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QColor(3qt)							   QColor(3qt)

NAME
       QColor - Colors based on RGB or HSV values

SYNOPSIS
       #include <qcolor.h>

   Public Members
       enum Spec { Rgb, Hsv }
       QColor ()
       QColor ( int r, int g, int b )
       QColor ( int x, int y, int z, Spec colorSpec )
       QColor ( QRgb rgb, uint pixel = 0xffffffff )
       QColor ( const QString & name )
       QColor ( const char * name )
       QColor ( const QColor & c )
       QColor & operator= ( const QColor & c )
       bool isValid () const
       QString name () const
       void setNamedColor ( const QString & name )
       QRgb rgb () const
       void setRgb ( int r, int g, int b )
       void setRgb ( QRgb rgb )
       void getRgb ( int * r, int * g, int * b ) const
       void rgb ( int * r, int * g, int * b ) const  (obsolete)
       int red () const
       int green () const
       int blue () const
       void setHsv ( int h, int s, int v )
       void getHsv ( int * h, int * s, int * v ) const
       void hsv ( int * h, int * s, int * v ) const  (obsolete)
       void getHsv ( int & h, int & s, int & v ) const	(obsolete)
       QColor light ( int factor = 150 ) const
       QColor dark ( int factor = 200 ) const
       bool operator== ( const QColor & c ) const
       bool operator!= ( const QColor & c ) const
       uint alloc ()
       uint pixel () const
       uint pixel ( int screen ) const

   Static Public Members
       int maxColors ()
       int numBitPlanes ()
       int enterAllocContext ()
       void leaveAllocContext ()
       int currentAllocContext ()
       void destroyAllocContext ( int context )
       void initialize ()
       void cleanup ()
       QStringList colorNames ()

RELATED FUNCTION DOCUMENTATION
       QDataStream & operator<< ( QDataStream & s, const QColor & c )
       QDataStream & operator>> ( QDataStream & s, QColor & c )
       int qRed ( QRgb rgb )
       int qGreen ( QRgb rgb )
       int qBlue ( QRgb rgb )
       int qAlpha ( QRgb rgba )
       QRgb qRgb ( int r, int g, int b )
       QRgb qRgba ( int r, int g, int b, int a )
       int qGray ( int r, int g, int b )
       int qGray ( qRgb rgb )

DESCRIPTION
       The QColor class provides colors based on RGB or HSV values.

       A color is normally specified in terms of RGB (red, green and blue)
       components, but it is also possible to specify HSV (hue, saturation and
       value) or set a color name (the names are copied from from the X11
       color database).

       In addition to the RGB value, a QColor also has a pixel value and a
       validity. The pixel 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.

       The validity (isValid()) indicates whether the color is legal at all.
       For example, a RGB color with RGB values out of range is illegal. For
       performance reasons, QColor mostly disregards illegal colors. The
       result of using an invalid color is unspecified and will usually be
       surprising.

       There are 19 predefined QColor objects: white, black, red, darkRed,
       green, darkGreen, blue, darkBlue, cyan, darkCyan, magenta, darkMagenta,
       yellow, darkYellow, gray, darkGray, lightGray, color0 and color1,
       accessible as members of the Qt namespace (ie. Qt::red).

       <center>
				   [Image Omitted]

       </center>

       The colors color0 (zero pixel value) and color1 (non-zero pixel value)
       are special colors for drawing in bitmaps. Painting with color0 sets
       the bitmap bits to 0 (transparent, i.e. background), and painting with
       color1 sets the bits to 1 (opaque, i.e. foreground).

       The QColor class has an efficient, dynamic color allocation strategy. A
       color is normally allocated the first time it is used (lazy
       allocation), that is, whenever the pixel() function is called. The
       following steps are taken to allocate a color. If, at any point, a
       suitable color is found then the appropriate pixel value is returned
       and the subsequent steps are not taken:

       <ol type=1>

       1      Is the pixel value valid? If it is, just return it; otherwise,
	      allocate a pixel value.

       2      Check an internal hash table to see if we allocated an equal RGB
	      value earlier. If we did, set the corresponding pixel value for
	      the color and return it.

       3      Try to allocate the RGB value. If we succeed, we get a pixel
	      value that we save in the internal table with the RGB value.
	      Return the pixel value.

       4      The color could not be allocated. Find the closest matching
	      color, save it in the internal table, and return it.

       A color can be set by passing setNamedColor() an RGB string like"
       #112233", or a color name, e.g. "blue". The names are taken from X11's
       rgb.txt database but can also be used under Windows. To get a lighter
       or darker color use light() and dark() respectively. Colors can also be
       set using setRgb() and setHsv(). The color components can be accessed
       in one go with rgb() and hsv(), or individually with red(), green() and
       blue().

