QRect 类

QRect class defines a rectangle in the plane using integer precision. 更多...

Header: #include <QRect>
qmake: QT += core

注意: 此类的所有函数 可重入 .

公共函数

QRect ()
QRect (const QPoint & topLeft , const QPoint & bottomRight )
QRect (const QPoint & topLeft , const QSize & size )
QRect (int x , int y , int width , int height )
void adjust (int dx1 , int dy1 , int dx2 , int dy2 )
QRect adjusted (int dx1 , int dy1 , int dx2 , int dy2 ) const
int bottom () const
QPoint bottomLeft () const
QPoint bottomRight () const
QPoint center () const
bool contains (const QPoint & point , bool proper = false) const
bool contains (const QRect & rectangle , bool proper = false) const
bool contains (int x , int y ) const
bool contains (int x , int y , bool proper ) const
void getCoords (int * x1 , int * y1 , int * x2 , int * y2 ) const
void getRect (int * x , int * y , int * width , int * height ) const
int height () const
QRect intersected (const QRect & rectangle ) const
bool intersects (const QRect & rectangle ) const
bool isEmpty () const
bool isNull () const
bool isValid () const
int left () const
QRect marginsAdded (const QMargins & margins ) const
QRect marginsRemoved (const QMargins & margins ) const
void moveBottom (int y )
void moveBottomLeft (const QPoint & position )
void moveBottomRight (const QPoint & position )
void moveCenter (const QPoint & position )
void moveLeft (int x )
void moveRight (int x )
void moveTo (int x , int y )
void moveTo (const QPoint & position )
void moveTop (int y )
void moveTopLeft (const QPoint & position )
void moveTopRight (const QPoint & position )
QRect normalized () const
int right () const
void setBottom (int y )
void setBottomLeft (const QPoint & position )
void setBottomRight (const QPoint & position )
void setCoords (int x1 , int y1 , int x2 , int y2 )
void setHeight (int height )
void setLeft (int x )
void setRect (int x , int y , int width , int height )
void setRight (int x )
void setSize (const QSize & size )
void setTop (int y )
void setTopLeft (const QPoint & position )
void setTopRight (const QPoint & position )
void setWidth (int width )
void setX (int x )
void setY (int y )
QSize size () const
CGRect toCGRect () const
int top () const
QPoint topLeft () const
QPoint topRight () const
void translate (int dx , int dy )
void translate (const QPoint & offset )
QRect translated (int dx , int dy ) const
QRect translated (const QPoint & offset ) const
QRect transposed () const
QRect united (const QRect & rectangle ) const
int width () const
int x () const
int y () const
QRect operator& (const QRect & rectangle ) const
QRect & operator&= (const QRect & rectangle )
QRect & operator+= (const QMargins & margins )
QRect & operator-= (const QMargins & margins )
QRect operator| (const QRect & rectangle ) const
QRect & operator|= (const QRect & rectangle )
bool operator!= (const QRect & r1 , const QRect & r2 )
QRect operator+ (const QRect & rectangle , const QMargins & margins )
QRect operator+ (const QMargins & margins , const QRect & rectangle )
QRect operator- (const QRect & lhs , const QMargins & rhs )
QDataStream & operator<< (QDataStream & stream , const QRect & rectangle )
bool operator== (const QRect & r1 , const QRect & r2 )
QDataStream & operator>> (QDataStream & stream , QRect & rectangle )

详细描述

QRect class defines a rectangle in the plane using integer precision.

A rectangle is normally expressed as a top-left corner and a size. The size (width and height) of a QRect is always equivalent to the mathematical rectangle that forms the basis for its rendering.

A QRect can be constructed with a set of left, top, width and height integers, or from a QPoint QSize . The following code creates two identical rectangles.

QRect r1(100, 200, 11, 16);
QRect r2(QPoint(100, 200), QSize(11, 16));
							

There is a third constructor that creates a QRect using the top-left and bottom-right coordinates, but we recommend that you avoid using it. The rationale is that for historical reasons the values returned by the bottom () 和 right () functions deviate from the true bottom-right corner of the rectangle.

