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C++ 如何使用复选框更改QGraphicsView背景

c++ qt

C++ 如何使用复选框更改QGraphicsView背景,c++,qt,background,qt5,qgraphicsview,C++,Qt,Background,Qt5,Qgraphicsview,在这段代码中，它改变了QGraphicsView背景。现在，当我选中true复选框时，我需要改变背景。当我设置为checkBox以选中true时，我需要像这样设置背景。当我设置checkBox以选中false时。我需要将QGraphicsView设置为正常默认方式。我怎样才能做到这一点 这是我的密码： main window.cpp #include "mainwindow.h" #include <QGraphicsTextItem> MainWindow::MainWindow

在这段代码中，它改变了
QGraphicsView
背景。现在，当我选中true
复选框时，我需要改变背景。当我设置为
checkBox
以选中
true
时，我需要像这样设置背景。当我设置
checkBox
以选中
false
时。我需要将
QGraphicsView
设置为正常默认方式。我怎样才能做到这一点

这是我的密码：

main window.cpp


#include "mainwindow.h"
#include <QGraphicsTextItem>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    scene = new Scene(this);
    scene->setSceneRect(10,10,260,200);
    view = new QGraphicsView(scene);
    setCentralWidget(view);
}



#include "scene.h"

Scene::Scene(QObject *parent) : QGraphicsScene(parent), gridSize(20)
{
    Q_ASSERT(gridSize > 0);
}

void Scene::drawBackground(QPainter *painter, const QRectF &rect)
{
        QColor c (10,140,255,155);
        painter->setPen(c);
        qreal left = int(rect.left()) - (int(rect.left()) % gridSize);
        qreal top = int(rect.top()) - (int(rect.top()) % gridSize);
        QVarLengthArray<QLineF,100> lines;
        for (qreal x = left; x < rect.right(); x += gridSize)
            lines.append(QLineF(x,rect.top(),x,rect.bottom()));

        for (qreal y = top; y < rect.bottom(); y += gridSize)
            lines.append(QLineF(rect.left(),y,rect.right(),y));
        painter->drawLines(lines.data(),lines.size());
}



#包括“mainwindow.h”
#包括
主窗口：：主窗口（QWidget*父窗口）：
QMainWindow（父窗口）
{
场景=新场景（此）；
场景->设置场景（10,10260200）；
视图=新的QGraphicsView（场景）；
setCentralWidget（视图）；
}


main window.h


#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsView>
#include "scene.h"
#include "customrectitem.h"

class MainWindow : public QMainWindow
{
public:
    explicit MainWindow(QWidget *parent = 0);
private:
    QGraphicsView* view;
    QGraphicsScene* scene;
};

#endif // MAINWINDOW_H



#ifndef SCENE_H
#define SCENE_H

#include <QGraphicsScene>
#include <QPainter>
#include <QApplication>

class Scene : public QGraphicsScene
{
    Q_OBJECT
public:
    explicit Scene(QObject *parent = 0);
    int getGridSize() const {return this->gridSize;}

protected:
    void drawBackground (QPainter* painter, const QRectF &rect);
private:
    int gridSize;

};

#endif // SCENE_H



\ifndef主窗口
#定义主窗口
#包括
#包括
#包括“scene.h”
#包括“customrectitem.h”
类主窗口：公共QMainWindow
{
公众：
显式主窗口（QWidget*parent=0）；
私人：
QGraphicsView*视图；
qgraphicscene*场景；
};
#endif//main窗口


场景.h


#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsView>
#include "scene.h"
#include "customrectitem.h"

class MainWindow : public QMainWindow
{
public:
    explicit MainWindow(QWidget *parent = 0);
private:
    QGraphicsView* view;
    QGraphicsScene* scene;
};

#endif // MAINWINDOW_H



#ifndef SCENE_H
#define SCENE_H

#include <QGraphicsScene>
#include <QPainter>
#include <QApplication>

class Scene : public QGraphicsScene
{
    Q_OBJECT
public:
    explicit Scene(QObject *parent = 0);
    int getGridSize() const {return this->gridSize;}

protected:
    void drawBackground (QPainter* painter, const QRectF &rect);
private:
    int gridSize;

