qcolor.3qt

linux下GUI编程工具qt的在线连接帮助手册

.PP
Returns a darker color if \fIfactor\fR is greater than 100. Setting \fIfactor\fR to 300 returns a color that has one-third the brightness.
.PP
Returns a lighter color if \fIfactor\fR is less than 100. We recommend using lighter() for this purpose. If \fIfactor\fR is 0 or negative, the return value is unspecified.
.PP
(This function converts the current RGB color to HSV, divides V by \fIfactor\fR and converts back to RGB.)
.PP
See also light().
.PP
Examples:
.)l desktop/desktop.cpp and themes/wood.cpp.
.SH "void QColor::destroyAllocContext ( int context )\fC [static]\fR"
Destroys a color allocation context, \fIcontext\fR.
.PP
This function deallocates all colors that were allocated in the specified \fIcontext\fR. If \fIcontext\fR == -1, it frees up all colors that the application has allocated. If \fIcontext\fR == -2, it frees up all colors that the application has allocated, except those in the default context.
.PP
The function does nothing for true color displays.
.PP
See also enterAllocContext() and alloc().
.PP
Example: showimg/showimg.cpp.
.SH "int QColor::enterAllocContext ()\fC [static]\fR"
Enters a color allocation context and returns a nonzero unique identifier.
.PP
Color allocation contexts are useful for programs that need to allocate many colors and throw them away later, like image viewers. The allocation context functions work for true color displays as well as colormap display, except that QColor::destroyAllocContext() does nothing for true color.
.PP
Example:
.PP
.nf
.br
    QPixmap loadPixmap( QString fileName )
.br
    {
.br
        static int alloc_context = 0;
.br
        if ( alloc_context )
.br
            QColor::destroyAllocContext( alloc_context );
.br
        alloc_context = QColor::enterAllocContext();
.br
        QPixmap pm( fileName );
.br
        QColor::leaveAllocContext();
.br
        return pm;
.br
    }
.br
.fi
.PP
The example code loads a pixmap from file. It frees up all colors that were allocated the last time loadPixmap() was called.
.PP
The initial/default context is 0. Qt keeps a list of colors associated with their allocation contexts. You can call destroyAllocContext() to get rid of all colors that were allocated in a specific context.
.PP
Calling enterAllocContext() enters an allocation context. The allocation context lasts until you call leaveAllocContext(). QColor has an internal stack of allocation contexts. Each call to enterAllocContex() must have a corresponding leaveAllocContext().
.PP
.nf
.br
      // context 0 active
.br
    int c1 = QColor::enterAllocContext();       // enter context c1
.br
      // context c1 active
.br
    int c2 = QColor::enterAllocContext();       // enter context c2
.br
      // context c2 active
.br
    QColor::leaveAllocContext();                // leave context c2
.br
      // context c1 active
.br
    QColor::leaveAllocContext();                // leave context c1
.br
      // context 0 active
.br
      // Now, free all colors that were allocated in context c2
.br
    QColor::destroyAllocContext( c2 );
.br
.fi
.PP
You may also want to set the application's color specification. See QApplication::setColorSpec() for more information.
.PP
See also leaveAllocContext(), currentAllocContext(), destroyAllocContext() and QApplication::setColorSpec().
.PP
Example: showimg/showimg.cpp.
.SH "void QColor::getHsv ( int & h, int & s, int & v ) const"
\fBThis function is obsolete.\fR It is provided to keep old source working. We strongly advise against using it in new code.
.SH "int QColor::green () const"
Returns the G (green) component of the RGB value.
.SH "void QColor::hsv ( int * h, int * s, int * v ) const"
Returns the current RGB value as HSV. The contents of the \fIh\fR, \fIs\fR and \fIv\fR pointers are set to the HSV values. If any of the three pointers are null, the function does nothing.
.PP
The hue (which \fIh\fR points to) is set to -1 if the color is achromatic.
.PP
See also setHsv() and rgb().
.PP
Example: themes/metal.cpp.
.SH "void QColor::initialize ()\fC [static]\fR"
Internal initialization required for QColor. This function is called from the QApplication constructor.
.PP
See also cleanup().
.SH "bool QColor::isValid () const"
Returns FALSE if the color is invalid, i.e., it was constructed using the default constructor.
.PP
Use of this function is discouraged, as it is slightly slow on Truecolor displays. If you need a "null" QColor, it may be better to use q QColor* where possible.
.PP
Example: scribble/scribble.cpp.
.SH "void QColor::leaveAllocContext ()\fC [static]\fR"
Leaves a color allocation context.
.PP
See enterAllocContext() for a detailed explanation.
.PP
See also enterAllocContext() and currentAllocContext().
.PP
Example: showimg/showimg.cpp.
.SH "QColor QColor::light ( int factor = 150 ) const"
Returns a lighter (or darker) color, but does not change this object.
.PP
Returns a lighter color if \fIfactor\fR is greater than 100. Setting \fIfactor\fR to 150 returns a color that is 50% brighter.
.PP
Returns a darker color if \fIfactor\fR is less than 100. We recommend using dark() for this purpose. If \fIfactor\fR is 0 or negative, the return value is unspecified.
.PP
(This function converts the current RGB color to HSV, multiplies V by \fIfactor\fR, and converts the result back to RGB.)
