[PyQt4] Smooth text scrolling in QLabel (again)

[cw9000]

I changed WidgetMarqueeLabel.h and.cpp to the following.

#ifndef _WIDGETMARQUEELABEL_H_
#define _WIDGETMARQUEELABEL_H_
 
#include <QLabel>
#include <QTimer>
 
class WidgetMarqueeLabel : public QLabel
{
	Q_OBJECT
 
	public: //Member Functions
		enum Direction{LeftToRight,RightToLeft};
                WidgetMarqueeLabel(QWidget *parent = 0,int spd=50,int dir=WidgetMarqueeLabel::RightToLeft,bool start=FALSE);
		~WidgetMarqueeLabel();	
		void show();
		void setAlignment(Qt::Alignment);
                int getSpeed();
 
	public slots: //Public Member Slots
                void setSpeed(int s);
		void setDirection(int d);
                void updateCoordinates();
	protected: //Member Functions
		void paintEvent(QPaintEvent *evt);
		void resizeEvent(QResizeEvent *evt);
 
 
	private: //Data Members
                bool autostart;
                int px;
		int py;
		QTimer timer;
		Qt::Alignment m_align;
                int speed;
		int direction;
		int fontPointSize;
		int textLength;
 
	private slots: //Private Member Slots
		void refreshLabel();
};
#endif /*_WIDGETMARQUEELABEL_H_*/

#ifndef _WIDGETMARQUEELABEL_H_
#define _WIDGETMARQUEELABEL_H_

#include <QLabel>
#include <QTimer>

class WidgetMarqueeLabel : public QLabel
{
	Q_OBJECT

	public: //Member Functions
		enum Direction{LeftToRight,RightToLeft};
                WidgetMarqueeLabel(QWidget *parent = 0,int spd=50,int dir=WidgetMarqueeLabel::RightToLeft,bool start=FALSE);
		~WidgetMarqueeLabel();	
		void show();
		void setAlignment(Qt::Alignment);
                int getSpeed();
		
	public slots: //Public Member Slots
                void setSpeed(int s);
		void setDirection(int d);
                void updateCoordinates();
	protected: //Member Functions
		void paintEvent(QPaintEvent *evt);
		void resizeEvent(QResizeEvent *evt);


	private: //Data Members
                bool autostart;
                int px;
		int py;
		QTimer timer;
		Qt::Alignment m_align;
                int speed;
		int direction;
		int fontPointSize;
		int textLength;

	private slots: //Private Member Slots
		void refreshLabel();
};
#endif /*_WIDGETMARQUEELABEL_H_*/

To copy to clipboard, switch view to plain text mode 

#include "WidgetMarqueeLabel.h"
#include <QPainter>
#include <QDebug>
 
WidgetMarqueeLabel::WidgetMarqueeLabel(QWidget *parent,int spd,int dir,bool start)
    :QLabel(parent)
{	
	px = 0;
        py = 15;
        speed = spd;
        direction = dir;
        autostart=start;
	connect(&timer, SIGNAL(timeout()), this, SLOT(refreshLabel()));
        if (autostart==FALSE){
            if (fontMetrics().width(text())> width())
                timer.start(10);
        }
        else
            timer.start(10);
}
 
void WidgetMarqueeLabel::refreshLabel()
{
    if(direction==RightToLeft)
    {
            px -=1;
            if(px <= (-textLength))
                    px = width();
    }
    else
    {
 
            px +=1;
            if(px >= width())
                    px = - textLength;
    }
    timer.start(speed);
    repaint();
}
 
WidgetMarqueeLabel::~WidgetMarqueeLabel()
{}
 
void WidgetMarqueeLabel::show()
{	
	QLabel::show();
}
 
void WidgetMarqueeLabel::setAlignment(Qt::Alignment al)
{
	m_align = al;
	updateCoordinates();
	QLabel::setAlignment(al);
}
 
void WidgetMarqueeLabel::paintEvent(QPaintEvent *evt)
{
	QPainter p(this);
 
	p.drawText(px, py + fontPointSize, text());	
	p.translate(px,0);
 
