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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.gui.QFontMetrics
public class QFontMetrics
The QFontMetrics class provides font metrics information.
QFontMetrics functions calculate the size of characters and strings for a given font. There are three ways you can create a QFontMetrics object:
(Note: If you use a printer font the values returned may be inaccurate. Printer fonts are not always accessible so the nearest screen font is used if a printer font is supplied.)
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("times", 24); QFontMetrics fm(font); int pixelsWide = fm.width("What's the width of this text?"); int pixelsHigh = fm.height();
Map Example
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<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Constructor Summary | |
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QFontMetrics(QFont arg__1)
Constructs a font metrics object for arg__1. |
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QFontMetrics(QFontMetrics arg__1)
Constructs a copy of arg__1. |
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QFontMetrics(QFont arg__1,
QPaintDeviceInterface pd)
Constructs a font metrics object for arg__1 and pd. |
Method Summary | |
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int |
ascent()
Returns the ascent of the font. |
int |
averageCharWidth()
Returns the average width of glyphs in the font. |
QRect |
boundingRect(char arg__1)
Returns the rectangle that is covered by ink if character arg__1 were to be drawn at the origin of the coordinate system. |
QRect |
boundingRect(int x,
int y,
int width,
int height,
int flags,
java.lang.String text)
This is an overloaded method provided for convenience. |
QRect |
boundingRect(int x,
int y,
int width,
int height,
int flags,
java.lang.String text,
int tabStops)
This is an overloaded method provided for convenience. |
QRect |
boundingRect(int x,
int y,
int width,
int height,
int flags,
java.lang.String text,
int tabStops,
int[] tabArray)
Returns the bounding rectangle for the given text within the rectangle specified by the x and y coordinates, width, and height. |
QRect |
boundingRect(QRect rect,
int flags,
java.lang.String text)
This is an overloaded function provided for convenience. |
QRect |
boundingRect(QRect rect,
int flags,
java.lang.String text,
int tabStops)
This is an overloaded function provided for convenience. |
QRect |
boundingRect(QRect rect,
int flags,
java.lang.String text,
int tabStops,
int[] tabArray)
Returns the bounding rectangle of the characters in the string specified by text, which is the set of pixels the text would cover if drawn at (0, 0). |
QRect |
boundingRect(java.lang.String text)
Returns the bounding rectangle of the characters in the string specified by text. |
int |
charWidth(java.lang.String str,
int pos)
Returns the width of the character at position pos in the string str. |
int |
descent()
Returns the descent of the font. |
java.lang.String |
elidedText(java.lang.String text,
Qt.TextElideMode mode,
int width)
Equivalent to elidedText(text, mode, width, 0). |
java.lang.String |
elidedText(java.lang.String text,
Qt.TextElideMode mode,
int width,
int flags)
If the string text is wider than width, returns an elided version of the string (i.e., a string with "..." in it). |
boolean |
equals(java.lang.Object other)
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static QFontMetrics |
fromNativePointer(QNativePointer nativePointer)
This function returns the QFontMetrics instance pointed to by nativePointer |
int |
height()
Returns the height of the font. |
boolean |
inFont(char arg__1)
Returns true if character arg__1 is a valid character in the font; otherwise returns false. |
int |
leading()
Returns the leading of the font. |
int |
leftBearing(char arg__1)
Returns the left bearing of character arg__1 in the font. |
int |
lineSpacing()
Returns the distance from one base line to the next. |
int |
lineWidth()
Returns the width of the underline and strikeout lines, adjusted for the point size of the font. |
int |
maxWidth()
Returns the width of the widest character in the font. |
int |
minLeftBearing()
Returns the minimum left bearing of the font. |
int |
minRightBearing()
Returns the minimum right bearing of the font. |
static QNativePointer |
nativePointerArray(QFontMetrics[] array)
This function returns a QNativePointer that is pointing to the specified QFontMetrics array. |
int |
overlinePos()
Returns the distance from the base line to where an overline should be drawn. |
int |
rightBearing(char arg__1)
Returns the right bearing of character arg__1 in the font. |
QSize |
size(int flags,
java.lang.String text)
This is an overloaded method provided for convenience. |
QSize |
size(int flags,
java.lang.String text,
int tabStops)
This is an overloaded method provided for convenience. |
QSize |
size(int flags,
java.lang.String text,
int tabStops,
int[] tabArray)
Returns the size in pixels of text. |
int |
strikeOutPos()
Returns the distance from the base line to where the strikeout line should be drawn. |
QRect |
tightBoundingRect(java.lang.String text)
Returns a tight bounding rectangle around the characters in the string specified by text. |
int |
underlinePos()
Returns the distance from the base line to where an underscore should be drawn. |
int |
width(char arg__1)
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int |
width(java.lang.String arg__1)
Equivalent to width(arg__1, -1). |
int |
width(java.lang.String arg__1,
int len)
Returns the width in pixels of the first len characters of arg__1. |
int |
xHeight()
Returns the 'x' height of the font. |
Methods inherited from class com.trolltech.qt.QtJambiObject |
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dispose, disposed, 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 java.lang.Object |
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clone, 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 QFontMetrics(QFont arg__1, QPaintDeviceInterface pd)
Constructs a font metrics object for arg__1 and pd.