QRect class provides a collection of functions that return the various rectangle coordinates, and enable manipulation of these. QRect also provides functions to move the rectangle relative to the various coordinates. In addition there is a moveTo () function that moves the rectangle, leaving its top left corner at the given coordinates. Alternatively, the translate () function moves the rectangle the given offset relative to the current position, and the translated () function returns a translated copy of this rectangle.

size () function returns the rectange's dimensions as a QSize . The dimensions can also be retrieved separately using the width () 和 height () functions. To manipulate the dimensions use the setSize (), setWidth () 或 setHeight () functions. Alternatively, the size can be changed by applying either of the functions setting the rectangle coordinates, for example, setBottom () 或 setRight ().

contains () function tells whether a given point is inside the rectangle or not, and the intersects () 函数返回 true if this rectangle intersects with a given rectangle. The QRect class also provides the intersected () function which returns the intersection rectangle, and the united () function which returns the rectangle that encloses the given rectangle and this:

isEmpty () 函数返回 true if left () > right () 或 top () > bottom (). Note that an empty rectangle is not valid: The isValid () 函数返回 true if left () <= right () and top () <= bottom (). A null rectangle ( isNull () == true) on the other hand, has both width and height set to 0.

Note that due to the way QRect and QRectF are defined, an empty QRect is defined in essentially the same way as QRectF .

Finally, QRect objects can be streamed as well as compared.

渲染

When using an anti-aliased painter, the boundary line of a QRect will be rendered symmetrically on both sides of the mathematical rectangle's boundary line. But when using an aliased painter (the default) other rules apply.

Then, when rendering with a one pixel wide pen the QRect 's boundary line will be rendered to the right and below the mathematical rectangle's boundary line.

When rendering with a two pixels wide pen the boundary line will be split in the middle by the mathematical rectangle. This will be the case whenever the pen is set to an even number of pixels, while rendering with a pen with an odd number of pixels, the spare pixel will be rendered to the right and below the mathematical rectangle as in the one pixel case.

Logical representation One pixel wide pen
Two pixel wide pen Three pixel wide pen

坐标

QRect class provides a collection of functions that return the various rectangle coordinates, and enable manipulation of these. QRect also provides functions to move the rectangle relative to the various coordinates.

For example the left (), setLeft () 和 moveLeft () functions as an example: left () returns the x-coordinate of the rectangle's left edge, setLeft () sets the left edge of the rectangle to the given x coordinate (it may change the width, but will never change the rectangle's right edge) and moveLeft () moves the entire rectangle horizontally, leaving the rectangle's left edge at the given x coordinate and its size unchanged.

Note that for historical reasons the values returned by the bottom () 和 right () functions deviate from the true bottom-right corner of the rectangle: The right () 函数返回 left () + width () - 1 bottom () 函数返回 top () + height () - 1 . The same is the case for the point returned by the bottomRight () convenience function. In addition, the x and y coordinate of the topRight () 和 bottomLeft () functions, respectively, contain the same deviation from the true right and bottom edges.

We recommend that you use x () + width () 和 y () + height () to find the true bottom-right corner, and avoid right () 和 bottom (). Another solution is to use QRectF : The QRectF class defines a rectangle in the plane using floating point accuracy for coordinates, and the QRectF::right () 和 QRectF::bottom () functions do return the right and bottom coordinates.

It is also possible to add offsets to this rectangle's coordinates using the adjust () function, as well as retrieve a new rectangle based on adjustments of the original one using the adjusted () function. If either of the width and height is negative, use the normalized () function to retrieve a rectangle where the corners are swapped.

此外, QRect provides the getCoords () function which extracts the position of the rectangle's top-left and bottom-right corner, and the getRect () function which extracts the rectangle's top-left corner, width and height. Use the setCoords () 和 setRect () function to manipulate the rectangle's coordinates and dimensions in one go.

约束

QRect is limited to the minimum and maximum values for the int type. Operations on a QRect that could potentially result in values outside this range will result in undefined behavior.

另请参阅 QRectF and QRegion .

成员函数文档编制

QRect:: QRect ()

Constructs a null rectangle.

另请参阅 isNull ().

