QT之利用QGraphicsScene图布完成在图片上层图画并放缩保持相对位置不变_qgraphicsscene上添加图片

作者vip1024c交流
110 阅读2分钟

//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(); unsigned short green = color.green(); unsigned short red = color.red();

int nRet = color.blue() << 16|color.green() << 8| color.red();
return nRet;

}

void Widget::clearAllPaint() { if (m_scene) m_scene->clear(); m_markAllData.clear(); }

//可以用于底层图片的变化 void Widget::updateImage(const QImage &image) { m_image = image; //触发paintEvent绘画事件 根据屏幕图案，不改变批注位置的 update(); } //绘画 void Widget::paintEvent(QPaintEvent *event) { QPainter painter(this); if (!m_image.isNull()) { m_Sizemutex.lock(); ///m_image = m_image.scaled(width()-40, height()-40, Qt::KeepAspectRatio, Qt::SmoothTransformation); // 按比例缩放 QRect srcRect(0, 0, m_image.width(), m_image.height()); QRect dstRect(2, 40, width()-2, height()-40); painter.drawImage(dstRect, m_image, srcRect); m_Sizemutex.unlock(); }

QWidget::paintEvent(event);

} //三个按钮的点击事件 void Widget::on_startMark_clicked() { m_bIsMark = true; }

void Widget::on_clearMark_clicked() { if (m_scene) m_scene->clear(); m_markAllData.clear(); }

void Widget::on_endMark_clicked() { m_bIsMark = false; }

avatar
文章
阅读
粉丝