Qt学习之路之图像打印

首先，设置工程文件：QT += printsupport

  打印图像实际实在一个QPaintDevice中画图。打印创建QPrinter对象进行画图，QPrinter本质上也是一个绘图设备QPaintDevice。

~~~~~上代码~~~~

pic_widget.h

#ifndef PICWIDGET_H
#define PICWIDGET_H

#include <QPainter>
#include <QWidget>
#include <QPushButton>
#include <QPrintDialog>
#include <QPrinter>
#include <QPainter>
#include <QRect>
#include <QImage>

class PicWidget : public QWidget
{
	Q_OBJECT
public:
	explicit PicWidget(QWidget *parent = 0);

	public slots:
		void slotPrintPic();
private:
	QPushButton *pintPicBtn;
	QImage img;
};

#endif	//--PICWIDGET_H

pic_widget.cpp

#include "pic_widget.h"

PicWidget::PicWidget(QWidget *parent /*= 0*/) : QWidget(parent)
{
	//---按钮
	pintPicBtn = new QPushButton("print", this);
	pintPicBtn->setGeometry(70, 40, 50, 30);
	connect(pintPicBtn, SIGNAL(clicked()), this, SLOT(slotPrintPic()));

	//--导入图片
	img.load(":/1");

	//---窗口属性
	resize(200, 100);
}

//---按钮槽函数
void PicWidget::slotPrintPic()
{
	QPrinter printer;		//---构建新对象
	QPrintDialog printDlg(&printer, this);
	if (printDlg.exec())			// 用于判断用户是否点击“打印”按钮
	{
		QPainter painter(&printer);
		QRect rect = painter.viewport();	//---获取Qpainter对象的矩形区域
		QSize size = img.size();			//--获取图片的大小
		size.scale(rect.size(), Qt :: KeepAspectRatio);		//----按照图形比例大小重新设置视口矩形区域

		//---打印图片
		painter.setViewport(rect.x(), rect.y(), size.width(), size.height());
		painter.setWindow(img.rect());
		painter.drawImage(0, 0, img);
	}
}

main.cpp

#include <QtWidgets/QApplication>
#include "pic_widget.h"


int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	PicWidget win;
	win.show();
	
	return a.exec();
}

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