Qt编程点积

QPixmap绘制图形：

#include
#include
#include

class MyWidget : public QWidget
{
public:
    MyWidget(QWidget *parent = 0);
protected:
 void mouseMoveEvent(QMouseEvent *event);
    void paintEvent(QPaintEvent *event);
private:
    int x,y;
    QPixmap pixmap;
    QPixmap background;
 QPixmap pixImg;
 QBitmap bitImg;
 QImage image;
};
// 在构造函数中装入背景图
MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
{
 resize(800,600);
 pixmap = QPixmap(100,50);
 background = QPixmap("background.jpg");
 pixImg = QPixmap("tt.gif");
 bitImg = QBitmap("tt.gif");

 image = QImage(3, 3, QImage::Format_RGB32);
 QRgb value;
 value = qRgb(189, 149, 39); // 0xffbd9527
 image.setPixel(1, 1, value);
 value = qRgb(122, 163, 39); // 0xff7aa327
 image.setPixel(0, 1, value);
 image.setPixel(1, 0, value);
 value = qRgb(237, 187, 51); // 0xffedba31
 image.setPixel(2, 1, value);

 x = -1;
 y = -1;
}
// 鼠标移动时形成一个pixmap
void MyWidget::mouseMoveEvent(QMouseEvent *event)
{
 x = event->x();
 y = event->y();
 pixmap.fill(QColor(0,255,255,127));
 QPainter painter(&pixmap);
 painter.setPen(QColor(255,0,0,127));
 painter.drawText(20, 40, QString("%1").arg(x) + "," +
  QString("%1").arg(y));
 update(); 
}
// 绘制背景图和透明的pixmap
void MyWidget::paintEvent(QPaintEvent *event)
{
 QPainter painter(this);
 painter.drawPixmap(0, 0, background);
 painter.drawPixmap(x, y, pixmap);
 painter.drawPixmap(20, 10, pixImg);
 painter.drawPixmap(20, 60, bitImg);
 QRectF rc(50,50, 100, 100);
 painter.drawImage( rc, image);
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QTextCodec::setCodecForTr(QTextCodec::codecForLocale());
    MyWidget widget;
    widget.setMouseTracking(true);
    widget.show();

 QPicture picture;
 QPainter painter;
 painter.begin(&picture);
 painter.drawRect(10, 20, 100, 50);
 painter.end();
 picture.save("draw_record.pic");

    return app.exec();
}