需求描述

在場景中實現拖動，縮放，并在場景的縮略圖中顯示其對應在視口中顯示的矩形區域。
程序效果圖如下：

開發環境：Qt 5.13.1
編譯環境：MinGW64
項目結構：

直接上程序:
main.cpp

#include "dialog.h" #include "log.hpp" #include <QMutex> #include <QDateTime> #include <QFile>#include <QApplication> void MessageTypePut(QtMsgType type, const QMessageLogContext &context, const QString &msg); int main(int argc, char *argv[]) { #ifdef OUTPUT_LOGqInstallMessageHandler(MessageTypePut); #endifQApplication a(argc, argv);Dialog w;w.show();return a.exec(); }void MessageTypePut(QtMsgType type, const QMessageLogContext &context, const QString &msg) { // getCurrFilePath();static QMutex mutex;mutex.lock();QString text;switch(type){case QtDebugMsg:text = QString("Debug:");break;case QtWarningMsg:text = QString("Warning:");break;case QtCriticalMsg:text = QString("Critical:");break;case QtFatalMsg:text = QString("Fatal:");break;default:break;}//日志寫到文件QString current_date_time = QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss");QString message = QString("%1 %2%3").arg(current_date_time).arg(text).arg(msg);QFile file(LOG_FILE);file.open(QIODevice::WriteOnly | QIODevice::Append);QTextStream text_stream(&file);text_stream << message << "\r\n";file.flush();//將緩沖的數據刷新到文件file.close();mutex.unlock(); }

breviarydlg.h

#ifndef BREVIARYDLG_H #define BREVIARYDLG_H#include <QDialog> #include "graphicsview.h"//視口的長寬比需要與縮略圖的長寬比保持一致 #define SMALL_W 400 #define SMALL_H 400//class QGraphicsScene; class MyGraphicsScene; class QGraphicsView; class QGraphicsPixmapItem;class BreviaryDlg : public QDialog {Q_OBJECT public:BreviaryDlg(QWidget *parent = nullptr, Qt::WindowFlags f = Qt::WindowFlags());void setSize(int w,int h);void setPosSize(int x,int y,int w,int h);void setPixmap(QPixmap &pix);QSize getSize();void fitInView();void transViewPtr(GraphicsView *view); protected:void resizeEvent(QResizeEvent *event); // void paintEvent(QPaintEvent *event); public slots:void slot_setRectSize(QRect &rect); private:QPixmap m_pixmap; // bool isUpdate;QRect m_rect; // QGraphicsScene *scene;MyGraphicsScene *scene;QGraphicsView *view;QGraphicsPixmapItem *item;GraphicsView *m_view1; }; #endif // BREVIARYDLG_H

breviarydlg.cpp

#include "breviarydlg.h" #include <QPalette> #include <QPainter> #include <QDebug> #include <QGraphicsRectItem> #include "MyGraphicsScene.h" #include <QGraphicsView>BreviaryDlg::BreviaryDlg(QWidget *parent, Qt::WindowFlags f):QDialog(parent,f)/*,isUpdate(false)*/ {resize(SMALL_W,SMALL_H);setWindowFlag(Qt::FramelessWindowHint);//因為是場景所以加載背景會被場景覆蓋，另外設置了無邊框之后，場景也會覆蓋窗口可以不用重繪窗口QPalette palette = this->palette();palette.setColor(QPalette::Background,QColor(34,34,34));setWindowOpacity(0.8);setPalette(palette);scene = new MyGraphicsScene(this); // scene->setBackgroundBrush(QBrush(QColor(Qt::red))); // scene->setForegroundBrush(QBrush(QColor(Qt::red))); // scene->setSceneRect(0,0,400,400);view = new QGraphicsView(scene,this);view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);view->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);view->setGeometry(0,0,SMALL_W,SMALL_H);item = NULL; }void BreviaryDlg::setSize(int w, int h) { // resize(w,h);setFixedSize(w,h); }void BreviaryDlg::setPosSize(int x, int y, int w, int h) {setGeometry(x,y,w,h); }QSize BreviaryDlg::getSize() {return QSize(SMALL_W,SMALL_H); }void BreviaryDlg::setPixmap(QPixmap &pix) {m_pixmap = pix; // isUpdate = true;qDebug()<<"setPixmap";if (item != NULL){scene->removeItem(item);delete item;}if(m_pixmap.isNull()){qDebug()<<"pixmap is null";}/*加載Pixmap圖片加載不上去，畫布的大小與圖片的尺寸不一*/item = scene->addPixmap(m_pixmap);//QPixmap(":/new/prefix1/11.png")fitInView(); }void BreviaryDlg::fitInView() {QRectF bounds = view->scene()->itemsBoundingRect();view->fitInView(bounds, Qt::KeepAspectRatio); }void BreviaryDlg::transViewPtr(GraphicsView *view) {m_view1 = new GraphicsView;m_view1 = view;connect(scene,&MyGraphicsScene::previewRectMoved,m_view1,&GraphicsView::slot_MoveView); }void BreviaryDlg::resizeEvent(QResizeEvent *event) {QDialog::resizeEvent(event);fitInView(); }//void BreviaryDlg::paintEvent(QPaintEvent *event) //{ // QPainter painter(this); // QPen pen(QColor(34,34,34));//34,34,34 // pen.setWidth(2); // pen.setStyle(Qt::SolidLine);// painter.drawRect(0,0,SMALL_W,SMALL_H); //}void BreviaryDlg::slot_setRectSize(QRect &rect) {m_rect = rect;scene->onSetPreviewRect(rect); }

