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QRegion Class Reference
[модуль QtGui]

The QRegion class specifies a clip region for a painter. Далее...

 #include <QRegion>

Открытые типы

Открытые функции

Связанные нечлены класса

  • QDataStream & operator<< ( QDataStream & s, const QRegion & r )
  • QDataStream & operator>> ( QDataStream & s, QRegion & r )

Подробное описание

The QRegion class specifies a clip region for a painter.

QRegion is used with QPainter::setClipRegion() to limit the paint area to what needs to be painted. There is also a QWidget::repaint() function that takes a QRegion parameter. QRegion is the best tool for minimizing the amount of screen area to be updated by a repaint.

This class is not suitable for constructing shapes for rendering, especially as outlines. Use QPainterPath to create paths and shapes for use with QPainter.

QRegion is an implicitly shared class.

Creating and Using Regions

A region can be created from a rectangle, an ellipse, a polygon or a bitmap. Complex regions may be created by combining simple regions using united(), intersected(), subtracted(), or xored() (exclusive or). You can move a region using translate().

You can test whether a region isEmpty() or if it contains() a QPoint or QRect. The bounding rectangle can be found with boundingRect().

The function rects() gives a decomposition of the region into rectangles.

Example of using complex regions:

 void MyWidget::paintEvent(QPaintEvent *)
 {
     QRegion r1(QRect(100, 100, 200, 80),    // r1: elliptic region
                QRegion::Ellipse);
     QRegion r2(QRect(100, 120, 90, 30));    // r2: rectangular region
     QRegion r3 = r1.intersected(r2);        // r3: intersection

     QPainter painter(this);
     painter.setClipRegion(r3);
     ...                                     // paint clipped graphics
 }

Warning: Due to window system limitations, the whole coordinate space for a region is limited to the points between -32767 and 32767 on Windows 95/98/ME. You can circumvent this limitation by using a QPainterPath.

Additional License Information

On Embedded Linux, Windows CE and X11 platforms, parts of this class rely on code obtained under the following licenses:

Copyright (c) 1987 X Consortium

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of the X Consortium shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the X Consortium.


Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.

All Rights Reserved

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of Digital not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission.

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

See also QPainter::setClipRegion(), QPainter::setClipRect(), and QPainterPath.

Описание типов-членов

enum QRegion::RegionType

Specifies the shape of the region to be created.

КонстантаЗначениеОписание
QRegion::Rectangle0the region covers the entire rectangle.
QRegion::Ellipse1the region is an ellipse inside the rectangle.

Описание функций-членов

QRegion::QRegion ()

Constructs an empty region.

Смотрите также isEmpty().

QRegion::QRegion ( int x, int y, int w, int h, RegionType t = Rectangle )

Constructs a rectangular or elliptic region.

If t is Rectangle, the region is the filled rectangle (x, y, w, h). If t is Ellipse, the region is the filled ellipse with center at (x + w / 2, y + h / 2) and size (w ,h).

QRegion::QRegion ( const QPolygon & a, Qt::FillRule fillRule = Qt::OddEvenFill )

Constructs a polygon region from the point array a with the fill rule specified by fillRule.

If fillRule is Qt::WindingFill, the polygon region is defined using the winding algorithm; if it is Qt::OddEvenFill, the odd-even fill algorithm is used.

Warning: This constructor can be used to create complex regions that will slow down painting when used.

QRegion::QRegion ( const QRegion & r )

Constructs a new region which is equal to region r.

QRegion::QRegion ( const QBitmap & bm )

Constructs a region from the bitmap bm.

The resulting region consists of the pixels in bitmap bm that are Qt::color1, as if each pixel was a 1 by 1 rectangle.

This constructor may create complex regions that will slow down painting when used. Note that drawing masked pixmaps can be done much faster using QPixmap::setMask().

QRegion::QRegion ( const QRect & r, RegionType t = Rectangle )

Это перегруженная функция.

Create a region based on the rectange r with region type t.

If the rectangle is invalid a null region will be created.

See also QRegion::RegionType.

