如何在Qt中的特定座標上顯示圖像？

Question

我有這樣的對話窗口類的Qt：

class Board : public QDialog 
{ 
    Q_OBJECT 

public: 
    explicit Board(QWidget *parent = 0); 
    ~Board(); 

private: 
    Ui::Board *ui; 

    void mousePressEvent(QMouseEvent *mouseEvent); 
}; 

我想dislay用戶給定座標PNG圖像的功能mousePressEvent，這被稱爲每當用戶點擊對話窗口上的某個地方。所以我需要像displayImage("path/to/image.png", coordX, coordY);。我該怎麼做？

新代碼：

class Board : public QDialog 
{ 
public: 
    Board(QWidget *parent = 0) : 
    QDialog(parent), 
    ui(new Ui::Board), 
    view(&scene) 
{ 
    // Set background image 
    /**************/ 
    ui->setupUi(this); 

    QPixmap pix("path/background.png"); 
    ui->label_board->setPixmap(pix); 

    /**************/ 
    /Set layout for displaying other images on the background 
    QVBoxLayout *layout = new QVBoxLayout(this); 
    layout->addWidget(&view); 
    //or set the layout and the view in the designer if using Qt Creator 
} 

protected: 
virtual void mousePressEvent(QMouseEvent *mouseEvent) override 
{ 
    QGraphicsPixmapItem *item = new QGraphicsPixmapItem(QPixmap("path/to/image.png")); 
    scene.addItem(item); 
    item->setPos(coordX, coordY); 
} 

private: 
    Ui::Board *ui; 
    QGraphicsScene scene; 
    QGraphicsView view; 
}; 

的label_board是500×500的標籤設置爲使用Qt Designer一些位置。

Answer 1

您將需要使用QGraphicsView（docs）和QGraphicsScene（docs）：

class Board : public QDialog 
{ 
public: 
    Board(QWidget *parent = 0) : 
     QDialog(parent), 
     ui(new Ui::Board), 
     view(&scene) 
    { 
     QVBoxLayout *layout = new QVBoxLayout(this); 
     layout->addWidget(&view); 
     //or set the layout and the view in the designer if using Qt Creator 

     //EDIT: add background like this first 
     QGraphicsPixmapItem *background = QGraphicsPixmapItem(QPixmap("path/to/background.png")); 
     scene.addItem(background); 
     background.setPos(0, 0); //position it to cover all the scene so at 0,0 which is the origin point 
     background.setScale(2.0); //scale the image to the scene rectangle to fill it 
     background.setZValue(-0.1); //to ensure it is always at the back 
    } 

protected: 
    virtual void mousePressEvent(QMouseEvent *mouseEvent) override 
    { 
     QGraphicsPixmapItem *item = new QGraphicsPixmapItem(QPixmap("path/to/image.png")); 
     scene.addItem(item); 
     item->setPos(coordX, coordY); 
    } 

private: 
    Ui::Board *ui; 
    QGraphicsScene scene; 
    QGraphicsView view; 
}; 

這是相當多了。另請注意，該位置是該項目左上角的位置（圖像）。如果你想要居中，你需要根據物品的比例（圖像）來調整位置。