Qt常用代码片段(2017.6.17更新)

1.Returns the directory that contains the application executable.

[static] QString QCoreApplication::applicationDirPath()

或

qApp->applicationDirPath();

2.Returns pathName with the '/' separators converted to separators that are appropriate for the underlying operating system.

On Windows, toNativeSeparators("c:/winnt/system32") returns "c:\winnt\system32".
The returned string may be the same as the argument on some operating systems, for example on Unix.
This function was introduced in Qt 4.2.

[static] QString QDir::toNativeSeparators(const QString &pathName)

QString path = QApplication::applicationDirPath() + "/" + "24rgb.bmp";
path = QDir::toNativeSeparators(path);

3.Returns a copy of the image in the given format(图像格式转换).

QImage QImage::convertToFormat(Format format, Qt::ImageConversionFlags flags = Qt::AutoColor) const

4.获取文件路径的绝对路径

QString QFileInfo::absolutePath() const

QFileInfo file("C:\\Program Files\\Microsoft SQL Server\\80\\COM\\sqlvdi.dll");
QString absolutePath = file.absolutePath(); // "C:/Program Files/Microsoft SQL Server/80/COM" 

5.显示非模态对话框，阻塞后面的调用，直到该非模态对话框关闭

QDialog dlg;
dlg.show();
QEventLoop loop;
connect(&dlg, SIGNAL(finished(int)), &loop, SLOT(quit()));
loop.exec(QEventLoop::ExcludeUserInputEvents);//loop.exec(),不排除用户输入事件

http://blog.youkuaiyun.com/cocoasprite/article/details/54631692
6.测量运行时间：QElapsedTimer与QTime

a.QElapsedTimer可以获得纳秒级时间间隔；

b.QTime可以获得毫秒级时间间隔。