头文件
#ifndef TICKER_H
#define TICKER_H
#include <QWidget>
class Ticker : public QWidget
{
Q_OBJECT
Q_PROPERTY(QString text READ text WRITE setText)
public:
Ticker(QWidget *parent = 0);
void setText(const QString &newText);
QString text() const { return myText; }
QSize sizeHint() const;
protected:
void paintEvent(QPaintEvent *event);
void timerEvent(QTimerEvent *event);
void showEvent(QShowEvent *event);
void hideEvent(QHideEvent *event);
private:
QString myText;
int offset;
int myTimerId;
};
#endif
cpp文件
#include <QtGui>
#include "ticker.h"
Ticker::Ticker(QWidget *parent)
: QWidget(parent)
{
offset = 0;
myTimerId = 0;
}
void Ticker::setText(const QString &newText)
{
myText = newText;
update();
updateGeometry();
}
QSize Ticker::sizeHint() const
{
return fontMetrics().size(0, text());
}
void Ticker::paintEvent(QPaintEvent * /* event */)
{
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());
x += textWidth;
}
}
void Ticker::showEvent(QShowEvent * /* event */)
{
myTimerId = startTimer(30);
}
void Ticker::timerEvent(QTimerEvent *event)
{
if (event->timerId() == myTimerId) {
++offset;
if (offset >= fontMetrics().width(text()))
offset = 0;
scroll(-1, 0);
} else {
QWidget::timerEvent(event);
}
}
void Ticker::hideEvent(QHideEvent * /* event */)
{
killTimer(myTimerId);
myTimerId = 0;
}
main文件
#include <QApplication>
#include "ticker.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Ticker ticker;
ticker.setWindowTitle(QObject::tr("Ticker"));
ticker.setText(QObject::tr("How long it lasted was impossible to "
"say ++ "));
ticker.show();
return app.exec();
}
C++ GUI qt4 编程第二版 第7章的例子
要多看书……
