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## com.trolltech.qt.gui
Class QTextLayout

    java.lang.Object
      com.trolltech.qt.internal.QSignalEmitterInternal
          com.trolltech.qt.QSignalEmitter
              com.trolltech.qt.QtJambiObject
                  com.trolltech.qt.gui.QTextLayout

All Implemented Interfaces:
  QtJambiInterface

    public class QTextLayout

extends QtJambiObject

The QTextLayout class is used to lay out and paint a single paragraph of text. It offers most features expected from a modern text layout engine, including Unicode compliant rendering, line breaking and handling of cursor positioning. It can also produce and render device independent layout, something that is important for WYSIWYG applications.

The class has a rather low level API and unless you intend to implement your own text rendering for some specialized widget, you probably won't need to use it directly.

QTextLayout can currently deal with plain text and rich text paragraphs that are part of a `QTextDocument`.

QTextLayout can be used to create a sequence of `QTextLine`'s with given widths and can position them independently on the screen. Once the layout is done, these lines can be drawn on a paint device.

Here's some pseudo code that presents the layout phase:

            int leading = fontMetrics.leading();
            double height = 0;
            double widthUsed = 0;
            textLayout.beginLayout();
            while (1==1) {
                QTextLine line = textLayout.createLine();
                if (!line.isValid())
                    break;

                line.setLineWidth(lineWidth);
                height += leading;
                line.setPosition(new QPointF(0.0, height));
                height += line.height();
                widthUsed = Math.max(widthUsed, line.naturalTextWidth());
            }
            textLayout.endLayout();

The text can be drawn by calling the layout's `draw()` function:

            QPainter painter = new QPainter();
            textLayout.draw(painter,new QPointF(), new ArrayList<QTextLayout_FormatRange>());

The text layout's text is set in the constructor or with `setText()`. The layout can be seen as a sequence of `QTextLine` objects; use `lineAt()` or `lineForTextPosition()` to get a `QTextLine`, `createLine()` to create one. For a given position in the text you can find a valid cursor position with `isValidCursorPosition()`, `nextCursorPosition()`, and `previousCursorPosition()`. The layout itself can be positioned with `setPosition()`; it has a `boundingRect()`, and a `minimumWidth()` and a `maximumWidth()`. A text layout can be drawn on a painter device using `draw()`.

Nested Class Summary
`static class` | `QTextLayout.CursorMode`

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
`QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9`

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal`

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`currentSender`

Constructor Summary
`QTextLayout()` Constructs an empty text layout.
`QTextLayout(java.lang.String text)` Constructs a text layout to lay out the given `text`.
`QTextLayout(java.lang.String text, QFont font)` Constructs a text layout to lay out the given `text` with the specified `font`.
`QTextLayout(java.lang.String text, QFont font, QPaintDeviceInterface paintdevice)` Constructs a text layout to lay out the given `text` with the specified `font`.

Method Summary
`java.util.List` | `additionalFormats()` Returns the list of additional formats supported by the text layout.
`void` | `beginLayout()` Begins the layout process.
`QRectF` | `boundingRect()` The smallest rectangle that contains all the lines in the layout.
`boolean` | `cacheEnabled()` Returns true if the complete layout information is cached; otherwise returns false.
`void` | `clearAdditionalFormats()` Clears the list of additional formats supported by the text layout.
`void` | `clearLayout()` Clears the line information in the layout.
`QTextLine` | `createLine()` Returns a new text line to be laid out if there is text to be inserted into the layout; otherwise returns an invalid text line.
`void` | `draw(QPainter p, QPointF pos, java.util.List selections)` Draws the whole layout on the painter `p` at the position specified by `pos`.
`void` | `draw(QPainter p, QPointF pos, java.util.List selections, QRectF clip)` Draws the whole layout on the painter `p` at the position specified by `pos`.
`void` | `drawCursor(QPainter p, QPointF pos, int cursorPosition)` Draws a text cursor with the current pen at the given `position` using the `painter` specified.
`void` | `drawCursor(QPainter p, QPointF pos, int cursorPosition, int width)` Draws a text cursor with the current pen and the specified `width` at the given `position` using the `painter` specified.
`void` | `endLayout()` Ends the layout process.
`QFont` | `font()` Returns the current font that is used for the layout, or a default font if none is set.
`boolean` | `isValidCursorPosition(int pos)` Returns true if position `pos` is a valid cursor position.
`QTextLine` | `lineAt(int i)` Returns the `i`-th line of text in this text layout.
`int` | `lineCount()` Returns the number of lines in this text layout.
`QTextLine` | `lineForTextPosition(int pos)` Returns the line that contains the cursor position specified by `pos`.
`double` | `maximumWidth()` The maximum width the layout could expand to; this is essentially the width of the entire text.
`double` | `minimumWidth()` The minimum width the layout needs.
`int` | `nextCursorPosition(int oldPos)` Returns the next valid cursor position after `oldPos` that respects the given cursor `mode`.
`int` | `nextCursorPosition(int oldPos, QTextLayout.CursorMode mode)` Returns the next valid cursor position after `oldPos` that respects the given cursor `mode`.
`QPointF` | `position()` The global position of the layout.
`int` | `preeditAreaPosition()` Returns the position of the area in the text layout that will be processed before editing occurs.
`java.lang.String` | `preeditAreaText()` Returns the text that is inserted in the layout before editing occurs.
`int` | `previousCursorPosition(int oldPos)` Returns the first valid cursor position before `oldPos` that respects the given cursor `mode`.
`int` | `previousCursorPosition(int oldPos, QTextLayout.CursorMode mode)` Returns the first valid cursor position before `oldPos` that respects the given cursor `mode`.
`void` | `setAdditionalFormats(java.util.List overrides)` Sets the additional formats supported by the text layout to `formatList`.
`void` | `setCacheEnabled(boolean enable)` Enables caching of the complete layout information if `enable` is true; otherwise disables layout caching.
`void` | `setFont(QFont f)` Sets the layout's font to the given `font`.
`void` | `setPosition(QPointF p)` Moves the text layout to point `p`.
`void` | `setPreeditArea(int position, java.lang.String text)` Sets the `position` and `text` of the area in the layout that is processed before editing occurs.
`void` | `setText(java.lang.String string)` Sets the layout's text to the given `string`.
`void` | `setTextOption(QTextOption option)` Sets the text option structure that controls the layout process to the given `option`.
`java.lang.String` | `text()` Returns the layout's text.
`QTextOption` | `textOption()` Returns the current text option used to control the layout process.

