qt 动态布局的例子，dynamic layout

动态布局的例子，dynamic layout；包括滑块，进度条。刻度盘，旋转框等子控件。

//**************************************************************

#include <QApplication>

#include "dialog.h"

int main(int argc, char *argv[])

{

QApplication app(argc, argv);

Dialog dialog;

return dialog.exec();

}

//*****************************************************************

#ifndef DIALOG_H

#define DIALOG_H

#include <QDialog>

#include <QQueue>

QT_BEGIN_NAMESPACE

class QComboBox;

class QDialogButtonBox;

class QGridLayout;

class QGroupBox;

class QLabel;

class QPushButton;

QT_END_NAMESPACE

class Dialog : public QDialog

{

Q_OBJECT

public:

Dialog(QWidget *parent = 0);

private slots:

void buttonsOrientationChanged(int index);

void rotateWidgets();

void help();

private:

void createRotableGroupBox();

void createOptionsGroupBox();

void createButtonBox();

QGroupBox *rotableGroupBox;

QQueue<QWidget *> rotableWidgets;//控件队列，实现控件循环显示

QGroupBox *optionsGroupBox;

QLabel *buttonsOrientationLabel;

QComboBox *buttonsOrientationComboBox;

QDialogButtonBox *buttonBox;

QPushButton *closeButton;

QPushButton *helpButton;

QPushButton *rotateWidgetsButton;

QGridLayout *mainLayout;

QGridLayout *rotableLayout;

QGridLayout *optionsLayout;

};

#endif

//**********************************************************

/****************************************************************************/

#include <QtGui>

#include "dialog.h"

Dialog::Dialog(QWidget *parent)

: QDialog(parent)

{

createRotableGroupBox();

createOptionsGroupBox();

createButtonBox();

mainLayout = new QGridLayout;

mainLayout->addWidget(rotableGroupBox, 0, 0);

mainLayout->addWidget(optionsGroupBox, 1, 0);

mainLayout->addWidget(buttonBox, 2, 0);

setLayout(mainLayout);

mainLayout->setSizeConstraint(QLayout::SetMinimumSize);

setWindowTitle(tr("Dynamic Layouts"));

}

void Dialog::buttonsOrientationChanged(int index)

{

////布局的大小限制（Constraint）模式：无限制（NoConstraint）

mainLayout->setSizeConstraint(QLayout::SetNoConstraint);

setMinimumSize(0, 0);

//获取方位（orientation）信息

Qt::Orientation orientation = Qt::Orientation(

buttonsOrientationComboBox->itemData(index).toInt());//转换成整数

if (orientation == buttonBox->orientation())//与原值一致则直接返回

return;

mainLayout->removeWidget(buttonBox);//删除按钮框

int spacing = mainLayout->spacing();//如果横向和纵向长度一致返回这个长度，否则返回-1

QSize oldSizeHint = buttonBox->sizeHint() + QSize(spacing, spacing);

buttonBox->setOrientation(orientation);//设置按钮框的布局方向（Orientation）

QSize newSizeHint = buttonBox->sizeHint() + QSize(spacing, spacing);

if (orientation == Qt::Horizontal) {

mainLayout->addWidget(buttonBox, 2, 0);

resize(size() + QSize(-oldSizeHint.width(), newSizeHint.height()));

} else {

mainLayout->addWidget(buttonBox, 0, 3, 2, 1);

resize(size() + QSize(newSizeHint.width(), -oldSizeHint.height()));

}

mainLayout->setSizeConstraint(QLayout::SetDefaultConstraint);

}

void Dialog::rotateWidgets()

{

Q_ASSERT(rotableWidgets.count() % 2 == 0);//断言：偶数个子部件

//foreach宏的实质就是在宏中定义循环申明部分，而不包括循环体。

//在使用的时候，紧接着写循环体就行了。

//foreach（variables ，container）关键字是Qt对c++的一个扩展，

// 主要用于按顺序历经容器（container）中的对象

foreach (QWidget *widget, rotableWidgets)

rotableLayout->removeWidget(widget);//删除子部件

rotableWidgets.enqueue(rotableWidgets.dequeue());//头部部件出队列后入队尾

const int n = rotableWidgets.count();

for (int i = 0; i < n / 2; ++i) {//变换控件显示的位置

rotableLayout->addWidget(rotableWidgets[n - i - 1], 0, i);

rotableLayout->addWidget(rotableWidgets[i], 1, i);

}

}

//帮助对话框

void Dialog::help()

{

QMessageBox::information(this, tr("Dynamic Layouts Help"),

tr("This example shows how to change layouts "

"dynamically."));

}

void Dialog::createRotableGroupBox()

{

rotableGroupBox = new QGroupBox(tr("Rotable Widgets"));

rotableWidgets.enqueue(new QSpinBox);//旋转框入队

rotableWidgets.enqueue(new QSlider);//滑块

rotableWidgets.enqueue(new QDial);//刻度盘

rotableWidgets.enqueue(new QProgressBar);//进度条

int n = rotableWidgets.count();//返回子部件数

for (int i = 0; i < n; ++i) {

connect(rotableWidgets[i], SIGNAL(valueChanged(int)),

rotableWidgets[(i + 1) % n], SLOT(setValue(int)));

}//四个部件首尾相连，关系是一个环形，一个改变便会改变其它几个

rotableLayout = new QGridLayout;

rotableGroupBox->setLayout(rotableLayout);

rotateWidgets();

}

void Dialog::createOptionsGroupBox()

{

optionsGroupBox = new QGroupBox(tr("Options"));//groupbox周围显示一个圈

buttonsOrientationLabel = new QLabel(tr("Orientation of buttons:"));

buttonsOrientationComboBox = new QComboBox;//Combo : 结合物, 联合体.下拉菜单

buttonsOrientationComboBox->addItem(tr("Horizontal"), Qt::Horizontal);//item:条目

buttonsOrientationComboBox->addItem(tr("Vertical"), Qt::Vertical);

//void QComboBox::addItem ( const QString & text,

// const QVariant & userData = QVariant() )

//Combo中的索引值（index）改变的信号连接到信号槽buttonsOrientationChanged(int)

connect(buttonsOrientationComboBox, SIGNAL(currentIndexChanged(int)),

this, SLOT(buttonsOrientationChanged(int)));

optionsLayout = new QGridLayout;

optionsLayout->addWidget(buttonsOrientationLabel, 0, 0);

optionsLayout->addWidget(buttonsOrientationComboBox, 0, 1);

optionsLayout->setColumnStretch(2, 1);//设置第二列的延伸属性（stretch factor）

optionsGroupBox->setLayout(optionsLayout);

}

void Dialog::createButtonBox()

{

buttonBox = new QDialogButtonBox;

closeButton = buttonBox->addButton(QDialogButtonBox::Close);//标准关闭按钮

helpButton = buttonBox->addButton(QDialogButtonBox::Help);//标准帮助按钮

rotateWidgetsButton = buttonBox->addButton(tr("Rotate &Widgets"),

QDialogButtonBox::ActionRole);

connect(rotateWidgetsButton, SIGNAL(clicked()), this, SLOT(rotateWidgets()));

connect(closeButton, SIGNAL(clicked()), this, SLOT(close()));

connect(helpButton, SIGNAL(clicked()), this, SLOT(help()));

}