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java.lang.Objectcom.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.gui.QFontMetricsF
public class QFontMetricsF
The QFontMetricsF
class provides font metrics information. QFontMetricsF
functions calculate the size of characters and strings for a given font. You can construct a QFontMetricsF
object with an existing QFont
to obtain metrics for that font. If the font is changed later, the font metrics object is not updated.
Once created, the object provides functions to access the individual metrics of the font, its characters, and for strings rendered in the font.
There are several functions that operate on the font: ascent()
, descent()
, height()
, leading()
and lineSpacing()
return the basic size properties of the font. The underlinePos()
, overlinePos()
, strikeOutPos()
and lineWidth()
functions, return the properties of the line that underlines, overlines or strikes out the characters. These functions are all fast.
There are also some functions that operate on the set of glyphs in the font: minLeftBearing()
, minRightBearing()
and maxWidth()
. These are by necessity slow, and we recommend avoiding them if possible.
For each character, you can get its width()
, leftBearing()
and rightBearing()
and find out whether it is in the font using inFont()
. You can also treat the character as a string, and use the string functions on it.
The string functions include width()
, to return the width of a string in pixels (or points, for a printer), boundingRect()
, to return a rectangle large enough to contain the rendered string, and size()
, to return the size of that rectangle.
Example:
QFont font = new QFont("times", 24); QFontMetricsF fm = new QFontMetricsF(font); double pixelsWide = fm.width("What's the width of this text?"); double pixelsHigh = fm.height();
QFont
, QFontInfo
, and QFontDatabase
.
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
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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 |
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com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal |
Field Summary |
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Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
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currentSender |
Constructor Summary | |
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QFontMetricsF(QFont arg__1)
Constructs a font metrics object for font. |
|
QFontMetricsF(QFontMetrics arg__1)
Constructs a font metrics object with floating point precision from the given fontMetrics object. |
|
QFontMetricsF(QFontMetricsF arg__1)
Constructs a copy of fm. |
|
QFontMetricsF(QFont arg__1,
QPaintDeviceInterface pd)
Constructs a font metrics object for font and paintdevice. |
Method Summary | |
---|---|
double |
ascent()
Returns the ascent of the font. |
double |
averageCharWidth()
Returns the average width of glyphs in the font. |
QRectF |
boundingRect(char arg__1)
Returns the bounding rectangle of the character ch relative to the left-most point on the base line. |
QRectF |
boundingRect(QRectF rect,
int flags,
java.lang.String text)
This is an overloaded function provided for convenience. |
QRectF |
boundingRect(QRectF rect,
int flags,
java.lang.String text,
int tabStops)
Returns the bounding rectangle of the characters in the given text. |
QRectF |
boundingRect(QRectF rect,
int flags,
java.lang.String text,
int tabStops,
int[] tabArray)
Returns the bounding rectangle of the characters in the given text. |
QRectF |
boundingRect(java.lang.String string)
Returns the bounding rectangle of the characters in the string specified by text. |
QFontMetricsF |
clone()
This method is reimplemented for internal reasons |
double |
descent()
Returns the descent of the font. |
java.lang.String |
elidedText(java.lang.String text,
Qt.TextElideMode mode,
double width)
If the string text is wider than width, returns an elided version of the string (i. |
java.lang.String |
elidedText(java.lang.String text,
Qt.TextElideMode mode,
double width,
int flags)
If the string text is wider than width, returns an elided version of the string (i. |
double |
height()
Returns the height of the font. |
boolean |
inFont(char arg__1)
Returns true if character ch is a valid character in the font; otherwise returns false. |
double |
leading()
Returns the leading of the font. |
double |
leftBearing(char arg__1)
Returns the left bearing of character ch in the font. |
double |
lineSpacing()
Returns the distance from one base line to the next. |
double |
lineWidth()
Returns the width of the underline and strikeout lines, adjusted for the point size of the font. |
double |
maxWidth()
Returns the width of the widest character in the font. |
double |
minLeftBearing()
Returns the minimum left bearing of the font. |
double |
minRightBearing()
Returns the minimum right bearing of the font. |
double |
overlinePos()
Returns the distance from the base line to where an overline should be drawn. |
double |
rightBearing(char arg__1)
Returns the right bearing of character ch in the font. |
QSizeF |
size(int flags,
java.lang.String text)
This is an overloaded function provided for convenience. |
QSizeF |
size(int flags,
java.lang.String text,
int tabStops)
This is an overloaded function provided for convenience. |
QSizeF |
size(int flags,
java.lang.String text,
int tabStops,
int[] tabArray)
Returns the size in pixels of the characters in the given text. |
double |
strikeOutPos()
Returns the distance from the base line to where the strikeout line should be drawn. |
QRectF |
tightBoundingRect(java.lang.String text)
Returns a tight bounding rectangle around the characters in the string specified by text. |
double |
underlinePos()
Returns the distance from the base line to where an underscore should be drawn. |
double |
width(char arg__1)
See the description for details. |
double |
width(java.lang.String string)
Returns the width in pixels of the characters in the given text. |
double |
xHeight()
Returns the 'x' height of the font. |
Methods inherited from class com.trolltech.qt.QtJambiObject |
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dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
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blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal |
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__qt_signalInitialization |
Methods inherited from class java.lang.Object |
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getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
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disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
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public QFontMetricsF(QFont arg__1)
The font metrics will be compatible with the paintdevice used to create font.
