在有些情况下，我们需要对屏幕上的像素点进行大量的绘制操作。比如我之前模拟写的一个渲染管线开源练习，涉及到了大量的像素点操作。而Qt本身的QPen和QPainter::drawPoint的API如果操作大量的像素点，会非常耗时，因此我Google了这个方式：
原文链接：https://www.vikingsoftware.com/qwidget-pixel-drawing-2/
以下是核心代码：
#include <QApplication>#include <QWidget>#include <QPainter>#include <QTime>#include <QDebug>const int loop = 25;const int windowWidth = 400;const int windowHeight = 300;class PainterWindow : public QWidget { void paintEvent(QPaintEvent*) { QTime time; time.start(); for (int i = 0; i < ::loop; ++i) { QPainter painter(this); for (int x = 0; x < width(); ++x) { for (int y = 0; y < height(); ++y) { const QColor color(static_cast<QRgb>(i+x+y)); painter.setPen(color); painter.drawPoint(x, y); } } } qDebug() << "drawPoint time:" << time.elapsed(); close(); }}; class ImageWindow : public QWidget { void paintEvent(QPaintEvent*) { QRgb* pixels = new QRgb[width()*height()]; QTime time; time.start(); for (int i = 0; i < ::loop; ++i) { QPainter painter(this); QImage image((uchar*)pixels, width(), height(), QImage::Format_ARGB32); for (int x = 0; x < width(); ++x) { for (int y = 0; y < height(); ++y) { pixels[x + y * height()] = static_cast<QRgb>(i+x+y); } } painter.drawImage(0, 0, image); } qDebug() << "drawImage time:" << time.elapsed(); close(); delete[] pixels; }}; int main(int argc, char *argv[]) { QApplication a(argc, argv); PainterWindow w; w.resize(::windowWidth, ::windowHeight); w.show(); a.exec(); ImageWindow imageWindow; imageWindow.resize(::windowWidth, ::windowHeight); imageWindow.show(); a.exec();}