回调函数使用(三）

1.最近在研究太阳神三国杀源码，在三国杀的源码中采用很多函数指针的方式进行数据传递，感觉很实用，

class ConfigDialog : public FlatDialog {
    Q_OBJECT
public:
    ConfigDialog(QWidget *parent = 0);
    ~ConfigDialog();

private:
    Ui::ConfigDialog *ui;

    typedef void (ConfigDialog::*Callback) (const QVariant &); //采用QVariant类型可以任意转换
    QList<Callback> resetCallbacks; //保存函数指针
    QVariantList callbackArgs;     //保存参数
    void doCallback(Callback callback, const QVariant &oldValue, const QVariant &newValue);
    void setBackground(const QVariant &path);
    void on_resetBgButton_clicked();
}

ConfigDialog::ConfigDialog(QWidget *parent)
    : FlatDialog(parent, false), ui(new Ui::ConfigDialog)
{
    ui->setupUi(this);
}

void ConfigDialog::doCallback(ConfigDialog::Callback callback, const QVariant &oldValue, const QVariant &newValue)
{
    if (!resetCallbacks.contains(callback)) {
        resetCallbacks << callback;
        callbackArgs << oldValue;
    }
    (this->*callback)(newValue);//调用函数指针
}

//相应信号
void ConfigDialog::on_resetBgButton_clicked() {
    QString fileName = "image/backdrop/bg.jpg";
    if (fileName != ui->bgPathLineEdit->text())
        doCallback(&ConfigDialog::setBackground, Config.BackgroundImage, fileName);//进行函数的调用传递
}

void ConfigDialog::setBackground(const QVariant &path)
{
    QString fileName = path.toString();
    ui->bgPathLineEdit->setText(fileName);
    Config.BackgroundImage = fileName;

    emit bg_changed();
}

//如果没有保存数据的话，就感觉函数指针的保存内容进行还原
void ConfigDialog::discardSettings()
{
    const int n = resetCallbacks.size();
    for (int i = 0; i < n; ++i)
        (this->*(resetCallbacks[i]))(callbackArgs.at(i));

    resetCallbacks.clear();
    callbackArgs.clear();
}