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学习笔记 QT之Graphic图形编辑器_qt 图片编辑器 csdn

作者：凡人多烦事01 | 2024-02-16 07:06:52

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qt 图片编辑器 csdn

注：本人学习阶段，仅供参考。如有错误，请指正，谢谢！

一、简单介绍GraphicsView框架

        Graphics View框架实现了模型到视图结构的图形管理，能对大量图元进行管理，支持坐标变换和图元组等多种方便的功能。

框架结构三个主要的类：

1）场景类：QGraphicsScene类（管理多个图形项，用于放置图元的容器，但本身不可见）

2）视图类：QGraphicsView类（提供可视窗口，显示场景中的图元，一个场景中有多个视图）

3）图元类：QGraphicsItem类（各个图元的基础类，QT提供了常用图元的标准类）

三元素关系

        QGraphicsItem(图形项) -----addItem()------>QGraphicsScene(图形项的容器，场景)--------setScene()------>QGraphicsView(可视化使场景中的内容)

三元素坐标系

         QGraphicsView提供QGraphicsView::mapToScene()和QGraphicsView:: mapFromScene()函数用于视图与场景的坐标进行转换

QT提供常用图元标准类

        当然，也可以在QGraphicsItem类的基础上实现自定义的图元类，即用户可以继承QGraphicsItem实现符合自己需要的图元。

  • QGraphicsLineItem    用来绘制直线，可以通过setLine(const QLineF&)来添加。
  • QGraphicsRectItem    用来绘制矩形，通过setRect()来进行添加
  • QGraphicsEllipseItem    用来绘制椭圆，或者部分椭圆。通过设置setStartAngle(int)和setSpanAngle(int)可以绘制椭圆的一部分。设置的值是1度的1/16。
  • QGraphicsPolygonItem    用来绘制多边形，通过setPolygon()添加
  • QGraphicsPathItem    绘制一个路径，通过setPath()来进行添加
  • QGraphicsSimpleTextItem    绘制简单文本，除了可以设置字体以外，不支持其它的富文本样式
  • QGraphicsTextItem    绘制格式化的文本，可以通过setHtml()或者setDocument()设置html，还可以添加有交互内容的URL超链接。
  • QGraphicsPixmapItem    绘制图片，或者渲染一个图片
  • QGraphicsProxyWidget    绘制任意的QWdiget控件，视图框架允许我们与添加的控件进行交互。

 二、Graphic图形编辑器

        这是一个简单的图形编辑器，它只对视图部分进行了部分重写。添加了各种图元，如圆、椭圆、矩形、文本、图片等，可进行旋转、放大、缩小、前置、后置、组合、散开、删除等功能。

        在代码中有很多地方添加了注释，这里就不一一赘述了。

效果展示：

 源码展示：

ui界面：

mainwindow.h

  1. #ifndef MAINWINDOW_H
  2. #define MAINWINDOW_H
  3.  
  4. #include <QMainWindow>
  5. #include <QGraphicsScene>
  6. #include <QLabel>
  7.  
  8. namespace Ui {
  9. class MainWindow;
  10. }
  11.  
  12. class MainWindow : public QMainWindow
  13. {
  14.     Q_OBJECT
  15. private:
  16.     static const int ItemId = 1; //绘图项自定义数据的key
  17.     static const int ItemDesciption = 2;//绘图自定义数据的key
  18.  
  19.     int seqNum = 0;
  20.     int backZ = 0;
  21.     int frontZ = 0;
  22.  
  23. //    bool isMode = true;
  24.     QPoint linePoint;
  25.     //直线
  26.     bool isline = true;
  27.     //矩形
  28.     bool isrectangle = true;
  29.     //三角形
  30.     bool isTriangle = true;
  31.     //椭圆
  32.     bool isEllipse= true;
  33.  
  34.     QGraphicsScene *scene;
  35.     //显示各种坐标
  36.     QLabel *labViewCord; //视图
  37.     QLabel *labSceneCord; //场景
  38.     QLabel *labItemCord; //图元
  39.     QLabel *labItemInfo;
  40.     QPoint actPoint;
  41.  
  42. public:
  43.     explicit MainWindow(QWidget *parent = 0);
  44.     ~MainWindow();
  45.     void initview();
  46.     void initSlots();
  47.     void wheelEvent(QWheelEvent *event); //滑轮
  48. private slots:
  49.     void onMouseMovePoint(QPoint ponit); //接收鼠标移动传过来的坐标槽函数
  50.     void onMouseClicked(QPoint point); //接收鼠标点击传过来的坐标槽函数
  51.     void onMouseRightClicked(QPoint point); //接收鼠标右击传过来的坐标槽函数
  52.     void actionTrigger(QAction *act); //菜单槽函数
  53.     void onMouseDoubleClick(QPoint point); //接收鼠标双击传过来的坐标槽函数
  54.     void onKeyPress(QKeyEvent *event); //接收按键传过来的按键槽函数
  55. //画图的槽函数
  56.     void drawPressLine(QPoint point);
  57.     void drawReleaseLine(QPoint point);
  58.     void onDrawPressRecdangle(QPoint point);
  59.     void onDrawReleaseRecdangle(QPoint point);
  60.     void drawPressTriangle(QPoint point);
  61.     void drawReleaseTriangle(QPoint point);
  62.     void drawPressEllipse(QPoint point);
  63.     void drawReleaseEllipse(QPoint point);
  64. //各种转到槽
  65.     void on_rectangleButton_clicked();
  66.     void on_ellipseButton_clicked();
  67.     void on_circularButton_clicked();
  68.     void on_triangleButton_clicked();
  69.     void on_lineButton_clicked();
  70.     void on_textButton_clicked();
  71.     void on_enlargeButton_clicked();
  72.     void on_narrowButton_clicked();
  73.     void on_leftButton_clicked();
  74.     void on_rightButton_clicked();
  75.     void on_frontButton_clicked();
  76.     void on_afterButton_clicked();
  77.     void on_deleteButton_clicked();
  78.     void on_conbButton_clicked();
  79.     void on_disperseButton_clicked();
  80.     void on_recoveryButton_clicked();
  81.     void on_pictrueButton_clicked();
  82.     void on_pixmapButton_clicked();
  83.     void on_stop_clicked();
  84.     void on_run_clicked();
  85.  
  86. private:
  87.     Ui::MainWindow *ui;
  88. };
  89.  
  90. #endif // MAINWINDOW_H

