0019：Qt常用类 - QRect
1 开发环境
在介绍内容之前，先说明一下开发环境，如下图：
Qt版本：Qt5.3.2；
Qt开发工具：Qt Creater 3.2.1；
Qt构建工具：Desktop Qt 5.3 MinGW 32bit；
Qt开发平台：Windows 7 64bit。
2 QRect
QRect类代表一个矩形区域，实现在QtCore库，是一个QPoint对象和一个QSize对象的组合，QPoint对象是它的左上角的坐标，QSize对象则是它的大小。首先，将QRect中的常用接口整理出来，分为初始化、获取属性、设置属性、移动、计算、友元函数（操作符重载）共6类，这样方便学习和理解。
//
//初始化
//
QRect();
QRect(const QPoint &topLeft, const QPoint &bottomRight);
QRect(const QPoint &topLeft, const QSize &size);
QRect(int x, int y, int width, int height);
bool isEmpty() const; //w < 0 or h < 0
bool isNull() const; //w = 0 and h = 0
bool isValid() const; //w > 0 and h > 0
QRect normalized() const; //调换left和right,或调换top和bottom,使Valid
//
//获取属性
//
int left() const;
int right() const;
int top() const;
int bottom() const;
QPoint topLeft() const;
QPoint topRight() const;
QPoint bottomLeft() const;
QPoint bottomRight() const;
QPoint center() const;
int x() const;
int y() const;
int width() const;
int height() const;
QSize size() const;
void getCoords(int *x1, int *y1, int *x2, int *y2) const;
void getRect(int *x, int *y, int *width, int *height) const;
//
//设置属性
//
void setLeft(int x);
void setRight(int x);
void setTop(int y);
void setBottom(int y);
void setCoords(int x1, int y1, int x2, int y2);
void setTopLeft(const QPoint &position);
void setTopRight(const QPoint &position);
void setBottomLeft(const QPoint &position);
void setBottomRight(const QPoint &position);
void setX(int x);
void setY(int y);
void setWidth(int width);
void setHeight(int height);
void setSize(const QSize &size);
void setRect(int x, int y, int width, int height);
//
//移动
//
void moveLeft(int x); //左边 移动到x
void moveRight(int x); //右边 移动到x
void moveTop(int y); //上边 移动到y
void moveBottom(int y); //下边 移动到y
void moveTopLeft(const QPoint &position); //左上角 移动到position
void moveTopRight(const QPoint &position); //右上角 移动到position
void moveBottomLeft(const QPoint &position); //左下角 移动到position
void moveBottomRight(const QPoint &position); //右下角 移动到position
void moveCenter(const QPoint &position); //中心点 移动到position
void moveTo(int x, int y); //左上角 移动到(x, y)
void moveTo(const QPoint &position); //左上角 移动到(x, y)
void translate(int dx, int dy); //Rect 偏移量(dx, dy), 改变自身
void translate(const QPoint &offset); //Rect 偏移量(offset.x(), offset.y()), 改变自身
QRect translated(int dx, int dy) const; //Rect 偏移量(dx, dy), 不改变自身
QRect translated(const QPoint &offset) const; //Rect 偏移量(offset.x(), offset.y()), 不改变自身
//
//计算
//
void adjust(int dx1, int dy1, int dx2, int dy2); //调整Rect, 参数分别对应l/t/r/b的偏移量, 改变自身
QRect adjusted(int dx1, int dy1, int dx2, int dy2) const;//调整Rect, 参数分别对应l/t/r/b的偏移量, 不改变自身
QRect marginsAdded(const QMargins &margins) const; //扩展Rect, 不改变自身
QRect marginsRemoved(const QMargins &margins) const; //收缩Rect, 不改变自身
QRect & operator+=(const QMargins &margins); //同marginsAdded
QRect & operator-=(const QMargins &margins); //同marginsReomved
bool contains(int x, int y, bool proper) const; //proper: true - 不包含边界, false - 包含边界
bool contains(const QPoint &rectangle, bool proper = false) const;//proper: 同上
bool contains(int x, int y) const; //proper is true
bool contains(const QRect &rectangle, bool proper = false) const;
//
//友元函数：操作符重载
//
bool operator!=(const QRect &r1, const QRect &r2);
bool operator==(const QRect &r1, const QRect &r2);
QRect operator+(const QMargins &margins, const QRect &rectangle);//同marginsAdded
QRect operator+(const QRect &rectangle, const QMargins &margins);//同marginsAdded
QRect operator-(const QRect &lhs, const QMargins &rhs);//同marginsRemoved
下面，是上述接口的使用例程。
//
//初始化
//
//QRect();
//QRect(const QPoint &topLeft, const QPoint &bottomRight);
//QRect(const QPoint &topLeft, const QSize &size);
//QRect(int x, int y, int width, int height);
//bool isEmpty() const; //w <= 0 or h <= 0
//bool isNull() const; //w = 0 and h = 0
//bool isValid() const; //w > 0 and h > 0
/*
* null rect is: l = 0, r = -1, t = 0, b = -1, w = 0, h = 0.
