Qt 使用QGraphicsPixmapItem、QGraphicsScene、QMatrix 的QGraphicsView的显示，缩放

.h

    QGraphicsScene *scene; 2     QGraphicsPixmapItem *theFrame; 3     QMatrix matrix;

.cpp

MainWindow::MainWindow(QWidget *parent) :  2  QMainWindow(parent),  3     ui(new Ui::MainWindow)  4 {  5     ui->setupUi(this);  6 　　 // 初始化
    scene = new QGraphicsScene(this);  8     theFrame = new QGraphicsPixmapItem();  9     theFrame->setFlag(QGraphicsPixmapItem::ItemIsSelectable, false); 10     theFrame->setFlag(QGraphicsPixmapItem::ItemIsMovable, false); 11     theFrame->setFlag(QGraphicsPixmapItem::ItemSendsGeometryChanges); 12 
    scene->addItem(theFrame); 14 
    scene->setSceneRect(0,0,4096,2160);//设置 scene 尺寸

    matrix.scale(0.1, 0.1); //缩放比例
    ui->graphicsView->setMatrix(matrix); 19     ui->graphicsView->scale(1,-1); 20     ui->graphicsView->setScene(scene); 21     ui->graphicsView->show(); 22 }

刷新图像

theFrame->setPixmap(Pixmap);