};

#endif // SCENE_H



#如果场景不可用#
#定义场景
#包括
#包括
#包括
课堂场景：公共Qgraphicscene
{
Q_对象
公众：
显式场景（QObject*parent=0）；
int getGridSize（）常量{返回此->gridSize；}
受保护的：
无效牵引地面（油漆工*油漆工、施工工和维修工）；
私人：
整数网格大小；
};
#endif//SCENE_H


场景.cpp


#include "mainwindow.h"
#include <QGraphicsTextItem>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    scene = new Scene(this);
    scene->setSceneRect(10,10,260,200);
    view = new QGraphicsView(scene);
    setCentralWidget(view);
}



#include "scene.h"

Scene::Scene(QObject *parent) : QGraphicsScene(parent), gridSize(20)
{
    Q_ASSERT(gridSize > 0);
}

void Scene::drawBackground(QPainter *painter, const QRectF &rect)
{
        QColor c (10,140,255,155);
        painter->setPen(c);
        qreal left = int(rect.left()) - (int(rect.left()) % gridSize);
        qreal top = int(rect.top()) - (int(rect.top()) % gridSize);
        QVarLengthArray<QLineF,100> lines;
        for (qreal x = left; x < rect.right(); x += gridSize)
            lines.append(QLineF(x,rect.top(),x,rect.bottom()));

        for (qreal y = top; y < rect.bottom(); y += gridSize)
            lines.append(QLineF(rect.left(),y,rect.right(),y));
        painter->drawLines(lines.data(),lines.size());
}



#包括“scene.h”
场景：：场景（QObject*父对象）：QGraphicscene（父对象），gridSize（20）
{
Q_断言（gridSize>0）；
}
无效场景：：牵引地面（油漆工*油漆工、施工工和rect）
{
QColor c（1014025555）；
画师->设置笔（c）；
qreal left=int（rect.left（））-（int（rect.left（））%gridSize）；
qreal top=int（rect.top（））-（int（rect.top（））%gridSize）；
QVarLengthArray线；
对于（qreal x=left；x绘图线（lines.data（），lines.size（））；
}

我想到了两个绘制网格的机会：


  • 从
    QGraphicsView
    派生类，重载
    paintEvent（）
    并绘制网格，然后返回到
    QGraphicsView:：paintEvent（）
    • 

  • 在允许控制可见性的
    QGraphicsItemGroup
    下添加网格线作为场景项
    • 
第一种方法的优点是它可以无缝地适应视口的任何大小调整
    
这是我的示例代码testQGraphicsView BgGrid.cc
    ：

    #include <QtWidgets>

class Canvas: public QGraphicsView {
  private:
    int _gridSize;
    QColor _gridColor;
    bool _gridVisible;

  public:
    explicit Canvas(QWidget *pQParent = nullptr):
      QGraphicsView(pQParent),
      _gridSize(20), _gridColor(0x0a8affu), _gridVisible(true)
    { }

    bool gridVisible() const { return _gridVisible; }
    void setGridVisible(bool gridVisible)
    {
      _gridVisible = gridVisible;
      viewport()->update();
    }

  protected:
    virtual void paintEvent(QPaintEvent *pQEvent) override
    {
      QPainter qPainter(viewport());
      if (_gridVisible) {
        const int wView = viewport()->width(), hView = viewport()->height();
        qPainter.setPen(_gridColor);
        for (int x = _gridSize / 2; x < wView; x += _gridSize) {
          qPainter.drawLine(x, 0, x, hView - 1);
        }
        for (int y = _gridSize / 2; y < hView; y += _gridSize) {
          qPainter.drawLine(0, y, wView - 1, y);
        }
      }
      QGraphicsView::paintEvent(pQEvent);
    }
};

void makeGrid(
  QGraphicsItemGroup &qItemGrp, const QSize &size,
  int gridSize = 20, const QColor &gridColor = 0x0a8affu)
{
  const int wView = size.width(), hView = size.height();
  for (int x = gridSize / 2; x < wView; x += gridSize) {
    QGraphicsLineItem *pQItem = new QGraphicsLineItem(x, 0, x, hView - 1);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
  for (int y = gridSize / 2; y < hView; y += gridSize) {
    QGraphicsLineItem *pQItem = new QGraphicsLineItem(0, y, wView - 1, y);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
}

