QMatrix ¶

QMatrix class specifies 2D transformations of a coordinate system. 更多 …

概要 ¶

函数 ¶

def __eq__ (arg__1)
def __imul__ (arg__1)
def __mul__ (o)
def __ne__ (arg__1)
def __reduce__ ()
def __repr__ ()
def determinant ()
def dx ()
def dy ()
def inverted ()
def isIdentity ()
def isInvertible ()
def m11 ()
def m12 ()
def m21 ()
def m22 ()
def map (a)
def map (a)
def map (l)
def map (l)
def map (p)
def map (p)
def map (p)
def map (r)
def map (x, y)
def map (x, y)
def mapRect (arg__1)
def mapRect (arg__1)
def mapToPolygon (r)
def reset ()
def rotate (a)
def scale (sx, sy)
def setMatrix (m11, m12, m21, m22, dx, dy)
def shear (sh, sv)
def translate (dx, dy)

详细描述 ¶

A matrix specifies how to translate, scale, shear or rotate the coordinate system, and is typically used when rendering graphics. QMatrix , in contrast to QTransform , does not allow perspective transformations. QTransform is the recommended transformation class in Qt.

A QMatrix object can be built using the setMatrix() , scale() , rotate() , translate() and shear() functions. Alternatively, it can be built by applying basic matrix operations . The matrix can also be defined when constructed, and it can be reset to the identity matrix (the default) using the reset() 函数。

QMatrix class supports mapping of graphic primitives: A given point, line, polygon, region, or painter path can be mapped to the coordinate system defined by this matrix using the map() function. In case of a rectangle, its coordinates can be transformed using the mapRect() function. A rectangle can also be transformed into a polygon (mapped to the coordinate system defined by this matrix), using the mapToPolygon() 函数。

QMatrix provides the isIdentity() function which returns true if the matrix is the identity matrix, and the isInvertible() function which returns true if the matrix is non-singular (i.e. AB = BA = I). The inverted() function returns an inverted copy of this matrix if it is invertible (otherwise it returns the identity matrix). In addition, QMatrix provides the determinant() function returning the matrix’s determinant.

Finally, the QMatrix class supports matrix multiplication, and objects of the class can be streamed as well as compared.

渲染图形 ¶

When rendering graphics, the matrix defines the transformations but the actual transformation is performed by the drawing routines in QPainter .

默认情况下， QPainter operates on the associated device’s own coordinate system. The standard coordinate system of a QPaintDevice has its origin located at the top-left position. The x values increase to the right; y values increase downward. For a complete description, see the coordinate system 文档编制。

QPainter has functions to translate, scale, shear and rotate the coordinate system without using a QMatrix 。例如：
def paintEvent(self, event):
    painter = QPainter(self)
    painter.setPen(QPen(Qt.blue, 1, Qt.DashLine))
    painter.drawRect(0, 0, 100, 100)
    painter.rotate(45)
    painter.setFont(QFont("Helvetica", 24))
    painter.setPen(QPen(Qt.black, 1))
    painter.drawText(20, 10, "QMatrix")
																
Although these functions are very convenient, it can be more efficient to build a QMatrix 和调用 setMatrix() if you want to perform more than a single transform operation. For example:
def paintEvent(self, event)
    painter = QPainter(self)
    painter.setPen(QPen(Qt.blue, 1, Qt.DashLine))
    painter.drawRect(0, 0, 100, 100)
    matrix = QMatrix()
    matrix.translate(50, 50)
    matrix.rotate(45)
    matrix.scale(0.5, 1.0)
    painter.setMatrix(matrix)
    painter.setFont(QFont("Helvetica", 24))
    painter.setPen(QPen(Qt.black, 1))
    painter.drawText(20, 10, "QMatrix")
																

基本矩阵运算 ¶

A QMatrix object contains a 3 x 3 matrix. The dx and dy elements specify horizontal and vertical translation. The m11 and m22 elements specify horizontal and vertical scaling. And finally, the m21 and m12 elements specify horizontal and vertical shearing .

QMatrix transforms a point in the plane to another point using the following formulas:
x' = m11*x + m21*y + dx
y' = m22*y + m12*x + dy
												
The point (x, y) is the original point, and (x’, y’) is the transformed point. (x’, y’) can be transformed back to (x, y) by performing the same operation on the inverted() matrix.

The various matrix elements can be set when constructing the matrix, or by using the setMatrix() function later on. They can also be manipulated using the translate() , rotate() , scale() and shear() convenience functions, The currently set values can be retrieved using the m11() , m12() , m21() , m22() , dx() and dy() 函数。

Translation is the simplest transformation. Setting dx and dy will move the coordinate system dx units along the X axis and dy units along the Y axis. Scaling can be done by setting m11 and m22 . For example, setting m11 to 2 and m22 to 1.5 will double the height and increase the width by 50%. The identity matrix has m11 and m22 set to 1 (all others are set to 0) mapping a point to itself. Shearing is controlled by m12 and m21 . Setting these elements to values different from zero will twist the coordinate system. Rotation is achieved by carefully setting both the shearing factors and the scaling factors.

