qt4 简单绘图

最新推荐文章于 2022-01-26 14:36:38 发布

原创最新推荐文章于 2022-01-26 14:36:38 发布 · 1.7k 阅读

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#qt #dialog #class #system

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在继承自QPaintDevice 的类实例上才可以绘图
QPaintDevice Class Reference

Detailed Description

The QPaintDevice class is the base class of objects that can be painted.

A paint device is an abstraction of a two-dimensional space that can be drawn using a QPainter. Its default coordinate system has its origin located at the top-left position. X increases to the right and Y increases downwards. The unit is one pixel.

The drawing capabilities of QPaintDevice are currently implemented by the QWidget, QImage, QPixmap, QGLPixelBuffer, QPicture, andQPrinter subclasses.

QMainWindow QDialog的基类都是QWidget，所以可以在其上面绘图

在dialog上绘图

    QPainter painter(this);
    painter.drawRect(0,0,50,50);

在dialog的pixmap上绘图

    QPixmap pix(200,200);  
    pix.fill(Qt::white);   //背景填充为白色  
    QPainter pp(&pix);   //新建QPainter类对象，在pix上进行绘图  
    pp.drawLine(0,0,50,50);     //在pix上的（0，0）点和（50，50）点之间绘制直线  

    QPainter painter(this);      
    painter.drawPixmap(100,100,pix);

所有的绘图设备都有自己的坐标系统，它们互不影响。
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