QRect QRegion::boundingRect () const

Returns the bounding rectangle of this region. An empty region gives a rectangle that is QRect::isNull().

bool QRegion::contains ( const QPoint & p ) const

Returns true if the region contains the point p; otherwise returns false.

bool QRegion::contains ( const QRect & r ) const

Это перегруженная функция.

Returns true if the region overlaps the rectangle r; otherwise returns false.

Handle QRegion::handle () const

Returns a platform-specific region handle. The Handle type is HRGN on Windows, Region on X11, and RgnHandle on Mac OS X. On Qt for Embedded Linux it is void *.

Warning: This function is not portable.

QRegion QRegion::intersected ( const QRegion & r ) const

Returns a region which is the intersection of this region and r.

Region Intersection

The figure shows the intersection of two elliptical regions.

Эта функция была введена в Qt 4.2.

See also subtracted(), united(), and xored().

QRegion QRegion::intersected ( const QRect & rect ) const

Returns a region which is the intersection of this region and the given rect.

Эта функция была введена в Qt 4.4.

See also subtracted(), united(), and xored().

bool QRegion::intersects ( const QRegion & region ) const

Returns true if this region intersects with region, otherwise returns false.

Эта функция была введена в Qt 4.2.

bool QRegion::intersects ( const QRect & rect ) const

Returns true if this region intersects with rect, otherwise returns false.

Эта функция была введена в Qt 4.2.

bool QRegion::isEmpty () const

Returns true if the region is empty; otherwise returns false. An empty region is a region that contains no points.

Пример:

 QRegion r1(10, 10, 20, 20);
 r1.isNull();                // false
 r1.isEmpty();               // false

 QRegion r2(40, 40, 20, 20);
 QRegion r3;
 r3.isNull();                // true
 r3.isEmpty();               // true

 r3 = r1.intersected(r2);    // r3: intersection of r1 and r2
 r3.isNull();                // false
 r3.isEmpty();               // true

 r3 = r1.united(r2);         // r3: union of r1 and r2
 r3.isNull();                // false
 r3.isEmpty();               // false

int QRegion::numRects () const

Returns the number of rectangles that will be returned in rects().

Эта функция была введена в Qt 4.4.

QVector<QRect> QRegion::rects () const

Returns an array of non-overlapping rectangles that make up the region.

The union of all the rectangles is equal to the original region.

See also setRects().

void QRegion::setRects ( const QRect * rects, int number )

Sets the region using the array of rectangles specified by rects and number. The rectangles must be optimally Y-X sorted and follow these restrictions:

  • The rectangles must not intersect.
  • All rectangles with a given top coordinate must have the same height.
  • No two rectangles may abut horizontally (they should be combined into a single wider rectangle in that case).
  • The rectangles must be sorted in ascending order, with Y as the major sort key and X as the minor sort key.

See also rects().

QRegion QRegion::subtracted ( const QRegion & r ) const

Returns a region which is r subtracted from this region.

Region Subtraction

The figure shows the result when the ellipse on the right is subtracted from the ellipse on the left (left - right).

Эта функция была введена в Qt 4.2.

See also intersected(), united(), and xored().

void QRegion::translate ( int dx, int dy )

Translates (moves) the region dx along the X axis and dy along the Y axis.

void QRegion::translate ( const QPoint & point )

Это перегруженная функция.

Translates the region point.x() along the x axis and point.y() along the y axis, relative to the current position. Positive values move the region to the right and down.

Translates to the given point.

QRegion QRegion::translated ( int dx, int dy ) const

Returns a copy of the region that is translated dx along the x axis and dy along the y axis, relative to the current position. Positive values move the region to the right and down.

Эта функция была введена в Qt 4.1.

Смотрите также translate().

QRegion QRegion::translated ( const QPoint & p ) const

Это перегруженная функция.

Returns a copy of the regtion that is translated p.x() along the x axis and p.y() along the y axis, relative to the current position. Положительные значения перемещают прямоугольник вправо и вниз.

Эта функция была введена в Qt 4.1.

