The QRegion class specifies a clip region for a painter. More...
#include <qregion.h>
Public Types | |
| enum | RegionType { Rectangle , Ellipse } |
| typedef const QRect * | const_iterator |
| typedef std::reverse_iterator< const_iterator > | const_reverse_iterator |
Friends | |
| struct | QRegionPrivate |
| Q_GUI_EXPORT QDataStream & | operator<< (QDataStream &, const QRegion &) |
| Q_GUI_EXPORT QDataStream & | operator>> (QDataStream &, QRegion &) |
| Q_GUI_EXPORT friend bool | qt_region_strictContains (const QRegion ®ion, const QRect &rect) |
Related Functions | |
(Note that these are not member functions.) | |
| QDataStream & | operator<< (QDataStream &s, const QRegion &r) |
| QDataStream & | operator>> (QDataStream &s, QRegion &r) |
Detailed Description
The QRegion class specifies a clip region for a painter.
\inmodule QtGui
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 \l{implicitly shared} class.
Member Typedef Documentation
◆ const_iterator
◆ const_reverse_iterator
Member Enumeration Documentation
◆ RegionType
| enum QRegion::RegionType |
Constructor & Destructor Documentation
◆ QRegion() [1/7]
| QRegion::QRegion | ( | ) |
◆ QRegion() [2/7]
| 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).
Definition at line 196 of file qregion.cpp.
◆ QRegion() [3/7]
| QRegion::QRegion | ( | const QRect & | r, |
| RegionType | t = Rectangle |
||
| ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Create a region based on the rectangle r with region type t.
If the rectangle is invalid a null region will be created.
- See also
- QRegion::RegionType
◆ QRegion() [4/7]
| 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 \l{Qt::WindingFill}, the polygon region is defined using the winding algorithm; if it is \l{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() [5/7]
◆ QRegion() [6/7]
|
inlinenoexcept |
◆ QRegion() [7/7]
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::~QRegion | ( | ) |
Member Function Documentation
◆ begin()
|
noexcept |
◆ boundingRect()
|
noexcept |
Returns the bounding rectangle of this region. An empty region gives a rectangle that is QRect::isNull().
◆ cbegin()
|
inlinenoexcept |
◆ cend()
|
inlinenoexcept |
◆ contains() [1/2]
Returns true if the region contains the point p; otherwise returns false.
◆ contains() [2/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
Returns true if the region overlaps the rectangle r; otherwise returns false.
◆ crbegin()
|
inlinenoexcept |
◆ crend()
|
inlinenoexcept |
◆ end()
|
noexcept |
◆ intersected() [1/2]
- Since
- 4.4
Returns a region which is the intersection of this region and the given rect.
- See also
- subtracted(), united(), xored()
◆ intersected() [2/2]
- Since
- 4.2
Returns a region which is the intersection of this region and r.
Region Intersection
The figure shows the intersection of two elliptical regions.
- See also
- subtracted(), united(), xored()
◆ intersects() [1/2]
- Since
- 4.2
Returns true if this region intersects with rect, otherwise returns false.
◆ intersects() [2/2]
- Since
- 4.2
Returns true if this region intersects with region, otherwise returns false.
Definition at line 649 of file qregion.cpp.
◆ isEmpty()
| bool QRegion::isEmpty | ( | ) | const |
Returns true if the region is empty; otherwise returns false. An empty region is a region that contains no points.
Example:
◆ isNull()
| bool QRegion::isNull | ( | ) | const |
- Since
- 5.0
Returns true if the region is empty; otherwise returns false. An empty region is a region that contains no points. This function is the same as isEmpty
- See also
- isEmpty()
◆ operator QVariant()
| QRegion::operator QVariant | ( | ) | const |
Returns the region as a QVariant
Definition at line 585 of file qregion.cpp.
◆ operator!=()
|
inline |
◆ operator&() [1/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
- Since
- 4.4
Definition at line 469 of file qregion.cpp.
◆ operator&() [2/2]
Applies the intersected() function to this region and r. r1&r2 is equivalent to r1.intersected(r2).
- See also
- intersected()
Definition at line 462 of file qregion.cpp.
◆ operator&=() [1/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
- Since
- 4.4
Definition at line 547 of file qregion.cpp.
◆ operator&=() [2/2]
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).
- See also
- intersected()
Definition at line 534 of file qregion.cpp.