}
 
void WidgetMarqueeLabel::resizeEvent(QResizeEvent *evt)
{	
	updateCoordinates();
	QLabel::resizeEvent(evt);
}
 
void WidgetMarqueeLabel::updateCoordinates()
{
        px=0;
        switch(m_align)
	{
		case Qt::AlignTop:
			py = 10;
			break;
		case Qt::AlignBottom:
			py = height()-10;
			break;
		case Qt::AlignVCenter:
			py = height()/2;
			break;
	}
	fontPointSize = font().pointSize()/2;
	textLength = fontMetrics().width(text());
        if (textLength>width())
            timer.start(10);
        else{
            timer.stop();
            repaint();
        }
}
 
void WidgetMarqueeLabel::setSpeed(int s)
{
	speed = s;
}
 
int WidgetMarqueeLabel::getSpeed()
{
	return speed;
}
 
void WidgetMarqueeLabel::setDirection(int d)
{
	direction = d;
        if (direction==RightToLeft){
            px = width() - textLength;
 
        }
        else
            px = 0;
	refreshLabel();
}

#include "WidgetMarqueeLabel.h"
#include <QPainter>
#include <QDebug>

WidgetMarqueeLabel::WidgetMarqueeLabel(QWidget *parent,int spd,int dir,bool start)
    :QLabel(parent)
{	
	px = 0;
        py = 15;
        speed = spd;
        direction = dir;
        autostart=start;
	connect(&timer, SIGNAL(timeout()), this, SLOT(refreshLabel()));
        if (autostart==FALSE){
            if (fontMetrics().width(text())> width())
                timer.start(10);
        }
        else
            timer.start(10);
}

void WidgetMarqueeLabel::refreshLabel()
{
    if(direction==RightToLeft)
    {
            px -=1;
            if(px <= (-textLength))
                    px = width();
    }
    else
    {

            px +=1;
            if(px >= width())
                    px = - textLength;
    }
    timer.start(speed);
    repaint();
}

WidgetMarqueeLabel::~WidgetMarqueeLabel()
{}

void WidgetMarqueeLabel::show()
{	
	QLabel::show();
}

void WidgetMarqueeLabel::setAlignment(Qt::Alignment al)
{
	m_align = al;
	updateCoordinates();
	QLabel::setAlignment(al);
}

void WidgetMarqueeLabel::paintEvent(QPaintEvent *evt)
{
	QPainter p(this);

	p.drawText(px, py + fontPointSize, text());	
	p.translate(px,0);

}

void WidgetMarqueeLabel::resizeEvent(QResizeEvent *evt)
{	
	updateCoordinates();
	QLabel::resizeEvent(evt);
}

void WidgetMarqueeLabel::updateCoordinates()
{
        px=0;
        switch(m_align)
	{
		case Qt::AlignTop:
			py = 10;
			break;
		case Qt::AlignBottom:
			py = height()-10;
			break;
		case Qt::AlignVCenter:
			py = height()/2;
			break;
	}
	fontPointSize = font().pointSize()/2;
	textLength = fontMetrics().width(text());
        if (textLength>width())
            timer.start(10);
        else{
            timer.stop();
            repaint();
        }
}

void WidgetMarqueeLabel::setSpeed(int s)
{
	speed = s;
}

int WidgetMarqueeLabel::getSpeed()
{
	return speed;
}

void WidgetMarqueeLabel::setDirection(int d)
{
	direction = d;
        if (direction==RightToLeft){
            px = width() - textLength;

