Qt用边框绘制一个填充的圆角矩形 [英] Qt drawing a filled rounded rectangle with border

问题描述

我想要绘制一个带有圆角的矩形（边框半径与所有四个角相同），其中特定颜色填充整个矩形，以及单独的边框颜色（例如边框宽度为1像素）。

从我的观察，Qt提供了三个方法 - fillRect 和 drawRect 和 drawRoundedRect 。我试过他们，他们不工作，因为我想。没有像 fillRoundedRect 的方法。这意味着我可以绘制一个圆角矩形，但它不会填充我想要的颜色。

我该怎么做？而且，我读到，由于一些混叠问题，角落通常是相等的。如何将它设置为相等的所有四个？ painter.setRenderHint（QPainter :: Antialiasing）足够了吗？

解决方案

您可以创建一个 QPainterPath ，将圆角矩形添加到它，然后填充和描边：

  QPainter p 
 p.setRenderHint（QPainter :: Antialiasing）; 
 QPainterPath path; 
 path.addRoundedRect（QRectF（10，10，100，50），10，10）; 
 QPen pen（Qt :: black，10）; 
 p.setPen（pen）; 
 p.fillPath（path，Qt :: red）; 
 p.drawPath（path）;请注意，即使使用抗锯齿，1像素边框可能永远不会真的看起来不错，特别是在低DPI的情况下桌面显示器，在高DPI移动设备上几乎不可见。
 
 
 
  
 
 
 
如果您创建矩形为 QRectF（9.5，9.5，100，50）它将看起来更好与1像素的抗锯齿边框，因为它会捕捉在正确的像素：
 
 
 
  
 
I want to draw a rectangle with rounded corners (border radius same for all 4 corners) with a specific color filling the entire rectangle, and a separate border color (say border is 1 px wide).

From my observation, Qt provides three methods - fillRect and drawRect and drawRoundedRect. I have tried them, they don't work like I want to. There is  no method like fillRoundedRect. Which means that I can draw a rounded rectangle but it won't be filled with the color I want.

How do I do it? And also, I read that due to some aliasing problems, the corners are often rendered equal. How do I set it as equal for all four? Will painter.setRenderHint(QPainter::Antialiasing) suffice? Or do I have to do anything else?
解决方案
You can create a QPainterPath, add the rounded rect to it, and then fill and stroke it:
QPainter p(this);
p.setRenderHint(QPainter::Antialiasing);
QPainterPath path;
path.addRoundedRect(QRectF(10, 10, 100, 50), 10, 10);
QPen pen(Qt::black, 10);
p.setPen(pen);
p.fillPath(path, Qt::red);
p.drawPath(path);
Note that even with antialiasing, 1 px border will probably never really look good, especially on a low DPI desktop monitor, on a high DPI mobile device it will be almost invisible.



If you create the rectangle as QRectF(9.5, 9.5, 100, 50) it will look better with 1 px antialiased border, because it will "snap" on the right pixel:



                        
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