config.h

#ifndef CONFIG_H #define CONFIG_H#include <QSettings> #include <QVariant>class Config {public:Config(QString qstrfilename = "");virtual ~Config(void);void Set(QString,QString,QVariant);QVariant Get(QString,QString); private:QString m_qstrFileName;QSettings *m_psetting; };#endif // CONFIG_H

config.cpp

#include "config.h" #include <QCoreApplication> #include <QDebug>Config::Config(QString qstrfilename) {if (qstrfilename.isEmpty()){m_qstrFileName = QCoreApplication::applicationDirPath() + "/Config.ini";}else{m_qstrFileName = qstrfilename;}m_psetting = new QSettings(m_qstrFileName, QSettings::IniFormat);qDebug() << m_qstrFileName; } Config::~Config() {delete m_psetting;m_psetting = 0; } void Config::Set(QString qstrnodename,QString qstrkeyname,QVariant qvarvalue) {m_psetting->setValue(QString("/%1/%2").arg(qstrnodename).arg(qstrkeyname), qvarvalue); }QVariant Config::Get(QString qstrnodename,QString qstrkeyname) {QVariant qvar = m_psetting->value(QString("/%1/%2").arg(qstrnodename).arg(qstrkeyname));return qvar; }

dialog.h

#ifndef DIALOG_H #define DIALOG_H#include <QDialog> #include <QGraphicsScene> #include "graphicsview.h" #include "breviarydlg.h" #include <QTimer>struct stuRatio{qreal xRatio;qreal yRatio; };#define SMALL_W 400 #define SMALL_H 400class QVideoWidget; class QMediaPlayer;QT_BEGIN_NAMESPACE namespace Ui { class Dialog; } QT_END_NAMESPACEclass Dialog : public QDialog {Q_OBJECTpublic:Dialog(QWidget *parent = nullptr);~Dialog();// void drawRect();stuRatio getScalingRatio();signals:void signalDrawRect(QRect &rect);void signalSetDrawRectSize(); private slots:void slot_createNaviBar(qreal scale);void slot_HvalueChanged(int value);void slot_VvalueChanged(int value);void slot_scrollValueChanged();void slot_setViewRect();void slot_timeout(); private:Ui::Dialog *ui;QGraphicsScene *scene;GraphicsView *view;QVideoWidget *video;QMediaPlayer *player;BreviaryDlg *dlg;QTimer *timer;qreal m_scale;QRect rectViewport;quint32 m_y;quint32 m_x;QSize m_viewSize;QString str; }; #endif // DIALOG_H