The font metrics object holds the information for the font that is passed in the constructor at the time it is created, and is not updated if the font's attributes are changed later.
Use QFontMetricsF
(const QFont
&, QPaintDevice
*) to get the font metrics that are compatible with a certain paint device.
public QFontMetricsF(QFont arg__1, QPaintDeviceInterface pd)
The font metrics will be compatible with the paintdevice passed. If the paintdevice is 0, the metrics will be screen-compatible, ie. the metrics you get if you use the font for drawing text on a widgets
or pixmaps
, not on a QPicture
or QPrinter
.
The font metrics object holds the information for the font that is passed in the constructor at the time it is created, and is not updated if the font's attributes are changed later.
public QFontMetricsF(QFontMetrics arg__1)
public QFontMetricsF(QFontMetricsF arg__1)
Method Detail |
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public final double ascent()
The ascent of a font is the distance from the baseline to the highest position characters extend to. In practice, some font designers break this rule, e.g. when they put more than one accent on top of a character, or to accommodate an unusual character in an exotic language, so it is possible (though rare) that this value will be too small.
descent()
.
public final double averageCharWidth()
public final QRectF boundingRect(char arg__1)
Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the text output may cover all pixels in the bounding rectangle.
Note that the rectangle usually extends both above and below the base line.
width()
.
public final QRectF boundingRect(java.lang.String string)
Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the width of the returned rectangle might be different than what the width()
method returns.
If you want to know the advance width of the string (to layout a set of strings next to each other), use width()
instead.
Newline characters are processed as normal characters, not as linebreaks.
The height of the bounding rectangle is at least as large as the value returned height()
.
width()
, height()
, and QPainter::boundingRect()
.
public final double descent()
The descent is the distance from the base line to the lowest point characters extend to. (Note that this is different from X, which adds 1 pixel.) In practice, some font designers break this rule, e.g. to accommodate an unusual character in an exotic language, so it is possible (though rare) that this value will be too small.
ascent()
.
public final java.lang.String elidedText(java.lang.String text, Qt.TextElideMode mode, double width)
The mode parameter specifies whether the text is elided on the left (e.g., "...tech"), in the middle (e.g., "Tr...ch"), or on the right (e.g., "Trol...").
The width is specified in pixels, not characters.
The flags argument is optional and currently only supports Qt::TextShowMnemonic
as value.
public final java.lang.String elidedText(java.lang.String text, Qt.TextElideMode mode, double width, int flags)
The mode parameter specifies whether the text is elided on the left (e.g., "...tech"), in the middle (e.g., "Tr...ch"), or on the right (e.g., "Trol...").
The width is specified in pixels, not characters.
The flags argument is optional and currently only supports Qt::TextShowMnemonic
as value.
public final double height()
This is always equal to ascent()
+descent()
+1 (the 1 is for the base line).
leading()
, and lineSpacing()
.
public final boolean inFont(char arg__1)
public final double leading()
This is the natural inter-line spacing.
height()
, and lineSpacing()
.
public final double leftBearing(char arg__1)
The left bearing is the right-ward distance of the left-most pixel of the character from the logical origin of the character. This value is negative if the pixels of the character extend to the left of the logical origin.
See width(QChar) for a graphical description of this metric.
rightBearing()
, minLeftBearing()
, and width()
.
public final double lineSpacing()
height()
, and leading()
.
public final double lineWidth()
underlinePos()
, overlinePos()
, and strikeOutPos()
.
public final double maxWidth()
public final double minLeftBearing()
This is the smallest leftBearing(char) of all characters in the font.
Note that this function can be very slow if the font is large.
minRightBearing()
, and leftBearing()
.
public final double minRightBearing()
This is the smallest rightBearing(char) of all characters in the font.
Note that this function can be very slow if the font is large.
minLeftBearing()
, and rightBearing()
.
public final double overlinePos()
underlinePos()
, strikeOutPos()
, and lineWidth()
.
public final double rightBearing(char arg__1)
The right bearing is the left-ward distance of the right-most pixel of the character from the logical origin of a subsequent character. This value is negative if the pixels of the character extend to the right of the width()
of the character.
See width()
for a graphical description of this metric.
leftBearing()
, minRightBearing()
, and width()
.
public final double strikeOutPos()
underlinePos()
, overlinePos()
, and lineWidth()
.
public final QRectF tightBoundingRect(java.lang.String text)
Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the width of the returned rectangle might be different than what the width()
method returns.
