nsObject PerformSelector问题

Hooooookay这是另一个 “我只是不知道发生了什么事” 问题:

我第一次打电话给 getFullWL() 下面,我得到了我所有的期望值。但是,每次后续调用都会返回 nan 而不是真值( -nan(0x400000000) 在Xcode或其他地方)

此外,如果我将“调试”行放入 SFLog 值打印为 南 但返回正确的值! 如果我发表评论 斯弗洛格 (这只是一个定义 NSLog 根据我设置的级别-无特殊),则该值不会被捕获 isnan() 在里面 View 但是被检查为 ISNN() 在里面 Window

窗口 和 视图 坐在一根线上,而 DataModule 和 DCMPix 坐在另一个(我相信是主线)。 DCMPIX 还从核心数据对象获取一些数据( fImage 我相信。

void Window::PopUp()
{
    // Grab the View from the Pipe Thread and cast it to my local namespace subclass View
    View *view = static_cast< View* >(getPipe()->getView(event.context.view));

    float fullww = view->getFullWW();
    float fullwl = view->getFullWL();
    //SFLog(@"WindowLevel Window %f", wl);

    // set SLider Values
    if (!isnan(fullwl)){
        [[vc winLevel] setMinValue:fullwl];
        [[vc winLevel] setMaxValue:(-1.0f*fullwl)];
    }
}


float View::getFullWL()
{
    float wl = _callPixMethod(@selector(fullwl)).floatValue;
    if ( isnan(wl) ) wl = _wl * 2.0f; //<-- is never detected as NaN here
    //SFLog(@"WindowLevel View %f", wl);  //<-- but is *printed* as NaN here
    return wl;
}

// A Union to "cast" the return from the [object performSelector:] method.
//   Since it returns `id` and (float)(id) doesn't work.
union performReturn {
    id OBJC_ID;
    int intValue;
    float floatValue;
    bool boolValue;
};


performReturn View::_callPixMethod(SEL method)
{
    DataModule* data;
    DataVisitor getdata(&data);
    getConfig()->accept(getdata);
    performReturn retVal;
    retVal.OBJC_ID = data->callPixMethod(_datasetIndex, _datasetID, method);
    return retVal;
}


id DataModule::callPixMethod(int index, std::string predicate, SEL method)
{
    DCMPix *pix =[[getSeriesData(predicate) pixList_] objectAtIndex:index];

    pthread_mutex_lock(&_mutex);

    id retVal = [pix performSelector:method];

    pthread_mutex_unlock(&_mutex);

    return retVal;
}

// DCMPix.m (from API, can't change)
- (float) fullwl
{
 if( fullww == 0 && fullwl == 0) [self computePixMinPixMax];
 return fullwl;
}

- (void)computePixMinPixMax
{
    float pixmin, pixmax;

    if( fImage == nil || width * height <= 0) return;

    [checking lock];

    @try 
    {
        if( isRGB)
        {
            pixmax = 255;
            pixmin = 0;
        }
        else
        {
            float fmin, fmax;

            vDSP_minv ( fImage,  1, &fmin, width * height);
            vDSP_maxv ( fImage , 1, &fmax, width * height);

            pixmax = fmax;
            pixmin = fmin;

            if( pixmin == pixmax)
            {
                pixmax = pixmin + 20;
            }
        }

        fullwl = pixmin + (pixmax - pixmin)/2;
        fullww = (pixmax - pixmin);
    }
    @catch (NSException * e) 
    {
        NSLog( @"***** exception in %s: %@", __PRETTY_FUNCTION__, e);
    }

    [checking unlock];
}

救命!为什么我不能得到正确的值 窗口 ?

我也没有 南 打电话的时候 view->getFullWW() 即使它遵循相同的执行路径。(但电话 @selector(fullww) )

不会引发任何错误或异常。只是奇怪的行为。

谢谢!

在进一步测试之后,以下更改会产生所有差异:

float View::getFullWL()
{
    float wl = _callPixMethod(@selector(fullwl)).floatValue;
    if ( isnan(wl) ) wl = _wl * 2.0f; //<-- is never detected as NaN here
    NSLog(@"WindowLevel View %f", wl);  //<-- is *printed* as NaN here
    return wl; //<-- returns expected value
}

float View::getFullWL()
{
    float wl = _callPixMethod(@selector(fullwl)).floatValue;
    if ( isnan(wl) ) wl = _wl * 2.0f; //<-- is never detected as NaN here
    return wl; //<-- returns `nan`
}

经过更多的测试后,如果nslog()语句出现在 float fullwl = 被分配。

void Window::PopUp()
{
    // Grab the View from the Pipe Thread and cast it to my local namespace subclass View
    View *view = static_cast< View* >(getPipe()->getView(event.context.view));

    float fullww = view->getFullWW();
    NSLog("Putting this here, makes fullwl work.  Removing it, stores fullwl as nan");
    float fullwl = view->getFullWL();
    //SFLog(@"WindowLevel Window %f", wl);