Qt5位置相关函数异同详解（附源码）

Qt5中提供了丰富的位置和区域大小相关函数。下面讲一讲他们的区别。

主要函数：

1、x(),y(),pos()：获取整个窗体左上角的坐标位置。

2、frameGeometry()：获取整个窗体左上角的坐标和长宽值。

3、geometry()：获取窗体中央区域左上角的坐标和长宽值。

4、width()和height()：获取窗体中央区域的长宽值。

5、size()：获取窗体中央区域的长宽值。

6、rect()：获得的左上角坐标始终为（0,0），长宽值为中央区域的长宽值。

下面举一个实例，来区分这几个函数的功能。

实例：

1、新建GUI应用，项目名称为“Geometry”,基类选择“QDialog”，类名自定，取消“创建界面”复选框，最后完成项目工程的建立。

2、打开“dialog.h”,添加如下代码：

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>
#include <QLabel>
#include <QGridLayout>

class Dialog : public QDialog
{
    Q_OBJECT

public:
    Dialog(QWidget *parent = 0);
    ~Dialog();

    void updateLabel();

private:
    QLabel *xLabel;
    QLabel *xValueLabel;

    QLabel *yLabel;
    QLabel *yValueLabel;

    QLabel *frmLabel;
    QLabel *frmValueLabel;

    QLabel *posLabel;
    QLabel *posValueLabel;

    QLabel *geoLabel;
    QLabel *geoValueLabel;

    QLabel *widthLabel;
    QLabel *widthValueLabel;

    QLabel *heightLabel;
    QLabel *heightValueLabel;

    QLabel *rectLabel;
    QLabel *rectValueLabel;

    QLabel *sizeLabel;
    QLabel *sizeValueLabel;

    QGridLayout *mainLayout;

protected:
    void moveEvent(QMoveEvent *);   //鼠标移动事件
    void resizeEvent(QResizeEvent *);   //大小改变
};

#endif // DIALOG_H

3、打开"dialog.cpp"，添加如下代码：

#include "dialog.h"

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
{
    setWindowTitle(tr("Geometry"));

    xLabel = new QLabel(tr("X(): "));
    xValueLabel = new QLabel;

    yLabel = new QLabel(tr("Y(): "));
    yValueLabel = new QLabel;

    frmLabel = new QLabel(tr("FrameGeometry(): "));
    frmValueLabel = new QLabel;

    posLabel = new QLabel(tr("Pos(): "));
    posValueLabel = new QLabel;

    geoLabel = new QLabel(tr("Geometry(): "));
    geoValueLabel = new QLabel;

    widthLabel = new QLabel(tr("Width(): "));
    widthValueLabel = new QLabel;

    heightLabel = new QLabel(tr("Height(): "));
    heightValueLabel = new QLabel;

    rectLabel = new QLabel(tr("Rect(): "));
    rectValueLabel = new QLabel;

    sizeLabel = new QLabel(tr("Size(): "));
    sizeValueLabel = new QLabel;

    mainLayout = new QGridLayout(this);

    mainLayout->addWidget(xLabel,0,0);
    mainLayout->addWidget(xValueLabel,0,1);

    mainLayout->addWidget(yLabel,1,0);
    mainLayout->addWidget(yValueLabel,1,1);

    mainLayout->addWidget(posLabel,2,0);
    mainLayout->addWidget(posValueLabel,2,1);

    mainLayout->addWidget(frmLabel,3,0);
    mainLayout->addWidget(frmValueLabel,3,1);

    mainLayout->addWidget(geoLabel,4,0);
    mainLayout->addWidget(geoValueLabel,4,1);

    mainLayout->addWidget(widthLabel,5,0);
    mainLayout->addWidget(widthValueLabel,5,1);

    mainLayout->addWidget(heightLabel,6,0);
    mainLayout->addWidget(heightValueLabel,6,1);

    mainLayout->addWidget(rectLabel,7,0);
    mainLayout->addWidget(rectValueLabel,7,1);

    mainLayout->addWidget(sizeLabel,8,0);
    mainLayout->addWidget(sizeValueLabel,8,1);

    updateLabel();  //更新控件


}

Dialog::~Dialog()
{

}

void Dialog::updateLabel()
{
    QString xStr;
    xValueLabel->setText(xStr.setNum(x())); //获取整个窗体左上角的位置

    QString yStr;
    yValueLabel->setText(yStr.setNum(y())); //获取整个窗体左上角的位置

    QString frameStr;   //获取整个窗体左上角的位置和长宽值
    QString tempStr1,tempStr2,tempStr3,tempStr4;
    frameStr = tempStr1.setNum(frameGeometry().x()) + "," +
            tempStr2.setNum(frameGeometry().y()) + "," +
            tempStr3.setNum(frameGeometry().width()) + ","+
            tempStr4.setNum(frameGeometry().height());
    frmValueLabel->setText(frameStr);

    QString geoStr; //获取窗体中央区域的左上角位置和长宽值
    QString tempStr21,tempStr22,tempStr23,tempStr24;
    geoStr = tempStr21.setNum(geometry().x()) + "," +
            tempStr22.setNum(geometry().y()) + ","  +
            tempStr23.setNum(geometry().width()) + "," +
            tempStr24.setNum(geometry().height());
    geoValueLabel->setText(geoStr);

    QString positionStr;    //获取窗体左上角的位置
    QString tempStr11,tempStr12;
    positionStr = tempStr11.setNum(pos().x()) + "," +
            tempStr12.setNum(pos().y());
    posValueLabel->setText(positionStr);

    QString wStr,hStr;  //获取窗体中央区域的长宽值
    widthValueLabel->setText(wStr.setNum(width()));
    heightValueLabel->setText(hStr.setNum(height()));

    QString rectStr;    //获取窗体中央区域的左上角值和长宽值
    QString tempStr31,tempStr32,tempStr33,tempStr34;
    rectStr = tempStr31.setNum(rect().x()) + "," +
            tempStr32.setNum(rect().y()) + "," +
            tempStr33.setNum(rect().width()) + "," +
            tempStr34.setNum(rect().height());
    rectValueLabel->setText(rectStr);

    QString sizeStr;    //获取窗体中央区域的长宽值
    QString tempStr41,tempStr42;
    sizeStr = tempStr41.setNum(size().width()) + "," +
            tempStr42.setNum(size().height());
    sizeValueLabel->setText(sizeStr);


}

void Dialog::moveEvent(QMoveEvent *)
{
    updateLabel();
}

void Dialog::resizeEvent(QResizeEvent *)
{
    updateLabel();
}