dialog.cpp

#include "dialog.h" #include "ui_dialog.h" #include "log.hpp" #include <QScrollBar> #include <QSize> #include <QGraphicsProxyWidget> #include <QMediaPlayer> #include <QVideoWidget> //#include <QGraphicsRectItem> #include <QGraphicsVideoItem> #include <QPainter>Dialog::Dialog(QWidget *parent): QDialog(parent), ui(new Ui::Dialog),m_x(0),m_y(0),m_viewSize(100,100) {ui->setupUi(this);resize(QSize(1200,1000));scene = new QGraphicsScene(this);view = new GraphicsView(scene,this);//設置了視圖的父窗口之后就不需要調用show() // scene->setSceneRect(0,0,800,800); // view->setGeometry(0,0,800,800); // view->show();//場景中播放視頻 // QGraphicsRectItem *item = new QGraphicsRectItem(0,0,500,500);//item中手動嵌入的窗口的大小不會隨item大小一致// video = new QVideoWidget(this); // video->setWindowFlag(Qt::WindowStaysOnTopHint); // video->resize(500,500); // player = new QMediaPlayer(this); // player->setVideoOutput(video); // player->setMedia(QUrl::fromLocalFile("F:\\video\\漢化日記：第2話.mp4")); // player->play();// QGraphicsProxyWidget *proxy = new QGraphicsProxyWidget(item); // proxy->setWidget(video); // scene->addItem(item);//場景中播放視頻的正確打開方式QGraphicsVideoItem *item = new QGraphicsVideoItem();scene->addItem(item);item->setSize(QSizeF(800.0,800.0));player = new QMediaPlayer(this);player->setVideoOutput(item);player->setMedia(QUrl::fromLocalFile("F:\\video\\漢化日記：第2話.mp4"));player->play();connect(view,&GraphicsView::sinalCreateNavigaBar,this,&Dialog::slot_createNaviBar);dlg = NULL;str = QCoreApplication::applicationDirPath();str += "\\11.png";outPut<<"路徑名："<<str;timer = new QTimer;connect(timer,&QTimer::timeout,this,&Dialog::slot_timeout);connect(view->verticalScrollBar(),&QScrollBar::valueChanged,this,slot_VvalueChanged);connect(view->horizontalScrollBar(),&QScrollBar::valueChanged,this,slot_HvalueChanged);connect(this,&Dialog::signalSetDrawRectSize,this,&Dialog::slot_setViewRect); }Dialog::~Dialog() {delete ui; }void Dialog::slot_createNaviBar(qreal scale) {if(scale > 1){m_scale = scale;if(dlg == NULL){dlg = new BreviaryDlg(this,Qt::WindowStaysOnTopHint);// dlg->setGeometry(100,200,400,300);// dlg->setSize(400,300);connect(this,&Dialog::signalDrawRect,dlg,&BreviaryDlg::slot_setRectSize);// QImage image(QSize(400,300),QImage::Format_RGB32);// QPainter painter(&image);// image.save("E:\\11","png");// view->setViewport(dlg);// dlg->setPosSize(600,500,400,300);// QPalette palette = dlg->palette();// palette.setColor(QPalette::Background,QColor(34,34,34));// dlg->setWindowOpacity(0.8);// dlg->setPalette(palette);QSize size = dlg->getSize();view->smallWinSize(size);dlg->transViewPtr(view);dlg->show();//非模態}else{dlg->show();}QPixmap pixmap(SMALL_W,SMALL_H);pixmap.fill(Qt::transparent);QPainter painter(&pixmap);painter.setRenderHint(QPainter::Antialiasing);scene->render(&painter);pixmap.save(str,"png");dlg->setPixmap(pixmap);timer->start(100);}else{if(dlg != NULL){dlg->hide();}} }void Dialog::slot_scrollValueChanged() {m_viewSize = view->viewportSizeHint();//獲取視口大小QRect rectScene = scene->itemsBoundingRect().toRect();if (view->horizontalScrollBar()->isHidden()){rectViewport.setX(rectScene.x());rectViewport.setWidth(rectScene.width());}if(view->verticalScrollBar()->isHidden()){rectViewport.setY(0);rectViewport.setHeight(rectScene.height());}emit signalSetDrawRectSize(); }void Dialog::slot_HvalueChanged(int value) {m_viewSize = view->viewportSizeHint();//獲取視口大小outPut<<"slot_HvalueChanged"<<" "<<m_viewSize<</*" "<<rect<<" "<<*/value;if(value != 0 && dlg != NULL){if(dlg->isVisible()){m_x = value;emit signalSetDrawRectSize();}} }void Dialog::slot_VvalueChanged(int value) {m_viewSize = view->viewportSizeHint();//獲取視口大小 // QRect rect = view->viewPortRect();outPut<<"slot_VvalueChanged"<<" "<<m_viewSize<</*" "<<rect<<" "<<*/value;if(value != 0 && dlg != NULL){if(dlg->isVisible()){m_y = value;emit signalSetDrawRectSize();}} }void Dialog::slot_setViewRect() {view->viewPortSize(m_viewSize);int x = m_x / (m_viewSize.width() * m_scale)* SMALL_W;int y = m_y / (m_viewSize.height() * m_scale)* SMALL_H;int wid = SMALL_W / m_scale;int hei = SMALL_H / m_scale;outPut<<"小矩形坐標及大小："<<"("<<m_x<<" ,"<<m_y<<" ,"<<wid<<" ,"<<hei<<")";QRect rect(x,y,wid,hei);emit signalDrawRect(rect); }stuRatio Dialog::getScalingRatio() {stuRatio ratio;ratio.xRatio = (qreal)SMALL_W / m_viewSize.width();ratio.yRatio = (qreal)SMALL_H / m_viewSize.height();outPut<<"橫縱比："<<ratio.xRatio<<" "<<ratio.yRatio;return ratio; }void Dialog::slot_timeout() {QPixmap pixmap(SMALL_W,SMALL_H);pixmap.fill(Qt::transparent);QPainter painter(&pixmap);painter.setRenderHint(QPainter::Antialiasing);scene->render(&painter);pixmap.save(str,"png");dlg->setPixmap(pixmap); }

