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QRegion 类

QRegion 类为描绘器指定裁剪区域。 更多...

头： #include <QRegion>
qmake: QT += gui

公共类型

enum RegionType { Rectangle, Ellipse }
typedef const_iterator
typedef const_reverse_iterator

公共函数

QRegion (const QBitmap & bm )
QRegion (QRegion && other )
QRegion (const QRegion & r )
QRegion (const QPolygon & a , Qt::FillRule fillRule = Qt::OddEvenFill)
QRegion (const QRect & r , QRegion::RegionType t = Rectangle)
QRegion (int x , int y , int w , int h , QRegion::RegionType t = Rectangle)
QRegion ()
QRegion & operator= (QRegion && other )
QRegion & operator= (const QRegion & r )
QRegion::const_iterator begin () const
QRect boundingRect () const
QRegion::const_iterator cbegin () const
QRegion::const_iterator cend () const
bool contains (const QPoint & p ) const
bool contains (const QRect & r ) const
QRegion::const_reverse_iterator crbegin () const
QRegion::const_reverse_iterator crend () const
QRegion::const_iterator end () const
QRegion intersected (const QRegion & r ) const
QRegion intersected (const QRect & rect ) const
bool intersects (const QRegion & region ) const
bool intersects (const QRect & rect ) const
bool isEmpty () const
bool isNull () const
QRegion::const_reverse_iterator rbegin () const
int rectCount () const
QRegion::const_reverse_iterator rend () const
void setRects (const QRect * rects , int number )
QRegion subtracted (const QRegion & r ) const
void swap (QRegion & other )
void translate (int dx , int dy )
void translate (const QPoint & point )
QRegion translated (int dx , int dy ) const
QRegion translated (const QPoint & p ) const
QRegion united (const QRegion & r ) const
QRegion united (const QRect & rect ) const
QRegion xored (const QRegion & r ) const
QVariant operator QVariant () const
bool operator!= (const QRegion & other ) const
const QRegion operator& (const QRegion & r ) const
const QRegion operator& (const QRect & r ) const
QRegion & operator&= (const QRegion & r )
QRegion & operator&= (const QRect & r )
const QRegion operator+ (const QRegion & r ) const
const QRegion operator+ (const QRect & r ) const
QRegion & operator+= (const QRegion & r )
QRegion & operator+= (const QRect & rect )
const QRegion operator- (const QRegion & r ) const
QRegion & operator-= (const QRegion & r )
bool operator== (const QRegion & r ) const
const QRegion operator^ (const QRegion & r ) const
QRegion & operator^= (const QRegion & r )
const QRegion operator| (const QRegion & r ) const
QRegion & operator|= (const QRegion & r )
QDataStream & operator<< (QDataStream & s , const QRegion & r )
QDataStream & operator>> (QDataStream & s , QRegion & r )

详细描述

QRegion 用于 QPainter::setClipRegion () 以将描绘区域限制到需要描绘的区域。另外 QWidget::repaint () 函数也接受 QRegion 参数。QRegion 是最小化更新屏幕区域，重新描绘数量的最佳工具。

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 隐式共享 类。

创建和使用区域

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 ()，或 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 ().

Iteration over the region (with begin (), end (), or C++11 ranged-for loops) 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
}

另请参阅 QPainter::setClipRegion (), QPainter::setClipRect ()，和 QPainterPath .

成员类型文档编制

enum QRegion:: RegionType

Specifies the shape of the region to be created.

常量 值 描述
QRegion::Rectangle 0 the region covers the entire rectangle.
QRegion::Ellipse 1 the region is an ellipse inside the rectangle.

typedef QRegion:: const_iterator

An iterator over the non-overlapping rectangles that make up the region.

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

QRegion does not offer mutable iterators.

This typedef was introduced in Qt 5.8.

另请参阅 begin () 和 end ().

typedef QRegion:: const_reverse_iterator

A reverse iterator over the non-overlapping rectangles that make up the region.

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

QRegion does not offer mutable iterators.

This typedef was introduced in Qt 5.8.

另请参阅 rbegin () 和 rend ().

成员函数文档编制

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 ( QRegion && other )

Move-constructs a new region from region other . After the call, other is null.

该函数在 Qt 5.7 引入。

另请参阅 isNull ().

QRegion:: QRegion (const QRegion & r )

Constructs a new region which is equal to region r .

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 .

若 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.

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

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

这是重载函数。

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

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

另请参阅 QRegion::RegionType .

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

Constructs a rectangular or elliptic region.

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

QRegion:: QRegion ()

Constructs an empty region.

另请参阅 isEmpty ().

QRegion &QRegion:: operator= ( QRegion && other )

移动赋值 other 到此 QRegion 实例。

该函数在 Qt 5.2 引入。

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

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

QRegion::const_iterator QRegion:: begin () const

返回 const_iterator pointing to the beginning of the range of non-overlapping rectangles that make up the region.

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

该函数在 Qt 5.8 引入。

另请参阅 rbegin (), cbegin ()，和 end ().

QRect QRegion:: boundingRect () const

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

QRegion::const_iterator QRegion:: cbegin () const

如同 begin ().

该函数在 Qt 5.8 引入。

QRegion::const_iterator QRegion:: cend () const

如同 end ().

该函数在 Qt 5.8 引入。

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

返回 true if the region contains the point p ；否则返回 false .

