com.trolltech.qt.gui
Class QRegion

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.gui.QRegion
All Implemented Interfaces:
QtJambiInterface, java.lang.Cloneable

public class QRegion
extends QtJambiObject
implements java.lang.Cloneable

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 reducing flicker.

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:

    protected void paintEvent(QPaintEvent e) {
        // r1: elliptic region
        QRegion r1 = new QRegion(new QRect(100, 100, 200, 80),
                                 QRegion.RegionType.Ellipse);

        // r2: rectangular region
        QRegion r2 = new QRegion(new QRect(100, 120, 90, 30));

        // r3: intersection
        QRegion r3 = r1.intersected(r2);

        QPainter painter = new QPainter(this);
        painter.setClipRegion(r3);

        // paint clipped graphics
    }
QRegion is an implicitly shared class.

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 license:Copyright (c) 1987 X ConsortiumPermission 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 ReservedPermission 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.


Nested Class Summary
static class QRegion.RegionType
          Specifies the shape of the region to be created.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, 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
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QRegion()
          Constructs an empty region.
QRegion(int x, int y, int w, int h)
          Constructs a rectangular or elliptic region.
QRegion(int x, int y, int w, int h, QRegion.RegionType t)
          Constructs a rectangular or elliptic region.
QRegion(QBitmap bitmap)
          Constructs a region from the bitmap bm.
QRegion(QPolygon pa)
          Constructs a polygon region from the point array a with the fill rule specified by fillRule.
QRegion(QPolygon pa, Qt.FillRule fillRule)
          Constructs a polygon region from the point array a with the fill rule specified by fillRule.
QRegion(QRect r)
          This is an overloaded member function, provided for convenience.
QRegion(QRect r, QRegion.RegionType t)
          This is an overloaded member function, provided for convenience.
QRegion(QRegion region)
          Constructs a new region which is equal to region r.
 
Method Summary
 QRect boundingRect()
          Returns the bounding rectangle of this region.
 QRegion clone()
          This method is reimplemented for internal reasons
 boolean contains(QPoint p)
          Returns true if the region contains the point p; otherwise returns false.
 boolean contains(QRect r)
          This is an overloaded member function, provided for convenience.
 QRegion intersect(QRect r)
          Use intersected(rect) instead.
 QRegion intersected(QRect r)
          Returns a region which is the intersection of this region and the given rect.
 QRegion intersected(QRegion r)
          Returns a region which is the intersection of this region and r.
 boolean intersects(QRect r)
          Returns true if this region intersects with rect, otherwise returns false.
 boolean intersects(QRegion r)
          Returns true if this region intersects with region, otherwise returns false.
 boolean isEmpty()
          Returns true if the region is empty; otherwise returns false.
 int numRects()
          Returns the number of rectangles that will be returned in rects().
 QRegion operator_add(QRect r)
          This is an overloaded member function, provided for convenience.
 void readFrom(QDataStream arg__1)
          Reads a QRegion
 java.util.List rects()
          Returns an array of non-overlapping rectangles that make up the region.
 void setRects(QRect[] rects)
          Sets the region using the array of rectangles specified by rects and number.
 QRegion subtracted(QRegion r)
          Returns a region which is r subtracted from this region.
 java.lang.String toString()
          Returns a string representation of the this QRegion.
 void translate(int dx, int dy)
          Translates (moves) the region dx along the X axis and dy along the Y axis.
 void translate(QPoint p)
          This is an overloaded member function, provided for convenience.
 QRegion translated(int dx, int dy)
          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.
 QRegion translated(QPoint p)
          This is an overloaded member function, provided for convenience.
 QRegion unite(QRect r)
          Use united(rect) instead.
 QRegion united(QRect r)
          Returns a region which is the union of this region and the given rect.
 QRegion united(QRegion r)
          Returns a region which is the union of this region and r.
 void writeTo(QDataStream arg__1)
          Writes thisQRegion
 QRegion xored(QRegion r)
          Returns a region which is the exclusive or (XOR) of this region and r.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QRegion

public QRegion()
Constructs an empty region.

See also:
isEmpty().


QRegion

public QRegion(QBitmap bitmap)
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

public QRegion(QPolygon pa)
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

public QRegion(QPolygon pa,
               Qt.FillRule fillRule)
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

public QRegion(QRect r)
This is an overloaded member function, provided for convenience.

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 .


QRegion

public QRegion(QRect r,
               QRegion.RegionType t)
This is an overloaded member function, provided for convenience.

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 .


QRegion

public QRegion(QRegion region)
Constructs a new region which is equal to region r.


QRegion

public QRegion(int x,
               int y,
               int w,
               int h)
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

public QRegion(int x,
               int y,
               int w,
               int h,
               QRegion.RegionType t)
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).

Method Detail

boundingRect

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


contains

public final boolean contains(QPoint p)
Returns true if the region contains the point p; otherwise returns false.


contains

public final boolean contains(QRect r)
This is an overloaded member function, provided for convenience.

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


intersect

public final QRegion intersect(QRect r)
Use intersected(rect) instead.


intersected

public final QRegion intersected(QRect r)
Returns a region which is the intersection of this region and the given rect.

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


intersected

public final QRegion intersected(QRegion r)
Returns a region which is the intersection of this region and r.

The figure shows the intersection of two elliptical regions.

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


intersects

public final boolean intersects(QRect r)
Returns true if this region intersects with rect, otherwise returns false.


intersects

public final boolean intersects(QRegion r)
Returns true if this region intersects with region, otherwise returns false.


isEmpty

public final boolean isEmpty()
Returns true if the region is empty; otherwise returns false. An empty region is a region that contains no points.

Example:

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

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

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

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


numRects

public final int numRects()
Returns the number of rectangles that will be returned in rects().


operator_add

public final QRegion operator_add(QRect r)
This is an overloaded member function, provided for convenience.


writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQRegion


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QRegion


rects

public final java.util.List rects()
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().


subtracted

public final QRegion subtracted(QRegion r)
Returns a region which is r subtracted from this region.

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

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


translate

public final void translate(QPoint p)
This is an overloaded member function, provided for convenience.

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.


translate

public final void translate(int dx,
                            int dy)
Translates (moves) the region dx along the X axis and dy along the Y axis.


translated

public final QRegion translated(QPoint p)
This is an overloaded member function, provided for convenience.

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. Positive values move the rectangle to the right and down.

See also:
translate().


translated

public final QRegion translated(int dx,
                                int dy)
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.

See also:
translate().


unite

public final QRegion unite(QRect r)
Use united(rect) instead.


united

public final QRegion united(QRect r)
Returns a region which is the union of this region and the given rect.

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


united

public final QRegion united(QRegion r)
Returns a region which is the union of this region and r.

The figure shows the union of two elliptical regions.

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


xored

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

The figure shows the exclusive or of two elliptical regions.

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


setRects

public void setRects(QRect[] rects)
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:

See also:
rects().


toString

public java.lang.String toString()
Returns a string representation of the this QRegion.

Overrides:
toString in class java.lang.Object

clone

public QRegion clone()
This method is reimplemented for internal reasons

Overrides:
clone in class java.lang.Object