如何获得QQuickItem的变换矩阵？(How can I get transform matrix for QQuickItem?)

 我终于在一本书中找到了完整的答案： 
 
 通过声明结构就像这样： 
 
struct sigaction act_therm; 
act_therm.sa_handler=handler_therm;
 
 标志SA_RESETHAND（默认情况下）附加到结构。 每次使用它调用sigaction时，它都会恢复信号的默认行为。 
 
 有两种方法可以解决这个问题： 
 
 
 
 坏的一个，包括每次用sigaction调用信号时重新定义信号的行为 
 
 
 定义完整的结构（来自man）并创建sa_flags以便不调用SA_RESETHAND： 
 
 
 
 
struct sigaction {
    void     (*sa_handler) (int);
    void     (*sa_sigaction) (int, siginfo_t *, void *);
    sigset_t   sa_mask;
    int        sa_flags;
    void     (*sa_restorer) (void);
};
 

I finally found the complete answer in a book :
 
By declaring the structure just like this :
 
struct sigaction act_therm; 
act_therm.sa_handler=handler_therm;
 
The flag SA_RESETHAND is (by default) attached to the struct. Each time sigaction is called with it, It restore the default behavior of the signal.
 
There is two way to solve this problem :
 
 
 
The bad one, which consists of redefining the behavior of the signal each time the signal is called with a sigaction
 
 
Defining the complete structure (from the man) and creating sa_flags so that SA_RESETHAND is not called:
 
 
 
 
struct sigaction {
    void     (*sa_handler) (int);
    void     (*sa_sigaction) (int, siginfo_t *, void *);
    sigset_t   sa_mask;
    int        sa_flags;
    void     (*sa_restorer) (void);
};