QT 中QPainter绘制文字、图片

1. 把字符串绘制在QPixmap上

1. QPixmap MainWindow::text2Pixmap(QString text)

2. {

3. QFontMetrics fmt(m_font);

4. QPixmap result(fmt.width(text), fmt.height());

5.  

6. QRect rect(0,0,fmt.width(text), fmt.height());

7. result.fill(Qt::transparent);

8. QPainter painter(&result);

9. painter.setFont(m_font);

10. painter.setPen(QColor(255,143,36));

11. //painter.drawText(const QRectF(fmt.width(text), fmt.height()),Qt::AlignLeft, text);

12. painter.drawText((const QRectF)(rect),text);

13. return result;

14. }

2. 对图片进行水平拼接

1. //多张图片拼接合成一张图片

2. QPixmap MainWindow::pinjie(QVector<QPixmap> image)

3. {

4.  

5. int image_width=0;

6. int max_height = 0;

7. QVector <QPixmap > ::iterator it;

8. for(it = image.begin();it!=image.end();++it)

9. {

10. int width = (*it).width();

11. image_width += width;

12. image_width +=5;

13. if((*it).height()>max_height)

14. {

15. max_height =(*it).height();

16. }

17. }

18. QPixmap result_image_h(image_width,max_height);

19. result_image_h.fill(Qt::transparent);

20. QPainter painter_h;

21. painter_h.begin(&result_image_h);

22. int x_number=0;

23. for(it = image.begin();it!=image.end();++it)

24. {

25. painter_h.drawPixmap(x_number,0,(*it));

26. x_number += (*it).width();

27. x_number +=5;

28. }

29. painter_h.end();

30. return result_image_h;

31. }

3. 把一张图片绘制在空白图片上

1. QPixmap MainWindow::zoomOutPix(QPixmap pix ,int addWidth, int addHeight)

2. {

3. // addWidth pix增加的宽度，addHeight pix增加的高度

4. QPixmap res(pix.width() + addWidth, pix.height() + addHeight);

5. res.fill(Qt::transparent);

6. QPainter painter(&res);

7. painter.drawPixmap(addWidth/2, addHeight/2, pix.width(), pix.height(), pix);

8. return res;

9. }

4. 把一张图片绘制在另外一张图片上

1. //一张图片绘制在另外一张图片上

2. QPixmap MainWindow::dijia(QPixmap p1, QPixmap p2)

3. {

4. //p1作为底片， p2绘制在p1图片上

5. QPainter painter(&p1);

6. painter.drawPixmap(0,0,p2.width(),p2.height(), p2);

7. return p1;

8.  

9. }

5. 图片的缩放

使用scaled函数进行图片的缩放。

1. //缩放

2. QString str = QString::fromLocal8Bit("(侏罗纪)");

3. QPixmap p = text2Pixmap(str);

4. p = p.scaled(100, 30, Qt::KeepAspectRatio, Qt::SmoothTransformation);

6. Qt快捷键

添加注释： Ctrl + /       

代码格式快速对齐：Ctrl  + A ，Ctrl + I