QRect:: QRect (const QPoint & topLeft , const QPoint & bottomRight )

Constructs a rectangle with the given topLeft and bottomRight corners.

另请参阅 setTopLeft () 和 setBottomRight ().

QRect:: QRect (const QPoint & topLeft , const QSize & size )

Constructs a rectangle with the given topLeft corner and the given size .

另请参阅 setTopLeft () 和 setSize ().

QRect:: QRect ( int x , int y , int width , int height )

Constructs a rectangle with ( x , y ) as its top-left corner and the given width and height .

另请参阅 setRect ().

void QRect:: adjust ( int dx1 , int dy1 , int dx2 , int dy2 )

添加 dx1 , dy1 , dx2 and dy2 respectively to the existing coordinates of the rectangle.

另请参阅 adjusted () 和 setRect ().

QRect QRect:: adjusted ( int dx1 , int dy1 , int dx2 , int dy2 ) const

Returns a new rectangle with dx1 , dy1 , dx2 and dy2 added respectively to the existing coordinates of this rectangle.

另请参阅 adjust ().

int QRect:: bottom () const

Returns the y-coordinate of the rectangle's bottom edge.

Note that for historical reasons this function returns top () + height () - 1; use y () + height () to retrieve the true y-coordinate.

另请参阅 setBottom (), bottomLeft (),和 bottomRight ().

QPoint QRect:: bottomLeft () const

Returns the position of the rectangle's bottom-left corner. Note that for historical reasons this function returns QPoint ( left (), top () + height () - 1).

另请参阅 setBottomLeft (), bottom (),和 left ().

QPoint QRect:: bottomRight () const

Returns the position of the rectangle's bottom-right corner.

Note that for historical reasons this function returns QPoint ( left () + width () -1, top () + height () - 1).

另请参阅 setBottomRight (), bottom (),和 right ().

QPoint QRect:: center () const

Returns the center point of the rectangle.

另请参阅 moveCenter ().

bool QRect:: contains (const QPoint & point , bool proper = false) const

返回 true 若给定 point is inside or on the edge of the rectangle, otherwise returns false 。若 proper is true, this function only returns true 若给定 point is inside the rectangle (i.e., not on the edge).

另请参阅 intersects ().

bool QRect:: contains (const QRect & rectangle , bool proper = false) const

这是重载函数。

返回 true 若给定 rectangle is inside this rectangle. otherwise returns false 。若 proper is true, this function only returns true rectangle is entirely inside this rectangle (not on the edge).

bool QRect:: contains ( int x , int y ) const

这是重载函数。

返回 true if the point ( x , y ) is inside this rectangle, otherwise returns false .

bool QRect:: contains ( int x , int y , bool proper ) const

这是重载函数。

返回 true if the point ( x , y ) is inside or on the edge of the rectangle, otherwise returns false 。若 proper is true, this function only returns true if the point is entirely inside the rectangle(not on the edge).

void QRect:: getCoords ( int * x1 , int * y1 , int * x2 , int * y2 ) const

Extracts the position of the rectangle's top-left corner to * x1 and * y1 , and the position of the bottom-right corner to * x2 and * y2 .

另请参阅 setCoords () 和 getRect ().

void QRect:: getRect ( int * x , int * y , int * width , int * height ) const

Extracts the position of the rectangle's top-left corner to * x and * y , and its dimensions to * width and * height .

另请参阅 setRect () 和 getCoords ().

int QRect:: height () const

Returns the height of the rectangle.

另请参阅 setHeight (), width (),和 size ().

QRect QRect:: intersected (const QRect & rectangle ) const

Returns the intersection of this rectangle and the given rectangle 。注意 r.intersected(s) 相当于 r & s .

This function was introduced in Qt 4.2.

另请参阅 intersects (), united (),和 operator&= ().

bool QRect:: intersects (const QRect & rectangle ) const

返回 true if this rectangle intersects with the given rectangle (i.e., there is at least one pixel that is within both rectangles), otherwise returns false .

The intersection rectangle can be retrieved using the intersected () 函数。

另请参阅 contains ().

bool QRect:: isEmpty () const

返回 true if the rectangle is empty, otherwise returns false .

