|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.gui.QMatrix
public class QMatrix
The QMatrix
class specifies 2D transformations of a coordinate system. A matrix specifies how to translate, scale, shear or rotate the coordinate system, and is typically used when rendering graphics.
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()
function.
The 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()
function.
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 det()
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.
QPainter
. By default, 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 documentation.
QPainter
has functions to translate, scale, shear and rotate the coordinate system without using a QMatrix
. For example:
![]() | protected void paintEvent(QPaintEvent event) { QPainter painter = new QPainter(this); painter.setPen(new QPen(QColor.blue, 1, Qt.PenStyle.DashLine)); painter.drawRect(0, 0, 100, 100); painter.rotate(45); painter.setFont(new QFont("Helvetica", 24)); painter.setPen(new QPen(QColor.black, 1)); painter.drawText(20, 10, "QMatrix"); } |
QMatrix
and call QPainter::setMatrix() if you want to perform more than a single transform operation. For example: ![]() | protected void paintEvent(QPaintEvent event) { QPainter painter = new QPainter(this); painter.setPen(new QPen(QColor.blue, 1, Qt.PenStyle.DashLine)); painter.drawRect(0, 0, 100, 100); QMatrix matrix = new QMatrix(); matrix.translate(50, 50); matrix.rotate(45); matrix.scale(0.5, 1.0); painter.setWorldMatrix(matrix); painter.setFont(new QFont("Helvetica", 24)); painter.setPen(new QPen(QColor.black, 1)); painter.drawText(20, 10, "QMatrix"); } |
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 + m21 + dx y' = m22 + m12 + dyThe 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 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()
functions.
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:
![]() | protected void paintEvent(QPaintEvent event) { double pi = 3.14; double a = pi/180 * 45.0; double sina = Math.sin(a); double cosa = Math.cos(a); QMatrix translationMatrix = new QMatrix(1, 0, 0, 1, 50.0, 50.0); QMatrix rotationMatrix = new QMatrix(cosa, sina, -sina, cosa, 0, 0); QMatrix scalingMatrix = new QMatrix(0.5, 0, 0, 1.0, 0, 0); QMatrix matrix = new QMatrix(); matrix = scalingMatrix.multiply(rotationMatrix.multiply(translationMatrix)); QPainter painter = new QPainter(this); painter.setPen(new QPen(QColor.blue, 1, Qt.PenStyle.DashLine)); painter.drawRect(0, 0, 100, 100); painter.setWorldMatrix(matrix); painter.setFont(new QFont("Helvetica", 24)); painter.setPen(new QPen(QColor.black, 1)); painter.drawText(20, 10, "QMatrix"); } |
QPainter
, The Coordinate System, Affine Transformations Demo, and Transformations Example.
Nested Class Summary |
---|
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
---|
QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9 |
Constructor Summary | |
---|---|
QMatrix()
Constructs an identity matrix. |
|
QMatrix(double m11,
double m12,
double m21,
double m22,
double dx,
double dy)
Constructs a matrix with the elements, m11, m12, m21, m22, dx and dy. |
|
QMatrix(QMatrix matrix)
Constructs a matrix that is a copy of the given matrix. |
Method Summary | |
---|---|
QMatrix |
clone()
|
double |
det()
Returns the matrix's determinant. |
double |
dx()
Returns the horizontal translation factor. |
double |
dy()
Returns the vertical translation factor. |
static QMatrix |
fromNativePointer(QNativePointer nativePointer)
|
QMatrix |
inverted()
Returns an inverted copy of this matrix. |
boolean |
isIdentity()
Returns true if the matrix is the identity matrix, otherwise returns false. |
boolean |
isInvertible()
Returns true if the matrix is invertible, otherwise returns false. |
double |
m11()
Returns the horizontal scaling factor. |
double |
m12()
Returns the vertical shearing factor. |
double |
m21()
Returns the horizontal shearing factor. |
double |
m22()
Returns the vertical scaling factor. |
QLine |
map(QLine l)
Creates and returns a QLine object that is a copy of the given line, mapped into the coordinate system defined by this matrix. |
QLineF |
map(QLineF l)
Creates and returns a QLineF object that is a copy of the given line, mapped into the coordinate system defined by this matrix. |
QPainterPath |
map(QPainterPath p)
Creates and returns a QPainterPath object that is a copy of the given path, mapped into the coordinate system defined by this matrix. |
QPoint |
map(QPoint p)
Creates and returns a QPoint object that is a copy of the given point, mapped into the coordinate system defined by this matrix. |
QPointF |
map(QPointF p)
Creates and returns a QPointF object that is a copy of the given point, mapped into the coordinate system defined by this matrix. |
QPolygon |
map(QPolygon a)
Creates and returns a QPolygon object that is a copy of the given polygon, mapped into the coordinate system defined by this matrix. |
QPolygonF |
map(QPolygonF a)
Creates and returns a QPolygonF object that is a copy of the given polygon, mapped into the coordinate system defined by this matrix. |
QRegion |
map(QRegion r)
Creates and returns a QRegion object that is a copy of the given region, mapped into the coordinate system defined by this matrix. |
QRect |
mapRect(QRect arg__1)
Creates and returns a QRect object that is a copy of the given rectangle, mapped into the coordinate system defined by this matrix. |
QRectF |
mapRect(QRectF arg__1)
Creates and returns a QRectF object that is a copy of the given rectangle, mapped into the coordinate system defined by this matrix. |
QPolygon |
mapToPolygon(QRect r)