If you want to know the advance width of the string (to layout a set of strings next to each other), use width()
instead.
Newline characters are processed as normal characters, not as linebreaks.
Warning: Calling this method is very slow on Windows.
width()
, height()
, and boundingRect()
.
public final double underlinePos()
overlinePos()
, strikeOutPos()
, and lineWidth()
.
public final double width(char arg__1)
Some of the metrics are described in the image to the right. The central dark rectangles cover the logical width()
of each character. The outer pale rectangles cover the leftBearing()
and rightBearing()
of each character. Notice that the bearings of "f" in this particular font are both negative, while the bearings of "o" are both positive.
Warning: This function will produce incorrect results for Arabic characters or non-spacing marks in the middle of a string, as the glyph shaping and positioning of marks that happens when processing strings cannot be taken into account. Use charWidth() instead if you aren't looking for the width of isolated characters.
boundingRect()
.
public final double width(java.lang.String string)
Note that this value is not equal to the width returned by boundingRect()
.width()
because boundingRect()
returns a rectangle describing the pixels this string will cover whereas width()
returns the distance to where the next string should be drawn.
boundingRect()
.
public final double xHeight()
public final QRectF boundingRect(QRectF rect, int flags, java.lang.String text, int tabStops, int[] tabArray)
The flags argument is the bitwise OR of the following flags:
Qt::AlignLeft
aligns to the left border, except for Arabic and Hebrew where it aligns to the right.Qt::AlignRight
aligns to the right border, except for Arabic and Hebrew where it aligns to the left.Qt::AlignJustify
produces justified text.Qt::AlignHCenter
aligns horizontally centered.Qt::AlignTop
aligns to the top border.Qt::AlignBottom
aligns to the bottom border.Qt::AlignVCenter
aligns vertically centeredQt::AlignCenter
(== Qt::AlignHCenter | Qt::AlignVCenter)Qt::TextSingleLine
ignores newline characters in the text.Qt::TextExpandTabs
expands tabs (see below)Qt::TextShowMnemonic
interprets "&x" as x, i.e. underlined.Qt::TextWordWrap
breaks the text to fit the rectangle.Qt::Horizontal
alignment defaults to Qt::AlignLeft
and vertical alignment defaults to Qt::AlignTop
. If several of the horizontal or several of the vertical alignment flags are set, the resulting alignment is undefined.
These flags are defined in Qt::AlignmentFlag
.
If Qt::TextExpandTabs
is set in flags, the following behavior is used to interpret tab characters in the text:
Newline characters are processed as line breaks.
Despite the different actual character heights, the heights of the bounding rectangles of "Yes" and "yes" are the same.
The bounding rectangle returned by this function is somewhat larger than that calculated by the simpler boundingRect()
function. This function uses the maximum left
and right
font bearings as is necessary for multi-line text to align correctly. Also, fontHeight() and lineSpacing()
are used to calculate the height, rather than individual character heights.
width()
, QPainter::boundingRect()
, and Qt::Alignment.
public final QRectF boundingRect(QRectF rect, int flags, java.lang.String text, int tabStops)
The flags argument is the bitwise OR of the following flags:
Qt::Horizontal alignment defaults to Qt::AlignLeft and vertical alignment defaults to Qt::AlignTop.
If several of the horizontal or several of the vertical alignment flags are set, the resulting alignment is undefined.
These flags are defined in Qt::AlignmentFlag.
If Qt::TextExpandTabs is set in flags, the following behavior is used to interpret tab characters in the text:
Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts.
Newline characters are processed as line breaks.
Despite the different actual character heights, the heights of the bounding rectangles of "Yes" and "yes" are the same.
The bounding rectangle returned by this function is somewhat larger than that calculated by the simpler boundingRect() function. This function uses the minLeftBearing() maximum left and minRightBearing() right font bearings as is necessary for multi-line text to align correctly. Also, fontHeight() and lineSpacing() are used to calculate the height, rather than individual character heights.
public final QRectF boundingRect(QRectF rect, int flags, java.lang.String text)
public final QSizeF size(int flags, java.lang.String text, int tabStops, int[] tabArray)
The flags argument is the bitwise OR of the following flags:
Qt::TextSingleLine
ignores newline characters.Qt::TextExpandTabs
expands tabs (see below)Qt::TextShowMnemonic
interprets "&x" as x, i.e. underlined.Qt::TextWordBreak
breaks the text to fit the rectangle.If Qt::TextExpandTabs
is set in flags, the following behavior is used to interpret tab characters in the text:
Note: Despite the different actual character heights, the heights of the bounding rectangles of "Yes" and "yes" are the same.
boundingRect()
.
public final QSizeF size(int flags, java.lang.String text, int tabStops)
public final QSizeF size(int flags, java.lang.String text)
public QFontMetricsF clone()
clone
in class java.lang.Object
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