An empty rectangle has a left () > right () 或 top () > bottom (). An empty rectangle is not valid (i.e., isEmpty() == ! isValid ()).

使用 normalized () function to retrieve a rectangle where the corners are swapped.

另请参阅 isNull (), isValid (),和 normalized ().

bool QRect:: isNull () const

返回 true if the rectangle is a null rectangle, otherwise returns false .

A null rectangle has both the width and the height set to 0 (i.e., right () == left () - 1 and bottom () == top () - 1). A null rectangle is also empty, and hence is not valid.

另请参阅 isEmpty () 和 isValid ().

bool QRect:: isValid () const

返回 true if the rectangle is valid, otherwise returns false .

A valid rectangle has a left () <= right () 和 top () <= bottom (). Note that non-trivial operations like intersections are not defined for invalid rectangles. A valid rectangle is not empty (i.e., isValid() == ! isEmpty ()).

另请参阅 isNull (), isEmpty (),和 normalized ().

int QRect:: left () const

Returns the x-coordinate of the rectangle's left edge. Equivalent to x ().

另请参阅 setLeft (), topLeft (),和 bottomLeft ().

QRect QRect:: marginsAdded (const QMargins & margins ) const

Returns a rectangle grown by the margins .

This function was introduced in Qt 5.1.

另请参阅 operator+= (), marginsRemoved (),和 operator-= ().

QRect QRect:: marginsRemoved (const QMargins & margins ) const

移除 margins from the rectangle, shrinking it.

This function was introduced in Qt 5.1.

另请参阅 marginsAdded (), operator+= (),和 operator-= ().

void QRect:: moveBottom ( int y )

Moves the rectangle vertically, leaving the rectangle's bottom edge at the given y coordinate. The rectangle's size is unchanged.

另请参阅 bottom (), setBottom (),和 moveTop ().

void QRect:: moveBottomLeft (const QPoint & position )

Moves the rectangle, leaving the bottom-left corner at the given position . The rectangle's size is unchanged.

另请参阅 setBottomLeft (), moveBottom (),和 moveLeft ().

void QRect:: moveBottomRight (const QPoint & position )

Moves the rectangle, leaving the bottom-right corner at the given position . The rectangle's size is unchanged.

另请参阅 setBottomRight (), moveRight (),和 moveBottom ().

void QRect:: moveCenter (const QPoint & position )

Moves the rectangle, leaving the center point at the given position . The rectangle's size is unchanged.

另请参阅 center ().

void QRect:: moveLeft ( int x )

Moves the rectangle horizontally, leaving the rectangle's left edge at the given x coordinate. The rectangle's size is unchanged.

另请参阅 left (), setLeft (),和 moveRight ().

void QRect:: moveRight ( int x )

Moves the rectangle horizontally, leaving the rectangle's right edge at the given x coordinate. The rectangle's size is unchanged.

另请参阅 right (), setRight (),和 moveLeft ().

void QRect:: moveTo ( int x , int y )

Moves the rectangle, leaving the top-left corner at the given position ( x , y ). The rectangle's size is unchanged.

另请参阅 translate () 和 moveTopLeft ().

void QRect:: moveTo (const QPoint & position )

Moves the rectangle, leaving the top-left corner at the given position .

void QRect:: moveTop ( int y )

Moves the rectangle vertically, leaving the rectangle's top edge at the given y coordinate. The rectangle's size is unchanged.

另请参阅 top (), setTop (),和 moveBottom ().

void QRect:: moveTopLeft (const QPoint & position )

Moves the rectangle, leaving the top-left corner at the given position . The rectangle's size is unchanged.

另请参阅 setTopLeft (), moveTop (),和 moveLeft ().

void QRect:: moveTopRight (const QPoint & position )

Moves the rectangle, leaving the top-right corner at the given position . The rectangle's size is unchanged.

另请参阅 setTopRight (), moveTop (),和 moveRight ().

QRect QRect:: normalized () const

Returns a normalized rectangle; i.e., a rectangle that has a non-negative width and height.

width () < 0 the function swaps the left and right corners, and it swaps the top and bottom corners if height () < 0.