mainwindow.cpp

  1. #include "mainwindow.h"
  2. #include "ui_mainwindow.h"
  3. #include <QGraphicsRectItem>
  4. #include <QInputDialog>
  5. #include <QColorDialog>
  6. #include <QFontDialog>
  7. #include <QTime>
  8. #include <QMenu>
  9. #include <QColor>
  10. #include <QPixmap>
  11. #include <QKeyEvent>
  12. #include <QFileDialog>
  13. #include <QDebug>
  14.  
  15. template<class T>
  16. void setBrushColor(T *item)
  17. {
  18.     //关于更改方块的颜色的模板函数
  19.     QColor color = item->brush().color();
  20.     color = QColorDialog::getColor(color,NULL,"选择填充颜色");
  21.     if(color.isValid()){ //如果存在与此键关联的缓存像素映射，则返回true。否则，如果pixmap被刷新，密钥将不再有效。
  22.         item->setBrush(QBrush(color));
  23.     }
  24. }
  25.  
  26. MainWindow::MainWindow(QWidget *parent) :
  27.     QMainWindow(parent),
  28.     ui(new Ui::MainWindow)
  29. {
  30.     ui->setupUi(this);
  31.  
  32.     initview();//美化界面
  33.  
  34.     labViewCord = new QLabel("View 坐标：");
  35.     labViewCord->setMinimumWidth(150); //设置最小宽度
  36.     ui->statusBar->addWidget(labViewCord);//QStatusBar类提供了一个适合显示状态信息的水平条。
  37.  
  38.     labSceneCord= new QLabel("Scene 坐标：");
  39.     labSceneCord->setMinimumWidth(150);
  40.     ui->statusBar->addWidget(labSceneCord);
  41.  
  42.     labItemCord = new QLabel("Item 坐标：");
  43.     labItemCord->setMinimumWidth(150);
  44.     ui->statusBar->addWidget(labItemCord);
  45.  
  46.     labItemInfo = new QLabel("ItemInfo： ");
  47.     labItemInfo->setMinimumWidth(200);
  48.     ui->statusBar->addWidget(labItemInfo);
  49.  
  50.     scene = new QGraphicsScene(-300, -200, 600, 200);//创建一个场景
  51.  
  52.     ui->graphicsView->setScene(scene); //与view关联
  53.  
  54.     ui->graphicsView->setCursor(Qt::CrossCursor);//设置鼠标，十字光标，通常用于帮助用户准确选择屏幕上的点。
  55.     ui->graphicsView->setMouseTracking(true);//启用了鼠标跟踪，即使没有按下按钮，小部件也会接收鼠标移动事件。
  56.     //此属性保留按住鼠标左键时在场景上拖动鼠标的行为。
  57.     ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//将出现一条橡皮筋。拖动鼠标将设置橡皮筋几何体，并选择橡皮筋覆盖的所有项目
  58. //    this->setCentralWidget(ui->graphicsView); //将给定的小部件设置为主窗口的中心小部件。
  59.     initSlots(); //信号与槽
  60.     qsrand(QTime::currentTime().second()); //关于线程的一个函数
  61. }
  62.  
  63. void MainWindow::initview()
  64. {
  65.     //保存图片
  66.     ui->pictrueButton->setToolTip(QString("保存图片"));
  67.     ui->pictrueButton->setIcon(QIcon(":/pictrue/save.png"));
  68.     //放大
  69.     ui->enlargeButton->setToolTip(QString("放大"));
  70.     ui->enlargeButton->setIcon(QIcon(":/pictrue/enlarge.png"));
  71.     //缩小
  72.     ui->narrowButton->setToolTip(QString("缩小"));
  73.     ui->narrowButton->setIcon(QIcon(":/pictrue/narrow.png"));
  74.     //左右转
  75.     ui->leftButton->setToolTip(QString("左转"));
  76.     ui->leftButton->setIcon(QIcon(":/pictrue/rightRotation.png"));
  77.     ui->rightButton->setToolTip(QString("右转"));
  78.     ui->rightButton->setIcon(QIcon(":/pictrue/leftRotation.png"));
  79.     //前面置
  80.     ui->frontButton->setToolTip(QString("前置"));
  81.     ui->frontButton->setIcon(QIcon(":/pictrue/524.bmp"));
  82.     ui->afterButton->setToolTip(QString("后置"));
  83.     ui->afterButton->setIcon(QIcon(":/pictrue/522.bmp"));
  84.     //恢复
  85.     ui->recoveryButton->setToolTip(QString("恢复"));
  86.     ui->recoveryButton->setIcon(QIcon(":/pictrue/toFront.png"));
  87.     //组合
  88.     ui->conbButton->setToolTip(QString("组合"));
  89.     ui->conbButton->setIcon(QIcon(":/pictrue/con.png"));
  90.     //打散
  91.     ui->disperseButton->setToolTip(QString("打散"));
  92.     ui->disperseButton->setIcon(QIcon(":/pictrue/dis.png"));
  93.     //删除
  94.     ui->deleteButton->setToolTip(QString("删除"));
  95.     ui->deleteButton->setIcon(QIcon(":/pictrue/108.bmp"));
  96.     //图形
  97.     ui->circularButton->setIcon(QIcon(":/pictrue/iage/cir.png"));
  98.     ui->circularButton->setToolTip(QString("圆形"));
  99.     ui->ellipseButton->setIcon(QIcon(":/pictrue/iage/ell1.png"));
  100.     ui->ellipseButton->setToolTip(QString("椭圆"));
  101.     ui->lineButton->setIcon(QIcon(":/pictrue/iage/line1.png"));
  102.     ui->lineButton->setToolTip(QString("直线"));
  103.     ui->rectangleButton->setIcon(QIcon(":/pictrue/iage/rec1.png"));
  104.     ui->rectangleButton->setToolTip(QString("矩形"));
  105.     ui->textButton->setIcon(QIcon(":/pictrue/iage/text.bmp"));
  106.     ui->textButton->setToolTip(QString("添加文本"));
  107.     ui->triangleButton->setIcon(QIcon(":/pictrue/iage/tri1.png"));
  108.     ui->triangleButton->setToolTip(QString("三角形"));
  109.     ui->pixmapButton->setIcon(QIcon(":/pictrue/iage/K1.png"));
  110.     ui->pixmapButton->setToolTip(QString("添加图片"));
