Qt流式布局

当我们希望控件会随着窗口大小的变化&＃xff0c;自动填充布局&＃xff0c;例如&＃xff1a;

这时候&＃xff0c;就需要用到流式布局了&＃xff0c;但是Qt官方没有吧流式布局集成到IDE中&＃xff0c;如果需要的话&＃xff0c;可查阅官方案例&＃xff1a;https://doc.qt.io/qt-5/qtwidgets-layouts-flowlayout-example.html



直接把源码copy到自己新建的类中即可使用&＃xff0c;源码如下&＃xff1a;

#ifndef FLOWLAYOUT_H
#define FLOWLAYOUT_H#include
#include
#include
class FlowLayout : public QLayout
{
public:explicit FlowLayout(QWidget *parent, int margin &＃61; -1, int hSpacing &＃61; -1, int vSpacing &＃61; -1);explicit FlowLayout(int margin &＃61; -1, int hSpacing &＃61; -1, int vSpacing &＃61; -1);~FlowLayout();void addItem(QLayoutItem *item) override;int horizontalSpacing() const;int verticalSpacing() const;Qt::Orientations expandingDirections() const override;bool hasHeightForWidth() const override;int heightForWidth(int) const override;int count() const override;QLayoutItem *itemAt(int index) const override;QSize minimumSize() const override;void setGeometry(const QRect &rect) override;QSize sizeHint() const override;QLayoutItem *takeAt(int index) override;private:int doLayout(const QRect &rect, bool testOnly) const;int smartSpacing(QStyle::PixelMetric pm) const;QList<QLayoutItem *> itemList;int m_hSpace;int m_vSpace;
};#endif // FLOWLAYOUT_H

#include #include "flowlayout.h"
FlowLayout::FlowLayout(QWidget *parent, int margin, int hSpacing, int vSpacing): QLayout(parent), m_hSpace(hSpacing), m_vSpace(vSpacing)
{setContentsMargins(margin, margin, margin, margin);
}FlowLayout::FlowLayout(int margin, int hSpacing, int vSpacing): m_hSpace(hSpacing), m_vSpace(vSpacing)
{setContentsMargins(margin, margin, margin, margin);
}FlowLayout::~FlowLayout()
{QLayoutItem *item;while ((item &＃61; takeAt(0)))delete item;
}void FlowLayout::addItem(QLayoutItem *item)
{itemList.append(item);
}int FlowLayout::horizontalSpacing() const
{if (m_hSpace >&＃61; 0) {return m_hSpace;} else {return smartSpacing(QStyle::PM_LayoutHorizontalSpacing);}
}int FlowLayout::verticalSpacing() const
{if (m_vSpace >&＃61; 0) {return m_vSpace;} else {return smartSpacing(QStyle::PM_LayoutVerticalSpacing);}
}int FlowLayout::count() const
{return itemList.size();
}QLayoutItem *FlowLayout::itemAt(int index) const
{return itemList.value(index);
}QLayoutItem *FlowLayout::takeAt(int index)
{if (index >&＃61; 0 && index < itemList.size())return itemList.takeAt(index);elsereturn 0;
}Qt::Orientations FlowLayout::expandingDirections() const
{return 0;
}bool FlowLayout::hasHeightForWidth() const
{return true;
}int FlowLayout::heightForWidth(int width) const
{int height &＃61; doLayout(QRect(0, 0, width, 0), true);return height;
}void FlowLayout::setGeometry(const QRect &rect)
{QLayout::setGeometry(rect);doLayout(rect, false);
}QSize FlowLayout::sizeHint() const
{return minimumSize();
}QSize FlowLayout::minimumSize() const
{QSize size;QLayoutItem *item;foreach (item, itemList)size &＃61; size.expandedTo(item->minimumSize());size &＃43;&＃61; QSize(2*margin(), 2*margin());return size;
}int FlowLayout::doLayout(const QRect &rect, bool testOnly) const
{int left, top, right, bottom;getContentsMargins(&left, &top, &right, &bottom);QRect effectiveRect &＃61; rect.adjusted(&＃43;left, &＃43;top, -right, -bottom);int x &＃61; effectiveRect.x();int y &＃61; effectiveRect.y();int lineHeight &＃61; 0;QLayoutItem *item;foreach (item, itemList) {QWidget *wid &＃61; item->widget();int spaceX &＃61; horizontalSpacing();if (spaceX &＃61;&＃61; -1)spaceX &＃61; wid->style()->layoutSpacing(QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Horizontal);int spaceY &＃61; verticalSpacing();if (spaceY &＃61;&＃61; -1)spaceY &＃61; wid->style()->layoutSpacing(QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Vertical);int nextX &＃61; x &＃43; item->sizeHint().width() &＃43; spaceX;if (nextX - spaceX > effectiveRect.right() && lineHeight > 0) {x &＃61; effectiveRect.x();y &＃61; y &＃43; lineHeight &＃43; spaceY;nextX &＃61; x &＃43; item->sizeHint().width() &＃43; spaceX;lineHeight &＃61; 0;}if (!testOnly)item->setGeometry(QRect(QPoint(x, y), item->sizeHint()));x &＃61; nextX;lineHeight &＃61; qMax(lineHeight, item->sizeHint().height());}return y &＃43; lineHeight - rect.y() &＃43; bottom;
}
int FlowLayout::smartSpacing(QStyle::PixelMetric pm) const
{QObject *parent &＃61; this->parent();if (!parent) {return -1;} else if (parent->isWidgetType()) {QWidget *pw &＃61; static_cast<QWidget *>(parent);return pw->style()->pixelMetric(pm, 0, pw);} else {return static_cast<QLayout *>(parent)->spacing();}
}