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  // setup GUI
  QWidget qWnd;
  QGridLayout qGrid;
  QLabel qLblL(QString::fromUtf8("Grid as part of scene"));
  qGrid.addWidget(&qLblL, 0, 0);
  QCheckBox qTglGridL(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridL, 0, 1);
  QGraphicsView qGraphView;
  qGrid.addWidget(&qGraphView, 1, 0, 1, 2);
  QLabel qLblR(QString::fromUtf8("Grid painted as background"));
  qGrid.addWidget(&qLblR, 0, 2);
  QCheckBox qTglGridR(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridR, 0, 3);
  Canvas canvas;
  qGrid.addWidget(&canvas, 1, 2, 1, 2);
  qWnd.setLayout(&qGrid);
  qWnd.show();
  // init GUI
  QGraphicsScene qGraphSceneL;
  QGraphicsItemGroup qItemGrid;
  makeGrid(qItemGrid, qGraphView.viewport()->size());
  qGraphSceneL.addItem(&qItemGrid);
  qGraphView.setScene(&qGraphSceneL);
  qTglGridL.setCheckState(
    qItemGrid.isVisible() ? Qt::Checked : Qt::Unchecked);
  qTglGridR.setCheckState(
    canvas.gridVisible() ? Qt::Checked : Qt::Unchecked);
  // install signal handlers
  QObject::connect(&qTglGridL, &QCheckBox::stateChanged,
    [&qItemGrid](int state)
    {
      qItemGrid.setVisible(state != Qt::Unchecked);
    });
  QObject::connect(&qTglGridR, &QCheckBox::stateChanged,
    [&canvas](int state)
    {
      canvas.setGridVisible(state != Qt::Unchecked);
    });
  // runtime loop
  return app.exec();
}

    #include <QtWidgets>

class Canvas: public QGraphicsView {
  private:
    int _gridSize;
    QColor _gridColor;
    bool _gridVisible;

  public:
    explicit Canvas(QWidget *pQParent = nullptr):
      QGraphicsView(pQParent),
      _gridSize(20), _gridColor(0x0a8affu), _gridVisible(true)
    { }

    bool gridVisible() const { return _gridVisible; }
    void setGridVisible(bool gridVisible)
    {
      _gridVisible = gridVisible;
      viewport()->update();
    }

  protected:
    virtual void paintEvent(QPaintEvent *pQEvent) override
    {
      QPainter qPainter(viewport());
      if (_gridVisible) {
        const int wView = viewport()->width(), hView = viewport()->height();
        const QPointF offs = mapToScene(0, 0);
        qPainter.setPen(_gridColor);
        for (int x = (int)offs.x() % _gridSize; x < wView; x += _gridSize) {
          qPainter.drawLine(x, 0, x, hView - 1);
        }
        for (int y = (int)offs.y() % _gridSize; y < hView; y += _gridSize) {
          qPainter.drawLine(0, y, wView - 1, y);
        }
      }
      QGraphicsView::paintEvent(pQEvent);
    }
};

void makeGrid(
  QGraphicsItemGroup &qItemGrp, const QRect &rect,
  int gridSize = 20, const QColor &gridColor = 0x0a8affu)
{
  for (int x = rect.x(), xE = x + rect.width(); x < xE; x += gridSize) {
    QGraphicsLineItem *pQItem
      = new QGraphicsLineItem(x, rect.y(), x, rect.height() - 1);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
  for (int y = rect.y(), yE = y + rect.height(); y < yE; y += gridSize) {
    QGraphicsLineItem *pQItem
      = new QGraphicsLineItem(rect.x(), y, rect.width() - 1, y);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
}