  111. }
  112.  
  113. void MainWindow::initSlots() //各种事件的信号与槽
  114. {
  115.     connect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(onMouseClicked(QPoint)));
  116.     connect(ui->graphicsView, SIGNAL(mouseRightClicked(QPoint)), this, SLOT(onMouseRightClicked(QPoint)));
  117.     connect(ui->graphicsView, SIGNAL(mouseDoubleClick(QPoint)), this, SLOT(onMouseDoubleClick(QPoint)));
  118.     connect(ui->graphicsView, SIGNAL(mouseMovePoint(QPoint)), this, SLOT(onMouseMovePoint(QPoint)));
  119.     connect(ui->graphicsView, SIGNAL(keyPress(QKeyEvent*)), this, SLOT(onKeyPress(QKeyEvent*)));
  120.     connect(ui->preser, SIGNAL(triggered(bool)), this, SLOT(on_pictrueButton_clicked()));
  121.     connect(ui->out, SIGNAL(triggered(bool)), this, SLOT(close()));
  122.  
  123. }
  124.  
  125. void MainWindow::wheelEvent(QWheelEvent *event)  //鼠标滑轮事件
  126. {
  127.     if(event->delta() > 0){
  128.         on_enlargeButton_clicked();
  129.     }else{
  130.         on_narrowButton_clicked();
  131.     }
  132. }
  133.  
  134. void MainWindow::onMouseMovePoint(QPoint ponit)//鼠标移动事件，ponit表示view的坐标
  135. {
  136.     labViewCord->setText(QString::asprintf("View 坐标：%d,%d", ponit.x(), ponit.y()));
  137.     QPointF pointScene = ui->graphicsView->mapToScene(ponit); //转换到Scene坐标
  138.     labSceneCord->setText(QString::asprintf("Scene 坐标：%.0f,%.0f", pointScene.x(),pointScene.y()));
  139. }
  140.  
  141. void MainWindow::onMouseClicked(QPoint point)//鼠标左击事件
  142. {
  143.     QPointF pointScene = ui->graphicsView->mapToScene(point); //转换到Scene坐标
  144.     QGraphicsItem *item = NULL;
  145.     item = scene->itemAt(pointScene, ui->graphicsView->transform()); //获取光标下的绘图项
  146.     if(item != NULL)
  147.     {
  148.         QPointF pointItem = item->mapFromScene(pointScene); //转换为绘图项的局部坐标
  149.         labItemCord->setText(QString::asprintf("Item 坐标：%.0f,%.0f", pointItem.x(), pointItem.y()));
  150.         labItemInfo->setText(item->data(ItemDesciption).toString()+", ItemId="+item->data(ItemId).toString());
  151.     }
  152. }
  153.  
  154. void MainWindow::onMouseRightClicked(QPoint point) //鼠标右击出菜单
  155. {
  156.     actPoint = point;
  157.     QPointF pointScene = ui->graphicsView->mapToScene(point); //转换到scene坐标
  158.     QGraphicsItem *item = NULL;
  159.     item = scene->itemAt(pointScene, ui->graphicsView->transform()); //获取光标下的绘图项
  160.     if(item == NULL) //没有绘图项
  161.     {
  162.         return;
  163.     }
  164.     QMenu *menu = new QMenu(this);
  165.     menu->addAction(QString("放大"));
  166.     menu->addAction(QString("缩小"));
  167.     menu->addAction(QString("左转"));
  168.     menu->addAction(QString("右转"));
  169.     menu->addAction(QString("前置"));
  170.     menu->addAction(QString("后置"));
  171.     menu->addAction(QString("组合"));
  172.     menu->addAction(QString("散开"));
  173.     menu->addAction(QString("删除"));
  174.     connect(menu, SIGNAL(triggered(QAction*)), this, SLOT(actionTrigger(QAction*)));
  175.     menu->exec(QCursor::pos());
  176. }
  177.  
  178. void MainWindow::actionTrigger(QAction *act)
  179. {
  180.     if(act->text() == "放大"){
  181.         on_enlargeButton_clicked();
  182.     }else if(act->text() == "缩小"){
  183.         on_narrowButton_clicked();
  184.     }else if(act->text() == "左转"){
  185.         on_leftButton_clicked();
  186.     }else if(act->text() == "右转"){
  187.         on_rightButton_clicked();
  188.     }else if(act->text() == "前置"){
  189.         on_frontButton_clicked();
  190.     }else if(act->text() == "后置"){
  191.         on_afterButton_clicked();
  192.     }else if(act->text() == "组合"){
  193.         on_conbButton_clicked();
  194.     }else if(act->text() == "散开"){
  195.         on_disperseButton_clicked();
  196.     }else if(act->text() == "删除"){
  197.         on_deleteButton_clicked();
  198.     }
  199. }
  200.  
  201. void MainWindow::onMouseDoubleClick(QPoint point)//鼠标双击事件，调用相应的对话框，设置填充颜色、字体
  202. {
  203.  
  204.     QPointF pointScene = ui->graphicsView->mapToScene(point);//转换到scene的坐标
  205.     QGraphicsItem *item = NULL;
  206.     item = scene->itemAt(pointScene, ui->graphicsView->transform()); //获取光标下的绘图项
  207.     if(item == NULL) //没有绘图项
  208.     {
  209.         return;
  210.     }
  211.     switch(item->type()) //绘图项的类型
  212.     {
  213.         case QGraphicsRectItem::Type:  //矩形框
  214.         {
  215.             //强制类型转换
  216.             QGraphicsRectItem *theItem = qgraphicsitem_cast<QGraphicsRectItem*>(item);
  217.             setBrushColor(theItem);//更改颜色的模板函数
  218.             break;
  219.         }