       Use maxColors() and numBitPlanes() to determine the maximum number of
       colors and the number of bit planes supported by the underlying window
       system,

       If you need to allocate many colors temporarily, for example in an
       image viewer application, enterAllocContext(), leaveAllocContext() and
       destroyAllocContext() will prove useful.

HSV Colors
       Because many people don't know the HSV color model very well, we'll
       cover it briefly here.

       The RGB model is hardware-oriented. Its representation is close to what
       most monitors show. In contrast, HSV represents color in a way more
       suited to the human perception of color. For example, the relationships
       "stronger than", "darker than" and "the opposite of" are easily
       expressed in HSV but are much harder to express in RGB.

       HSV, like RGB, has three components:

       H, for hue, is either 0-359 if the color is chromatic (not gray), or
       meaningless if it is gray. It represents degrees on the color wheel
       familiar to most people. Red is 0 (degrees), green is 120 and blue is
       240.

       S, for saturation, is 0-255, and the bigger it is, the stronger the
       color is. Grayish colors have saturation near 0; very strong colors
       have saturation near 255.

       V, for value, is 0-255 and represents lightness or brightness of the
       color. 0 is black; 255 is as far from black as possible.

       Here are some examples: Pure red is H=0, S=255, V=255. A dark red,
       moving slightly towards the magenta, could be H=350 (equivalent to
       -10), S=255, V=180. A grayish light red could have H about 0 (say
       350-359 or 0-10), S about 50-100, and S=255.

       Qt returns a hue value of -1 for achromatic colors. If you pass a too-
       big hue value, Qt forces it into range. Hue 360 or 720 is treated as 0;
       hue 540 is treated as 180.

       See also QPalette, QColorGroup, QApplication::setColorSpec(), Color
       FAQ, Widget Appearance and Style, Graphics Classes, and Image
       Processing Classes.

   Member Type Documentation
QColor::Spec
       The type of color specified, either RGB or HSV, e.g. in the
       QColor::QColor( x, y, z, colorSpec) constructor.

       QColor::Rgb

       QColor::Hsv

MEMBER FUNCTION DOCUMENTATION
QColor::QColor ()
       Constructs an invalid color with the RGB value (0, 0, 0). An invalid
       color is a color that is not properly set up for the underlying window
       system.

       The alpha value of an invalid color is unspecified.

       See also isValid().

QColor::QColor ( int r, int g, int b )
       Constructs a color with the RGB value r, g, b, in the same way as
       setRgb().

       The color is left invalid if any or the arguments are illegal.

       See also setRgb().

QColor::QColor ( int x, int y, int z, Spec colorSpec )
       Constructs a color with the RGB or HSV value x, y, z.

       The arguments are an RGB value if colorSpec is QColor::Rgb. x (red), y
       (green), and z (blue). All of them must be in the range 0-255.

       The arguments are an HSV value if colorSpec is QColor::Hsv. x (hue)
       must be -1 for achromatic colors and 0-359 for chromatic colors; y
       (saturation) and z (value) must both be in the range 0-255.

       See also setRgb() and setHsv().

QColor::QColor ( QRgb rgb, uint pixel = 0xffffffff )
       Constructs a color with the RGB value rgb and a custom pixel value
       pixel.

       If pixel == 0xffffffff (the default), then the color uses the RGB value
       in a standard way. If pixel is something else, then the pixel value is
       set directly to pixel, skipping the normal allocation procedure.

QColor::QColor ( const QString & name )
       Constructs a named color in the same way as setNamedColor() using name
       name.

       The color is left invalid if name cannot be parsed.

       See also setNamedColor().

QColor::QColor ( const char * name )
       Constructs a named color in the same way as setNamedColor() using name
       name.

       The color is left invalid if name cannot be parsed.

       See also setNamedColor().

QColor::QColor ( const QColor & c )
       Constructs a color that is a copy of c.

uint QColor::alloc ()
       Allocates the RGB color and returns the pixel value.

       Allocating a color means to obtain a pixel value from the RGB
       specification. The pixel value is an index into the global color table,
       but should be considered an arbitrary platform-dependent value.

       The pixel() function calls alloc() if necessary, so in general you
       don't need to call this function.

       See also enterAllocContext().

int QColor::blue () const
       Returns the B (blue) component of the RGB value.

void QColor::cleanup () [static]
       Internal clean up required for QColor. This function is called from the
       QApplication destructor.

       See also initialize().

QStringList QColor::colorNames () [static]
       Returns a QStringList containing the color names Qt knows about.

int QColor::currentAllocContext () [static]
       Returns the current color allocation context.

