c++ - Qt调整窗口大小以适应滚动区域问题中的纵横比

Question

我使用 Qt 制作了一个预览对象，它是一个容器，里面有屏幕小部件。为了使其宽高比正确，当屏幕的宽度改变时，高度也需要改变。

这会导致问题，因为屏幕在滚动区域内，当它的高度超过某个点时，滚动条就会出现。这会减小宽度，因此需要减小高度，这可能会导致循环滚动条不断进出。

我尝试解决此问题的一种方法是获取所需的大小，并在负责计算和设置大小的函数的多次迭代中取平均值，如果平均值与所需的大小没有显着差异，则大小不会改变。这在某种程度上解决了问题，但在我看来并不是最佳选择......

我想知道是否有人知道如何解决这个问题？

//********************************************************************************
/// \brief Called to make the size of the preview pane the correct size
void PreviewDisplayWidget::SetSizeOfScreen()
{
  double aspect_ratio = _preview_controls->_video_settings.getVideoFormat().GetAspectRatio();

  // Calculate the new minimum size
  int minimum_size = _container->width()/aspect_ratio;

  // HACK TO FIX ISSUE WITH RESIZING:
  // The preview sets its height from the width, if the width is changed, so will the height.
  // This causes an issue with the scroll area as it can be in a situation that will cause the
  // scroll area to get thinner (due to scroll bars being added), causing the width of the widget
  // to change, therefore causing the height to change. Which can be enough to make the scroll bar go
  // away. This can loop and cause a stack overflow.
  //
  // Store the last 10 sizes.
  _previous_sizes.push_back(minimum_size);

  const int sizes_to_scan = 10;
  if (_previous_sizes.size() > sizes_to_scan)
  {
    _previous_sizes.pop_front();
  }

  int sum = 0;
  for (auto i =_previous_sizes.begin(); i != _previous_sizes.end(); i++)
  {
    sum += *i;
  }

  double average = (double) sum / (double) _previous_sizes.size();

  std::cout << "Average " << average << std::endl;

  bool change_in_average = false;
  // Significant change in average means a size change should occur
  if (average > minimum_size + 5 || average < minimum_size - 5)
  {
    change_in_average = true;
  }


  if (change_in_average || _previous_sizes.size() < sizes_to_scan - 1)
  {
    _preview_frame->setMinimumHeight(minimum_size);
    std::cout << "Preview sizes " << minimum_size << std::endl;
    _preview_frame->updateGeometry();
  }

  SetPreviewSize();
}

Answer 1

这行得通吗？

int minimum_size;

if(scrollArea->verticalScrollBar())
minimum_size = (_container->width()+scrollArea->verticalScrollBar()->width())/aspect_ratio;
else
minimum_size = _container->width()/aspect_ratio;