Qt之自定义布局管理器(QFlowLayout)
2016-05-27 18:49
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简述
QFlowLayout,顾名思义-流布局,实现了处理不同窗口大小的布局。根据应用窗口的宽度来进行控件放置的变化。具体实现要求不再赘述,请参考前两节内容。
简述
实现
效果
源码
实现
QFlowLayout主要采用QLayout和QWidgetItem实现,而窗口使用了QWidget和QPushButton。效果
源码
QFlowLayout.h#ifndef QFLOWLAYOUT_H #define QFLOWLAYOUT_H #include <QLayout> #include <QRect> #include <QStyle> class QFlowLayout : public QLayout { public: explicit QFlowLayout(QWidget *parent, int margin = -1, int hSpacing = -1, int vSpacing = -1); explicit QFlowLayout(int margin = -1, int hSpacing = -1, int vSpacing = -1); ~QFlowLayout(); void addItem(QLayoutItem *item) Q_DECL_OVERRIDE; int horizontalSpacing() const; int verticalSpacing() const; Qt::Orientations expandingDirections() const Q_DECL_OVERRIDE; bool hasHeightForWidth() const Q_DECL_OVERRIDE; int heightForWidth(int) const Q_DECL_OVERRIDE; int count() const Q_DECL_OVERRIDE; QLayoutItem *itemAt(int index) const Q_DECL_OVERRIDE; QSize minimumSize() const Q_DECL_OVERRIDE; void setGeometry(const QRect &rect) Q_DECL_OVERRIDE; QSize sizeHint() const Q_DECL_OVERRIDE; QLayoutItem *takeAt(int index) Q_DECL_OVERRIDE; private: int doLayout(const QRect &rect, bool testOnly) const; int smartSpacing(QStyle::PixelMetric pm) const; private: QList<QLayoutItem *> itemList; int m_hSpace; int m_vSpace; }; #endif // QFLOWLAYOUT_H
QFlowLayout.cpp
#include <QWidget> #include "QFlowLayout.h" QFlowLayout::QFlowLayout(QWidget *parent, int margin, int hSpacing, int vSpacing) : QLayout(parent), m_hSpace(hSpacing), m_vSpace(vSpacing) { setContentsMargins(margin, margin, margin, margin); } QFlowLayout::QFlowLayout(int margin, int hSpacing, int vSpacing) : m_hSpace(hSpacing), m_vSpace(vSpacing) { setContentsMargins(margin, margin, margin, margin); } QFlowLayout::~QFlowLayout() { QLayoutItem *item; while ((item = takeAt(0))) delete item; } void QFlowLayout::addItem(QLayoutItem *item) { itemList.append(item); } int QFlowLayout::horizontalSpacing() const { if (m_hSpace >= 0) { return m_hSpace; } else { return smartSpacing(QStyle::PM_LayoutHorizontalSpacing); } } int QFlowLayout::verticalSpacing() const { if (m_vSpace >= 0) { return m_vSpace; } else { return smartSpacing(QStyle::PM_LayoutVerticalSpacing); } } int QFlowLayout::count() const { return itemList.size(); } QLayoutItem *QFlowLayout::itemAt(int index) const { return itemList.value(index); } QLayoutItem *QFlowLayout::takeAt(int index) { if (index >= 0 && index < itemList.size()) return itemList.takeAt(index); else return 0; } Qt::Orientations QFlowLayout::expandingDirections() const { return 0; } bool QFlowLayout::hasHeightForWidth() const { return true; } int QFlowLayout::heightForWidth(int width) const { int height = doLayout(QRect(0, 0, width, 0), true); return height; } void QFlowLayout::setGeometry(const QRect &rect) { QLayout::setGeometry(rect); doLayout(rect, false); } QSize QFlowLayout::sizeHint() const { return minimumSize(); } QSize QFlowLayout::minimumSize() const { QSize size; QLayoutItem *item; foreach (item, itemList) size = size.expandedTo(item->minimumSize()); size += QSize(2*margin(), 2*margin()); return size; } int QFlowLayout::doLayout(const QRect &rect, bool testOnly) const { int left, top, right, bottom; getContentsMargins(&left, &top, &right, &bottom); QRect effectiveRect = rect.adjusted(+left, +top, -right, -bottom); int x = effectiveRect.x(); int y = effectiveRect.y(); int lineHeight = 0; QLayoutItem *item; foreach (item, itemList) { QWidget *wid = item->widget(); int spaceX = horizontalSpacing(); if (spaceX == -1) spaceX = wid->style()->layoutSpacing( QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Horizontal); int spaceY = verticalSpacing(); if (spaceY == -1) spaceY = wid->style()->layoutSpacing( QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Vertical); int nextX = x + item->sizeHint().width() + spaceX; if (nextX - spaceX > effectiveRect.right() && lineHeight > 0) { x = effectiveRect.x(); y = y + lineHeight + spaceY; nextX = x + item->sizeHint().width() + spaceX; lineHeight = 0; } if (!testOnly) item->setGeometry(QRect(QPoint(x, y), item->sizeHint())); x = nextX; lineHeight = qMax(lineHeight, item->sizeHint().height()); } return y + lineHeight - rect.y() + bottom; } int QFlowLayout::smartSpacing(QStyle::PixelMetric pm) const { QObject *parent = this->parent(); if (!parent) { return -1; } else if (parent->isWidgetType()) { QWidget *pw = static_cast<QWidget *>(parent); return pw->style()->pixelMetric(pm, 0, pw); } else { return static_cast<QLayout *>(parent)->spacing(); } }
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