m_graphicsView->setGeometry(2, 40, width(), height()); m_graphicsView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff); m_graphicsView->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
m_graphicsView->show(); m_scene = new QGraphicsScene(); m_scene->setSceneRect(2, 40, width(), height()); m_graphicsView->setScene(m_scene);
窗口大小变化是也要跟着变化
//同步将画布大小变化 m_graphicsView->setGeometry(2, 40, width(), height()); m_scene->setSceneRect(2, 40, width(), height()); m_graphicsView->setScene(m_scene);
绘画 添加一横
m_scene->addLine(m_pStart.x(), m_pStart.y(), pt.x(), pt.y(), m_pen);
四、代码实践
头文件
#ifndef WIDGET_H #define WIDGET_H
#include #include #include #include #include namespace Ui { class Widget; } struct Position { int x; int y; }; class Widget : public QWidget { Q_OBJECT
public: explicit Widget(QWidget *parent = 0); ~Widget(); void updateImage( const QImage &image); void clearAllPaint();
int QColorToInt(const QColor &color);
void setWhiteboardId(const std::string &boardId);
protected: void mousePressEvent(QMouseEvent *event); void mouseMoveEvent(QMouseEvent *event); void mouseReleaseEvent(QMouseEvent *event); virtual void paintEvent(QPaintEvent *event); void resizeEvent(QResizeEvent *event);
private slots: void on_startMark_clicked();
void on\_clearMark\_clicked();
void on\_endMark\_clicked();
private: void repaint(); Ui::Widget *ui; QImage m_image;
QGraphicsView \*m_graphicsView = NULL;
QGraphicsScene \*m_scene = NULL;
qreal m_scale = 1;
std::vector<QGraphicsLineItem \*> m_vcItem;
QPen m_pen;
QPoint m_pStart;
bool m_bValild = false;
bool m_bIsMark = false;
bool m_bRepaint = false;
QMutex m_Sizemutex;
std::string m_strConfId;
std::string m_strUsrId;
std::vector<Position> m_lstPoint;
std::vector<std::vector<Position>> m_markAllData;
};
#endif // WIDGET_H
#include "widget.h" #include "ui_widget.h" #include #include #include #include #include #include #include #include #include Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) { ui->setupUi(this);
//利用 QGraphicsView 试图结合 QGraphicsScene 画布在图片上方叠加一层实现图画
m_graphicsView = new QGraphicsView(this);
m_graphicsView->setStyleSheet("padding:0px;border:0px");
m_graphicsView->setStyleSheet("background:transparent;border:0px");
m_graphicsView->setAttribute(Qt::WA_TransparentForMouseEvents);
m_graphicsView->setGeometry(2, 40, width(), height());
m_graphicsView->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
m_graphicsView->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
m_graphicsView->show();
m_scene = new QGraphicsScene();
m_scene->setSceneRect(2, 40, width(), height());
m_graphicsView->setScene(m_scene);
m_pen.setStyle(Qt::SolidLine);
m_pen.setColor(Qt::red);
m_pen.setWidth(2);
m_image.load("1.png");
}
Widget::~Widget() { if (m_graphicsView) { delete m_graphicsView; m_graphicsView = NULL; }
if (m_scene) { delete m_scene; m_scene = NULL; }
delete ui; } //重绘事件 当窗口图片大小变化的时候我们的图画应该也要随着变化，保持与图片位置的不变性 void Widget::repaint() { int currentWidth = width(); int currentHeight = height(); if(currentWidth == 40 || currentHeight== 40)//做一下保护 return ; //qDebug()<<currentWidth << " " << currentHeight;
//重绘
m_Sizemutex.lock();
if (m_scene)
m_scene->clear();
int lines = m_markAllData.size();
for(int i = 0; i < lines; i++)
{
//算法保持相对位置
//-2是是x轴留一部分不填充 -40是上面按钮的高度抽出来
int startX = ((float)m_markAllData[i][0].x)/m_image.width()\*(currentWidth - 2);
startX += 2;
int startY = ((float)m_markAllData[i][0].y)/m_image.height()\*(currentHeight - 40);
startY += 40;
qDebug() << "startX=" << startX << "startY" << startY << "currentWidth=" << currentWidth << "currentHeight" << currentHeight;
for (int j = 1; j < m_markAllData[i].size(); j++) {
int x = ((float)m_markAllData[i][j].x)/m_image.width()\*(currentWidth - 2);
int y = ((float)m_markAllData[i][j].y)/m_image.height()\*(currentHeight - 40);
x += 2;
y += 40;
m_scene->addLine(startX, startY, x, y, m_pen);
startX = x;
startY = y;
}
}
m_Sizemutex.unlock();
} //窗口大小变化触发事件 void Widget::resizeEvent(QResizeEvent *event) { //同步将画布大小变化 m_graphicsView->setGeometry(2, 40, width(), height()); m_scene->setSceneRect(2, 40, width(), height()); m_graphicsView->setScene(m_scene);
//并根据记录的位置重新图画保持与图片位置的一致性
repaint();
QWidget::resizeEvent(event);
} //鼠标按下事件 表示图画开始 void Widget::mousePressEvent(QMouseEvent *event) { if ((event->button() == Qt::LeftButton) && (m_bIsMark == true)) { m_bValild = true; Position curPoint;
//记录鼠标当前点击的坐标
m_pStart = event->pos();
curPoint.x = event->pos().x();
curPoint.y = event->pos().y();
//转换到窗口坐标
if(width() <= 2 || height() <= 40)
return ;
if((float)curPoint.x <= 2 || (float)curPoint.y <= 40)
return ;
//转换为相对位置 窗口与图片的相对位置
curPoint.x = ((float)curPoint.x - 2)/(width() - 2)\*m_image.width();
curPoint.y = ((float)curPoint.y - 40)/(height() - 40)\*m_image.height();
m_lstPoint.push\_back(curPoint);
}
} //鼠标移动事件 结合变量记录图画的轨迹 void Widget::mouseMoveEvent(QMouseEvent *event) { if (m_bValild) { QPoint pt = event->pos();
Position curPoint;
curPoint.x = event->pos().x();
curPoint.y = event->pos().y();
// //转换到窗口坐标 if(width() <= 2 || height() <= 40) return ; if((float)curPoint.x <= 2 || (float)curPoint.y <= 40) return ;
m_scene->addLine(m_pStart.x(), m_pStart.y(), pt.x(), pt.y(), m_pen);
m_pStart = pt;
curPoint.x = ((float)curPoint.x - 2)/(width() - 2)\*m_image.width();
curPoint.y = ((float)curPoint.y - 40)/(height() - 40)\*m_image.height();
m_lstPoint.push\_back(curPoint);
}
} //鼠标释放事件 表示当前一次图画结束 void Widget::mouseReleaseEvent(QMouseEvent *event) { if (m_bValild && m_bIsMark == true) { m_bValild = false; m_markAllData.push_back(m_lstPoint); m_bRepaint = true; m_lstPoint.clear(); } }
int Widget::QColorToInt(const QColor &color) { unsigned short blue = color.blue();
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