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  // setup GUI
  QWidget qWnd;
  QGridLayout qGrid;
  QLabel qLblL(QString::fromUtf8("Grid as part of scene"));
  qGrid.addWidget(&qLblL, 0, 0);
  QCheckBox qTglGridL(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridL, 0, 1);
  QGraphicsView qGraphView;
  qGrid.addWidget(&qGraphView, 1, 0, 1, 2);
  QLabel qLblR(QString::fromUtf8("Grid painted as background"));
  qGrid.addWidget(&qLblR, 0, 2);
  QCheckBox qTglGridR(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridR, 0, 3);
  Canvas canvas;
  qGrid.addWidget(&canvas, 1, 2, 1, 2);
  qWnd.setLayout(&qGrid);
  qWnd.show();
  // init GUI
  QGraphicsScene qGraphSceneL;
  QGraphicsItemGroup qItemGrid;
  makeGrid(qItemGrid, QRect(0, 0, 320, 240));
  qGraphSceneL.addItem(&qItemGrid);
  qGraphView.setScene(&qGraphSceneL);
  qTglGridL.setCheckState(
    qItemGrid.isVisible() ? Qt::Checked : Qt::Unchecked);
  qTglGridR.setCheckState(
    canvas.gridVisible() ? Qt::Checked : Qt::Unchecked);
  // install signal handlers
  QObject::connect(&qTglGridL, &QCheckBox::stateChanged,
    [&qItemGrid](int state)
    {
      qItemGrid.setVisible(state != Qt::Unchecked);
    });
  QObject::connect(&qTglGridR, &QCheckBox::stateChanged,
    [&canvas](int state)
    {
      canvas.setGridVisible(state != Qt::Unchecked);
    });
  // runtime loop
  return app.exec();
}
    在cygwin上的
    bash
    中构建和测试：

    $qmake-qt5 testQGraphicsView-BgGrid.pro
$make
g++-c-fno保持内联dllexport-D_GNU_SOURCE-pipe-O2-Wall-W-D_REENTRANT-DQT_NO_DEBUG-DQT_WIDGETS-LIB-DQT_GUI_LIB-DQT_CORE_LIB-I.-isystem/usr/include/qt5-isystem/usr/include/qt5/QtWidgets-isystem/usr/include/QtGui/QtGui-isystem/usr/include/QtGui-isystem/usr/QtCore/QtCore-I.-I/usr/qt5/qts/cygwtestQGraphicsView-BgGrid.cc
g++-o testQGraphicsView-BgGrid.exe testQGraphicsView-BgGrid.o-lQt5Widgets-lQt5Gui-lQt5Core-lGL-lpthread
$./testQGraphicsView BgGrid
    与X11应用程序相同的程序：

    另一个更新：

    我必须承认，在我的第一个版本中，我着重于如何使用复选框更改QGraphicsView背景，重点是复选框忽略（我不知道）和忽略网格渲染本身的问题（我使用了它）。正如中所指出的，这两种解决方案都存在一些弱点（至少）我应该记录下来

  • 左视图（将栅格包含到场景中）不一定会填充
    视口（）
    。IMHO，如果网格填充场景使用的相关范围，这是可以接受的。（这可能是为了将场景可视化为仅覆盖
    视口（）
    的一部分）但是，
    makeGrid（）
    的参数
    const QSize&size
    与此意图有关，是一个不幸的选择。我修复了这个设计问题，用
    constqrect&rect
    替换它

    • ＞P>右视图（重载<代码> PANTEVION（）/代码>）没有考虑场景的可能滚动。通过将左上角映射到场景坐标（<代码> const qPototfOffs= MpToSCONEN（0, 0）；），并将偏移作为循环起始值考虑。 更新示例代码
    TestQGraphicsView BgGrid.cc
    ：

