QT使用QPainter加水印

加水印的代码

//为QPixmap添加水印
void MainWindow::addMask(QPixmap& pm, const QString& text)
{
    QPainter painter(&pm);
    int fontSize = 25, spacing = 10;
    QFont font("微软雅黑", fontSize, QFont::Thin);
    font.setLetterSpacing(QFont::AbsoluteSpacing, spacing);
    painter.setFont(font);
    painter.setPen(QColor(150, 150, 150));
    painter.translate(pm.width() / 2, -pm.width() / 2);//调整位置
    painter.rotate(45);
    int squareEdgeSize = pm.width() * sin(45.0) + pm.height() * sin(45.0);//对角线长度
    int hCount = squareEdgeSize / ((fontSize + spacing) * (text.size() + 1)) + 1;
    int x = squareEdgeSize / hCount + (fontSize + spacing) * 3;
    int y = x / 2;

    for (int i = 0; i < hCount; i++)
    {
        for (int j = 0; j < hCount * 2; j++)
        {
           painter.drawText(x * i, y * j,text);
        }
    }
}
//给某个路径的图片添加水印
void MainWindow::addMaskByPath(QString& imgPath, const QString& text)
{
    QFileInfo newPicture(imgPath);
    QPixmap qpm = FaceIdentityUtils::readImage(imgPath);
    MainWindow::addMask(qpm, text);
    QFile file(imgPath);
    file.open(QIODevice::WriteOnly);
    qpm.save(&file, "JPEG");
    file.close();
}