QRegion

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

Inheritance diagram of PySide6.QtGui.QRegion

Synopsis

Functions

Detailed Description

QRegion is used with setClipRegion() to limit the paint area to what needs to be painted. There is also a 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 C++11 ranged-for loops) gives a decomposition of the region into rectangles.

Example of using complex regions:

class MyWidget (QWidget):
    # ...
    def paintEvent(self):
        r1 = QRegion(QRect(100, 100, 200, 80), QRegion.Ellipse) # r1: elliptic region
                )
        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 PySide6.QtGui.QRegion

PySide6.QtGui.QRegion(bitmap)

PySide6.QtGui.QRegion(pa[, fillRule=Qt.OddEvenFill])

PySide6.QtGui.QRegion(r[, t=Rectangle])

PySide6.QtGui.QRegion(region)

PySide6.QtGui.QRegion(x, y, w, h[, t=Rectangle])

Parameters

Constructs an empty region.

See also

isEmpty()

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``).

PySide6.QtGui.QRegion.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.

PySide6.QtGui.QRegion.begin()
Return type

PySide6.QtCore.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()

PySide6.QtGui.QRegion.boundingRect()
Return type

PySide6.QtCore.QRect

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

PySide6.QtGui.QRegion.cbegin()
Return type

PySide6.QtCore.QRect

Same as begin() .

PySide6.QtGui.QRegion.cend()
Return type

PySide6.QtCore.QRect

Same as end() .

PySide6.QtGui.QRegion.contains(p)
Parameters

pPySide6.QtCore.QPoint

Return type

bool

PySide6.QtGui.QRegion.contains(r)
Parameters

rPySide6.QtCore.QRect

Return type

bool

PySide6.QtGui.QRegion.end()
Return type

PySide6.QtCore.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()

PySide6.QtGui.QRegion.intersected(r)
Parameters

rPySide6.QtCore.QRect

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.intersected(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.intersects(r)
Parameters

rPySide6.QtCore.QRect

Return type

bool

PySide6.QtGui.QRegion.intersects(r)
Parameters

rPySide6.QtGui.QRegion

Return type

bool

PySide6.QtGui.QRegion.isEmpty()
Return type

bool

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.isNull()                // false
r1.isEmpty()               // false

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

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

r3 = r1.united(r2)         // r3: union of r1 and r2
r3.isNull()                // false
r3.isEmpty()               // false
PySide6.QtGui.QRegion.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()

PySide6.QtGui.QRegion.__ne__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

bool

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

PySide6.QtGui.QRegion.__and__(r)
Parameters

rPySide6.QtCore.QRect

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__and__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__mul__(m)
Parameters

mPySide6.QtGui.QTransform

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__add__(r)
Parameters

rPySide6.QtCore.QRect

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__add__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__iadd__(r)
Parameters

rPySide6.QtCore.QRect

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__iadd__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.__sub__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

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

See also

subtracted()

PySide6.QtGui.QRegion.__isub__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.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()

PySide6.QtGui.QRegion.__eq__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

bool

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

PySide6.QtGui.QRegion.__xor__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

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

See also

xored()

PySide6.QtGui.QRegion.__ixor__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.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()

PySide6.QtGui.QRegion.__or__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

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

See also

united() operator+()

PySide6.QtGui.QRegion.__ior__(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.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()

PySide6.QtGui.QRegion.rectCount()
Return type

int

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

PySide6.QtGui.QRegion.setRects(rect, num)
Parameters

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.

PySide6.QtGui.QRegion.subtracted(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

Returns a region which is r subtracted from this region.

../../_images/rsubtract.png

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

PySide6.QtGui.QRegion.swap(other)
Parameters

otherPySide6.QtGui.QRegion

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

PySide6.QtGui.QRegion.translate(p)
Parameters

pPySide6.QtCore.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.

PySide6.QtGui.QRegion.translate(dx, dy)
Parameters
  • dx – int

  • dy – int

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

PySide6.QtGui.QRegion.translated(p)
Parameters

pPySide6.QtCore.QPoint

Return type

PySide6.QtGui.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()

PySide6.QtGui.QRegion.translated(dx, dy)
Parameters
  • dx – int

  • dy – int

Return type

PySide6.QtGui.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()

PySide6.QtGui.QRegion.united(r)
Parameters

rPySide6.QtCore.QRect

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.united(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

PySide6.QtGui.QRegion.xored(r)
Parameters

rPySide6.QtGui.QRegion

Return type

PySide6.QtGui.QRegion

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

../../_images/rxor.png

The figure shows the exclusive or of two elliptical regions.