Methods inherited from class com.trolltech.qt.QtJambiObject
`dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr`

Methods inherited from class com.trolltech.qt.QSignalEmitter
`blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread`

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`__qt_signalInitialization`

Methods inherited from class java.lang.Object
`clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface com.trolltech.qt.QtJambiInterface
`disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership`

Constructor Detail

### QTextLayout

    public QTextLayout()

  Constructs an empty text layout.

See also:
  `setText()`.

### QTextLayout

    public QTextLayout(java.lang.String text)

  Constructs a text layout to lay out the given `text`.

### QTextLayout

    public QTextLayout(java.lang.String text,
                       QFont font)

  Constructs a text layout to lay out the given `text` with the specified `font`.

  All the metric and layout calculations will be done in terms of the paint device, `paintdevice`. If `paintdevice` is 0 the calculations will be done in screen metrics.

### QTextLayout

    public QTextLayout(java.lang.String text,
                       QFont font,
                       QPaintDeviceInterface paintdevice)

  Constructs a text layout to lay out the given `text` with the specified `font`.

  All the metric and layout calculations will be done in terms of the paint device, `paintdevice`. If `paintdevice` is 0 the calculations will be done in screen metrics.

Method Detail

### additionalFormats

    public final java.util.List additionalFormats()

  Returns the list of additional formats supported by the text layout.

See also:
  `setAdditionalFormats()`, and `clearAdditionalFormats()`.

### beginLayout

    public final void beginLayout()

  Begins the layout process.

### boundingRect

    public final QRectF boundingRect()

  The smallest rectangle that contains all the lines in the layout.

### cacheEnabled

    public final boolean cacheEnabled()

  Returns true if the complete layout information is cached; otherwise returns false.

See also:
  `setCacheEnabled()`.

### clearAdditionalFormats

    public final void clearAdditionalFormats()

  Clears the list of additional formats supported by the text layout.

See also:
  `additionalFormats()`, and `setAdditionalFormats()`.

### clearLayout

    public final void clearLayout()

  Clears the line information in the layout. After having called this function, `lineCount()` returns 0.

### createLine

    public final QTextLine createLine()

  Returns a new text line to be laid out if there is text to be inserted into the layout; otherwise returns an invalid text line.

  The text layout creates a new line object that starts after the last line in the layout, or at the beginning if the layout is empty. The layout maintains an internal cursor, and each line is filled with text from the cursor position onwards when the `QTextLine::setLineWidth()` function is called.

  Once `QTextLine::setLineWidth()` is called, a new line can be created and filled with text. Repeating this process will lay out the whole block of text contained in the QTextLayout. If there is no text left to be inserted into the layout, the `QTextLine` returned will not be valid (isValid() will return false).

### draw

    public final void draw(QPainter p,
                           QPointF pos,
                           java.util.List selections)

  Draws the whole layout on the painter `p` at the position specified by `pos`. The rendered layout includes the given `selections`.

### draw

    public final void draw(QPainter p,
                           QPointF pos,
                           java.util.List selections,
                           QRectF clip)

  Draws the whole layout on the painter `p` at the position specified by `pos`. The rendered layout includes the given `selections` and is clipped within the rectangle specified by `clip`.

### drawCursor

    public final void drawCursor(QPainter p,
                                 QPointF pos,
                                 int cursorPosition)

  Draws a text cursor with the current pen at the given `position` using the `painter` specified. The corresponding position within the text is specified by `cursorPosition`.

### drawCursor

    public final void drawCursor(QPainter p,
                                 QPointF pos,
                                 int cursorPosition,
                                 int width)

  Draws a text cursor with the current pen and the specified `width` at the given `position` using the `painter` specified. The corresponding position within the text is specified by `cursorPosition`.