Смотрите также translate().

QRegion QRegion::united ( const QRegion & r ) const

Returns a region which is the union of this region and r.

Region Union

The figure shows the union of two elliptical regions.

Эта функция была введена в Qt 4.2.

See also intersected(), subtracted(), and xored().

QRegion QRegion::united ( const QRect & rect ) const

Returns a region which is the union of this region and the given rect.

Эта функция была введена в Qt 4.4.

See also intersected(), subtracted(), and xored().

QRegion QRegion::xored ( const QRegion & r ) const

Returns a region which is the exclusive or (XOR) of this region and r.

Region XORed

The figure shows the exclusive or of two elliptical regions.

Эта функция была введена в Qt 4.2.

See also intersected(), united(), and subtracted().

QRegion::operator QVariant () const

Returns the region as a QVariant

bool QRegion::operator!= ( const QRegion & other ) const

Returns true if this region is different from the other region; otherwise returns false.

const QRegion QRegion::operator& ( const QRegion & r ) const

Applies the intersected() function to this region and r. r1&r2 is equivalent to r1.intersected(r2).

Смотрите также intersected().

const QRegion QRegion::operator& ( const QRect & r ) const

Это перегруженная функция.

Эта функция была введена в Qt 4.4.

QRegion & QRegion::operator&= ( const QRegion & r )

Applies the intersected() function to this region and r and assigns the result to this region. r1&=r2 is equivalent to r1 = r1.intersected(r2).

Смотрите также intersected().

QRegion & QRegion::operator&= ( const QRect & r )

Это перегруженная функция.

Эта функция была введена в Qt 4.4.

const QRegion QRegion::operator+ ( const QRegion & r ) const

Applies the united() function to this region and r. r1+r2 is equivalent to r1.united(r2).

Смотрите также united() и operator|().

const QRegion QRegion::operator+ ( const QRect & r ) const

Это перегруженная функция.

Эта функция была введена в Qt 4.4.

QRegion & QRegion::operator+= ( const QRegion & r )

Applies the united() function to this region and r and assigns the result to this region. r1+=r2 is equivalent to r1 = r1.united(r2).

Смотрите также intersected().

QRegion & QRegion::operator+= ( const QRect & rect )

Returns a region that is the union of this region with the specified rect.

See also united().

const QRegion QRegion::operator- ( const QRegion & r ) const

Applies the subtracted() function to this region and r. r1-r2 is equivalent to r1.subtracted(r2).

See also subtracted().

QRegion & QRegion::operator-= ( const QRegion & r )

Applies the subtracted() function to this region and r and assigns the result to this region. r1-=r2 is equivalent to r1 = r1.subtracted(r2).

See also subtracted().

QRegion & QRegion::operator= ( const QRegion & r )

Assigns r to this region and returns a reference to the region.

bool QRegion::operator== ( const QRegion & r ) const

Returns true if the region is equal to r; otherwise returns false.

const QRegion QRegion::operator^ ( const QRegion & r ) const

Applies the xored() function to this region and r. r1^r2 is equivalent to r1.xored(r2).

See also xored().

QRegion & QRegion::operator^= ( const QRegion & r )

Applies the xored() function to this region and r and assigns the result to this region. r1^=r2 is equivalent to r1 = r1.xored(r2).

See also xored().

const QRegion QRegion::operator| ( const QRegion & r ) const

Applies the united() function to this region and r. r1|r2 is equivalent to r1.united(r2).

See also united() and operator+().

QRegion & QRegion::operator|= ( const QRegion & r )

Applies the united() function to this region and r and assigns the result to this region. r1|=r2 is equivalent to r1 = r1.united(r2).

See also united().

Связанные нечлены класса

QDataStream & operator<< ( QDataStream & s, const QRegion & r )

Writes the region r to the stream s and returns a reference to the stream.

Смотрите также Формат операторов QDataStream.

QDataStream & operator>> ( QDataStream & s, QRegion & r )

Reads a region from the stream s into r and returns a reference to the stream.

Смотрите также Формат операторов QDataStream.

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