c – 当数据添加到当前位置以上时,停止滚动QTableView

我的问题是这样的：如果我在一个列上排序表,然后滚动到一个特定的行,然后在该行上方添加更多行,它将该行向下推.数据进入速度足够快,以至于在没有光标下方的行更改的情况下,很难点击行来编辑它们.

有没有办法阻止表滚动并保持表相对于所选行的位置？

可以使用信号处理程序在插入行之前和之后检索它.

因此,可以在插入之后在信号处理器中相应地调整滚动.这样做会改变垂直滚动条的值. (垂直滚动模式更改为QTableView :: ScrollPerPixel以确保正确的垂直调整.)

最小代码示例：

#include <iostream>

#include <QApplication>
#include <QMainWindow>
#include <QScrollBar>
#include <QStandardItemModel>
#include <QTableView>
#include <QTimer>

enum { NCols = 2 }; // number of columns
enum { Interval = 1000 }; // interval of auto action
enum { NRep = 5 }; // how often selected auto action is repeated

// fills a table model with sample data
void populate(QStandardItemModel &tblModel, bool prepend)
{
  int row = tblModel.rowCount();
  if (prepend) tblModel.insertRow(0);
  for (int col = 0; col < NCols; ++col) {
    QStandardItem *pItem = new QStandardItem(QString("row %0, col %1").arg(row).arg(col));
    tblModel.setItem(prepend ? 0 : row, col, pItem);
  }
}

// does some auto action
void timeout(QTimer &timer, QStandardItemModel &tblModel)
{
  static int step = 0;
  ++step;
  std::cout << "step: " << step << std::endl;
  switch (step / NRep % 3) {
    case 0: break; // pause
    case 1: populate(tblModel, false); break; // append
    case 2: populate(tblModel, true); break; // prepend
  }
}

// managing the non-scrolling when something is inserted.
struct NoScrCtxt {
  QTableView &tblView;
  int y;
  NoScrCtxt(QTableView &tblView_): tblView(tblView_) { }

  void rowsAboutToBeInserted()
  {
    y = tblView.rowViewportPosition(tblView.currentIndex().row());
  }

  void rowsInserted()
  {
    int yNew = tblView.rowViewportPosition(tblView.currentIndex().row());
    if (y != yNew) {
      if (QScrollBar *pScrBar = tblView.verticalScrollBar()) {
        pScrBar->setValue(pScrBar->value() + yNew - y);
      }
    }
  }
};

int main(int argc, char **argv)
{
  QApplication app(argc, argv);
  // build some GUI
  QMainWindow win;
  QStandardItemModel tblModel(0, NCols);
  for (int i = 0; i < 10; ++i) populate(tblModel, false);
  QTableView tblView;
  tblView.setVerticalScrollMode(QTableView::ScrollPerPixel);
  tblView.setModel(&tblModel);
  win.setCentralWidget(&tblView);
  win.show();
  // setup a "no-scroll manager"
  NoScrCtxt ctxt(tblView);
  QObject::connect(&tblModel, &QStandardItemModel::rowsAboutToBeInserted,
    [&ctxt](const QModelIndex&, int, int) { ctxt.rowsAboutToBeInserted(); });
  QObject::connect(&tblModel, &QStandardItemModel::rowsInserted,
    [&ctxt](const QModelIndex&, int, int) { ctxt.rowsInserted(); });
  // initiate some auto action
  QTimer timer;
  timer.setInterval(Interval); // ms
  QObject::connect(&timer, &QTimer::timeout,
    [&timer, &tblModel]() { timeout(timer, tblModel); });
  timer.start();
  // exec. application
  return app.exec();
}

我在Windows 10,VS2013,Qt 5.7中编译并测试了它：