二十、Qt位置相关函数

 

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目录

一、函数概述

 二、函数实践

 三、总结

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一、函数概述

        Qt 提供了很多关于获取窗体位置及显示区域大小的函数，如 x()、y()和 pos()、react()、size()、geometry()等，统称为“位置相关函数”或“位置函数”， 如下图所示是几种主要的位置函数，图中清楚地标出了它们之间的区别。

 二、函数实践

geometry.h

#ifndef GEOMETRY_H
#define GEOMETRY_H

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

class Geometry : public QDialog
{
    Q_OBJECT
    
public:
    Geometry(QWidget *parent = 0);
    ~Geometry();
    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 *);
    void resizeEvent(QResizeEvent *);
};

#endif // GEOMETRY_H

geometry.cpp

#include "geometry.h"

Geometry::Geometry(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("Frame:"));
    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();
}

Geometry::~Geometry()
{
    
}

void Geometry::updateLabel()
{
    QString xStr;                      //获得x()函数的结果并显示
    xValueLabel->setText(xStr.setNum(x()));

    QString yStr;                      //获得y()函数的结果并显示
    yValueLabel->setText(yStr.setNum(y()));

    QString frameStr;                 //获得frameGeometry()函数的结果并显示
    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 positionStr;            //获得pos()函数的结果并显示
    QString tempStr11,tempStr12;
    positionStr =tempStr11.setNum(pos().x())+","+tempStr12.setNum(pos().y());
    posValueLabel->setText(positionStr);

    QString geoStr;               //获得geometry()函数的结果并显示
    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 wStr,hStr;                  //获得width()、height()函数的结果并显示
    widthValueLabel->setText(wStr.setNum(width()));
    heightValueLabel->setText(hStr.setNum(height()));

    QString rectStr;                    //获得rect()函数的结果并显示
    QString tempStr31,tempStr32,tempStr33,tempStr34;
    rectStr =tempStr31.setNum(rect().x())+","+tempStr32.setNum(rect().y())+","+tempStr33.setNum(/*rect().width()*/width())+","+tempStr34.setNum(height()/*rect().height()*/);
    rectValueLabel->setText(rectStr);

    QString sizeStr;                 //获得size()函数的结果并显示
    QString tempStr41,tempStr42;
    sizeStr =tempStr41.setNum(size().width())+","+tempStr42.setNum(size().height());
    sizeValueLabel->setText(sizeStr);
}

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

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

main.cpp

#include "geometry.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Geometry w;
    w.show();
    
    return a.exec();
}

效果展示：

 三、总结

        在实际应用中需要根据情况使用正确的位置信息函数以获得准确的位置尺寸信息，尤其是在编写对位置精度要求较高的程序 (如地图浏览程序) 时，更应注意函数的选择，避免产生不必要的误差。

原文地址：https://blog.csdn.net/qq_45790916/article/details/140597087

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