另请参阅 isValid () 和 isEmpty ().

Returns the x-coordinate of the rectangle's right edge.

Note that for historical reasons this function returns left () + width () - 1; use x () + width () to retrieve the true x-coordinate.

另请参阅 setRight (), topRight (),和 bottomRight ().

void QRect:: setBottom ( int y )

Sets the bottom edge of the rectangle to the given y coordinate. May change the height, but will never change the top edge of the rectangle.

另请参阅 bottom () 和 moveBottom ().

void QRect:: setBottomLeft (const QPoint & position )

Set the bottom-left corner of the rectangle to the given position . May change the size, but will never change the top-right corner of the rectangle.

另请参阅 bottomLeft () 和 moveBottomLeft ().

void QRect:: setBottomRight (const QPoint & position )

Set the bottom-right corner of the rectangle to the given position . May change the size, but will never change the top-left corner of the rectangle.

另请参阅 bottomRight () 和 moveBottomRight ().

void QRect:: setCoords ( int x1 , int y1 , int x2 , int y2 )

Sets the coordinates of the rectangle's top-left corner to ( x1 , y1 ), and the coordinates of its bottom-right corner to ( x2 , y2 ).

另请参阅 getCoords () 和 setRect ().

void QRect:: setHeight ( int height )

Sets the height of the rectangle to the given height . The bottom edge is changed, but not the top one.

另请参阅 height () 和 setSize ().

void QRect:: setLeft ( int x )

Sets the left edge of the rectangle to the given x coordinate. May change the width, but will never change the right edge of the rectangle.

相当于 setX ().

另请参阅 left () 和 moveLeft ().

void QRect:: setRect ( int x , int y , int width , int height )

Sets the coordinates of the rectangle's top-left corner to ( x , y ), and its size to the given width and height .

另请参阅 getRect () 和 setCoords ().

void QRect:: setRight ( int x )

Sets the right edge of the rectangle to the given x coordinate. May change the width, but will never change the left edge of the rectangle.

另请参阅 right () 和 moveRight ().

void QRect:: setSize (const QSize & size )

Sets the size of the rectangle to the given size . The top-left corner is not moved.

另请参阅 size (), setWidth (),和 setHeight ().

void QRect:: setTop ( int y )

Sets the top edge of the rectangle to the given y coordinate. May change the height, but will never change the bottom edge of the rectangle.

相当于 setY ().

另请参阅 top () 和 moveTop ().

void QRect:: setTopLeft (const QPoint & position )

Set the top-left corner of the rectangle to the given position . May change the size, but will never change the bottom-right corner of the rectangle.

另请参阅 topLeft () 和 moveTopLeft ().

void QRect:: setTopRight (const QPoint & position )

Set the top-right corner of the rectangle to the given position . May change the size, but will never change the bottom-left corner of the rectangle.

另请参阅 topRight () 和 moveTopRight ().

void QRect:: setWidth ( int width )

Sets the width of the rectangle to the given width . The right edge is changed, but not the left one.

另请参阅 width () 和 setSize ().

void QRect:: setX ( int x )

Sets the left edge of the rectangle to the given x coordinate. May change the width, but will never change the right edge of the rectangle.

相当于 setLeft ().

另请参阅 x (), setY (),和 setTopLeft ().

void QRect:: setY ( int y )

Sets the top edge of the rectangle to the given y coordinate. May change the height, but will never change the bottom edge of the rectangle.

相当于 setTop ().

另请参阅 y (), setX (),和 setTopLeft ().

QSize QRect:: size () const

Returns the size of the rectangle.

另请参阅 setSize (), width (),和 height ().

CGRect QRect:: toCGRect () const

Creates a CGRect from a QRect .

This function was introduced in Qt 5.8.

另请参阅 QRectF::fromCGRect ().

int QRect:: top () const

Returns the y-coordinate of the rectangle's top edge. Equivalent to y ().

另请参阅 setTop (), topLeft (),和 topRight ().

QPoint QRect:: topLeft () const

Returns the position of the rectangle's top-left corner.

