class QRegion¶

The QRegion class specifies a clip region for a painter. More…

Synopsis¶

Methods¶

def __init__()
def __getitem__()
def __len__()
def begin()
def boundingRect()
def cbegin()
def cend()
def contains()
def end()
def intersected()
def intersects()
def isEmpty()
def isNull()
def __ne__()
def __and__()
def __mul__()
def __add__()
def __iadd__()
def __sub__()
def __isub__()
def __eq__()
def __xor__()
def __ixor__()
def __or__()
def __ior__()
def rectCount()
def setRects()
def subtracted()
def swap()
def translate()
def translated()
def united()
def xored()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description¶

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

QRegion is used with 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() .

Iteration over the region (with begin() , end() , or ranged-for loops) gives a decomposition of the region into rectangles.

Example of using complex regions:

def paintEvent(self, arg__0):

    QRegion r1(QRect(100, 100, 200, 80), // r1: elliptic region
               QRegion.Ellipse)
    QRegion r2(QRect(100, 120, 90, 30)) # r2: rectangular region
    r3 = r1.intersected(r2) # r3: intersection
    painter = QPainter(self)
    painter.setClipRegion(r3)
    # ...                                  // paint clipped graphics

class RegionType¶

Specifies the shape of the region to be created.

Constant

Description

QRegion.Rectangle

the region covers the entire rectangle.

QRegion.Ellipse

the region is an ellipse inside the rectangle.

Constant	Description
QRegion.Rectangle	the region covers the entire rectangle.
QRegion.Ellipse	the region is an ellipse inside the rectangle.

__init__()¶

Constructs an empty region.

See also

isEmpty()

__init__(bitmap)

Parameters:: bitmap – QBitmap

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 setMask() .

__init__(region)

Parameters:: region – QRegion

Constructs a new region which is equal to region r.

__init__(pa[, fillRule=Qt.OddEvenFill])

Parameters:

pa – QPolygon
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.

__init__(r[, t=QRegion.RegionType.Rectangle])

Parameters:

r – QRect
t – RegionType

This is an overloaded function.

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

RegionType

__init__(x, y, w, h[, t=QRegion.RegionType.Rectangle])

Parameters:

x – int
y – int
w – int
h – int
t – RegionType

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``).

__getitem__()¶

__len__()¶

begin()¶

Return type:: QRect

Returns a 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.

See also

rbegin() cbegin() end()

boundingRect()¶

Return type:: QRect

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

cbegin()¶

Return type:: QRect

Same as begin() .

cend()¶

Return type:: QRect

Same as end() .

contains(p)¶

Parameters:: p – QPoint
Return type:: bool

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

contains(r)

Parameters:: r – QRect
Return type:: bool

This is an overloaded function.

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

end()¶

Return type:: QRect

Returns a 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.

See also

rend() cend() begin()

intersected(r)¶

Parameters:: r – QRect
Return type:: QRegion

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

See also

subtracted() united() xored()

intersected(r)

Parameters:: r – QRegion
Return type:: QRegion

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() xored()

intersects(r)¶

Parameters:: r – QRect
Return type:: bool

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

intersects(r)

Parameters:: r – QRegion
Return type:: bool

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

isEmpty()¶

Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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

Example:

r1 = QRegion(10, 10, 20, 20)
r1.isEmpty() # false
r3 = QRegion()
r3.isEmpty() # true
r2 = QRegion(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

isNull()¶

Return type:: bool

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()

__ne__(r)¶

Parameters:: r – QRegion
Return type:: bool

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

__and__(r)¶

Parameters:: r – QRect
Return type:: QRegion

This is an overloaded function.

__and__(r)

Parameters:: r – QRegion
Return type:: QRegion

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

See also

intersected()

__mul__(m)¶

Parameters:: m – QTransform
Return type:: QRegion

__add__(r)¶

Parameters:: r – QRect
Return type:: QRegion

This is an overloaded function.

__add__(r)

Parameters:: r – QRegion
Return type:: QRegion

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

See also

united() operator|()

__iadd__(r)¶

Parameters:: r – QRect
Return type:: QRegion

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

See also

united()

__iadd__(r)

Parameters:: r – QRegion
Return type:: QRegion

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()

__sub__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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

See also

subtracted()

__isub__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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()

__eq__(r)¶

Parameters:: r – QRegion
Return type:: bool

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

__xor__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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

See also

xored()

__ixor__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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()

__or__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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

See also

united() operator+()

__ior__(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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()

rectCount()¶

Return type:: int

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

setRects(rect, num)¶

Parameters:

rect – QRect
num – int

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.

subtracted(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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() xored()

swap(other)¶

Parameters:: other – QRegion

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

translate(p)¶

Parameters:: p – QPoint

This is an overloaded function.

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(dx, dy)

Parameters:

dx – int
dy – int

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

translated(p)¶

Parameters:: p – QPoint
Return type:: QRegion

This is an overloaded function.

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(dx, dy)

Parameters:

dx – int
dy – int

Return type:

QRegion

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()

united(r)¶

Parameters:: r – QRect
Return type:: QRegion

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

See also

intersected() subtracted() xored()

united(r)

Parameters:: r – QRegion
Return type:: QRegion

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() xored()

xored(r)¶

Parameters:: r – QRegion
Return type:: QRegion

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() subtracted()