◆ operator+() [1/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
- Since
- 4.4
Definition at line 453 of file qregion.cpp.
◆ operator+() [2/2]
Applies the united() function to this region and r. r1+r2 is equivalent to r1.united(r2).
- See also
- united(), operator|()
Definition at line 446 of file qregion.cpp.
◆ operator+=() [1/2]
Returns a region that is the union of this region with the specified rect.
- See also
- united()
Definition at line 519 of file qregion.cpp.
◆ operator+=() [2/2]
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
- intersected()
◆ operator-()
Applies the subtracted() function to this region and r. r1-r2 is equivalent to r1.subtracted(r2).
- See also
- subtracted()
Definition at line 480 of file qregion.cpp.
◆ operator-=()
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()
Definition at line 562 of file qregion.cpp.
◆ operator=()
Assigns r to this region and returns a reference to the region.
Move-assigns other to this QRegion instance.
- Since
- 5.2
◆ operator==()
Returns true if the region is equal to r; otherwise returns false.
◆ operator^()
Applies the xored() function to this region and r. r1^r2 is equivalent to r1.xored(r2).
- See also
- xored()
Definition at line 489 of file qregion.cpp.
◆ operator^=()
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()
Definition at line 572 of file qregion.cpp.
◆ operator|()
Applies the united() function to this region and r. r1|r2 is equivalent to r1.united(r2).
- See also
- united(), operator+()
Definition at line 437 of file qregion.cpp.
◆ operator|=()
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()
Definition at line 499 of file qregion.cpp.
◆ rbegin()
|
inlinenoexcept |
◆ rectCount()
|
noexcept |
◆ rend()
|
inlinenoexcept |
- Since
- 5.8
Returns a const_reverse_iterator pointing to one past the end of the range of non-overlapping rectangles that make up the region.
The union of all the rectangles is equal to the original region.
Definition at line 91 of file qregion.h.
◆ setRects()
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:
\list
- 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. \endlist \omit Only some platforms have these restrictions (Qt for Embedded Linux, X11 and \macos). \endomit
◆ subtracted()
- Since
- 4.2
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}).
- See also
- intersected(), united(), xored()
◆ swap()
◆ translate() [1/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
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.
Definition at line 98 of file qregion.h.
◆ translate() [2/2]
| void QRegion::translate | ( | int | dx, |
| int | dy | ||
| ) |
Translates (moves) the region dx along the X axis and dy along the Y axis.
◆ translated() [1/2]
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
- Since
- 4.1
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()
Definition at line 100 of file qregion.h.
◆ translated() [2/2]
| QRegion QRegion::translated | ( | int | dx, |
| int | dy | ||
| ) | const |
- Since
- 4.1
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()
Definition at line 629 of file qregion.cpp.
◆ united() [1/2]
- Since
- 4.4
Returns a region which is the union of this region and the given rect.
- See also
- intersected(), subtracted(), xored()
◆ united() [2/2]
- Since
- 4.2
Returns a region which is the union of this region and r.
Region Union
The figure shows the union of two elliptical regions.
- See also
- intersected(), subtracted(), xored()
◆ xored()
- Since
- 4.2
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.
- See also
- intersected(), united(), subtracted()
Friends And Related Function Documentation
◆ operator<< [1/2]
|
friend |
Writes the region r to the stream s and returns a reference to the stream.
- See also
- {Serializing Qt Data Types}{Format of the QDataStream operators}
Definition at line 349 of file qregion.cpp.
◆ operator<<() [2/2]
|
related |
Writes the region r to the stream s and returns a reference to the stream.
- See also
- {Serializing Qt Data Types}{Format of the QDataStream operators}
Definition at line 349 of file qregion.cpp.
◆ operator>> [1/2]
|
friend |
Reads a region from the stream s into r and returns a reference to the stream.
- See also
- {Serializing Qt Data Types}{Format of the QDataStream operators}
Definition at line 383 of file qregion.cpp.
◆ operator>>() [2/2]
|
related |
Reads a region from the stream s into r and returns a reference to the stream.
- See also
- {Serializing Qt Data Types}{Format of the QDataStream operators}
Definition at line 383 of file qregion.cpp.
◆ QRegionPrivate
◆ qt_region_strictContains
|
friend |
The documentation for this class was generated from the following files:
- src/gui/painting/qregion.h
- src/gui/painting/qregion.cpp