另请参阅 setTopLeft (), top (),和 left ().

QPoint QRect:: topRight () const

Returns the position of the rectangle's top-right corner.

Note that for historical reasons this function returns QPoint ( left () + width () -1, top ()).

另请参阅 setTopRight (), top (),和 right ().

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

Moves the rectangle dx along the x axis and dy along the y axis, relative to the current position. Positive values move the rectangle to the right and down.

另请参阅 moveTopLeft (), moveTo (),和 translated ().

void QRect:: translate (const QPoint & offset )

这是重载函数。

Moves the rectangle offset . x() along the x axis and offset . y() along the y axis, relative to the current position.

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

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

另请参阅 translate ().

QRect QRect:: translated (const QPoint & offset ) const

这是重载函数。

Returns a copy of the rectangle that is translated offset . x() along the x axis and offset . y() along the y axis, relative to the current position.

QRect QRect:: transposed () const

Returns a copy of the rectangle that has its width and height exchanged:

QRect r = {15, 51, 42, 24};
r = r.transposed(); // r == {15, 51, 24, 42}
							

This function was introduced in Qt 5.7.

另请参阅 QSize::transposed ().

QRect QRect:: united (const QRect & rectangle ) const

Returns the bounding rectangle of this rectangle and the given rectangle .

This function was introduced in Qt 4.2.

另请参阅 intersected ().

int QRect:: width () const

Returns the width of the rectangle.

另请参阅 setWidth (), height (),和 size ().

int QRect:: x () const

Returns the x-coordinate of the rectangle's left edge. Equivalent to left ().

另请参阅 setX (), y (),和 topLeft ().

int QRect:: y () const

Returns the y-coordinate of the rectangle's top edge. Equivalent to top ().

另请参阅 setY (), x (),和 topLeft ().

QRect QRect:: operator& (const QRect & rectangle ) const

Returns the intersection of this rectangle and the given rectangle . Returns an empty rectangle if there is no intersection.

另请参阅 operator&= () 和 intersected ().

QRect &QRect:: operator&= (const QRect & rectangle )

Intersects this rectangle with the given rectangle .

另请参阅 intersected () 和 operator& ().

QRect &QRect:: operator+= (const QMargins & margins )

添加 margins to the rectangle, growing it.

This function was introduced in Qt 5.1.

另请参阅 marginsAdded (), marginsRemoved (),和 operator-= ().

QRect &QRect:: operator-= (const QMargins & margins )

Returns a rectangle shrunk by the margins .

This function was introduced in Qt 5.1.

另请参阅 marginsRemoved (), operator+= (),和 marginsAdded ().

QRect QRect:: operator| (const QRect & rectangle ) const

Returns the bounding rectangle of this rectangle and the given rectangle .

另请参阅 operator|= () 和 united ().

QRect &QRect:: operator|= (const QRect & rectangle )

Unites this rectangle with the given rectangle .

另请参阅 united () 和 operator| ().

相关非成员

bool operator!= (const QRect & r1 , const QRect & r2 )

返回 true if the rectangles r1 and r2 are different, otherwise returns false .

QRect operator+ (const QRect & rectangle , const QMargins & margins )

返回 rectangle grown by the margins .

This function was introduced in Qt 5.1.

QRect operator+ (const QMargins & margins , const QRect & rectangle )

这是重载函数。

返回 rectangle grown by the margins .

This function was introduced in Qt 5.1.

QRect operator- (const QRect & lhs , const QMargins & rhs )

返回 lhs rectangle shrunk by the rhs margins.

This function was introduced in Qt 5.3.

QDataStream & operator<< ( QDataStream & stream , const QRect & rectangle )

写入给定 rectangle 到给定 stream , and returns a reference to the stream.

另请参阅 序列化 Qt 数据类型 .

bool operator== (const QRect & r1 , const QRect & r2 )

返回 true if the rectangles r1 and r2 are equal, otherwise returns false .

QDataStream & operator>> ( QDataStream & stream , QRect & rectangle )

Reads a rectangle from the given stream into the given rectangle , and returns a reference to the stream.

另请参阅 序列化 Qt 数据类型 .