    #include <QtWidgets>

class Canvas: public QGraphicsView {
  private:
    int _gridSize;
    QColor _gridColor;
    bool _gridVisible;

  public:
    explicit Canvas(QWidget *pQParent = nullptr):
      QGraphicsView(pQParent),
      _gridSize(20), _gridColor(0x0a8affu), _gridVisible(true)
    { }

    bool gridVisible() const { return _gridVisible; }
    void setGridVisible(bool gridVisible)
    {
      _gridVisible = gridVisible;
      viewport()->update();
    }

  protected:
    virtual void paintEvent(QPaintEvent *pQEvent) override
    {
      QPainter qPainter(viewport());
      if (_gridVisible) {
        const int wView = viewport()->width(), hView = viewport()->height();
        qPainter.setPen(_gridColor);
        for (int x = _gridSize / 2; x < wView; x += _gridSize) {
          qPainter.drawLine(x, 0, x, hView - 1);
        }
        for (int y = _gridSize / 2; y < hView; y += _gridSize) {
          qPainter.drawLine(0, y, wView - 1, y);
        }
      }
      QGraphicsView::paintEvent(pQEvent);
    }
};

void makeGrid(
  QGraphicsItemGroup &qItemGrp, const QSize &size,
  int gridSize = 20, const QColor &gridColor = 0x0a8affu)
{
  const int wView = size.width(), hView = size.height();
  for (int x = gridSize / 2; x < wView; x += gridSize) {
    QGraphicsLineItem *pQItem = new QGraphicsLineItem(x, 0, x, hView - 1);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
  for (int y = gridSize / 2; y < hView; y += gridSize) {
    QGraphicsLineItem *pQItem = new QGraphicsLineItem(0, y, wView - 1, y);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
}

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  // setup GUI
  QWidget qWnd;
  QGridLayout qGrid;
  QLabel qLblL(QString::fromUtf8("Grid as part of scene"));
  qGrid.addWidget(&qLblL, 0, 0);
  QCheckBox qTglGridL(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridL, 0, 1);
  QGraphicsView qGraphView;
  qGrid.addWidget(&qGraphView, 1, 0, 1, 2);
  QLabel qLblR(QString::fromUtf8("Grid painted as background"));
  qGrid.addWidget(&qLblR, 0, 2);
  QCheckBox qTglGridR(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridR, 0, 3);
  Canvas canvas;
  qGrid.addWidget(&canvas, 1, 2, 1, 2);
  qWnd.setLayout(&qGrid);
  qWnd.show();
  // init GUI
  QGraphicsScene qGraphSceneL;
  QGraphicsItemGroup qItemGrid;
  makeGrid(qItemGrid, qGraphView.viewport()->size());
  qGraphSceneL.addItem(&qItemGrid);
  qGraphView.setScene(&qGraphSceneL);
  qTglGridL.setCheckState(
    qItemGrid.isVisible() ? Qt::Checked : Qt::Unchecked);
  qTglGridR.setCheckState(
    canvas.gridVisible() ? Qt::Checked : Qt::Unchecked);
  // install signal handlers
  QObject::connect(&qTglGridL, &QCheckBox::stateChanged,
    [&qItemGrid](int state)
    {
      qItemGrid.setVisible(state != Qt::Unchecked);
    });
  QObject::connect(&qTglGridR, &QCheckBox::stateChanged,
    [&canvas](int state)
    {
      canvas.setGridVisible(state != Qt::Unchecked);
    });
  // runtime loop
  return app.exec();
}

    #include <QtWidgets>

class Canvas: public QGraphicsView {
  private:
    int _gridSize;
    QColor _gridColor;
    bool _gridVisible;

  public:
    explicit Canvas(QWidget *pQParent = nullptr):
      QGraphicsView(pQParent),
      _gridSize(20), _gridColor(0x0a8affu), _gridVisible(true)
    { }

    bool gridVisible() const { return _gridVisible; }
    void setGridVisible(bool gridVisible)
    {
      _gridVisible = gridVisible;
      viewport()->update();
    }