       The default context is 0.

       See also enterAllocContext() and leaveAllocContext().

QColor QColor::dark ( int factor = 200 ) const
       Returns a darker (or lighter) color, but does not change this object.

       Returns a darker color if factor is greater than 100. Setting factor to
       300 returns a color that has one-third the brightness.

       Returns a lighter color if factor is less than 100. We recommend using
       lighter() for this purpose. If factor is 0 or negative, the return
       value is unspecified.

       (This function converts the current RGB color to HSV, divides V by
       factor and converts back to RGB.)

       See also light().

       Examples:

void QColor::destroyAllocContext ( int context ) [static]
       Destroys a color allocation context, context.

       This function deallocates all colors that were allocated in the
       specified context. If context == -1, it frees up all colors that the
       application has allocated. If context == -2, it frees up all colors
       that the application has allocated, except those in the default
       context.

       The function does nothing for true color displays.

       See also enterAllocContext() and alloc().

       Example: showimg/showimg.cpp.

int QColor::enterAllocContext () [static]
       Enters a color allocation context and returns a non-zero unique
       identifier.

       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
       for colormap displays, except that QColor::destroyAllocContext() does
       nothing for true color.

       Example:

	   QPixmap loadPixmap( QString fileName )
	   {
	       static int alloc_context = 0;
	       if ( alloc_context )
		   QColor::destroyAllocContext( alloc_context );
	       alloc_context = QColor::enterAllocContext();
	       QPixmap pm( fileName );
	       QColor::leaveAllocContext();
	       return pm;
	   }

       The example code loads a pixmap from file. It frees up all colors that
       were allocated the last time loadPixmap() was called.

       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.

       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().

	       // context 0 active
	   int c1 = QColor::enterAllocContext();    // enter context c1
	       // context c1 active
	   int c2 = QColor::enterAllocContext();    // enter context c2
	       // context c2 active
	   QColor::leaveAllocContext();		    // leave context c2
	       // context c1 active
	   QColor::leaveAllocContext();		    // leave context c1
	       // context 0 active
	       // Now, free all colors that were allocated in context c2
	   QColor::destroyAllocContext( c2 );

       You may also want to set the application's color specification. See
       QApplication::setColorSpec() for more information.

       See also leaveAllocContext(), currentAllocContext(),
       destroyAllocContext(), and QApplication::setColorSpec().

       Example: showimg/showimg.cpp.

void QColor::getHsv ( int * h, int * s, int * v ) const
       Returns the current RGB value as HSV. The contents of the h, s and v
       pointers are set to the HSV values. If any of the three pointers are
       null, the function does nothing.

       The hue (which h points to) is set to -1 if the color is achromatic.

       Warning: Colors are stored internally as RGB values, so getHSv() may
       return slightly different values to those set by setHsv().

       See also setHsv() and rgb().

void QColor::getHsv ( int & h, int & s, int & v ) const
       This function is obsolete. It is provided to keep old source working.
       We strongly advise against using it in new code.

void QColor::getRgb ( int * r, int * g, int * b ) const
       Sets the contents pointed to by r, g and b to the red, green and blue
       components of the RGB value respectively. The value range for a
       component is 0..255.

       See also rgb(), setRgb(), and getHsv().

int QColor::green () const
       Returns the G (green) component of the RGB value.

void QColor::hsv ( int * h, int * s, int * v ) const
       This function is obsolete. It is provided to keep old source working.
       We strongly advise against using it in new code. Use getHsv() instead.

       Example: themes/metal.cpp.

void QColor::initialize () [static]
       Internal initialization required for QColor. This function is called
       from the QApplication constructor.

       See also cleanup().

bool QColor::isValid () const
       Returns FALSE if the color is invalid, i.e. it was constructed using
       the default constructor; otherwise returns TRUE.

       Examples:

void QColor::leaveAllocContext () [static]
       Leaves a color allocation context.

       See enterAllocContext() for a detailed explanation.

       See also enterAllocContext() and currentAllocContext().

       Example: showimg/showimg.cpp.

QColor QColor::light ( int factor = 150 ) const
       Returns a lighter (or darker) color, but does not change this object.

       Returns a lighter color if factor is greater than 100. Setting factor
       to 150 returns a color that is 50% brighter.

       Returns a darker color if factor is less than 100. We recommend using
       dark() for this purpose. If factor is 0 or negative, the return value
       is unspecified.

       (This function converts the current RGB color to HSV, multiplies V by
       factor, and converts the result back to RGB.)

       See also dark().

       Examples:

int QColor::maxColors () [static]
       Returns the maximum number of colors supported by the underlying window
       system if the window system uses a palette.

