解决QPixmap报“QPixmap::grabWindow(): Unable to copy pixels from framebuffer“问题

    今天在使用QPixmap::grabWindow()截图时，弹出“QPixmap::grabWindow(): Unable to copy pixels from framebuffer”错误。

    问题原因：QPixmap::grabWindow()这个函数适用于Qt5版本截屏，但该函数在Qt4上表现不稳定，经常出现“Unable to copy pixels from framebuffer”错误。
    解决方法：建议改成QPixmap::grabWidget()来进行截图。
    详细步骤，请查看第2节【修复代码B】。

1 原始代码A

#include <QApplication>
#include <QPixmap>
#include <QScreen>
#include <QDebug>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 获取当前活动窗口的 IDWId windowId = QApplication::activeWindow()->winId();// 捕获窗口截图QPixmap screenshot = QPixmap::grabWindow(windowId); //此处经常报错，偶尔可用，但不稳定if (screenshot.isNull()) {qDebug() << "Failed to grab window screenshot.";} else {// 保存截图screenshot.save("screenshot.png");qDebug() << "Window screenshot saved successfully.";}return a.exec();
}

2 修复代码B

#include <QApplication>
#include <QPixmap>
#include <QScreen>
#include <QDebug>int main(int argc, char *argv[])
{QApplication a(argc, argv);// 获取当前活动窗口的 IDWId windowId = QApplication::activeWindow()->winId();// 捕获窗口截图//修复如下QRect rect = QApplication::desktop()->screenGeometry();QPixmap screenshot = QPixmap::grabWidget(QApplication::desktop(),rect);   if (screenshot.isNull()) {qDebug() << "Failed to grab window screenshot.";} else {// 保存截图screenshot.save("screenshot.png");qDebug() << "Window screenshot saved successfully.";}return a.exec();
}

参考文献：

【1】 github.2015.mumble-voip.修复QPixmap::grabWindow()报错