cpp
#ifndef WIDGET_H
#define WIDGET_H
#include <QWidget>
#include <QLabel>
#include <QDebug>
namespace Ui {
class Widget;
}
class Widget : public QWidget
{
Q_OBJECT
public:
explicit Widget(QWidget *parent = 0);
~Widget();
private:
void resize_label();
private slots:
void on_doubleSpinBox_h_valueChanged(double arg1);
void on_doubleSpinBox_v_valueChanged(double arg1);
private:
Ui::Widget *ui;
QLabel label;
QImage image;
QImage original_image;
QString path;
};
#endif // WIDGET_H
cpp
#include "widget.h"
#include "ui_widget.h"
Widget::Widget(QWidget *parent) :
QWidget(parent),
ui(new Ui::Widget)
{
ui->setupUi(this);
path=QApplication::applicationDirPath()+"/1.png";
qDebug()<<path;
original_image=QImage(path);
image=original_image;
label.setPixmap(QPixmap::fromImage(image));
label.show();
}
Widget::~Widget()
{
delete ui;
}
void Widget::resize_label()
{
QMatrix matrix;
qDebug()<<"h:"<<ui->doubleSpinBox_h->value();
matrix.scale(ui->doubleSpinBox_h->value(),ui->doubleSpinBox_v->value());
image=original_image.transformed(matrix);
label.setPixmap(QPixmap::fromImage(image));
label.resize(image.size());
}
void Widget::on_doubleSpinBox_h_valueChanged(double arg1)
{
resize_label();
}
void Widget::on_doubleSpinBox_v_valueChanged(double arg1)
{
resize_label();
}
效果:
如何显示一张图片:
1.png--->QImage--->QPixmap--->QLabel
改变图片的水平大小和垂直大小,其实是在改变QImage。