  220.         case QGraphicsEllipseItem::Type: //椭圆和圆
  221.         {
  222.             QGraphicsEllipseItem *theItem;
  223.             theItem = qgraphicsitem_cast<QGraphicsEllipseItem*>(item);
  224.             setBrushColor(theItem);
  225.             break;
  226.         }
  227.         case QGraphicsPolygonItem::Type:  //梯形和三角形
  228.         {
  229.             QGraphicsPolygonItem *theItem = qgraphicsitem_cast<QGraphicsPolygonItem*>(item);
  230.             setBrushColor(theItem);
  231.             break;
  232.         }
  233.         case QGraphicsLineItem::Type: //直线
  234.         {
  235.             QGraphicsLineItem *theItem = qgraphicsitem_cast<QGraphicsLineItem*>(item);
  236.             QPen pen = theItem->pen();
  237.             QColor color = theItem->pen().color();
  238.             color = QColorDialog::getColor(color, this,"选择线条颜色");
  239.             if(color.isValid()) //如果颜色有效，则返回true；否则返回false。
  240.             {
  241.                 pen.setColor(color);
  242.                 theItem->setPen(pen);
  243.             }
  244.             break;
  245.         }
  246.         case QGraphicsTextItem::Type: //文字，设置字体
  247.         {
  248.             QGraphicsTextItem *theItem = qgraphicsitem_cast<QGraphicsTextItem*>(item);
  249.             QFont font = theItem->font(); //QFont类指定用于绘制文本的字体。
  250.             bool ok = false;
  251.             font = QFontDialog::getFont(&ok, font, this, "设置字体");
  252.             if(ok)
  253.             {
  254.                 theItem->setFont(font);
  255.             }
  256.             break;
  257.         }
  258.     }
  259. }
  260.  
  261. void MainWindow::onKeyPress(QKeyEvent *event)
  262. {
  263.     //按键事件
  264.     if(scene->selectedItems().count()!=1)//没有选中的绘图项，或选中的多于1个
  265.     {
  266.         return;
  267.     }
  268.     QGraphicsItem *item = scene->selectedItems().at(0);
  269.  
  270.     if(event->key() == Qt::Key_Delete){//删除
  271.         scene->removeItem(item);
  272.     } else if(event->key() == Qt::Key_Space){ //顺时针旋转
  273.         item->setRotation(30+item->rotation());//设置围绕Z轴的顺时针旋转角度（以度为单位）。默认值为0
  274.     } else if(event->key() == Qt::Key_PageUp){ //放大
  275.         item->setScale(0.1+item->scale()); //设置项目的比例因子。默认比例因子为1.0（即，项目未缩放）
  276.     } else if(event->key() == Qt::Key_PageDown){ //缩小
  277.         item->setScale(-0.1+item->scale());
  278.     } else if(event->key() == Qt::Key_Left) { //左移
  279.         item->setX(-1+item->x());
  280.     } else if(event->key() == Qt::Key_Right){ //右移
  281.         item->setX(1+item->x());
  282.     } else if(event->key() == Qt::Key_Up){  //上移
  283.         item->setY(1+item->y());
  284.     } else if(event->key() == Qt::Key_Down){ //下移
  285.         item->setY(-1+item->y());
  286.     }
  287. }
  288.  
  289. void MainWindow::drawPressLine(QPoint point)
  290. {
  291.     qDebug() << point.x() << point.y();
  292.     linePoint = point;
  293. }
  294.  
  295. void MainWindow::drawReleaseLine(QPoint point)  //画直线
  296. {
  297.     qDebug() << "画直线";
  298.     QGraphicsLineItem *item = new QGraphicsLineItem(0,0,linePoint.x()-point.x(),linePoint.y()-point.y());
  299.     item->setFlags(QGraphicsItem::ItemIsMovable
  300.                    | QGraphicsItem::ItemIsSelectable
  301.                    | QGraphicsItem::ItemIsFocusable);
  302.  
  303.     QPen pen(Qt::red);
  304.     pen.setWidth(3);
  305.     item->setPen(pen);
  306.  
  307.     item->setZValue(++frontZ);
  308.     QPointF pointScene=ui->graphicsView->mapToScene(point); //转换到Scene坐标
  309.     item->setPos(pointScene.x(), pointScene.y());
  310.  
  311.     item->setData(ItemId,++seqNum);
  312.     item->setData(ItemDesciption,"直线");
  313.  
  314.     scene->addItem(item);
  315.     scene->clearSelection();
  316.     item->setSelected(true);
  317.  
  318. }
  319.  
  320. void MainWindow::onDrawPressRecdangle(QPoint point)
  321. {
  322.     linePoint = point;
  323. }
  324.  
  325. void MainWindow::onDrawReleaseRecdangle(QPoint point)  //画矩形
  326. {
  327.     QGraphicsRectItem *item = new QGraphicsRectItem(-abs(linePoint.x()-point.x())/2, -abs(linePoint.y()-point.y())/2, abs(linePoint.x()-point.x()), abs(linePoint.y()-point.y()));//x,y为左上角的图元局部坐标，图元中心为0,0
  328.     item->setBrush(QBrush(Qt::yellow)); //设置初始填充颜色
  329.     QPointF oldpoint=ui->graphicsView->mapToScene(linePoint); //转换到Scene坐标
  330.     QPointF newpoint=ui->graphicsView->mapToScene(point); //转换到Scene坐标
  331.     item->setPos((newpoint.x()-oldpoint.x())/2+oldpoint.x(),(newpoint.y()-oldpoint.y())/2+oldpoint.y()); //设置初始坐标
