qrect.cpp

奇趣公司比较新的qt/emd版本

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#include "qrect.h"
#include "qdatastream.h"
#include "qdebug.h"

#include <math.h>

/*!
    \class QRect
    \ingroup multimedia

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

    A rectangle is normally expressed as an upper-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 and a QSize.  The following code
    creates two identical rectangles.

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

    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() and right() functions deviate from
    the true bottom-right corner of the rectangle.

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

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

    The contains() function tells whether a given point is inside the
    rectangle or not, and the intersects() function returns 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:

    \table
    \row
    \o \inlineimage qrect-intersect.png
    \o \inlineimage qrect-unite.png
    \row
    \o intersected()
    \o united()
    \endtable

    The isEmpty() function returns true if left() > right() or top() >
    bottom(). Note that an empty rectangle is not valid: The isValid()
    function returns true if left() <= right() \e 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.

    \tableofcontents

    \section1 Rendering

    When using an \l {QPainter::Antialiasing}{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.

    \table
    \row
        \o \inlineimage qrect-diagram-zero.png
        \o \inlineimage qrect-diagram-one.png
    \row
        \o Logical representation
        \o One pixel wide pen
    \row
        \o \inlineimage qrect-diagram-two.png
        \o \inlineimage qrect-diagram-three.png
    \row
        \o Two pixel wide pen
        \o Three pixel wide pen
    \endtable

    \section1 Coordinates

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

    For example the left(), setLeft() and 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.

    \image qrect-coordinates.png

    Note that for historical reasons the values returned by the
    bottom() and right() functions deviate from the true bottom-right
    corner of the rectangle: The right() function returns \e { left()
    + width() - 1} and the bottom() function returns \e {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() and bottomLeft() functions,
    respectively, contain the same deviation from the true right and
    bottom edges.

    We recommend that you use x() + width() and y() + height() to find
    the true bottom-right corner, and avoid right() and
    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() and QRectF::bottom()
    functions \e 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.

    In addition, 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() and setRect()
    function to manipulate the rectangle's coordinates and dimensions
    in one go.

    \sa QRectF, QRegion
*/

/*****************************************************************************
  QRect member functions
 *****************************************************************************/

/*!
    \fn QRect::QRect()

    Constructs a null rectangle.

    \sa isNull()
*/

/*!
    \fn QRect::QRect(const QPoint &topLeft, const QPoint &bottomRight)

    Constructs a rectangle with the given \a topLeft and \a bottomRight corners.

    \sa setTopLeft(), setBottomRight()
*/


/*!
    \fn QRect::QRect(const QPoint &topLeft, const QSize &size)

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

    \sa setTopLeft(), setSize()
*/


/*!
    \fn QRect::QRect(int x, int y, int width, int height)

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

    \sa setRect()
*/


/*!
    \fn bool QRect::isNull() const

    Returns 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.

    \sa isEmpty(), isValid()
*/

/*!
    \fn bool QRect::isEmpty() const

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

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

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

    \sa isNull(), isValid(), normalized()
*/

/*!
    \fn bool QRect::isValid() const

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

    A valid rectangle has a left() < right() and 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()).

    \sa isNull(), isEmpty(), normalized()
*/


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

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

    \sa isValid(), isEmpty()
*/

QRect QRect::normalized() const
{
    if (isNull() || width() == 0 || height() == 0)
        return *this;
    QRect r;
    if (x2 < x1) {                                // swap bad x values
        r.x1 = x2;
        r.x2 = x1;
    } else {
        r.x1 = x1;
        r.x2 = x2;
    }
    if (y2 < y1) {                                // swap bad y values
        r.y1 = y2;
        r.y2 = y1;
    } else {
        r.y1 = y1;
        r.y2 = y2;
    }
    return r;
}


/*!
    \fn QRect QRect::normalize() const
    \compat

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

    Use the normalized() function instead
*/

/*!
    \fn int QRect::left() const

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

    \sa setLeft(),  topLeft(), bottomLeft()
*/

/*!
    \fn int QRect::top() const

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

    \sa setTop(), topLeft(), topRight()
*/

/*!
    \fn int QRect::right() const

    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.

    \sa setRight(), topRight(), bottomRight()
*/

/*!
    \fn 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.

    \sa setBottom(), bottomLeft(), bottomRight()
*/

/*!
    \fn int &QRect::rLeft()
    \compat

    Returns a reference to the left coordinate of the rectangle.

    Use the left() function instead.
*/

/*!
    \fn int &QRect::rTop()
    \compat

    Returns a reference to the top coordinate of the rectangle.

    Use the top() function instead.
*/

/*!
    \fn int &QRect::rRight()
    \compat

    Returns a reference to the right coordinate of the rectangle.

    Use the right() function instead.
*/

/*!
    \fn int &QRect::rBottom()
    \compat

    Returns a reference to the bottom coordinate of the rectangle.

    Use the bottom() function instead.
*/

/*!
    \fn int QRect::x() const

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

    \sa setX(), y(), topLeft()
*/

/*!
    \fn int QRect::y() const

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

    \sa setY(), x(), topLeft()
*/

/*!
    \fn void QRect::setLeft(int x)

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

    Equivalent to setX().

    \sa left(), moveLeft()
*/

/*!
    \fn void QRect::setTop(int y)

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

    Equivalent to setY().

    \sa top(), moveTop()
*/

/*!
    \fn void QRect::setRight(int x)

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

    \sa right(), moveRight()
*/

/*!
    \fn void QRect::setBottom(int y)

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

    \sa bottom(), moveBottom(),
*/

/*!
    \fn void QRect::setX(int x)

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

    Equivalent to setLeft().

    \sa x(), setY(), setTopLeft()
*/

/*!
    \fn void QRect::setY(int y)

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

    Equivalent to setTop().

    \sa y(), setX(), setTopLeft()
*/

/*!
    \fn void QRect::setTopLeft(const QPoint &position)

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

    \sa topLeft(), moveTopLeft()
*/

/*!
    \fn void QRect::setBottomRight(const QPoint &position)

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

    \sa bottomRight(), moveBottomRight()
*/

/*!
    \fn void QRect::setTopRight(const QPoint &position)

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

    \sa topRight(), moveTopRight()
*/

/*!
    \fn void QRect::setBottomLeft(const QPoint &position)

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

    \sa bottomLeft(), moveBottomLeft()
*/

/*!
    \fn QPoint QRect::topLeft() const

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

    \sa setTopLeft(), top(), left()
*/

/*!
    \fn QPoint QRect::bottomRight() const

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

    Note that for historical reasons this function returns