Qt中关于控件QTextEdit用法的疑问

south2000

我在对话框上面放了一个控件QTextEdit,命名为myedit,希望让它显示信息。我想让它先显示“等待”，3秒后显示“完成”，如下
myedit->setText(QString::fromLocal8Bit("等待"));
sleep(3);
myedit->setText(QString::fromLocal8Bit("完成"));
可是，“等待”没有显示出来，而是有3秒的空白，然后直接显示“完成”。

我又这么写
myedit->setText(QString::fromLocal8Bit("等待"));
myedit->updateContents();
sleep(3);
myedit->setText(QString::fromLocal8Bit("完成"));
myedit->updateContents();
效果还是与前面的一样。

请问，如何才能达到我要的效果？
谢谢！

stdio

[code:1]#include <qtimer.h>

QTimer *timers = new QTimer(this,"timers");
connect( timers, SIGNAL(timeout()), this, SLOT(my_slot()) );
timers->start( 2000, TRUE );

void my_slot(){
  myedit->setText(QString::fromLocal8Bit("完成"));
  myedit->updateContents();
}

[/code:1]

south2000

stdio，感谢你，你的方法可以用的。

south2000

我有新问题了，现在是这样的

1。我设置了一个全局变量QString g_str;
2。设置一个slot
void my_slot(){
  myedit->setText(g_str);
  myedit->updateContents();
}
3。建立一个信号triger()，与my_slot()相关联
4。在某个函数里面：
g_str = QString::fromLocal8Bit("开始处理");
emit triger();
QTimer *timers = new QTimer(this,"timers");
connect( timers, SIGNAL(timeout()), this, SLOT(my_slot()) );
timers->start( 3000, TRUE );
g_str = QString::fromLocal8Bit("处理完成");
发现这样运行一切正常
////////////////////////////////////////////////////////////////////////////////////////



但是，我其实用不是一个定时器，而是先显示“开始处理”，接着程序处理，在程序处理完毕后显示“处理完成”
即
4。
g_str = QString::fromLocal8Bit("开始处理");
emit triger();

程序处理...

g_str = QString::fromLocal8Bit("处理完成");
emit triger();

这次就有问题了，“开始处理”没有显示，而是空白，到程序处理完成后，直接显示“处理完成”，请问怎么办？

谢谢！

stdio

用QT多线程处理文字显示

south2000

stdio,能不能不用多线程啊

stdio

我认为只能用线程

south2000

那么怎么给我一个例子看看啊。

stdio

ft……

你要不要我把整个程序帮你写完啊？！

自己看QT文档

south2000

能不能给几个函数啊，我去看看

stdio

IBM Linux专区有QT线程介绍
QT Assistant<---这个你不会不知道吧？

#include <qthread.h>

QThread Class Reference
The QThread class provides platform-independent threads. More...
All the functions in this class are thread-safe when Qt is built with thread support.
#include <qthread.h>
Inherits Qt.
List of all member functions.
Public Members
QThread ( unsigned int stackSize = 0 )
virtual ~QThread ()
bool wait ( unsigned long time = ULONG_MAX )
enum Priority { IdlePriority, LowestPriority, LowPriority, NormalPriority, HighPriority, HighestPriority, TimeCriticalPriority, InheritPriority }
void start ( Priority priority = InheritPriority )
void terminate ()
bool finished () const
bool running () const
Static Public Members
Qt::HANDLE currentThread ()
void postEvent ( QObject * receiver, QEvent * event )  (obsolete)
void exit ()
Protected Members
virtual void run () = 0
Static Protected Members
void sleep ( unsigned long secs )
void msleep ( unsigned long msecs )
void usleep ( unsigned long usecs )
Detailed Description
The QThread class provides platform-independent threads.
A QThread represents a separate thread of control within the program; it shares data with all the other threads within the process but executes independently in the way that a separate program does on a multitasking operating system. Instead of starting in main(), QThreads begin executing in run(). You inherit run() to include your code. For example:
    class MyThread : public QThread {

    public:

        virtual void run();

    };

    void MyThread::run()
    {
        for( int count = 0; count < 20; count++ ) {
            sleep( 1 );
            qDebug( "Ping!" );
        }
    }

    int main()
    {
        MyThread a;
        MyThread b;
        a.start();
        b.start();
        a.wait();
        b.wait();
    }
   
This will start two threads, each of which writes Ping! 20 times to the screen and exits. The wait() calls at the end of main() are necessary because exiting main() ends the program, unceremoniously killing all other threads. Each MyThread stops executing when it reaches the end of MyThread::run(), just as an application does when it leaves main().
See also Thread Support in Qt, Environment Classes, and Threading. Member Type Documentation
QThread:riority
This enum type indicates how the operating system should schedule newly created threads.
QThread::IdlePriority - scheduled only when no other threads are running.
QThread::LowestPriority - scheduled less often than LowPriority.
QThread::LowPriority - scheduled less often than NormalPriority.
QThread::NormalPriority - the default priority of the operating system.
QThread::HighPriority - scheduled more often than NormalPriority.
QThread::HighestPriority - scheduled more often then HighPriority.
QThread::TimeCriticalPriority - scheduled as often as possible.
QThread::InheritPriority - use the same priority as the creating thread. This is the default.
Member Function Documentation
QThread::QThread ( unsigned int stackSize = 0 )
Constructs a new thread. The thread does not begin executing until start() is called.
If stackSize is greater than zero, the maximum stack size is set to stackSize bytes, otherwise the maximum stack size is automatically determined by the operating system.
Warning: Most operating systems place minimum and maximum limits on thread stack sizes. The thread will fail to start if the stack size is outside these limits.
QThread::~QThread () [virtual]
QThread destructor.
Note that deleting a QThread object will not stop the execution of the thread it represents. Deleting a running QThread (i.e. finished() returns FALSE) will probably result in a program crash. You can wait() on a thread to make sure that it has finished.
Qt::HANDLE QThread::currentThread () [static]
This returns the thread handle of the currently executing thread.
Warning: The handle returned by this function is used for internal purposes and should not be used in any application code. On Windows, the returned value is a pseudo handle for the current thread, and it cannot be used for numerical comparison.
void QThread::exit () [static]
Ends the execution of the calling thread and wakes up any threads waiting for its termination.
bool QThread::finished () const
Returns TRUE if the thread is finished; otherwise returns FALSE.
void QThread::msleep ( unsigned long msecs ) [static protected]
System independent sleep. This causes the current thread to sleep for msecs milliseconds
void QThread::postEvent ( QObject * receiver, QEvent * event ) [static]
This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.
Use QApplication::postEvent() instead.
void QThread::run () [pure virtual protected]
This method is pure virtual, and must be implemented in derived classes in order to do useful work. Returning from this method will end the execution of the thread.
See also wait().
bool QThread::running () const
Returns TRUE if the thread is running; otherwise returns FALSE.
void QThread::sleep ( unsigned long secs ) [static protected]
System independent sleep. This causes the current thread to sleep for secs seconds.
void QThread::start ( Priority priority = InheritPriority )
Begins execution of the thread by calling run(), which should be reimplemented in a QThread subclass to contain your code. The operating system will schedule the thread according to the priority argument.
If you try to start a thread that is already running, this function will wait until the the thread has finished and then restart the thread.
See also Priority.
void QThread::terminate ()
This function terminates the execution of the thread. The thread may or may not be terminated immediately, depending on the operating system's scheduling policies. Use QThread::wait() after terminate() for synchronous termination.
When the thread is terminated, all threads waiting for the the thread to finish will be woken up.
Warning: This function is dangerous, and its use is discouraged. The thread can be terminated at any point in its code path. Threads can be terminated while modifying data. There is no chance for the thread to cleanup after itself, unlock any held mutexes, etc. In short, use this function only if absolutely necessary.
void QThread::usleep ( unsigned long usecs ) [static protected]
System independent sleep. This causes the current thread to sleep for usecs microseconds
bool QThread::wait ( unsigned long time = ULONG_MAX )
A thread calling this function will block until either of these conditions is met:
The thread associated with this QThread object has finished execution (i.e. when it returns from run()). This function will return TRUE if the thread has finished. It also returns TRUE if the thread has not been started yet.
time milliseconds has elapsed. If time is ULONG_MAX (the default), then the wait will never timeout (the thread must return from run()). This function will return FALSE if the wait timed out.
This provides similar functionality to the POSIX pthread_join() function. This file is part of the Qt toolkit. Copyright © 1995-2004 Trolltech. All Rights Reserved.

south2000

你说的用QThread,我搞不定,呵呵,Qt帮助文档太简明了。