Here’s the combined transformations example using basic matrix operations:
def paintEvent(self, event)
    pi = 3.14
    a    = pi/180 * 45.0
    sina = sin(a)
    cosa = cos(a)
    translationMatrix = QMatrix(1, 0, 0, 1, 50.0, 50.0)
    rotationMatrix = QMatrix(cosa, sina, -sina, cosa, 0, 0)
    scalingMatrix = QMatrix(0.5, 0, 0, 1.0, 0, 0)
    matrix = QMatrix()
    matrix =  scalingMatrix * rotationMatrix * translationMatrix
    painter = QPainter(self)
    painter.setPen(QPen(Qt.blue, 1, Qt::DashLine))
    painter.drawRect(0, 0, 100, 100)
    painter.setMatrix(matrix)
    painter.setFont(QFont("Helvetica", 24))
    painter.setPen(QPen(Qt.black, 1))
    painter.drawText(20, 10, "QMatrix")
																
另请参阅

QPainter QTransform 坐标系统仿射变换范例变换范例

class QMatrix ¶

QMatrix(other)

QMatrix(m11, m12, m21, m22, dx, dy)

param m12

qreal

param dx

qreal

param dy

qreal

param other

QMatrix

param m21

qreal

param m22

qreal

param m11

qreal

构造恒等矩阵。

All elements are set to zero except m11 and m22 (specifying the scale), which are set to 1.

另请参阅

reset()

构造矩阵采用元素 m11 , m12 , m21 , m22 , dx and dy .

另请参阅

setMatrix()

PySide2.QtGui.QMatrix. __reduce__ ( ) ¶

返回类型: PyObject

PySide2.QtGui.QMatrix. __repr__ ( ) ¶

返回类型: PyObject

PySide2.QtGui.QMatrix. determinant ( ) ¶

返回类型: qreal

Returns the matrix’s determinant.

PySide2.QtGui.QMatrix. dx ( ) ¶

返回类型: qreal

Returns the horizontal translation factor.

另请参阅

translate() 基本 Matrix Operations

PySide2.QtGui.QMatrix. dy ( ) ¶

返回类型: qreal

Returns the vertical translation factor.

另请参阅

translate() 基本 Matrix Operations

PySide2.QtGui.QMatrix. inverted ( ) ¶

返回类型: PyTuple

Returns an inverted copy of this matrix.

If the matrix is singular (not invertible), the returned matrix is the identity matrix. If invertible is valid (i.e. not 0), its value is set to true if the matrix is invertible, otherwise it is set to false.

另请参阅

isInvertible()

PySide2.QtGui.QMatrix. isIdentity ( ) ¶

返回类型: bool

返回 true if the matrix is the identity matrix, otherwise returns false .

另请参阅

reset()

PySide2.QtGui.QMatrix. isInvertible ( ) ¶

返回类型: bool

返回 true if the matrix is invertible, otherwise returns false .

另请参阅

inverted()

PySide2.QtGui.QMatrix. m11 ( ) ¶

返回类型: qreal

Returns the horizontal scaling factor.

另请参阅

scale() 基本 Matrix Operations

PySide2.QtGui.QMatrix. m12 ( ) ¶

返回类型: qreal

Returns the vertical shearing factor.

另请参阅

shear() 基本 Matrix Operations

PySide2.QtGui.QMatrix. m21 ( ) ¶

返回类型: qreal

Returns the horizontal shearing factor.

另请参阅

shear() 基本 Matrix Operations

PySide2.QtGui.QMatrix. m22 ( ) ¶

返回类型: qreal

Returns the vertical scaling factor.

另请参阅

scale() 基本 Matrix Operations

PySide2.QtGui.QMatrix. map ( x , y ) ¶

参数

x – qreal
y – qreal

Maps the given coordinates x and y into the coordinate system defined by this matrix. The resulting values are put in *``tx`` and *``ty`` , respectively.

The coordinates are transformed using the following formulas:

												x' = m11*x + m21*y + dx
y' = m22*y + m12*x + dy

The point (x, y) is the original point, and (x’, y’) is the transformed point.

另请参阅

基本 Matrix Operations

PySide2.QtGui.QMatrix. map ( x , y ) ¶

参数

x – int
y – int

这是重载函数。

Maps the given coordinates x and y into the coordinate system defined by this matrix. The resulting values are put in *``tx`` and *``ty`` , respectively. Note that the transformed coordinates are rounded to the nearest integer.

