QT 常用窗口api

• 常用窗口api
• 绘图框架设计 Qpainter
• 绘图双缓冲机制
• GraphicsView 绘图框架设计
• 示例: 图片缩放倾斜旋转

常用窗口api

#ifndef DIALOG_H
#define DIALOG_H

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

class Dialog : public QDialog
{
    Q_OBJECT

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


private:
    QGridLayout *layout;
    QLabel *label1;
    QLabel *label1_1;

    QLabel *label2;
    QLabel *label2_1;

    QLabel *label3;
    QLabel *label3_1;

    QLabel *label4;
    QLabel *label4_1;


    QLabel *label5;
    QLabel *label5_1;

    //窗口大小变化事件
    void resizeEvent(QResizeEvent *event) override;

    //窗口移动事件
    void moveEvent(QMoveEvent *event) override;

public:
    //更新标签内容
    void updateLabel();
};
#endif // DIALOG_H

#include "dialog.h"

Dialog::Dialog(QWidget *parent)
    : QDialog(parent)
{
    this->setWindowTitle("窗体常用api");
    this->resize(300,200);
    layout=new QGridLayout(this);

    label1=new QLabel("geometry:");
    label1_1=new QLabel();

    label2=new QLabel("width:");
    label2_1=new QLabel();


    label3=new QLabel("height:");
    label3_1=new QLabel();

    label4=new QLabel("rect:");
    label4_1=new QLabel();

    label5=new QLabel("size:");
    label5_1=new QLabel();


    layout->addWidget(label1,0,0);
    layout->addWidget(label1_1,0,1);
    layout->addWidget(label2,1,0);
    layout->addWidget(label2_1,1,1);
    layout->addWidget(label3,2,0);
    layout->addWidget(label3_1,2,1);
    layout->addWidget(label4,3,0);
    layout->addWidget(label4_1,3,1);
    layout->addWidget(label5,4,0);
    layout->addWidget(label5_1,4,1);


    updateLabel();
}

//窗口大小变化事件
void Dialog::resizeEvent(QResizeEvent *event) {
    updateLabel();
}

//窗口移动事件
void Dialog::moveEvent(QMoveEvent *event){
    updateLabel();
}

void Dialog::updateLabel(){
    QString str;
    QString str1;
    QString str2;
    QString str3;
    QString str4;
    str1.setNum(this->geometry().x());//它描述了窗口部件在屏幕上的实际矩形区域。
    str2.setNum(this->geometry().y());
    str3.setNum(this->geometry().width());
    str4.setNum(this->geometry().height());
    str=str1+" "+str2+" "+str3+" "+str4;
    label1_1->setText(str);



    QString strw,strh;


    label2_1->setText(strw.setNum(this->width()));
    label3_1->setText(strh.setNum(this->height()));



    QString  strrect;