  332.     item->setFlags(QGraphicsItem::ItemIsMovable
  333.                    | QGraphicsItem::ItemIsSelectable
  334.                    | QGraphicsItem::ItemIsFocusable); //设置图形项的属性，例如：可选择、可移动
  335.     item->setZValue(++frontZ);//将项目的Z值设置为Z。Z值决定同级（相邻）项目的堆叠顺序。Z值较高的同级项将始终绘制在Z值较低的另一个同级项的顶部。
  336.  
  337.     //自定义数据
  338.     item->setData(ItemId, ++seqNum);
  339.     item->setData(ItemDesciption, "矩形");
  340.  
  341.     scene->addItem(item);
  342. //    scene->clearSelection(); // 清除当前选择
  343.     item->setSelected(true); //初始选择该项目
  344.  
  345. }
  346.  
  347. void MainWindow::drawPressTriangle(QPoint point)
  348. {
  349.     linePoint = point;
  350. }
  351.  
  352. void MainWindow::drawReleaseTriangle(QPoint point)  //画三角形
  353. {
  354.     QGraphicsPolygonItem *item = new QGraphicsPolygonItem;
  355.     QPolygonF points; //QPolygonF类使用浮点精度提供点向量。
  356.     points.append(QPointF(0,0)); //QPointF类使用浮点精度定义平面中的点。
  357.     points.append(QPointF(-((linePoint.x()-point.x())/2),(linePoint.y()-point.y())));
  358.     points.append(QPointF((linePoint.x()-point.x())/2,linePoint.y()-point.y()));
  359.     item->setPolygon(points);
  360.     QPointF pointScene=ui->graphicsView->mapToScene(point); //转换到Scene坐标
  361.     item->setPos(pointScene.x()-(point.x()-linePoint.x())/2, pointScene.y());
  362.     item->setFlags(QGraphicsItem::ItemIsMovable
  363.                    | QGraphicsItem::ItemIsSelectable
  364.                    | QGraphicsItem::ItemIsFocusable);
  365.     item->setBrush(QBrush(Qt::magenta));
  366.     item->setZValue(++frontZ);
  367.  
  368.     item->setData(ItemId, ++seqNum);
  369.     item->setData(ItemDesciption, "三角形");
  370.  
  371.     scene->addItem(item);
  372.     scene->clearSelection();
  373.     item->setSelected(true);
  374. }
  375.  
  376. void MainWindow::drawPressEllipse(QPoint point)
  377. {
  378.     linePoint = point;
  379. }
  380.  
  381. void MainWindow::drawReleaseEllipse(QPoint point)  //画椭圆
  382. {
  383.     QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, linePoint.x()-point.x(), linePoint.y()-point.y());
  384.     item->setFlags(QGraphicsItem::ItemIsMovable
  385.                    | QGraphicsItem::ItemIsSelectable
  386.                    | QGraphicsItem::ItemIsFocusable);
  387.     item->setBrush(QBrush(Qt::blue));
  388.     item->setZValue(++frontZ);
  389.     QPointF pointScene=ui->graphicsView->mapToScene(point); //转换到Scene坐标
  390.     item->setPos(pointScene.x(), pointScene.y());
  391.  
  392.     item->setData(ItemId, ++seqNum);
  393.     item->setData(ItemDesciption, "椭圆");
  394.  
  395.     scene->addItem(item);
  396.     scene->clearSelection();
  397.     item->setSelected(true);
  398. }
  399.  
  400. MainWindow::~MainWindow()
  401. {
  402.     delete ui;
  403. }
  404.  
  405. void MainWindow::on_rectangleButton_clicked() //添加矩形
  406. {
  407.     if(isrectangle){
  408.         connect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(onDrawPressRecdangle(QPoint)));
  409.         connect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(onDrawReleaseRecdangle(QPoint)));
  410.         ui->rectangleButton->setIcon(QIcon(":/pictrue/iage/rec.png"));
  411.         isrectangle = false;
  412.     }else{
  413.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(onDrawPressRecdangle(QPoint)));
  414.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(onDrawReleaseRecdangle(QPoint)));
  415.         ui->rectangleButton->setIcon(QIcon(":/pictrue/iage/rec1.png"));
  416.         isrectangle = true;
  417.     }
  418.     qDebug() << isrectangle;
  419. }
  420.  
  421. void MainWindow::on_ellipseButton_clicked()  //添加椭圆
  422. {
  423.     if(isEllipse){
  424.         connect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressEllipse(QPoint)));
  425.         connect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseEllipse(QPoint)));
  426.         ui->ellipseButton->setIcon(QIcon(":/pictrue/iage/ell.png"));
  427.         isEllipse = false;
  428.     }else{
  429.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressEllipse(QPoint)));
  430.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseEllipse(QPoint)));
  431.         ui->ellipseButton->setIcon(QIcon(":/pictrue/iage/ell1.png"));
  432.         isEllipse = true;
  433.     }
  434. }
  435.  
  436. void MainWindow::on_circularButton_clicked() //添加圆形
  437. {
  438.     QGraphicsEllipseItem *item = new QGraphicsEllipseItem(-50, -50, 100, 100);
  439.     item->setFlags(QGraphicsItem::ItemIsMovable
  440.                    | QGraphicsItem::ItemIsSelectable