PySide2.QtGui.QMatrix. map ( r ) ¶

参数: r – QRegion
返回类型: QRegion

PySide2.QtGui.QMatrix. map ( a ) ¶

参数: a – QPolygonF
返回类型: QPolygonF

PySide2.QtGui.QMatrix. map ( a ) ¶

参数: a – QPolygon
返回类型: QPolygon

PySide2.QtGui.QMatrix. map ( p ) ¶

参数: p – QPoint
返回类型: QPoint

PySide2.QtGui.QMatrix. map ( p ) ¶

参数: p – QPainterPath
返回类型: QPainterPath

PySide2.QtGui.QMatrix. map ( l ) ¶

参数: l – QLineF
返回类型: QLineF

PySide2.QtGui.QMatrix. map ( l ) ¶

参数: l – QLine
返回类型: QLine

PySide2.QtGui.QMatrix. map ( p ) ¶

参数: p – QPointF
返回类型: QPointF

PySide2.QtGui.QMatrix. mapRect ( arg__1 ) ¶

参数: arg__1 – QRect
返回类型: QRect

PySide2.QtGui.QMatrix. mapRect ( arg__1 ) ¶

参数: arg__1 – QRectF
返回类型: QRectF

PySide2.QtGui.QMatrix. mapToPolygon ( r ) ¶

参数: r – QRect
返回类型: QPolygon

创建和返回 QPolygon representation of the given rectangle , mapped into the coordinate system defined by this matrix.

The rectangle’s coordinates are transformed using the following formulas:

												x' = m11*x + m21*y + dx
y' = m22*y + m12*x + dy

Polygons and rectangles behave slightly differently when transformed (due to integer rounding), so matrix.map(QPolygon(rectangle)) is not always the same as matrix.mapToPolygon(rectangle) .

另请参阅

mapRect() 基本 Matrix Operations

PySide2.QtGui.QMatrix. __ne__ ( arg__1 ) ¶

参数: arg__1 – QMatrix
返回类型: bool

返回 true if this matrix is not equal to the given matrix ，否则返回 false .

PySide2.QtGui.QMatrix. __mul__ ( o ) ¶

参数: o – QMatrix
返回类型: QMatrix

Returns the result of multiplying this matrix by the given matrix .

Note that matrix multiplication is not commutative, i.e. a*b != b*a.

PySide2.QtGui.QMatrix. __imul__ ( arg__1 ) ¶

参数: arg__1 – QMatrix
返回类型: QMatrix

这是重载函数。

Returns the result of multiplying this matrix by the given matrix .

PySide2.QtGui.QMatrix. __eq__ ( arg__1 ) ¶

参数: arg__1 – QMatrix
返回类型: bool

返回 true if this matrix is equal to the given matrix ，否则返回 false .

PySide2.QtGui.QMatrix. reset ( ) ¶: Resets the matrix to an identity matrix, i.e. all elements are set to zero, except m11 and m22 (specifying the scale) which are set to 1.

另请参阅

QMatrix() isIdentity() 基本 Matrix Operations

PySide2.QtGui.QMatrix. rotate ( a ) ¶

参数: a – qreal
返回类型: QMatrix

Rotates the coordinate system the given degrees counterclockwise.

Note that if you apply a QMatrix to a point defined in widget coordinates, the direction of the rotation will be clockwise because the y-axis points downwards.

Returns a reference to the matrix.

另请参阅

setMatrix()

PySide2.QtGui.QMatrix. scale ( sx , sy ) ¶

参数

sx – qreal
sy – qreal

返回类型

QMatrix

Scales the coordinate system by sx horizontally and sy vertically, and returns a reference to the matrix.

另请参阅

setMatrix()

PySide2.QtGui.QMatrix. setMatrix ( m11 , m12 , m21 , m22 , dx , dy ) ¶

参数

m11 – qreal
m12 – qreal
m21 – qreal
m22 – qreal
dx – qreal
dy – qreal

Sets the matrix elements to the specified values, m11 , m12 , m21 , m22 , dx and dy .

Note that this function replaces the previous values. QMatrix provide the translate() , rotate() , scale() and shear() convenience functions to manipulate the various matrix elements based on the currently defined coordinate system.

另请参阅

QMatrix()

PySide2.QtGui.QMatrix. shear ( sh , sv ) ¶

参数

sh – qreal
sv – qreal

返回类型

QMatrix

Shears the coordinate system by sh horizontally and sv vertically, and returns a reference to the matrix.

另请参阅

setMatrix()

PySide2.QtGui.QMatrix. translate ( dx , dy ) ¶

参数

dx – qreal
dy – qreal

返回类型

QMatrix

Moves the coordinate system dx along the x axis and dy along the y axis, and returns a reference to the matrix.

另请参阅

setMatrix()

内容表

上一话题

下一话题

快速搜索

QMatrix ¶

概要 ¶

函数 ¶

详细描述 ¶

渲染图形 ¶

基本矩阵运算 ¶