        }
        else
            px = 0;
	refreshLabel();
}

To copy to clipboard, switch view to plain text mode 

I changed a few things, including the paintEvent function. The scroll was too fast the way it was, so I made sure it was setup to the timer
that they had instead of just the paintEvent. I also added a few features, like only scrolling if the text amount is larger than the space.
If the text changes in my MainWindow.cpp I emit a SIGNAL songChanged and connect it to WidgetMarqueeLabel's SLOT updateCoordinates;
here is a snippet from my code:

song=new WidgetMarqueeLabel(ui->centralWidget,1);
     song->setObjectName(QString::fromUtf8("song"));
     song->setGeometry(QRect(60, 10, 281, 21));
connect(this,SIGNAL(songChanged()),song,SLOT(updateCoordinates()));
song->setText("hello");
     song->setSpeed(100);
 
void MainWindow::onSourceChanged(Phonon::MediaSource source)
 {
     QMultiMap<QString,QString> tags=getTags(source);
     QString file;
     if(tags.value("TITLE").isEmpty())
        file=source.fileName().mid(source.fileName().lastIndexOf("/")+1,source.fileName().size());
     else
         file=tags.value("ARTIST")+"-"+tags.value("TITLE");
     song->setText(file);
     emit songChanged();
     global_index=sources.indexOf(source);
     populateList();
}

song=new WidgetMarqueeLabel(ui->centralWidget,1);
     song->setObjectName(QString::fromUtf8("song"));
     song->setGeometry(QRect(60, 10, 281, 21));
connect(this,SIGNAL(songChanged()),song,SLOT(updateCoordinates()));
song->setText("hello");
     song->setSpeed(100);

void MainWindow::onSourceChanged(Phonon::MediaSource source)
 {
     QMultiMap<QString,QString> tags=getTags(source);
     QString file;
     if(tags.value("TITLE").isEmpty())
        file=source.fileName().mid(source.fileName().lastIndexOf("/")+1,source.fileName().size());
     else
         file=tags.value("ARTIST")+"-"+tags.value("TITLE");
     song->setText(file);
     emit songChanged();
     global_index=sources.indexOf(source);
     populateList();
}

To copy to clipboard, switch view to plain text mode 

There isn't any reason to include 1 as a speed in my instantiation of song but at least you can see me setting the speed.
take a look at the examples in the zip file.
I tried to make a plugin for this to Designer. I was able to get Designer to display the widget, but as soon as I went to click on it it would crash Designer/Qt Creator. So I'm stuck with programatically adding a WidgetMarqueeLabel. If you have any info on this feel free to share cw9000@hotmail.com

[Lykurg]

After a brief look, I would advice to cache the text in a pixmap and draw that. It should be much faster. Also do not use repaint(). Use update().

[enaud]

Hi,
I wondered if it was possibile to reappear before the text that reaches the end of the last letter on the right:
I want something like this: for example (white space are 25):

WidgetMarqueeLabel
Wi                         dgetMarqueeLabel
tMarqueeLabel                         Widge
eLabel                         WidgetMarque
el                           WidgetMarqueeLa
WidgetMarqueeLabel

WidgetMarqueeLabel
Wi                         dgetMarqueeLabel
tMarqueeLabel                         Widge
eLabel                         WidgetMarque
el                           WidgetMarqueeLa
WidgetMarqueeLabel

To copy to clipboard, switch view to plain text mode 

Is possibile?

thanks

[enaud]

up nothing here?

[Lykurg]

Ehm, yes, it is possible. What exactly is the problem?

[enaud]

Look here: I no want wait the end of text for restart text at beginning..
But i want restart text before the beginning of screen.

Hi,
I wondered if it was possibile to reappear before the text that reaches the end of the last letter on the right:
I want something like this: for example (white space are 25):

WidgetMarqueeLabel
Wi                         dgetMarqueeLabel
tMarqueeLabel                         Widge
eLabel                         WidgetMarque
el                           WidgetMarqueeLa
WidgetMarqueeLabel

WidgetMarqueeLabel
Wi                         dgetMarqueeLabel
tMarqueeLabel                         Widge
eLabel                         WidgetMarque
el                           WidgetMarqueeLa
WidgetMarqueeLabel

To copy to clipboard, switch view to plain text mode 

Is possibile?

thanks

[prsnot]

Hi enaud,

Since I'm on something realy simillar to your implemetation, did you make this Marquee effect happen in the end?

thanks.