关于QComboBox的currentIndexChanged()信号问题

http://blog.csdn.net/koilin/article/details/7599223

去年开始做界面，不过在过去的一年用的MFC，从今年开始用Qt.确实用Qt来做界面比MFC简单，而且更容易做出来炫炫的效果。折腾的这段时间里，其实每天都会发现新的问题，只是太懒了，一直都没记录下来。今天就来个开始吧：

问题描述：

我有两个QComboBox combo1, combo2：

[cpp] view plaincopyprint?

1. QComboBox *combo1 = new QComboBox;  
2. QComboBox *combo2 = new QComboBox;  
3. combo1->addItem("1-1");  
4. combo1->addItem("1-2");  
5. combo2->addItem("2-1");  
6. combo2->addItem("2-2");  
7. connect(combo1, SIGNAL(currentIndexChanged(int)), combo2, SLOT(process(int)));  
8. connect(combo2, SIGNAL(currentIndexChanged(int)), combo1, SLOT(process(int)));  

QComboBox *combo1 = new QComboBox;QComboBox *combo2 = new QComboBox;combo1->addItem("1-1");combo1->addItem("1-2");combo2->addItem("2-1");combo2->addItem("2-2");connect(combo1, SIGNAL(currentIndexChanged(int)), combo2, SLOT(process(int)));connect(combo2, SIGNAL(currentIndexChanged(int)), combo1, SLOT(process(int)));

然后是信号处理函数：

[cpp] view plaincopyprint?

1. void process(int index)  
2. {  
3.     QComboBox *combo1 = new QComboBox;  
4.     QComboBox *combo2 = new QComboBox;  
5.     if (sender() == combo1)  
6.     {  
7.         combo2->setCurrentIndex(index);  
8.     }  
9.     else if (sender() == combo2)  
10.     {  
11.         combo1->setCurrentIndex(index);  
12.     }  
13. }  

void process(int index){QComboBox *combo1 = new QComboBox;QComboBox *combo2 = new QComboBox;if (sender() == combo1){combo2->setCurrentIndex(index);}else if (sender() == combo2){combo1->setCurrentIndex(index);}}

这样两个combobox之间就产生了死循环。因为不管是手动改变combobox的当前index还是使用函数来设置当前的index都会发出index改变的消息，此时就需要使用关闭信号：

[cpp] view plaincopyprint?

1. void process(int index)  
2. {  
3.     QComboBox *combo1 = new QComboBox;  
4.     QComboBox *combo2 = new QComboBox;  
5.     if (sender() == combo1)  
6.     {  
7.         combo2->blockSignals(true);  
8.         combo2->setCurrentIndex(index);  
9.         combo2->blockSignals(false);  
10.     }  
11.     else if (sender() == combo2)  
12.     {  
13.         combo1->blockSignals(true);  
14.         combo1->setCurrentIndex(index);  
15.         combo1->blockSignals(false);  
16.     }  
17. }  

void process(int index){QComboBox *combo1 = new QComboBox;QComboBox *combo2 = new QComboBox;if (sender() == combo1){combo2->blockSignals(true);combo2->setCurrentIndex(index);combo2->blockSignals(false);}else if (sender() == combo2){combo1->blockSignals(true);combo1->setCurrentIndex(index);combo1->blockSignals(false);}}

好了，就这么多，写个文章还真不容易啊！