  441.                    | QGraphicsItem::ItemIsFocusable);
  442.     item->setBrush(QBrush(Qt::cyan)); //青色
  443.     item->setZValue(++frontZ);
  444.     item->setPos(-50+qrand()%100, -50+(qrand()%100));
  445.  
  446.     item->setData(ItemId, ++seqNum);
  447.     item->setData(ItemDesciption, "圆形");
  448.  
  449.     scene->addItem(item);
  450.     scene->clearSelection();
  451.     item->setSelected(true);
  452. }
  453.  
  454. void MainWindow::on_triangleButton_clicked() //添加三角形
  455. {
  456.     if(isTriangle){
  457.         connect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressTriangle(QPoint)));
  458.         connect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseTriangle(QPoint)));
  459.         ui->triangleButton->setIcon(QIcon(":/pictrue/iage/tri.png"));
  460.         isTriangle = false;
  461.     }else{
  462.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressTriangle(QPoint)));
  463.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseTriangle(QPoint)));
  464.         ui->triangleButton->setIcon(QIcon(":/pictrue/iage/tri1.png"));
  465.         isTriangle = true;
  466.     }
  467.  
  468.  
  469. }
  470.  
  471. void MainWindow::on_lineButton_clicked()  //添加直线
  472. {
  473.     if(isline){
  474.         connect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressLine(QPoint)));
  475.         connect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseLine(QPoint)));
  476.         ui->lineButton->setIcon(QIcon(":/pictrue/iage/line.BMP"));
  477.         isline = false;
  478.     }else{
  479.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseClicked(QPoint)), this, SLOT(drawPressLine(QPoint)));
  480.         ui->graphicsView->disconnect(ui->graphicsView, SIGNAL(mouseRelease(QPoint)), this, SLOT(drawReleaseLine(QPoint)));
  481.         ui->lineButton->setIcon(QIcon(":/pictrue/iage/line1.png"));
  482.         isline = true;
  483.     }
  484.     qDebug() << isline;
  485. }
  486.  
  487. void MainWindow::on_textButton_clicked()  //添加文字
  488. {
  489.     QString str = QInputDialog::getText(this, "输入文字", "请输入文字");
  490.     if(str.isEmpty())
  491.     {
  492.         return;
  493.     }
  494.     QGraphicsTextItem *item = new QGraphicsTextItem(str);
  495.     QFont font = this->font();
  496.     font.setPointSize(20);
  497.     font.setBold(true);
  498.     item->setFont(font);
  499.     item->setFlags(QGraphicsItem::ItemIsMovable
  500.                    | QGraphicsItem::ItemIsSelectable
  501.                    | QGraphicsItem::ItemIsFocusable);
  502.     item->setPos(-50+(qrand()%100), -50+(qrand()%100));
  503.     item->setZValue(++frontZ);
  504.  
  505.     item->setData(ItemId, ++seqNum);
  506.     item->setData(ItemDesciption, "文字");
  507.  
  508.     scene->addItem(item);
  509.     scene->clearSelection();
  510.     item->setSelected(true);
  511. }
  512.  
  513. void MainWindow::on_enlargeButton_clicked() //放大
  514. {
  515.    int cnt = scene->selectedItems().count();
  516.    if(cnt == 1){
  517.        QGraphicsItem *item;
  518.        item = scene->selectedItems().at(0);
  519.        item->setScale(0.1+item->scale()); // 比例因子
  520.    }else{
  521.        ui->graphicsView->scale(1.1,1.1); //按（sx，sy）缩放当前视图变换，正常比例为1，1。
  522.    }
  523. }
  524.  
  525. void MainWindow::on_narrowButton_clicked()   //缩小
  526. {
  527.     int cnt = scene->selectedItems().count();
  528.     if(cnt == 1){
  529.         QGraphicsItem *item;
  530.         item = scene->selectedItems().at(0);
  531.         item->setScale(-0.1+item->scale());
  532.     }else{
  533.         ui->graphicsView->scale(0.9,0.9); //正常比例为1，1
  534.     }
  535. }
  536.  
  537. void MainWindow::on_leftButton_clicked()  //左转
  538. {
  539.     int cnt = scene->selectedItems().count();
  540.     if(cnt == 1){
  541.         QGraphicsItem *item =scene->selectedItems().at(0);
  542.         item->setRotation(-30+item->rotation());
  543.     }else{
  544.         ui->graphicsView->rotate(-30); //rotate:顺时针旋转当前视图变换角度。
  545.     }
  546. }
  547.  
  548. void MainWindow::on_rightButton_clicked()  //右转
  549. {
  550.     int cnt = scene->selectedItems().count();  //返回所有当前选定项目的列表
  551.     if(cnt == 1){
  552.         QGraphicsItem *item = scene->selectedItems().at(0);
  553.         item->setRotation(30+item->rotation());
  554.     }else{
  555.         ui->graphicsView->rotate(30);
  556.     }
  557. }
  558.  
  559. void MainWindow::on_frontButton_clicked()  //前置
  560. {
  561.     int cnt = scene->selectedItems().count();
  562.     if(cnt > 0){
  563.         //只处理第一个选中项