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

这是重载函数。

返回 true if the region overlaps the rectangle r ；否则返回 false .

QRegion::const_reverse_iterator QRegion:: crbegin () const

如同 rbegin ().

该函数在 Qt 5.8 引入。

QRegion::const_reverse_iterator QRegion:: crend () const

如同 rend ().

该函数在 Qt 5.8 引入。

QRegion::const_iterator QRegion:: end () const

返回 const_iterator pointing to one past the end of non-overlapping rectangles that make up the region.

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

该函数在 Qt 5.8 引入。

另请参阅 rend (), cend ()，和 begin ().

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.

该函数在 Qt 4.2 引入。

另请参阅 subtracted (), united ()，和 xored ().

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

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

该函数在 Qt 4.4 引入。

另请参阅 subtracted (), united ()，和 xored ().

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

返回 true if this region intersects with region ，否则返回 false .

该函数在 Qt 4.2 引入。

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

返回 true if this region intersects with rect ，否则返回 false .

该函数在 Qt 4.2 引入。

bool QRegion:: isEmpty () const

返回 true 若区域为空；否则返回 false 。空区域是不包含任何点的区域。

范例： 

QRegion r1(10, 10, 20, 20);
r1.isEmpty();               // false
QRegion r3;
r3.isEmpty();               // true
QRegion r2(40, 40, 20, 20);
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

bool QRegion:: isNull () const

返回 true 若区域为空；否则返回 false . An empty region is a region that contains no points. This function is the same as isEmpty

该函数在 Qt 5.0 引入。

另请参阅 isEmpty ().

QRegion::const_reverse_iterator QRegion:: rbegin () const

返回 const_reverse_iterator pointing to the beginning of the range of non-overlapping rectangles that make up the region.

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

该函数在 Qt 5.8 引入。

另请参阅 begin (), crbegin ()，和 rend ().

int QRegion:: rectCount () const

Returns the number of rectangles that this region is composed of. Same as end() - begin() .

该函数在 Qt 4.6 引入。

QRegion::const_reverse_iterator QRegion:: rend () const

返回 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.

该函数在 Qt 5.8 引入。

另请参阅 end (), crend ()，和 rbegin ().

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.

另请参阅 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 ).

该函数在 Qt 4.2 引入。

另请参阅 intersected (), united ()，和 xored ().

void QRegion:: swap ( QRegion & other )

Swaps region other with this region. This operation is very fast and never fails.

该函数在 Qt 4.8 引入。

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 )

这是重载函数。

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

该函数在 Qt 4.1 引入。

另请参阅 translate ().

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

这是重载函数。

Returns a copy of the regtion that is translated p .x() 沿 X 轴和 p .y() along the y axis, relative to the current position. Positive values move the rectangle to the right and down.

该函数在 Qt 4.1 引入。

另请参阅 translate ().

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

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

Region Union

图形展示 2 椭圆区域的 union (并集)。

该函数在 Qt 4.2 引入。

另请参阅 intersected (), subtracted ()，和 xored ().

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

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

该函数在 Qt 4.4 引入。

另请参阅 intersected (), subtracted ()，和 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.

该函数在 Qt 4.2 引入。

另请参阅 intersected (), united ()，和 subtracted ().

QVariant QRegion:: operator QVariant () const

Returns the region as a QVariant

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

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

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

应用 intersected () 函数到此区域和 r . r1&r2 相当于 r1.intersected(r2) .

另请参阅 intersected ().

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

这是重载函数。

该函数在 Qt 4.4 引入。

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

应用 intersected () 函数到此区域和 r and assigns the result to this region. r1&=r2 相当于 r1 = r1.intersected(r2).

另请参阅 intersected ().

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

这是重载函数。

该函数在 Qt 4.4 引入。

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

应用 united () 函数到此区域和 r . r1+r2 相当于 r1.united(r2) .

另请参阅 united () 和 operator| ().

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

这是重载函数。

该函数在 Qt 4.4 引入。

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

应用 united () 函数到此区域和 r and assigns the result to this region. r1+=r2 相当于 r1 = r1.united(r2) .

另请参阅 intersected ().

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

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

另请参阅 united ().

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

应用 subtracted () 函数到此区域和 r . r1-r2 相当于 r1.subtracted(r2) .

另请参阅 subtracted ().

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

应用 subtracted () 函数到此区域和 r and assigns the result to this region. r1-=r2 相当于 r1 = r1.subtracted(r2) .

另请参阅 subtracted ().

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

返回 true if the region is equal to r ；否则返回 false。

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

应用 xored () 函数到此区域和 r . r1^r2 相当于 r1.xored(r2) .

另请参阅 xored ().

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

应用 xored () 函数到此区域和 r and assigns the result to this region. r1^=r2 相当于 r1 = r1.xored(r2) .

另请参阅 xored ().

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

应用 united () 函数到此区域和 r . r1|r2 相当于 r1.united(r2) .

另请参阅 united () 和 operator+ ().

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

应用 united () 函数到此区域和 r and assigns the result to this region. r1|=r2 相当于 r1 = r1.united(r2) .

另请参阅 united ().

相关非成员

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

写入区域 r 到流 s 并返回流引用。

另请参阅 QDataStream 运算符格式 .

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

读取区域从流 s into r 并返回流引用。

另请参阅 QDataStream 运算符格式 .