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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。为了使其纵横比正确，当屏幕宽度改变时，高度也需要改变。

这会导致一个问题，因为屏幕在滚动区域内，当它的高度超过某个点时，滚动条就会进入。这会减小宽度，因此需要减小高度，这可能会导致滚动条出现循环不断进出。

我尝试解决此问题的一种方法是获取所需的大小并对负责计算和设置大小的函数的多次迭代进行平均，如果平均值与所需大小没有显着差异，则大小不会改变. 这已经解决了这个问题，但在我看来不是最佳的......

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();
}
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1 回答 1

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;
于 2013-02-12T09:01:32.793 回答