.PP
See also dark().
.PP
Examples:
.)l desktop/desktop.cpp and themes/wood.cpp.
.SH "int QColor::maxColors ()\fC [static]\fR"
Returns the maximum number of colors supported by the underlying window system.
.SH "QString QColor::name () const"
Returns the name of the color in the format "#RRGGBB", i.e., a" #" character followed by three two-digit hexadecimal numbers.
.PP
See also setNamedColor().
.SH "int QColor::numBitPlanes ()\fC [static]\fR"
Returns the number of color bit planes for the underlying window system.
.PP
The returned values is equal to the default pixmap depth;
.PP
See also QPixmap::defaultDepth().
.SH "bool QColor::operator!= ( const QColor & c ) const"
Returns TRUE if this color has a different RGB value from \fIc\fR, or FALSE if they have equal RGB values.
.SH "QColor & QColor::operator= ( const QColor & c )"
Assigns a copy of the color \fIc\fR and returns a reference to this color.
.SH "bool QColor::operator== ( const QColor & c ) const"
Returns TRUE if this color has the same RGB value as \fIc\fR, or FALSE if they have different RGB values.
.SH "uint QColor::pixel () const"
Returns the pixel value.
.PP
This value is used by the underlying window system to refer to a color. It can be thought of as an index into the display hardware's color table, but the value is an arbitrary 32-bit value.
.PP
See also alloc().
.SH "int QColor::red () const"
Returns the R (red) component of the RGB value.
.SH "void QColor::rgb ( int * r, int * g, int * b ) const"
Sets the contents pointed to by \fIr\fR, \fIg\fR and \fIb\fR to the red, green and blue components of the RGB value respectively. The value range for a component is 0..255.
.PP
See also setRgb() and hsv().
.SH "QRgb QColor::rgb () const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Returns the RGB value.
.PP
The return type \fIQRgb\fR is equivalent to \fCunsigned\fR \fCint\fR.
.PP
For an invalid color, the alpha value of the returned valud is unspecified.
.PP
See also setRgb(), hsv(), qRed(), qBlue(), qGreen() and isValid().
.SH "void QColor::setHsv ( int h, int s, int v )"
Sets a HSV color value. \fIh\fR is the hue, \fIs\fR is the saturation and \fIv\fR is the value of the HSV color.
.PP
If \fIs\fR or \fIv\fR are not in the range 0-255, or \fIh\fR is < -1, the color is not changed.
.PP
See also hsv() and setRgb().
.PP
Examples:
.)l drawdemo/drawdemo.cpp, grapher/grapher.cpp and progress/progress.cpp.
.SH "void QColor::setNamedColor ( const QString & name )"
Sets the RGB value to \fIname\fR, which may be in one of these formats:
.TP
#RGB (each of R, G and B is a single hex digit)
.TP
#RRGGBB
.TP
#RRRGGGBBB
.TP
#RRRRGGGGBBBB
.TP
A name from the X color database (rgb.txt) (e.g." steelblue" or "gainsboro"). These color names also work under Qt for Windows.
.PP
The color is left invalid if \fIname\fR cannot be parsed.
.SH "void QColor::setRgb ( int r, int g, int b )"
Sets the RGB value to \fIr\fR, \fIg\fR, \fIb\fR. The arguments, \fIr\fR, \fIg\fR and \fIb\fR must all be in the range 0..255. If any of them are outside the legal range, the color is not changed.
.PP
See also rgb() and setHsv().
.SH "void QColor::setRgb ( QRgb rgb )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Sets the RGB value to \fIrgb\fR.
.PP
The type \fIQRgb\fR is equivalent to \fCunsigned\fR \fCint\fR.
.PP
See also rgb() and setHsv().
.SH RELATED FUNCTION DOCUMENTATION
.SH "QDataStream & operator<< ( QDataStream & s, const QColor & c )"
Writes a color object, \fIc\fR to the stream, \fIs\fR.
.PP
See also Format of the QDataStream operators.
.SH "QDataStream & operator>> ( QDataStream & s, QColor & c )"
Reads a color object, \fIc\fR, from the stream, \fIs\fR.
.PP
See also Format of the QDataStream operators.
.SH "int qAlpha ( QRgb rgba )"
Returns the alpha component of the RGBA quadruplet \fIrgba\fR.
.SH "int qBlue ( QRgb rgb )"
Returns the blue component of the RGB triplet \fIrgb\fR.
.PP
See also qRgb() and QColor::blue().
.SH "int qGray ( int r, int g, int b )"
Returns a gray value 0..255 from the (\fIr\fR, \fIg\fR, \fIb\fR) triplet.
.PP
The gray value is calculated using the formula (r*11 + g*16 + b*5)/32.
.SH "int qGray ( qRgb rgb )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Returns a gray value 0..255 from the given \fIrgb\fR colour.
.SH "int qGreen ( QRgb rgb )"
Returns the green component of the RGB triplet \fIrgb\fR.
.PP
See also qRgb() and QColor::green().
.SH "int qRed ( QRgb rgb )"
Returns the red component of the RGB triplet \fIrgb\fR.
.PP
See also qRgb() and QColor::red().
.SH "QRgb qRgb ( int r, int g, int b )"
Returns the RGB triplet \fI(r,g,b)\fR.
.PP
The return type QRgb is equivalent to \fCunsigned\fR \fCint\fR.
.PP
See also qRgba(), qRed(), qGreen() and qBlue().
.SH "QRgb qRgba ( int r, int g, int b, int a )"
Returns the RGBA quadruplet \fI(r,g,b,a)\fR.
.PP
The return type QRgba is equivalent to \fCunsigned\fR \fCint\fR.
.PP
See also qRgb(), qRed(), qGreen() and qBlue().

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qcolor.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
a web browser. This man page is provided as a convenience for those
users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR [e-mail] .
Please include the name of the manual page (qcolor.3qt) and the Qt
version (3.0.0).