qt - 适用于大型模型的 QCompleter

Question

QCompleter 在大型数据集(大型模型)上运行速度稍慢:当我开始在 QCombobox 中输入字符时，它会花费几秒钟的时间来显示带有变体的自动完成弹出窗口，当输入第二个字符时，QCompleter 也不会在几秒钟内对按键使用react。接下来的角色效果很好。模型大小约为 100K 条记录。是否可以提高 QCompleter 性能或在第二个或第三个输入符号后显示弹出窗口？有一些好的例子吗？

Answer 1

解决方案类似于:https://stackoverflow.com/a/33404207/630169因为 QCompleter 也在其 popup() 中使用 QListView。因此，加速 QCombobox 的完整解决方案是:

调整组合:

void ComboboxTools::tweak(QComboBox *combo)
{
  //  For performance reasons use this policy on large models
  // or AdjustToMinimumContentsLengthWithIcon
  combo->setSizeAdjustPolicy(QComboBox::AdjustToMinimumContentsLength);

  // Improve combobox view performance
  tweak((QListView *)combo->view());

  // Improve combobox completer performance
  tweak(combo->completer());
}

调整下拉/弹出窗口( View ):

void ComboboxTools::tweak(QListView *view)
{
  // Improving Performance:  It is possible to give the view hints
  // about the data it is handling in order to improve its performance
  // when displaying large numbers of items. One approach that can be taken
  // for views that are intended to display items with equal sizes
  // is to set the uniformItemSizes property to true.
  view->setUniformItemSizes(true);
  // This property holds the layout mode for the items. When the mode is Batched,
  // the items are laid out in batches of batchSize items, while processing events.
  // This makes it possible to instantly view and interact with the visible items
  // while the rest are being laid out.
  view->setLayoutMode(QListView::Batched);
  // batchSize : int
  // This property holds the number of items laid out in each batch
  // if layoutMode is set to Batched. The default value is 100.
  // view->setBatchSize(100);
}

调整完成器:

void ComboboxTools::tweak(QCompleter *completer)
{
  completer->setCaseSensitivity(Qt::CaseInsensitive);
  // If the model's data for the completionColumn() and completionRole() is sorted
  // in ascending order, you can set ModelSorting property
  // to CaseSensitivelySortedModel or CaseInsensitivelySortedModel.
  // On large models, this can lead to significant performance improvements
  // because the completer object can then use a binary search algorithm
  // instead of linear search algorithm.
  completer->setModelSorting(QCompleter::CaseSensitivelySortedModel);

  // Improve completer popup (view) performance
  tweak((QListView *)completer->popup());
}