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).
我想画一个圆角的矩形（所有4个角的边框半径相同），特定的颜色填充整个矩形，并且有一个单独的边框颜色（比如边框宽1 px）。
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.
根据我的观察，Qt提供了三种方法 - fillRect和drawRect以及drawRoundedRect。我试过它们，它们不像我想的那样工作。没有像fillRoundedRect这样的方法。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。
How do I do it? And also, I read that due to some aliasing problems, the corners are often rendered as unequal. How do I set it as equal for all four? Will painter.setRenderHint(QPainter::Antialiasing) suffice? Or do I have to do anything else?
我该怎么做？而且，我读到由于一些混叠问题，角落经常被渲染为不相等。如何将它设置为全部四个相等？请问painter.setRenderHint（QPainter :: Antialiasing）是否足够？或者我还需要做其他事情吗？
1 个解决方案
#1
38
You can create a QPainterPath, add the rounded rect to it, and then fill and stroke it:
您可以创建QPainterPath，向其添加圆角矩形，然后填充并描边：
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.
请注意，即使使用抗锯齿功能，1 px边框也可能永远不会看起来很好，特别是在低DPI桌面显示器上，在高DPI移动设备上，它几乎不可见。
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:
如果您将矩形创建为QRectF（9.5,9.5,100,50），使用1 px抗锯齿边框会更好看，因为它会在右侧像素上“捕捉”：
#1
38
You can create a QPainterPath, add the rounded rect to it, and then fill and stroke it:
您可以创建QPainterPath，向其添加圆角矩形，然后填充并描边：
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.
请注意，即使使用抗锯齿功能，1 px边框也可能永远不会看起来很好，特别是在低DPI桌面显示器上，在高DPI移动设备上，它几乎不可见。
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:
如果您将矩形创建为QRectF（9.5,9.5,100,50），使用1 px抗锯齿边框会更好看，因为它会在右侧像素上“捕捉”：