  564.         QGraphicsItem *item = scene->selectedItems().at(0);
  565.         item->setZValue(++frontZ);
  566.     }
  567. }
  568.  
  569. void MainWindow::on_afterButton_clicked()  //后置
  570. {
  571.     int cnt = scene->selectedItems().count();
  572.     if(cnt > 0){
  573.         QGraphicsItem *item = scene->selectedItems().at(0);
  574.         item->setZValue(--backZ);
  575.     }
  576. }
  577.  
  578. void MainWindow::on_deleteButton_clicked()  //删除
  579. {
  580.     int cnt = scene->selectedItems().count();
  581.     if(cnt > 0){
  582.       int i = 0;
  583.       for(i=0; i < cnt; i++){
  584.           QGraphicsItem *item = scene->selectedItems().at(0);
  585.           scene->removeItem(item); //删除绘图项
  586.       }
  587.     }
  588. }
  589.  
  590. void MainWindow::on_conbButton_clicked()  //组合
  591. {
  592.     int cnt = scene->selectedItems().count();
  593.     if(cnt > 1){
  594.         QGraphicsItemGroup *group = new QGraphicsItemGroup;//QGraphicsItemGroup类提供了一个容器，将一组项视为单个项。
  595. //        QGraphicsItemGroup是一种特殊类型的复合项，它将自身及其所有子项视为一个项（即，所有子项的所有事件和几何图形都合并在一起）。
  596.         scene->addItem(group);
  597.         for(int i=0; i<cnt; i++){
  598.             QGraphicsItem *item = scene->selectedItems().at(0);
  599.             item->setSelected(false);//清除虚线
  600.             item->clearFocus(); //
  601.             group->addToGroup(item); //添加到组合去
  602.         }
  603.         group->setFlags(QGraphicsItem::ItemIsMovable
  604.                         | QGraphicsItem::ItemIsSelectable
  605.                         | QGraphicsItem::ItemIsFocusable);
  606.         group->setZValue(++frontZ);
  607.         scene->clearSelection();
  608.         group->setSelected(true);
  609.     }
  610. }
  611.  
  612. void MainWindow::on_disperseButton_clicked()  //打散
  613. {
  614.     int cnt = scene->selectedItems().count();
  615.     if(cnt == 1){
  616.         QGraphicsItemGroup *group;
  617.         group=(QGraphicsItemGroup*)scene->selectedItems().at(0);
  618.         scene->destroyItemGroup(group);
  619.         //将组中的所有项目重设为组的父项目，然后从场景中移除组，最后将其删除。项目的位置和变换从组映射到组的父对象。
  620.     }
  621. }
  622.  
  623. void MainWindow::on_recoveryButton_clicked()  //视图恢复
  624. {
  625.     int cnt = scene->selectedItems().count();
  626.     if(cnt == 1){
  627.         QGraphicsItem *item = scene->selectedItems().at(0);
  628.         item->resetTransform();
  629.     }else{
  630.         ui->graphicsView->resetTransform();//将视图转换重置为标识矩阵。
  631.     }
  632. }
  633.  
  634. void MainWindow::on_pictrueButton_clicked()  //保存图片
  635. {
  636.     QPixmap map = ui->graphicsView->grab();
  637.     QString filename;
  638.     filename = QFileDialog::getSaveFileName(this, tr("保存图片"), "", tr("Image Files(*.png *.jpg *.bmp)"));
  639.     if(!filename.isNull()){
  640.         QFile *file = new QFile(filename);
  641.         file->open(QIODevice::ReadWrite);
  642.         map.save(file);
  643.         file->close();
  644.     }
  645. }
  646.  
  647. void MainWindow::on_pixmapButton_clicked()  //添加图片
  648. {
  649.     QGraphicsPixmapItem *pixmap = scene->addPixmap(QPixmap(QFileDialog::getOpenFileName(this, "Open", "./", "*.png")));
  650.     pixmap->setPos(0,0);
  651.     pixmap->setZValue(++frontZ);
  652.     pixmap->setFlags(QGraphicsItem::ItemIsMovable
  653.                      | QGraphicsItem::ItemIsSelectable
  654.                      | QGraphicsItem::ItemIsFocusable);
  655.     pixmap->setData(ItemId, ++seqNum);
  656.     pixmap->setData(ItemDesciption, "图片");
  657.  
  658.     scene->addItem(pixmap);
  659.     scene->clearSelection();
  660.     pixmap->setSelected(true);
  661. }
  662.  
  663. void MainWindow::on_stop_clicked()
  664. {
  665.     int cnt = scene->selectedItems().count();
  666.     if(cnt > 0){
  667.       int i = 0;
  668.       for(i=0; i < cnt; i++){
  669.           QGraphicsItem *item = scene->selectedItems().at(i);
  670.           item->setFlags(QGraphicsItem::ItemStopsFocusHandling
  671.                          | QGraphicsItem::ItemIsSelectable);
  672.       }
  673.     }
  674. }
  675.  
  676. void MainWindow::on_run_clicked()
  677. {
  678.     int cnt = scene->selectedItems().count();
  679.     if(cnt > 0){
  680.       int i = 0;
  681.       for(i=0; i < cnt; i++){
  682.           QGraphicsItem *item = scene->selectedItems().at(i);
  683.           item->setFlags(QGraphicsItem::ItemIsMovable
  684.                          | QGraphicsItem::ItemIsSelectable
  685.                          | QGraphicsItem::ItemIsFocusable);
  686.       }
  687.     }
  688. }
  689.