### endLayout

    public final void endLayout()

  Ends the layout process.

### font

    public final QFont font()

  Returns the current font that is used for the layout, or a default font if none is set.

See also:
  `setFont()`.

### isValidCursorPosition

    public final boolean isValidCursorPosition(int pos)

  Returns true if position `pos` is a valid cursor position.

  In a Unicode context some positions in the text are not valid cursor positions, because the position is inside a Unicode surrogate or a grapheme cluster.

  A grapheme cluster is a sequence of two or more Unicode characters that form one indivisible entity on the screen. For example the latin character `Ä' can be represented in Unicode by two characters, `A' (0x41), and the combining diaresis (0x308). A text cursor can only validly be positioned before or after these two characters, never between them since that wouldn't make sense. In indic languages every syllable forms a grapheme cluster.

### lineAt

    public final QTextLine lineAt(int i)

  Returns the `i`-th line of text in this text layout.

See also:
  `lineCount()`, and `lineForTextPosition()`.

### lineCount

    public final int lineCount()

  Returns the number of lines in this text layout.

See also:
  `lineAt()`.

### lineForTextPosition

    public final QTextLine lineForTextPosition(int pos)

  Returns the line that contains the cursor position specified by `pos`.

See also:
  `isValidCursorPosition()`, and `lineAt()`.

### maximumWidth

    public final double maximumWidth()

  The maximum width the layout could expand to; this is essentially the width of the entire text.

  Warning: This function only returns a valid value after the layout has been done.

See also:
  `minimumWidth()`.

### minimumWidth

    public final double minimumWidth()

  The minimum width the layout needs. This is the width of the layout's smallest non-breakable substring.

  Warning: This function only returns a valid value after the layout has been done.

See also:
  `maximumWidth()`.

### nextCursorPosition

    public final int nextCursorPosition(int oldPos)

  Returns the next valid cursor position after `oldPos` that respects the given cursor `mode`.

See also:
  `isValidCursorPosition()`, and `previousCursorPosition()`.

### nextCursorPosition

    public final int nextCursorPosition(int oldPos,
                                        QTextLayout.CursorMode mode)

  Returns the next valid cursor position after `oldPos` that respects the given cursor `mode`.

See also:
  `isValidCursorPosition()`, and `previousCursorPosition()`.

### position

    public final QPointF position()

  The global position of the layout. This is independent of the bounding rectangle and of the layout process.

See also:
  `setPosition()`.

### preeditAreaPosition

    public final int preeditAreaPosition()

  Returns the position of the area in the text layout that will be processed before editing occurs.

### preeditAreaText

    public final java.lang.String preeditAreaText()

  Returns the text that is inserted in the layout before editing occurs.

### previousCursorPosition

    public final int previousCursorPosition(int oldPos)

  Returns the first valid cursor position before `oldPos` that respects the given cursor `mode`.

See also:
  `isValidCursorPosition()`, and `nextCursorPosition()`.

### previousCursorPosition

    public final int previousCursorPosition(int oldPos,
                                            QTextLayout.CursorMode mode)

  Returns the first valid cursor position before `oldPos` that respects the given cursor `mode`.

See also:
  `isValidCursorPosition()`, and `nextCursorPosition()`.

### setAdditionalFormats

    public final void setAdditionalFormats(java.util.List overrides)

  Sets the additional formats supported by the text layout to `formatList`.

See also:
  `additionalFormats()`, and `clearAdditionalFormats()`.

### setCacheEnabled

    public final void setCacheEnabled(boolean enable)

  Enables caching of the complete layout information if `enable` is true; otherwise disables layout caching. Usually QTextLayout throws most of the layouting information away after a call to `endLayout()` to reduce memory consumption. If you however want to draw the laid out text directly afterwards enabling caching might speed up drawing significantly.

See also:
  `cacheEnabled()`.

### setFont

    public final void setFont(QFont f)

  Sets the layout's font to the given `font`. The layout is invalidated and must be laid out again.

See also:
  `font()`, and `text()`.

### setPosition

    public final void setPosition(QPointF p)

  Moves the text layout to point `p`.

See also:
  `position()`.

### setPreeditArea

    public final void setPreeditArea(int position,
                                     java.lang.String text)

  Sets the `position` and `text` of the area in the layout that is processed before editing occurs.

### setText

    public final void setText(java.lang.String string)

  Sets the layout's text to the given `string`. The layout is invalidated and must be laid out again.

  Notice that when using this QTextLayout as part of a `QTextDocument` this method will have no effect.

See also:
  `text()`.

### setTextOption

    public final void setTextOption(QTextOption option)

  Sets the text option structure that controls the layout process to the given `option`.

See also:
  `textOption()`, and `QTextOption`.

### text

    public final java.lang.String text()

  Returns the layout's text.

See also:
  `setText()`.

### textOption

    public final QTextOption textOption()

  Returns the current text option used to control the layout process.

See also:
  `setTextOption()`, and `QTextOption`.

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