       Otherwise returns -1. Use numBitPlanes() to calculate the available
       colors in that case.

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.

       See also setNamedColor().

       Example: chart/setdataform.cpp.

int QColor::numBitPlanes () [static]
       Returns the number of color bit planes for the underlying window
       system.

       The returned value is equal to the default pixmap depth.

       See also QPixmap::defaultDepth().

bool QColor::operator!= ( const QColor & c ) const
       Returns TRUE if this color has a different RGB value from c; otherwise
       returns FALSE.

QColor & QColor::operator= ( const QColor & c )
       Assigns a copy of the color c and returns a reference to this color.

bool QColor::operator== ( const QColor & c ) const
       Returns TRUE if this color has the same RGB value as c; otherwise
       returns FALSE.

uint QColor::pixel () const
       Returns the pixel value.

       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.

       See also alloc().

uint QColor::pixel ( int screen ) const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns the pixel value for screen screen.

       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.

       See also alloc().

int QColor::red () const
       Returns the R (red) component of the RGB value.

QRgb QColor::rgb () const
       Returns the RGB value.

       The return type QRgb is equivalent to unsigned int.

       For an invalid color, the alpha value of the returned color is
       unspecified.

       See also setRgb(), hsv(), qRed(), qBlue(), qGreen(), and isValid().

void QColor::rgb ( int * r, int * g, int * b ) const
       This function is obsolete. It is provided to keep old source working.
       We strongly advise against using it in new code. Use getRgb() instead

void QColor::setHsv ( int h, int s, int v )
       Sets a HSV color value. h is the hue, s is the saturation and v is the
       value of the HSV color.

       If s or v are not in the range 0-255, or h is < -1, the color is not
       changed.

       Warning: Colors are stored internally as RGB values, so getHSv() may
       return slightly different values to those set by setHsv().

       See also hsv() and setRgb().

       Examples:

void QColor::setNamedColor ( const QString & name )
       Sets the RGB value to name, which may be in one of these formats:

       #RGB (each of R, G and B is a single hex digit)

       #RRGGBB

       #RRRGGGBBB

       #RRRRGGGGBBBB

       A name from the X color database (rgb.txt) (e.g." steelblue" or
       "gainsboro"). These color names also work under Windows.

       The color is invalid if name cannot be parsed.

void QColor::setRgb ( int r, int g, int b )
       Sets the RGB value to r, g, b. The arguments, r, g and b must all be in
       the range 0..255. If any of them are outside the legal range, the color
       is not changed.

       See also rgb() and setHsv().

void QColor::setRgb ( QRgb rgb )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Sets the RGB value to rgb.

       The type QRgb is equivalent to unsigned int.

       See also rgb() and setHsv().

RELATED FUNCTION DOCUMENTATION
QDataStream & operator<;< ( QDataStream & s, const QColor & c )
       Writes a color object, c to the stream, s.

       See also Format of the QDataStream operators.

QDataStream & operator>> ( QDataStream & s, QColor & c )
       Reads a color object, c, from the stream, s.

       See also Format of the QDataStream operators.

int qAlpha ( QRgb rgba )
       Returns the alpha component of the RGBA quadruplet rgba.

int qBlue ( QRgb rgb )
       Returns the blue component of the RGB triplet rgb.

       See also qRgb() and QColor::blue().

int qGray ( int r, int g, int b )
       Returns a gray value 0..255 from the (r, g, b) triplet.

       The gray value is calculated using the formula (r*11 + g*16 + b*5)/32.

int qGray ( qRgb rgb )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns a gray value 0..255 from the given rgb colour.

int qGreen ( QRgb rgb )
       Returns the green component of the RGB triplet rgb.

       See also qRgb() and QColor::green().

int qRed ( QRgb rgb )
       Returns the red component of the RGB triplet rgb.

       See also qRgb() and QColor::red().

QRgb qRgb ( int r, int g, int b )
       Returns the RGB triplet (r,g,b).

       The return type QRgb is equivalent to unsigned int.

       See also qRgba(), qRed(), qGreen(), and qBlue().

QRgb qRgba ( int r, int g, int b, int a )
       Returns the RGBA quadruplet (r,g,b,a).

       The return type QRgba is equivalent to unsigned int.

       See also qRgb(), qRed(), qGreen(), and qBlue().

SEE ALSO
       http://doc.trolltech.com/qcolor.html
       http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
       license file included in the distribution for a complete license
       statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to
       help you. Thank you.

       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.

       If you find errors in this manual page, please report them to qt-
       bugs@trolltech.com.  Please include the name of the manual page
       (qcolor.3qt) and the Qt version (3.3.8).

Trolltech AS			2 February 2007			   QColor(3qt)
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