Qt:小部件方法 addButtons() 不能按需要工作

As mentioned in my other post, you only need to delete the buttons (it is removed from its parent automatically). However, if a widget was added to a layout, the parent of that layout becomes the parent of the widget, and an associated QLayoutItem is created that is managed by the layout itself. To the delete the buttons, the safest way is to take all the layout items (ownership the taker's responsibility), delete each items associated widget, and the delete each item. I'll try and find relevant references apart from the sources...

以下代码有效:

//ButtonWidget.h
#include <QWidget>
#include <QScrollArea>
#include <QHBoxLayout>

class ButtonWidget : public QScrollArea
{
    Q_OBJECT

  public:
    ButtonWidget(QWidget *parent = 0);
    ~ButtonWidget();
    void addButtons();
    void deleteButtons();
  private:
    QHBoxLayout* myLayout;
};

//ButtonWidget.cpp

#include "ButtonWidget.h"
#include <QGridLayout>
#include <QPushButton>
#include <QLayoutItem>

ButtonWidget::ButtonWidget(QWidget * parent) :
  QScrollArea(parent),
  myLayout(new QHBoxLayout(this))
{
}

ButtonWidget::~ButtonWidget()
{
}

void ButtonWidget::addButtons()
{
   QStringList texts{"1
ok", "2
ok", "3
ok", "4
ok", "5
ok", "6
ok"};

   for(int i = 0; i < texts.size(); i++)
   {
      myLayout->addWidget(new QPushButton(texts[i]));
   }
}

void ButtonWidget::deleteButtons()
{
    QLayoutItem * child;

    while((child = myLayout->takeAt(0)) != 0)
    {
      delete child->widget();
      delete child;
    }
}

#include "ButtonWidget.h"
#include <QApplication>
#include <QScrollArea>
#include <QPushButton>
#include <QGridLayout>
#include <QHBoxLayout>
#include <memory>

std::unique_ptr<QScrollArea> makeArea()
{
  std::unique_ptr<QScrollArea> area(new QScrollArea);
  auto layout = new QGridLayout(area.get());
  auto addButton  = new QPushButton("Add");
  auto removeButton  = new QPushButton("Remove");
  layout->addWidget(addButton, 0, 0);
  layout->addWidget(removeButton, 0, 1);
  auto btnWidget = new ButtonWidget;
  layout->addWidget(btnWidget,1,0,1,2);


  QObject::connect(addButton, &QPushButton::clicked, [=]()
  {
    btnWidget->addButtons();
  });

  QObject::connect(removeButton, &QPushButton::clicked, [=]()
  {
    btnWidget->deleteButtons();
  });
  return move(area);
}

int main(int argc, char *argv[])
{
  QApplication a(argc, argv);
  auto area = makeArea();
  area->show();
  return a.exec();
}

您需要在配置 (.pro) 中启用 c++11 才能使 lambda 工作.

CONFIG += c++11