graphicsview.h

#ifndef GRAPHICSVIEW_H #define GRAPHICSVIEW_H #include <QGraphicsView> #include <QGraphicsScene> #include <QEvent> #include "config.h" //#pragma execution_characters_set("utf-8") class GraphicsView : public QGraphicsView {Q_OBJECT public:GraphicsView(QWidget *parent = nullptr);GraphicsView(QGraphicsScene *scene, QWidget *parent = nullptr); #if QT_CONFIG(wheelevent)void wheelEvent(QWheelEvent *) override; #endifvoid setIsWheel(bool isScroll);//是否可以滾動//多邊形面積qreal PolygonArea(QList<QPointF>&posList);QSize viewportSizeHint();QRect viewPortRect();void viewPortSize(QSize &size);void smallWinSize(QSize &size); protected:bool event(QEvent *event); // void paintEvent(QPaintEvent *event); signals:void signalTransScale(qreal scale);void sinalCreateNavigaBar(qreal scale);//創建縮略圖 public slots:void slot_MoveView(QRect rect); //protected: // void mouseMoveEvent(QMouseEvent *event); // void mousePressEvent(QMouseEvent *event); // void mouseReleaseEvent(QMouseEvent *event); private: // QPointF beginPoint;bool m_isScroll;//是否可以執行滾輪放大縮小事件QPointF previous_touch_point0;QPointF previous_touch_point1;int touch_status = 0;qreal m_scale;//保存縮放比qreal firstArea;//剛接觸時多邊形面積Config *config;qreal upLimit;//放大的上限qreal lowLimit;//縮小的下限QSize m_viewPortWH;//視口的寬高QSize m_smallWinWH;//小窗口的寬高 }; #endif // GRAPHICSVIEW_H

