Returns:

the line spacing

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getStyle

public 
TextStyle getStyle(int offset)

Gets the style of the receiver at the specified character offset.

Parameters:

offset - the text offset

Returns:

the style or null if not set

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the character offset is out of range


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getStyles

public 
TextStyle[] getStyles()

Gets all styles of the receiver.

Returns:

the styles

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

See Also:

getRanges()

getTabs

public int[] getTabs()

Returns the tab list of the receiver.

Returns:

the tab list

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getText

public 
String getText()

Gets the receiver's text, which will be an empty string if it has never been set.

Returns:

the receiver's text

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

getWidth

public int getWidth()

Returns the width of the receiver.

Returns:

the width

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

isDisposed

public boolean isDisposed()

Returns true if the text layout has been disposed, and false otherwise.

This method gets the dispose state for the text layout. When a text layout has been disposed, it is an error to invoke any other method using the text layout.

Specified by:: isDisposed in class Resource

Returns:: true when the text layout is disposed and false otherwise

setAlignment

public void setAlignment(int alignment)

Sets the text alignment for the receiver. The alignment controls how a line of text is positioned horizontally. The argument should be one of SWT.LEFT, SWT.RIGHT or SWT.CENTER.

The default alignment is SWT.LEFT. Note that the receiver's width must be set in order to use SWT.RIGHT or SWT.CENTER alignment.

Parameters:

alignment - the new alignment

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

setWidth(int)

setAscent

public void setAscent(int ascent)

Sets the ascent of the receiver. The ascent is distance in pixels from the baseline to the top of the line and it is applied to all lines. The default value is -1 which means that the ascent is calculated from the line fonts.

Parameters:

ascent - the new ascent

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the ascent is less than -1


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setDescent

public void setDescent(int descent)

Sets the descent of the receiver. The descent is distance in pixels from the baseline to the bottom of the line and it is applied to all lines. The default value is -1 which means that the descent is calculated from the line fonts.

Parameters:

descent - the new descent

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the descent is less than -1


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

setAscent(int), getLineMetrics(int)

setFont

public void setFont(
Font font)

Sets the default font which will be used by the receiver to draw and measure text. If the argument is null, then a default font appropriate for the platform will be used instead. Note that a text style can override the default font.

Parameters:

font - the new font for the receiver, or null to indicate a default font

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the font has been disposed


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setIndent

public void setIndent(int indent)

Sets the indent of the receiver. This indent it applied of the first line of each paragraph.

Parameters:

indent - new indent

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

setJustify

public void setJustify(boolean justify)

Sets the justification of the receiver. Note that the receiver's width must be set in order to use justification.

Parameters:

justify - new justify

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

Since:

3.2

setOrientation

public void setOrientation(int orientation)

Sets the orientation of the receiver, which must be one of SWT.LEFT_TO_RIGHT or SWT.RIGHT_TO_LEFT.

Parameters:

orientation - new orientation style

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setSegments

public void setSegments(int[] segments)

Sets the offsets of the receiver's text segments. Text segments are used to override the default behaviour of the bidirectional algorithm. Bidirectional reordering can happen within a text segment but not between two adjacent segments.

Each text segment is determined by two consecutive offsets in the segments arrays. The first element of the array should always be zero and the last one should always be equals to length of the text.

Parameters:

segments - the text segments offset

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setSpacing

public void setSpacing(int spacing)

Sets the line spacing of the receiver. The line spacing is the space left between lines.

Parameters:

spacing - the new line spacing

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the spacing is negative


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setStyle

public void setStyle(
TextStyle style,
                     int start,
                     int end)

Sets the style of the receiver for the specified range. Styles previously set for that range will be overwritten. The start and end offsets are inclusive and will be clamped if out of range.

Parameters:

style - the style

start - the start offset

end - the end offset

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setTabs

public void setTabs(int[] tabs)

Sets the receiver's tab list. Each value in the tab list specifies the space in pixels from the origin of the text layout to the respective tab stop. The last tab stop width is repeated continuously.

Parameters:

tabs - the new tab list

Throws:


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setText

public void setText(
String text)

Sets the receiver's text.

Note: Setting the text also clears all the styles. This method returns without doing anything if the new text is the same as the current text.

Parameters:

text - the new text

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the text is null


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

setWidth

public void setWidth(int width)

Sets the line width of the receiver, which determines how text should be wrapped and aligned. The default value is -1 which means wrapping is disabled.

Parameters:

width - the new width

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the width is 0 or less than -1


SWTException

ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed

See Also:

setAlignment(int)

toString

public 
String toString()

Returns a string containing a concise, human-readable description of the receiver.

Overrides:: toString in class Object

Returns:: a string representation of the receiver

Overview

Package

Class

Use

Tree

Deprecated

Index

Help

Eclipse Platform
Release 3.5

PREV CLASS NEXT CLASS

NO FRAMES

SUMMARY: NESTED | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

Guidelines for using Eclipse APIs.

org.eclipse.swt.graphics Class TextLayout

TextLayout

draw

draw

draw

getAlignment

getAscent

getBounds

getBounds

getDescent

getFont

getIndent

getJustify

getLevel

getLineBounds

getLineCount

getLineIndex

getLineMetrics

getLineOffsets

getLocation

getNextOffset

getOffset

getOffset

getOrientation

getPreviousOffset

getRanges

getSegments

getSpacing

getStyle

getStyles

getTabs

getText

getWidth

isDisposed

setAlignment

setAscent

setDescent

setFont

setIndent

setJustify

setOrientation

setSegments

setSpacing

setStyle

setTabs

setText

setWidth

toString

org.eclipse.swt.graphics
Class TextLayout