* 判断Rect是否可用:
* if (rect.isValid())
* {
* //w > 0 and h > 0, 所以rect是可用的...
* }
*/
QRect rcNull;
qDebug("rcNull: l = %d, r = %d, t = %d, b = %d, w = %d, h = %d.",
rcNull.left(), rcNull.right(), rcNull.top(), rcNull.bottom(), rcNull.width(), rcNull.height());
qDebug("rcNull is null? %s.", rcNull.isNull() ? "yes" : "no");
qDebug("rcNull is empty? %s.", rcNull.isEmpty() ? "yes" : "no");
QRect rcEmpty1(0, 0, 0, 10), rcEmpty2(0, 0, -1, 10);
qDebug("rcEmpty1 is empty? %s.", rcEmpty1.isEmpty() ? "yes" : "no");
qDebug("rcEmpty2 is empty? %s.", rcEmpty2.isEmpty() ? "yes" : "no");
//
//获取属性
//
//int left() const;
//int right() const;
//int top() const;
//int bottom() const;
//QPoint topLeft() const;
//QPoint topRight() const;
//QPoint bottomLeft() const;
//QPoint bottomRight() const;
//QPoint center() const;
//int x() const;
//int y() const;
//int width() const;
//int height() const;
//QSize size() const;
//void getCoords(int *x1, int *y1, int *x2, int *y2) const;
//void getRect(int *x, int *y, int *width, int *height) const;
qDebug("QRect的获取属性类的接口，很好理解...");
//
//设置属性
//
//void setLeft(int x);
//void setRight(int x);
//void setTop(int y);
//void setBottom(int y);
//void setCoords(int x1, int y1, int x2, int y2);
//void setTopLeft(const QPoint &position);
//void setTopRight(const QPoint &position);
//void setBottomLeft(const QPoint &position);
//void setBottomRight(const QPoint &position);
//void setX(int x);
//void setY(int y);
//void setWidth(int width);
//void setHeight(int height);
//void setSize(const QSize &size);
//void setRect(int x, int y, int width, int height);
qDebug("QRect的设置属性类的接口，很好理解...");
//
//移动
//
//void moveLeft(int x);
//void moveRight(int x);
//void moveTop(int y);
//void moveBottom(int y);
//void moveTopLeft(const QPoint &position);
//void moveTopRight(const QPoint &position);
//void moveBottomLeft(const QPoint &position);
//void moveBottomRight(const QPoint &position);
//void moveCenter(const QPoint &position);
//void moveTo(int x, int y);
//void moveTo(const QPoint &position);
//void translate(int dx, int dy);
//void translate(const QPoint &offset);
//QRect translated(int dx, int dy) const;
//QRect translated(const QPoint &offset) const;
QRect rcMv(QPoint(0, 0), QPoint(10, 10));
qDebug("rcMv: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d, c = (%04d, %04d).",
rcMv.left(), rcMv.right(), rcMv.top(), rcMv.bottom(), rcMv.width(), rcMv.height(),
rcMv.center().x(), rcMv.center().y());
QRect rcML = rcMv;
rcML.moveLeft(-10);
qDebug("rcML: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcML.left(), rcML.right(), rcML.top(), rcML.bottom(), rcML.width(), rcML.height());
QRect rcMR = rcMv;
rcMR.moveRight(20);
qDebug("rcMR: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcMR.left(), rcMR.right(), rcMR.top(), rcMR.bottom(), rcMR.width(), rcMR.height());
QRect rcMT = rcMv;
rcMT.moveTop(-10);
qDebug("rcMT: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcMT.left(), rcMT.right(), rcMT.top(), rcMT.bottom(), rcMT.width(), rcMT.height());
QRect rcMB = rcMv;
rcMB.moveBottom(20);
qDebug("rcMB: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcMB.left(), rcMB.right(), rcMB.top(), rcMB.bottom(), rcMB.width(), rcMB.height());
QRect rcTL = rcMv;
rcTL.moveTopLeft(QPoint(-10, -10));
qDebug("rcTL: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcTL.left(), rcTL.right(), rcTL.top(), rcTL.bottom(), rcTL.width(), rcTL.height());
QRect rcTR = rcMv;
rcTR.moveTopRight(QPoint(20, -10));
qDebug("rcTR: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcTR.left(), rcTR.right(), rcTR.top(), rcTR.bottom(), rcTR.width(), rcTR.height());
QRect rcBL = rcMv;
rcBL.moveBottomLeft(QPoint(-10, 20));
qDebug("rcBL: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcBL.left(), rcBL.right(), rcBL.top(), rcBL.bottom(), rcBL.width(), rcBL.height());
QRect rcBR = rcMv;
rcBR.moveBottomRight(QPoint(20, 20));
qDebug("rcBR: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcBR.left(), rcBR.right(), rcBR.top(), rcBR.bottom(), rcBR.width(), rcBR.height());