graphicsview.cpp

#include "graphicsview.h" #include "log.hpp" #include <QWheelEvent> #include <QScrollBar> #include <QTouchEvent> #include <QLineF>#if QT_CONFIG(wheelevent) void GraphicsView::wheelEvent(QWheelEvent *e) {if(!m_isScroll){return ;}if (e->modifiers() & Qt::ControlModifier){qreal curScale = m_scale;if (e->delta() > 0)//遠離{if(curScale < upLimit){m_scale *= 1.2;emit sinalCreateNavigaBar(m_scale);scale(1.2,1.2); // m_scale *= 1.2;}}else{if(curScale > lowLimit){m_scale *= 0.8;emit sinalCreateNavigaBar(m_scale);scale(0.8,0.8);}}e->accept();}else{QGraphicsView::wheelEvent(e);} // if(m_scale > 2) // {emit sinalCreateNavigaBar(m_scale); // } // emit signalTransScale(1/m_scale); // outPut<<"視圖縮放的比例："<<1/m_scale; } #endifGraphicsView::GraphicsView(QWidget *parent):QGraphicsView(parent),m_isScroll(true),touch_status(0),m_scale(1),firstArea(1) {config = new Config();upLimit = config->Get("viewScale","upScale").toFloat();lowLimit = config->Get("viewScale","lowScale").toFloat();outPut<<"upLimit:"<<upLimit<<" "<<"lowLimit:"<<lowLimit;previous_touch_point0 = QPointF(0.0,0.0);previous_touch_point1 = QPointF(0.0,0.0);setAttribute(Qt::WA_AcceptTouchEvents);//捕獲touch事件 // setRenderHint(QPainter::Antialiasing, false);setDragMode(QGraphicsView::ScrollHandDrag);setOptimizationFlags(QGraphicsView::DontSavePainterState);setViewportUpdateMode(QGraphicsView::SmartViewportUpdate); }GraphicsView::GraphicsView(QGraphicsScene *scene, QWidget *parent):QGraphicsView(scene,parent),m_isScroll(true),touch_status(0),m_scale(1),firstArea(1) {config = new Config();upLimit = config->Get("viewScale","upScale").toFloat();lowLimit = config->Get("viewScale","lowScale").toFloat();outPut<<"upLimit:"<<upLimit<<" "<<"lowLimit:"<<lowLimit;previous_touch_point0 = QPointF(0.0,0.0);previous_touch_point1 = QPointF(0.0,0.0);setAttribute(Qt::WA_AcceptTouchEvents);//捕獲touch事件 // setRenderHint(QPainter::Antialiasing, false);setDragMode(QGraphicsView::ScrollHandDrag);setOptimizationFlags(QGraphicsView::DontSavePainterState);setViewportUpdateMode(QGraphicsView::SmartViewportUpdate); }void GraphicsView::setIsWheel(bool isScroll) {m_isScroll = isScroll; }qreal GraphicsView::PolygonArea(QList<QPointF> &posList) {QList<QPointF> tarPos;QList<QPointF> optList = posList;int nLen = posList.size();if(nLen==3){tarPos = posList;}else if(nLen>3){for(int i=0;i<optList.size()-1;++i)//按x點進行排序{for(int j=i+1;j<optList.size();++j){if(optList[j].x()<optList[i].x()){optList.swap(i,j);}}}for(int i=0;i<3-1;++i){for(int j=i+1;j<3;++j){if(optList[j].y()<optList[i].y()){optList.swap(i,j);}}tarPos.push_back(optList[i]);}tarPos.push_back(optList[2]);for(int i=3;i<optList.size()-1;++i){for(int j=i+1;j<optList.size();++j){if(optList[j].y()>optList[i].y()){optList.swap(i,j);}}tarPos.push_back(optList[i]);}tarPos.push_back(optList[optList.size()-1]);}qreal s=1;for(int k=0;k<nLen;++k){QPointF& pos1 = tarPos[k];QPointF& pos2 = tarPos[(k+1)%nLen];s +=(pos1.x()*pos2.y()-pos2.x()*pos1.y());}s=abs(0.5*s);return s; }QSize GraphicsView::viewportSizeHint() {return viewport()->size(); }QRect GraphicsView::viewPortRect() {return viewport()->rect(); }void GraphicsView::viewPortSize(QSize &size) {m_viewPortWH = size;outPut<<"視口："<<m_viewPortWH; }void GraphicsView::smallWinSize(QSize &size) {m_smallWinWH = size;outPut<<"窗口："<<m_smallWinWH; }bool GraphicsView::event(QEvent *event) {switch(event->type()){case QEvent::TouchBegin:{QTouchEvent* touch = static_cast<QTouchEvent*>(event);QList<QTouchEvent::TouchPoint> touchPoints = touch->touchPoints();outPut<<"TouchBegin點的個數為："<<touchPoints.count();return true;}case QEvent::TouchUpdate:{QTouchEvent *touchEvent = static_cast<QTouchEvent *>(event);QList<QTouchEvent::TouchPoint> touchPoints = touchEvent->touchPoints();outPut<<"TouchUpdate點的個數為："<<touchPoints.count();if (touchPoints.count() == 2 /*&& touch_status == 1*/){if(touchEvent->touchPointStates() & Qt::TouchPointPressed){const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first();const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last();previous_touch_point0.setX(touchPoint0.pos().x());previous_touch_point0.setY(touchPoint0.pos().y());previous_touch_point1.setX(touchPoint1.pos().x());previous_touch_point1.setY(touchPoint1.pos().y());outPut<<"剛開始點：("<<previous_touch_point0.x()<<","<<previous_touch_point0.y()<<")"<<"("<<previous_touch_point1.x()<<","<<previous_touch_point1.y()<<")";touch_status=2;}if(touchEvent->touchPointStates() & Qt::TouchPointMoved){if(touch_status == 2){const QTouchEvent::TouchPoint &touchPoint0 = touchPoints.first();const QTouchEvent::TouchPoint &touchPoint1 = touchPoints.last();qreal currentScaleFactor =QLineF(touchPoint0.pos(), touchPoint1.pos()).length()/ QLineF(previous_touch_point0, previous_touch_point1).length(); // qreal proper = currentScaleFactor>1?1.05:0.8;outPut<<"起點："<<touchPoint0.pos()<<touchPoint1.pos();outPut<<"移動后：("<<previous_touch_point0.x()<<","<<previous_touch_point0.y()<<")"<<"("<<previous_touch_point1.x()<<","<<previous_touch_point1.y()<<")";outPut<<"起點線長："<<QLineF(touchPoint0.pos(), touchPoint1.pos()).length();outPut<<"移動后線長："<<QLineF(previous_touch_point0, previous_touch_point1).length();outPut<<"縮放參考點為："<<currentScaleFactor;if(currentScaleFactor > 1){if(m_scale < upLimit){scale(1.2,1.2);m_scale *= 1.2;}}else{if(m_scale > lowLimit){scale(0.8,0.8);m_scale *= 0.8;}}// scale(proper,proper);previous_touch_point0.setX(touchPoint0.pos().x());previous_touch_point0.setY(touchPoint0.pos().y());previous_touch_point1.setX(touchPoint1.pos().x());previous_touch_point1.setY(touchPoint1.pos().y());}}}if (touchPoints.count() == 3){if(touchEvent->touchPointStates() & Qt::TouchPointPressed){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}firstArea = PolygonArea(pointList);touch_status = 3;}if(touchEvent->touchPointStates() & Qt::TouchPointMoved){if(touch_status == 3){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}qreal lastArea = PolygonArea(pointList);qreal currentScaleFactor = lastArea / firstArea;outPut<<"剛開始面積："<<firstArea;outPut<<"變化后面積："<<lastArea;outPut<<"面積比："<<currentScaleFactor; // qreal proper = currentScaleFactor>1?1.05:0.8; // scale(proper,proper);if(currentScaleFactor > 1){if(m_scale < upLimit){scale(1.2,1.2);m_scale *= 1.2;}}else{if(m_scale > lowLimit){scale(0.8,0.8);m_scale *= 0.8;}}firstArea = lastArea;}}}if (touchPoints.count() == 4){if(touchEvent->touchPointStates() & Qt::TouchPointPressed){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}firstArea = PolygonArea(pointList);touch_status = 4;}if(touchEvent->touchPointStates() & Qt::TouchPointMoved){if(touch_status == 4){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}qreal lastArea = PolygonArea(pointList);qreal currentScaleFactor = lastArea / firstArea;outPut<<"剛開始面積："<<firstArea;outPut<<"變化后面積："<<lastArea;outPut<<"面積比："<<currentScaleFactor; // qreal proper = currentScaleFactor>1?1.05:0.8; // scale(proper,proper);if(currentScaleFactor > 1){if(m_scale < upLimit){scale(1.2,1.2);m_scale *= 1.2;}}else{if(m_scale > lowLimit){scale(0.8,0.8);m_scale *= 0.8;}}firstArea = lastArea;}}}if (touchPoints.count() == 5){if(touchEvent->touchPointStates() & Qt::TouchPointPressed){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}firstArea = PolygonArea(pointList);touch_status = 5;}if(touchEvent->touchPointStates() & Qt::TouchPointMoved){if(touch_status == 5){QList<QPointF> pointList;QPointF siglePoint;for(int i = 0; i < touchPoints.size(); ++i){siglePoint = touchPoints[i].pos();pointList.push_back(siglePoint);}qreal lastArea = PolygonArea(pointList);qreal currentScaleFactor = lastArea / firstArea;outPut<<"剛開始面積："<<firstArea;outPut<<"變化后面積："<<lastArea;outPut<<"面積比："<<currentScaleFactor; // qreal proper = currentScaleFactor>1?1.05:0.8; // scale(proper,proper);if(currentScaleFactor > 1){if(m_scale < upLimit){scale(1.2,1.2);m_scale *= 1.2;}}else{if(m_scale > lowLimit){scale(0.8,0.8);m_scale *= 0.8;}}firstArea = lastArea;}}}else if(touchEvent->touchPointStates() & Qt::TouchPointReleased){touch_status=0;}event->accept();return true;}case QEvent::TouchEnd:{event->accept();return true;}default:break;}return QGraphicsView::event(event);//QWidget::event(event); }void GraphicsView::slot_MoveView(QRect rect) {verticalScrollBar()->setValue(rect.y()*m_scale*m_viewPortWH.height()/m_smallWinWH.height());horizontalScrollBar()->setValue(rect.x()*m_scale*m_viewPortWH.width()/m_smallWinWH.width()); }//void GraphicsView::mouseMoveEvent(QMouseEvent *event) //{ // if(event->buttons() & Qt::LeftButton) // { // QPointF pos = event->screenPos(); // qreal x = pos.x() - beginPoint.x(); // qreal y = pos.y() - beginPoint.y();// QScrollBar* verBar = verticalScrollBar(); // int nValue = verBar->value(); // verBar->setValue(nValue - y);// QScrollBar* horBar = horizontalScrollBar(); // nValue = horBar->value(); // horBar->setValue(nValue - x); // } // QGraphicsView::mouseMoveEvent(event); //}//void GraphicsView::mousePressEvent(QMouseEvent *event) //{ // if(event->button() == Qt::LeftButton) // { // beginPoint = event->screenPos(); // } // QGraphicsView::mousePressEvent(event); //}//void GraphicsView::mouseReleaseEvent(QMouseEvent *event) //{ // QGraphicsView::mouseReleaseEvent(event); //}