下面是对视图进行重写，在ui界面对控件进行提升

 mygraphicsview.h

  1. #ifndef MYGRAPHICSVIEW_H
  2. #define MYGRAPHICSVIEW_H
  3.  
  4. #include <QObject>
  5. #include <QGraphicsView>
  6.  
  7. class MyGraphicsView : public QGraphicsView
  8. {
  9.     Q_OBJECT
  10. public:
  11.     MyGraphicsView(QWidget *parent = 0);
  12.  
  13.  
  14.     QColor BackgroundColor = QColor(53,53,53);  //背景颜色
  15.     QColor FineGridColor = QColor(0,60,0);  //细网格颜色
  16.     QColor CoarseGridColor = QColor(120,25,25); //粗网格颜色
  17.  
  18. protected:
  19.     void mouseMoveEvent(QMouseEvent *event); //鼠标移动事件
  20.     void mousePressEvent(QMouseEvent *event); //鼠标按下事件
  21.     void mouseReleaseEvent(QMouseEvent *event); //鼠标释放事件
  22.     void mouseDoubleClickEvent(QMouseEvent *event);  //鼠标双击事件
  23.     void keyPressEvent(QKeyEvent *event); //键盘按下事件
  24.     void drawBackground(QPainter *painter, const QRectF &r); //改变背景颜色
  25. signals:
  26.     void mouseMovePoint(QPoint point); //鼠标移动坐标
  27.     void mouseClicked(QPoint point); //鼠标左击按下坐标
  28.     void mouseRelease(QPoint point); //鼠标释放坐标
  29.     void mouseRightClicked(QPoint point);//鼠标右击按下坐标
  30.     void mouseDoubleClick(QPoint point); //鼠标双击坐标
  31.     void keyPress(QKeyEvent *event); //键盘按下
  32. };
  33.  
  34. #endif // MYGRAPHICSVIEW_H

mygraphicsview.cpp

  1. #include "mygraphicsview.h"
  2. #include <QMouseEvent>
  3. #include <QPoint>
  4. #include <QRect>
  5. #include <cmath>
  6.  
  7. MyGraphicsView::MyGraphicsView(QWidget *parent):QGraphicsView(parent)
  8. {
  9.     //滚动条隐藏
  10.     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  11.     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  12.     //绘图抗锯齿
  13.     setRenderHints(QPainter::Antialiasing);
  14.     //设置背景颜色
  15.     setBackgroundBrush(BackgroundColor);
  16. }
  17.  
  18. void MyGraphicsView::mouseMoveEvent(QMouseEvent *event)
  19. {
  20.     //鼠标移动事件
  21.     QPoint point = event->pos(); //保存鼠标移动的坐标
  22.     emit mouseMovePoint(point);  //发送信号
  23.     QGraphicsView::mouseMoveEvent(event); //使父类的事件不受影响
  24. }
  25.  
  26. void MyGraphicsView::mousePressEvent(QMouseEvent *event)
  27. {
  28.     //鼠标按下事件
  29.     if(event->button() == Qt::LeftButton) //判断鼠标按下的是左键
  30.     {
  31.         QPoint point = event->pos(); //保存View此时的坐标
  32.         emit mouseClicked(point); //发送信号
  33.     }else if(event->button() == Qt::RightButton){  //判断鼠标按下的是右键
  34.         QPoint poind = event->pos();
  35.         emit mouseRightClicked(poind);
  36.     }
  37.     QGraphicsView::mousePressEvent(event);
  38. }
  39.  
  40. void MyGraphicsView::mouseReleaseEvent(QMouseEvent *event)
  41. {
  42.     if(event->button() == Qt::LeftButton) //判断鼠标释放的是左键
  43.     {
  44.         QPoint point = event->pos(); //保存View此时的坐标
  45.         emit mouseRelease(point); //发送信号
  46.     }
  47.     QGraphicsView::mouseReleaseEvent(event);
  48. }
  49.  
  50. void MyGraphicsView::mouseDoubleClickEvent(QMouseEvent *event)
  51. {
  52.     //鼠标双击事件
  53.     if(event->button() == Qt::LeftButton)
  54.     {
  55.         QPoint point = event->pos();//保存View此时的坐标
  56.         emit mouseDoubleClick(point); //发送信号
  57.     }
  58.     QGraphicsView::mouseDoubleClickEvent(event);
  59. }
  60.  
  61. void MyGraphicsView::keyPressEvent(QKeyEvent *event)
  62. {
  63.     emit keyPress(event);
  64.     QGraphicsView::keyPressEvent(event);
  65. }
  66.  
  67. void MyGraphicsView::drawBackground(QPainter *painter, const QRectF &r)
  68. {
  69.     QGraphicsView::drawBackground(painter, r);
  70.     auto drawGrid = [&](double gridStep){
  71.         QRect windowRect = rect();
  72.         QPointF tl = mapToScene(windowRect.topLeft());
  73.         QPointF br = mapToScene(windowRect.bottomRight());
  74.         double left = std::floor(tl.x() / gridStep - 0.5);
  75.         double right = std::floor(br.x() / gridStep + 1.0);
  76.         double bottom = std::floor(tl.y() / gridStep - 0.5);
  77.         double top = std::floor(br.y() / gridStep + 1.0);
  78.         //垂直线
  79.         for(int xi = int(left); xi <= int(right); ++xi){
  80.             QLine line(xi * gridStep, bottom * gridStep, xi * gridStep, top * gridStep);
  81.             painter->drawLine(line);
  82.         }
  83.         //水平线
  84.         for(int yi = int(bottom); yi<= int(top); ++yi){
  85.             QLine line(left * gridStep, yi * gridStep, right * gridStep, yi * gridStep);
  86.             painter->drawLine(line);
  87.         }
  88.     };
  89.     QPen pfine(FineGridColor, 1.0);
  90.     painter->setPen(pfine);
  91.     drawGrid(15);
  92.     QPen p(CoarseGridColor, 1.0);
  93.     painter->setPen(p);
  94.     drawGrid(150);
  95. }

结尾

       这是学习QT之后跟着写的一个小项目，很多地方还有bug,这篇文章只能做一个参考，谢谢！如对你有用，可以点一个小小赞，非常感谢！

       注：如有侵权，请联系本人删除此文章。

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