The font metrics will be compatible with the paintdevice passed. If the pd 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 QFontMetrics(QFontMetrics arg__1)
Constructs a copy of arg__1.
public QFontMetrics(QFont arg__1)
Constructs a font metrics object for arg__1.
The font metrics will be compatible with the paintdevice used to create arg__1.
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 QFontMetrics(const QFont &, QPaintDevice *) to get the font metrics that are compatible with a certain paint device.
Method Detail |
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public final int ascent()
Returns the ascent of the font.
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.
public final int averageCharWidth()
Returns the average width of glyphs in the font.
public final QRect boundingRect(java.lang.String text)
Returns the bounding rectangle of the characters in the string specified by text. The bounding rectangle always covers at least the set of pixels the text would cover if drawn at (0, 0).
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 by height.
public final QRect boundingRect(char arg__1)
Returns the rectangle that is covered by ink if character arg__1 were to be drawn at the origin of the coordinate system.
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. For a space character the rectangle will usually be empty.
Note that the rectangle usually extends both above and below the base line.
Warning: The width of the returned rectangle is not the advance width of the character. Use boundingRect(const QString &) or width instead.
public final int charWidth(java.lang.String str, int pos)
Returns the width of the character at position pos in the string str.
The whole string is needed, as the glyph drawn may change depending on the context (the letter before and after the current one) for some languages (e.g. Arabic).
This function also takes non spacing marks and ligatures into account.
public final int descent()
Returns the descent of the font.
The descent is the distance from the base line to the lowest point characters extend to. 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.
public final java.lang.String elidedText(java.lang.String text, Qt.TextElideMode mode, int width)
Equivalent to elidedText(text, mode, width, 0).
public final java.lang.String elidedText(java.lang.String text, Qt.TextElideMode mode, int width, int flags)
If the string text is wider than width, returns an elided version of the string (i.e., a string with "..." in it). Otherwise, returns the original string.
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 int height()
Returns the height of the font.
This is always equal to ascent+descent+1 (the 1 is for the base line).
public final boolean inFont(char arg__1)
Returns true if character arg__1 is a valid character in the font; otherwise returns false.
public final int leading()
Returns the leading of the font.
This is the natural inter-line spacing.
public final int leftBearing(char arg__1)
Returns the left bearing of character arg__1 in the font.
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.
public final int lineSpacing()
Returns the distance from one base line to the next.
This value is always equal to leading+height.
public final int lineWidth()
Returns the width of the underline and strikeout lines, adjusted for the point size of the font.
public final int maxWidth()
Returns the width of the widest character in the font.
public final int minLeftBearing()
Returns the minimum left bearing of the font.
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.
public final int minRightBearing()
Returns the minimum right bearing of the font.
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.
public final int overlinePos()
Returns the distance from the base line to where an overline should be drawn.
public final int rightBearing(char arg__1)
Returns the right bearing of character arg__1 in the font.
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.
public final int strikeOutPos()
Returns the distance from the base line to where the strikeout line should be drawn.
public final QRect tightBoundingRect(java.lang.String text)
Returns a tight bounding rectangle around the characters in the string specified by text. The bounding rectangle always covers at least the set of pixels the text would cover if drawn at (0, 0).
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.
public final int underlinePos()
Returns the distance from the base line to where an underscore should be drawn.
public final int width(char arg__1)
Returns the logical width of character arg__1 in pixels. This is a distance appropriate for drawing a subsequent character after 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.
public final int width(java.lang.String arg__1)
Equivalent to width(arg__1, -1).
public final int width(java.lang.String arg__1, int len)
Returns the width in pixels of the first len characters of arg__1. If len is negative (the default), the entire string is used.
Note that this value is not equal to boundingRect.width; boundingRect returns a rectangle describing the pixels this string will cover whereas width returns the distance to where the next string should be drawn.
public final int xHeight()
Returns the 'x' height of the font. This is often but not always the same as the height of the character 'x'.
public static QFontMetrics fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.public static QNativePointer nativePointerArray(QFontMetrics[] array)
array
- the array that the returned pointer will point to.
public boolean equals(java.lang.Object other)
equals
in class java.lang.Object
public final QRect boundingRect(int x, int y, int width, int height, int flags, java.lang.String text, int tabStops, int[] tabArray)
If Qt::TextExpandTabs is set in flags and tabArray is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs; otherwise, if tabStops is non-zero, it is used as the tab spacing (in pixels).
public final QRect boundingRect(int x, int y, int width, int height, int flags, java.lang.String text, int tabStops)
public final QRect boundingRect(int x, int y, int width, int height, int flags, java.lang.String text)
public final QRect boundingRect(QRect rect, int flags, java.lang.String text, int tabStops, int[] tabArray)
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.
If Qt::TextExpandTabs is set in flags, then: if tabArray is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs; otherwise if tabStops is non-zero, it is used as the tab spacing (in pixels).
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.
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 QRect boundingRect(QRect rect, int flags, java.lang.String text, int tabStops)
public final QRect boundingRect(QRect rect, int flags, java.lang.String text)
public final QSize size(int flags, java.lang.String text, int tabStops, int[] tabArray)
The flags argument is the bitwise OR of the following flags:
If Qt::TextExpandTabs is set in flags, then: if tabArray is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs; otherwise if tabStops is non-zero, it is used as the tab spacing (in pixels).
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.
public final QSize size(int flags, java.lang.String text, int tabStops)
public final QSize size(int flags, java.lang.String text)
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