QT学习笔记之十 Ticker

#include <QtGui>
#include "ticker.h"
#include "ui_ticker.h"
Ticker::Ticker(QWidget *parent)
: QWidget(parent), ui(new Ui::Ticker)
{
ui->setupUi(this);
offset = 0;
timerID = 0;
}
Ticker::~Ticker()
{
delete ui;
}
/**
设置文本
*/
void Ticker::setText(const QString &newText)
{
tickerText = newText;
update();
updateGeometry();
}
/**
获取文本内容
*/
QString Ticker::text() const
{
return tickerText;
}
/**
设置Widget大小
*/
QSize Ticker::sizeHint() const
{
return fontMetrics().size(0,text());   //fontMetrics(): Returns the font metrics for the widget's current font
}
/**
绘制事件
*/
void Ticker::paintEvent(QPaintEvent *)
{
QPainter painter(this);
int textWidth = fontMetrics().width(text());
if (textWidth < 1)
return ;
int x = -offset;
while (x < width()) {
painter.drawText(x,0,textWidth,height(),Qt::AlignLeft | Qt::AlignVCenter,text());   //绘制文本
x += textWidth;
}
}
/**
定时器事件
*/
void Ticker::timerEvent(QTimerEvent *event)
{
if (event->timerId() == timerID) {
++offset;
if(offset >= fontMetrics().width(text()))
offset = 0;
scroll(-1,0);    //向左滚动一个像素
} else {
QWidget::timerEvent(event);
}
}
/**
显示事件
*/
void Ticker::showEvent(QShowEvent *)
{
timerID = startTimer(30);   //Starts a timer and returns a timer identifier, or returns zero if it could not start a timer.
}
/**
隐藏事件
*/
void Ticker::hideEvent(QHideEvent *)
{
killTimer(timerID);
timerID = 0;
}