Qt 流式布局

Qt 流动布局,实现自适应

flowlayout.h

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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
 
#ifndef FLOWLAYOUT_H
#define FLOWLAYOUT_H
 
#include <QLayout>
#include <QRect>
#include <QStyle>
//! [0]
class FlowLayout : public QLayout
{
public:
    explicit FlowLayout(QWidget *parent, int margin = -1, int hSpacing = -1, int vSpacing = -1);
    explicit FlowLayout(int margin = -1, int hSpacing = -1, int vSpacing = -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;
};
//! [0]
 
#endif // FLOWLAYOUT_H
 
/*
demo
 
    //Qt 流式布局
    if(true){
        FlowLayout *flowLayout = new FlowLayout;
        flowLayout->addWidget(ui->btn_info_1);
        flowLayout->addWidget(ui->btn_info_2);
        flowLayout->addWidget(ui->btn_info_3);
        flowLayout->addWidget(ui->btn_info_4);
        flowLayout->addWidget(ui->btn_info_5);
        flowLayout->addWidget(ui->btn_info_6);
        flowLayout->addWidget(ui->btn_info_7);
        ui->groupBox__function->setLayout(flowLayout);
    }
 
 
*/

flowlayout.cpp

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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
 
#include <QtWidgets>
 
#include "flowlayout.h"
//! [1]
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);
}
//! [1]
 
//! [2]
FlowLayout::~FlowLayout()
{
    QLayoutItem *item;
    while ((item = takeAt(0)))
        delete item;
}
//! [2]
 
//! [3]
void FlowLayout::addItem(QLayoutItem *item)
{
    itemList.append(item);
}
//! [3]
 
//! [4]
int FlowLayout::horizontalSpacing() const
{
    if (m_hSpace >= 0) {
        return m_hSpace;
    } else {
        return smartSpacing(QStyle::PM_LayoutHorizontalSpacing);
    }
}
 
int FlowLayout::verticalSpacing() const
{
    if (m_vSpace >= 0) {
        return m_vSpace;
    } else {
        return smartSpacing(QStyle::PM_LayoutVerticalSpacing);
    }
}
//! [4]
 
//! [5]
int FlowLayout::count() const
{
    return itemList.size();
}
 
QLayoutItem *FlowLayout::itemAt(int index) const
{
    return itemList.value(index);
}
 
QLayoutItem *FlowLayout::takeAt(int index)
{
    if (index >= 0 && index < itemList.size())
        return itemList.takeAt(index);
    else
        return 0;
}
//! [5]
 
//! [6]
Qt::Orientations FlowLayout::expandingDirections() const
{
    return 0;
}
//! [6]
 
//! [7]
bool FlowLayout::hasHeightForWidth() const
{
    return true;
}
 
int FlowLayout::heightForWidth(int width) const
{
    int height = doLayout(QRect(0, 0, width, 0), true);
    return height;
}
//! [7]
 
//! [8]
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 = size.expandedTo(item->minimumSize());
 
    size += QSize(2*margin(), 2*margin());
    return size;
}
//! [8]
 
//! [9]
int FlowLayout::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;
//! [9]
 
//! [10]
    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);
//! [10]
//! [11]
        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;
}
//! [11]
//! [12]
int FlowLayout::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();
    }
}
//! [12]

//实际使用案例如下,此处使用时,根据自定义规则,实现了先后优先级

//Qt 流式布局
if(true){
    FlowLayout *flowLayout = new FlowLayout;
    auto childs = ui->groupBox__flow->children();
    QList<QWidget*> gs;
    for(auto child:childs){
        if(child->objectName().startsWith("gro")){gs.append((QWidget*)child);}
        else if(child->objectName().startsWith("gri")){continue;}
        else{flowLayout->addWidget((QWidget*)child);}
    }
    for(auto child:gs){flowLayout->addWidget(child);}
    ui->groupBox__flow->setLayout(flowLayout);
}