  protected:
    virtual void paintEvent(QPaintEvent *pQEvent) override
    {
      QPainter qPainter(viewport());
      if (_gridVisible) {
        const int wView = viewport()->width(), hView = viewport()->height();
        const QPointF offs = mapToScene(0, 0);
        qPainter.setPen(_gridColor);
        for (int x = (int)offs.x() % _gridSize; x < wView; x += _gridSize) {
          qPainter.drawLine(x, 0, x, hView - 1);
        }
        for (int y = (int)offs.y() % _gridSize; y < hView; y += _gridSize) {
          qPainter.drawLine(0, y, wView - 1, y);
        }
      }
      QGraphicsView::paintEvent(pQEvent);
    }
};

void makeGrid(
  QGraphicsItemGroup &qItemGrp, const QRect &rect,
  int gridSize = 20, const QColor &gridColor = 0x0a8affu)
{
  for (int x = rect.x(), xE = x + rect.width(); x < xE; x += gridSize) {
    QGraphicsLineItem *pQItem
      = new QGraphicsLineItem(x, rect.y(), x, rect.height() - 1);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
  for (int y = rect.y(), yE = y + rect.height(); y < yE; y += gridSize) {
    QGraphicsLineItem *pQItem
      = new QGraphicsLineItem(rect.x(), y, rect.width() - 1, y);
    pQItem->setPen(gridColor);
    qItemGrp.addToGroup(pQItem);
  }
}

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  // setup GUI
  QWidget qWnd;
  QGridLayout qGrid;
  QLabel qLblL(QString::fromUtf8("Grid as part of scene"));
  qGrid.addWidget(&qLblL, 0, 0);
  QCheckBox qTglGridL(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridL, 0, 1);
  QGraphicsView qGraphView;
  qGrid.addWidget(&qGraphView, 1, 0, 1, 2);
  QLabel qLblR(QString::fromUtf8("Grid painted as background"));
  qGrid.addWidget(&qLblR, 0, 2);
  QCheckBox qTglGridR(QString::fromUtf8("Show Grid"));
  qGrid.addWidget(&qTglGridR, 0, 3);
  Canvas canvas;
  qGrid.addWidget(&canvas, 1, 2, 1, 2);
  qWnd.setLayout(&qGrid);
  qWnd.show();
  // init GUI
  QGraphicsScene qGraphSceneL;
  QGraphicsItemGroup qItemGrid;
  makeGrid(qItemGrid, QRect(0, 0, 320, 240));
  qGraphSceneL.addItem(&qItemGrid);
  qGraphView.setScene(&qGraphSceneL);
  qTglGridL.setCheckState(
    qItemGrid.isVisible() ? Qt::Checked : Qt::Unchecked);
  qTglGridR.setCheckState(
    canvas.gridVisible() ? Qt::Checked : Qt::Unchecked);
  // install signal handlers
  QObject::connect(&qTglGridL, &QCheckBox::stateChanged,
    [&qItemGrid](int state)
    {
      qItemGrid.setVisible(state != Qt::Unchecked);
    });
  QObject::connect(&qTglGridR, &QCheckBox::stateChanged,
    [&canvas](int state)
    {
      canvas.setGridVisible(state != Qt::Unchecked);
    });
  // runtime loop
  return app.exec();
}

    #包括
类画布：公共QGraphicsView{
私人：
整数网格大小；
QColor\u gridColor；
布尔网格可见；
公众：
显式画布（QWidget*pQParent=nullptr）：
QGraphicsView（pQParent），
_gridSize（20），\u gridColor（0x0a8affu），\u gridVisible（true）
{ }
bool gridVisible（）常量{return\u gridVisible；}
void setGridVisible（bool gridVisible）
{
_gridVisible=gridVisible；
viewport（）->update（）；
}
受保护的：
虚拟无效paintEvent（QPaintEvent*pQEvent）覆盖
{
QPainter QPainter（视口（））；
如果（_gridVisible）{
const int wView=视口（）->宽度（），hView=视口（）->高度（）；
常数QPointF offs=maptosene（0,0）；
qPainter.setPen（_gridColor）；
对于（int x=（int）offs.x（）%\u gridSize；x