qt -- setGeometry函数的使用

ui->progressBar->setGeometry(0, 0, 60, 60 );

从窗体的（0，0）位置开始（即为最左上角的点），显示一个60*60的控件（宽60，高60）。

此函数的底层实现代码：

  void BorderLayout::setGeometry(const QRect &rect)
  {
      ItemWrapper *center = 0;
      int eastWidth = 0;
      int westWidth = 0;
      int northHeight = 0;
      int southHeight = 0;
      int centerHeight = 0;
      int i;

      QLayout::setGeometry(rect);

      for (i = 0; i < list.size(); ++i) {
          ItemWrapper *wrapper = list.at(i);
          QLayoutItem *item = wrapper->item;
          Position position = wrapper->position;

          if (position == North) {
              item->setGeometry(QRect(rect.x(), northHeight, rect.width(),
                                      item->sizeHint().height()));

              northHeight += item->geometry().height() + spacing();
          } else if (position == South) {
              item->setGeometry(QRect(item->geometry().x(),
                                      item->geometry().y(), rect.width(),
                                      item->sizeHint().height()));

              southHeight += item->geometry().height() + spacing();

              item->setGeometry(QRect(rect.x(),
                                rect.y() + rect.height() - southHeight + spacing(),
                                item->geometry().width(),
                                item->geometry().height()));
          } else if (position == Center) {
              center = wrapper;
          }
      }

      centerHeight = rect.height() - northHeight - southHeight;

      for (i = 0; i < list.size(); ++i) {
          ItemWrapper *wrapper = list.at(i);
          QLayoutItem *item = wrapper->item;
          Position position = wrapper->position;

          if (position == West) {
              item->setGeometry(QRect(rect.x() + westWidth, northHeight,
                                      item->sizeHint().width(), centerHeight));

              westWidth += item->geometry().width() + spacing();
          } else if (position == East) {
              item->setGeometry(QRect(item->geometry().x(), item->geometry().y(),
                                      item->sizeHint().width(), centerHeight));

              eastWidth += item->geometry().width() + spacing();

              item->setGeometry(QRect(
                                rect.x() + rect.width() - eastWidth + spacing(),
                                northHeight, item->geometry().width(),
                                item->geometry().height()));
          }
      }

      if (center)
          center->item->setGeometry(QRect(westWidth, northHeight,
                                          rect.width() - eastWidth - westWidth,
                                          centerHeight));
  }