如何提高 QPainter 的性能？
我有一个大显示器（大约 1000x2000 像素），我正在执行以下操作来将图像绘制到屏幕上：
QImage *pImage = GetImage(); // from wherever
QPainter painter(this);
painter.drawImage((0,0), *pImage); // this line takes over 100ms to complete.
我绘制的屏幕越大，绘制所需的时间就越长。我猜 pImage 正在被 memcpy'd，这就是区别。我怎样才能减少这种开销？我并不是想扩大规模或做任何事情。
谢谢。
I have a large display (about 1000x2000 pixels) and I'm doing the following to draw images to the screen:
QImage *pImage = GetImage(); // from wherever
QPainter painter(this);
painter.drawImage((0,0), *pImage); // this line takes over 100ms to complete.
The larger the screen is that I'm drawing to, the longer this paint takes. I guess the pImage is being memcpy'd and that's the difference. How can I reduce this overhead? I'm not trying to scale or anything here.
Thanks.
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您正在绘制 QImage。不要这样做，尝试使用 QPixmap 代替。
来自 QImage 文档：
根据平台的不同，将 QImage 数据转换为绘画所需的格式和位置，可以 PS：不需要
在堆上创建 QImage，因为
You're painting a QImage. Don't do that, try with a QPixmap instead.
From the QImage documentation:
Depending on the platform, getting the QImage data into the format and location needed for painting, can be extremely expensive.
P.S.: There is no need to create QImages on the heap, as
您可以进行的一项简单改进是仅绘制需要更新的区域（如果可以的话）。
QPaintEvent包含更改区域的矩形，并且QPainter::drawImage具有重载那可以取矩形作为要绘制的部分。您还可以查看
ImageConversionFlags更快的选项。One simple improvement you can make is to draw only the area that needs updated (if you can). The
QPaintEventcontains a rect for the changed area, and theQPainter::drawImagehas overloads that can take rects for the portion to draw.You might also look at the
ImageConversionFlagsoptions for faster options.