QRect rcMc = rcMv;
rcMc.moveCenter(QPoint(10, 10));
qDebug("rcMc: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d, c = (%04d, %04d).",
rcMc.left(), rcMc.right(), rcMc.top(), rcMc.bottom(), rcMc.width(), rcMc.height(),
rcMc.center().x(), rcMc.center().y());
QRect rcTo = rcMv;
rcTo.moveTo(QPoint(-10, -10));
qDebug("rcTo: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcTo.left(), rcTo.right(), rcTo.top(), rcTo.bottom(), rcTo.width(), rcTo.height());
QRect rcTr = rcMv;
rcTr.translate(QPoint(-10, -10));
qDebug("rcTr: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcTr.left(), rcTr.right(), rcTr.top(), rcTr.bottom(), rcTr.width(), rcTr.height());
//
//计算
//
//void adjust(int dx1, int dy1, int dx2, int dy2);
//QRect adjusted(int dx1, int dy1, int dx2, int dy2) const;
//QRect marginsAdded(const QMargins &margins) const;
//QRect marginsRemoved(const QMargins &margins) const;
//QRect & operator+=(const QMargins &margins);
//QRect & operator-=(const QMargins &margins);
//bool contains(int x, int y, bool proper) const;
//bool contains(const QPoint &rectangle, bool proper = false) const;
//bool contains(int x, int y) const;
//bool contains(const QRect &rectangle, bool proper = false) const;
QRect rcCacu(0, 0, 11, 11);
qDebug("rcCacu: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcCacu.left(), rcCacu.right(), rcCacu.top(), rcCacu.bottom(), rcCacu.width(), rcCacu.height());
QRect rcAjst = rcCacu;
rcAjst.adjust(-10, -10, 10, 10);
qDebug("rcAjst: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcAjst.left(), rcAjst.right(), rcAjst.top(), rcAjst.bottom(), rcAjst.width(), rcAjst.height());
QRect rcMAdd = rcCacu.marginsAdded(QMargins(2, 2, 2, 2));
qDebug("rcMAdd: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcMAdd.left(), rcMAdd.right(), rcMAdd.top(), rcMAdd.bottom(), rcMAdd.width(), rcMAdd.height());
QRect rcMRmv = rcCacu.marginsRemoved(QMargins(2, 2, 2, 2));
qDebug("rcMRmv: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcMRmv.left(), rcMRmv.right(), rcMRmv.top(), rcMRmv.bottom(), rcMRmv.width(), rcMRmv.height());
QRect rcOAdd = rcCacu;
rcOAdd += QMargins(2, 2, 2, 2);
qDebug("rcOAdd: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcOAdd.left(), rcOAdd.right(), rcOAdd.top(), rcOAdd.bottom(), rcOAdd.width(), rcOAdd.height());
QRect rcOMns = rcCacu;
rcOMns -= QMargins(2, 2, 2, 2);
qDebug("rcOMns: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcOMns.left(), rcOMns.right(), rcOMns.top(), rcOMns.bottom(), rcOMns.width(), rcOMns.height());
QPoint ptCenter = rcCacu.center();
qDebug("ptCenter of rcCacu is in rcCacu? %s.", rcCacu.contains(ptCenter, false) ? "yes" : "no");
QPoint ptTL = rcCacu.topLeft();
qDebug("ptTL of rcCacu is in rcCacu(include border)? %s.", rcCacu.contains(ptTL, false) ? "yes" : "no");
QRect rcSame = rcCacu;
qDebug("rcSame of rcCacu is in rcCacu(include border)? %s.", rcCacu.contains(rcSame, false) ? "yes" : "no");
//
//友元函数：操作符重载
//
//bool operator!=(const QRect &r1, const QRect &r2);
//bool operator==(const QRect &r1, const QRect &r2);
//QRect operator+(const QMargins &margins, const QRect &rectangle);
//QRect operator+(const QRect &rectangle, const QMargins &margins);
//QRect operator-(const QRect &lhs, const QMargins &rhs);
QRect rcFriend(QPoint(0, 0), QPoint(10, 10));
QRect rcCompare = rcFriend;
qDebug("rcCompare == rcFriend? %s.", rcCompare == rcFriend ? "yes" : "no");
qDebug("rcCompare != rcFriend? %s.", rcCompare != rcFriend ? "yes" : "no");
QRect rcOA = rcFriend + QMargins(2, 2, 2, 2);
qDebug("rcOA: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcOA.left(), rcOA.right(), rcOA.top(), rcOA.bottom(), rcOA.width(), rcOA.height());
QRect rcOM = rcFriend - QMargins(2, 2, 2, 2);
qDebug("rcOM: l = %04d, r = %04d, t = %04d, b = %04d, w = %04d, h = %04d.",
rcOM.left(), rcOM.right(), rcOM.top(), rcOM.bottom(), rcOM.width(), rcOM.height());
在学习过程中，可以将上述代码放到一个按钮的响应函数中，以调试方式运行，就可以在Qt Creater中的应用程序输出窗口看到输出结果了。