MyGraphicsScene.h

#pragma once//#include <vld.h> #include <QGraphicsScene>class MyGraphicsScene : public QGraphicsScene {Q_OBJECTpublic:MyGraphicsScene(QObject *parent = nullptr);virtual void mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent);virtual void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent);virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent);Q_SIGNALS:void previewRectMoved(QRect rect);public Q_SLOTS:void onSetPreviewRect(QRect rect);private:QGraphicsRectItem* m_pRectItem;QRect m_rectSaved;bool m_bRectClicked;QPoint m_ptRectRelated; // 鼠標點擊時，相對于紅色矩形框的位置 };

MyGraphicsScene.cpp

#include "MyGraphicsScene.h" #include <QGraphicsSceneMouseEvent> #include <QGraphicsRectItem> #include <QDebug>MyGraphicsScene::MyGraphicsScene(QObject *parent): QGraphicsScene(parent), m_bRectClicked(false) {m_pRectItem = new QGraphicsRectItem(0, 0, 0, 0);QPen penRectItem = QPen(QColor(255, 0, 0));penRectItem.setWidth(2);m_pRectItem->setPen(penRectItem);m_pRectItem->setZValue(1);addItem(m_pRectItem); }void MyGraphicsScene::onSetPreviewRect(QRect rect) {m_rectSaved = rect;// 內縮幾個像素，用矩形外邊框來標示viewport顯示區域m_pRectItem->setRect(rect.x() -2/*+ 5*/, rect.y() - 2/*+ 5*/, rect.width() - 4, rect.height() - 4); }void MyGraphicsScene::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent) {QGraphicsScene::mouseMoveEvent(mouseEvent);if (m_bRectClicked) {QPoint ptTopLeft = mouseEvent->scenePos().toPoint() - m_ptRectRelated;m_rectSaved.setTopLeft(ptTopLeft);emit previewRectMoved(m_rectSaved);} }void MyGraphicsScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent) {QGraphicsScene::mousePressEvent(mouseEvent);if (m_rectSaved.contains(mouseEvent->scenePos().x(), mouseEvent->scenePos().y())) {m_bRectClicked = true;m_ptRectRelated = mouseEvent->scenePos().toPoint() - m_rectSaved.topLeft();} }void MyGraphicsScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent) {QGraphicsScene::mouseReleaseEvent(mouseEvent);m_bRectClicked = false; }

所有程序的代碼上面已經全部貼出，由于還涉及到ui文件，所以要看運行效果，需先創建基于對話框QDialog的程序，在此基礎上修改添加創建對應的文件，另外還需注意，修改你本地的視頻所在路徑，并將配置文件拷貝到可執行目錄下，qt可能還不能直接運行，因為缺少解碼器，這時根據提示下載安裝解碼器，解決掉“那個”問題之后便可以運行，查看相應的效果。
注意：

修改需要你需要播放的視頻的路徑，重新指定需要播放的視頻；

將下面的配置文件拷貝到可執行目錄下。
Config.ini

[viewScale]
upScale = 3
lowScale = 0.3

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