Creates and returns a QPolygon representation of the given rectangle, mapped into the coordinate system defined by this matrix. |
QMatrix |
multiplied(QMatrix other)
|
QMatrix |
multiply(QMatrix other)
|
static QNativePointer |
nativePointerArray(QMatrix[] array)
|
void |
readFrom(QDataStream arg__1)
|
void |
reset()
Resets the matrix to an identity matrix, i.e. |
QMatrix |
rotate(double other)
Rotates the coordinate system the given other degrees counterclockwise. |
QMatrix |
scale(double sx,
double sy)
Scales the coordinate system by sx horizontally and sy vertically, and returns a reference to the matrix. |
void |
setMatrix(double m11,
double m12,
double m21,
double m22,
double dx,
double dy)
Sets the matrix elements to the specified values, m11, m12, m21, m22, dx and dy. |
QMatrix |
shear(double sh,
double sv)
Shears the coordinate system by sh horizontally and sv vertically, and returns a reference to the matrix. |
java.lang.String |
toString()
|
QMatrix |
translate(double dx,
double dy)
Moves the coordinate system dx along the x axis and dy along the y axis, and returns a reference to the matrix. |
void |
writeTo(QDataStream arg__1)
|
Methods inherited from class com.trolltech.qt.QtJambiObject |
---|
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class java.lang.Object |
---|
getClass, hashCode, notify, notifyAll, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
---|
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
---|
public QMatrix()
All elements are set to zero except m11 and m22 (specifying the scale), which are set to 1.
reset()
.
public QMatrix(QMatrix matrix)
public QMatrix(double m11, double m12, double m21, double m22, double dx, double dy)
setMatrix()
.
Method Detail |
---|
public final double det()
public final double dx()
translate()
, and Basic Matrix Operations
.
public final double dy()
translate()
, and Basic Matrix Operations
.
public final boolean isIdentity()
reset()
.
public final boolean isInvertible()
inverted()
.
public final double m11()
scale()
, and Basic Matrix Operations
.
public final double m12()
shear()
, and Basic Matrix Operations
.
public final double m21()
shear()
, and Basic Matrix Operations
.
public final double m22()
scale()
, and Basic Matrix Operations
.
public final QLine map(QLine l)
QLine
object that is a copy of the given line, mapped into the coordinate system defined by this matrix. Note that the transformed coordinates are rounded to the nearest integer.
public final QLineF map(QLineF l)
QLineF
object that is a copy of the given line, mapped into the coordinate system defined by this matrix.
public final QPainterPath map(QPainterPath p)
QPainterPath
object that is a copy of the given path, mapped into the coordinate system defined by this matrix.
public final QPoint map(QPoint p)
QPoint
object that is a copy of the given point, mapped into the coordinate system defined by this matrix. Note that the transformed coordinates are rounded to the nearest integer.
public final QPointF map(QPointF p)
QPointF
object that is a copy of the given point, mapped into the coordinate system defined by this matrix.
public final QPolygon map(QPolygon a)
QPolygon
object that is a copy of the given polygon, mapped into the coordinate system defined by this matrix. Note that the transformed coordinates are rounded to the nearest integer.
public final QPolygonF map(QPolygonF a)
QPolygonF
object that is a copy of the given polygon, mapped into the coordinate system defined by this matrix.
public final QRegion map(QRegion r)
QRegion
object that is a copy of the given region, mapped into the coordinate system defined by this matrix. Calling this method can be rather expensive if rotations or shearing are used.
public final QRect mapRect(QRect arg__1)
QRect
object that is a copy of the given rectangle, mapped into the coordinate system defined by this matrix. Note that the transformed coordinates are rounded to the nearest integer.
public final QRectF mapRect(QRectF arg__1)
QRectF
object that is a copy 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 + m21 + dx y' = m22 + m12 + dyIf rotation or shearing has been specified, this function returns the bounding rectangle. To retrieve the exact region the given rectangle maps to, use the
mapToPolygon()
function instead. mapToPolygon()
, and Basic Matrix Operations
.
public final QPolygon mapToPolygon(QRect r)
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 + m21 + dx y' = m22 + m12 + dyPolygons 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).
mapRect()
, and Basic Matrix Operations
.
public final void writeTo(QDataStream arg__1)
public final void readFrom(QDataStream arg__1)
public final void reset()
isIdentity()
, and Basic Matrix Operations
.
public final void setMatrix(double m11, double m12, double m21, double m22, double dx, double 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.
public static QMatrix fromNativePointer(QNativePointer nativePointer)
public static QNativePointer nativePointerArray(QMatrix[] array)
public final QMatrix rotate(double other)
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.
public final QMatrix scale(double sx, double sy)
public final QMatrix shear(double sh, double sv)
public final QMatrix translate(double dx, double dy)
public final QMatrix inverted()
java.lang.IllegalArgumentException
- If this matrix is not invertible.public final QMatrix multiply(QMatrix other)
public final QMatrix multiplied(QMatrix other)
public java.lang.String toString()
toString
in class java.lang.Object
public QMatrix clone()
clone
in class java.lang.Object
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |