我有一个关于QTimer的问题：
我现在用qt/e作一个仪器的界面，平常没有信号测试的时候，就在液晶界面上呈现随机的波形。我添加了一个定时器，50ms一个定时。等timeout()时，界面update()重画一场随机的波形。可是问题是，在程序运行的时候，发现波形是以1s为定时周期刷新的，而不是按照程序设定的50ms刷新的。我调整start(int msec)里的参数，发现改成2000后，波形就按照2s的周期刷新，而改成1000以下，无论什么数，波形始终按照1s的周期刷新。
请问大家，这是为什么呢？怎么样才能让我的随机波形以更快的速度刷新呢？
代码付下，请大家帮我看看，谢谢！
#include "mygui.h"
//#include "mymenu.h"
#include <qpen.h>
#include <qpixmap.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <qpaintdevice.h>
#include <qbitmap.h>
#include <qcolor.h>
MyMainWindow::MyMainWindow()
{
screentimer = new QTimer(this);
setBackgroundColor(QColor(80,80,80));
setBackgroundMode(NoBackground);
setGeometry(0,0,320,240);
setupbutton = new QPushButton("Setup",this);
setupbutton->setGeometry(0,0,40,25);
setupmenu = new MyMenuSetup(this);
setupbutton->setPopup(setupmenu);
filebutton = new QPushButton("File",this);
filebutton->setGeometry(41,0,40,25);
filemenu = new MyMenuFile(this);
filebutton->setPopup(filemenu);
resultbutton = new QPushButton("Result",this);
resultbutton->setGeometry(82,0,40,25);
helpbutton = new QPushButton("Help",this);
helpbutton->setGeometry(123,0,40,25);
startTimer(0);
connect(screentimer,SIGNAL(timeout()),this,SLOT(repaint()));
screentimer->changeInterval(1);
screentimer->start(50);
}
void MyMainWindow::keyPressEvent(QKeyEvent*k)
{
switch(k->ascii())
{
case 'a':
filebutton->setDown(false);
resultbutton->setDown(false);
helpbutton->setDown(false);
setupbutton->setDown(true);
//setupbutton->setFocus();
setupmenu->popup(QPoint(2,30));
//setupbutton->setFocus();
break;
case 'b':
setupbutton->setDown(false);
resultbutton->setDown(false);
helpbutton->setDown(false);
filebutton->setDown(true);
//filebutton->setFocus();
filemenu->popup(QPoint(42,30));
//filebutton->setFocus();
break;
case 'c':
setupbutton->setDown(false);
filebutton->setDown(false);
helpbutton->setDown(false);
resultbutton->setDown(true);
resultbutton->setFocus();
break;
case 'd':
setupbutton->setDown(false);
resultbutton->setDown(false);
filebutton->setDown(false);
helpbutton->setDown(true);
helpbutton->setFocus();
QApplication::exit();
break;
}
}
void MyMainWindow::paintEvent(QPaintEvent *)
{
int i;
int value;
int bak_value=130;
int w=this->width();
int h=this->height();
QPen exborderpen(blue,2,SolidLine);
QPen inblankpen(black,1,DotLine);
QPen datapen(cyan,1,SolidLine);
QPixmap pm(w,h);
pm.fill(white);
srand(time(NULL));
QPainter paint(&pm);
paint.setPen(exborderpen);
paint.drawRect(8,30,304,200);
paint.setPen(inblankpen);
for(i=1;i<8;i++)
{
paint.drawLine(10,30+i*25,309,30+i*25);
}
for(i=1;i<12;i++)
{
paint.drawLine(10+i*25,30,10+i*25,229);
}
paint.setPen(datapen);
for(i=0;i<299;i++)
{
value=rand()%50+105;
paint.drawLine(10+i,bak_value,11+i,value);
bak_value = value;
}
paint.end();
QPainter painter(this);
painter.drawPixmap(0,0,pm,0,0);
}
