QRubberBand painting in the scroll area widget

[sunil.thaha]

Ofcourse Everyone needs the code
We have a working example to refer to Don't we ?

[SkripT]

Ok here's the code:

void FotoEditorFotos::mousePressEvent(QMouseEvent *event)
{
	if (event -> button() != Qt::LeftButton) return;
 
	iniSeleccioX = event -> x();
	iniSeleccioY = event -> y();
 
	seleccio = true;
	x = iniSeleccioX;
	y = iniSeleccioY;
	w = 1;
	h = 1;
 
	update();
}
 
 
void FotoEditorFotos::mouseMoveEvent(QMouseEvent *event)
{
	if (event -> buttons() == Qt::LeftButton)
	{
		int auxX = event -> x();
		int auxY = event -> y();
		int posMaxX = width() - 1;
		int posMaxY = height() - 1;
 
		if (auxX < iniSeleccioX)
		{
			if (auxX < 0)
				x = 0;
			else
				x = auxX;
 
			w = iniSeleccioX - x + 1;
		}
		else
		{
			if (auxX >= posMaxX)
				w = posMaxX - iniSeleccioX + 1;
			else
				w = auxX - iniSeleccioX + 1;
 
			x = iniSeleccioX;
		}
 
		if (auxY < iniSeleccioY)
		{
			if (auxY < 0)
				y = 0;
			else
				y = auxY;
 
			h = iniSeleccioY - y + 1;
		}
		else
		{
			if (auxY >= posMaxY)
				h = posMaxY - iniSeleccioY + 1;
			else
				h = auxY - iniSeleccioY + 1;
 
			y = iniSeleccioY;
		}
 
		update();
	}
 
	//emit UpdateMouseCoords(event->x(), event->y());*/
	event -> ignore();
}
 
 
void FotoEditorFotos::mouseReleaseEvent(QMouseEvent *event)
{
	if (event -> button() == Qt::LeftButton) 
                // Do something with the selection rectangle...
		seleccio = false;
}
 
 
void FotoEditorFotos::paintEvent(QPaintEvent *event)
{
	int pixX, pixY;
 
	if (pixmap.width() < width())
		pixX = (width() - pixmap.width()) / 2;
	else
		pixX = 0;
	if (pixmap.height() < height())
		pixY = (height() - pixmap.height()) / 2;
	else
		pixY = 0;
 
	QPainter painter;
	painter.begin(this);
	QPen pen(Qt::blue, 2, Qt::DashLine);
	painter.setPen(pen);
	//painter.rotate(5);
	//painter.setBrush(Qt::Dense1Pattern);
	painter.drawPixmap(pixX, pixY, pixmap);
	if (seleccio)
		painter.drawRect(x, y, w, h);
	painter.end();
}

void FotoEditorFotos::mousePressEvent(QMouseEvent *event)
{
	if (event -> button() != Qt::LeftButton) return;
	
	iniSeleccioX = event -> x();
	iniSeleccioY = event -> y();

	seleccio = true;
	x = iniSeleccioX;
	y = iniSeleccioY;
	w = 1;
	h = 1;

	update();
}


void FotoEditorFotos::mouseMoveEvent(QMouseEvent *event)
{
	if (event -> buttons() == Qt::LeftButton)
	{
		int auxX = event -> x();
		int auxY = event -> y();
		int posMaxX = width() - 1;
		int posMaxY = height() - 1;

		if (auxX < iniSeleccioX)
		{
			if (auxX < 0)
				x = 0;
			else
				x = auxX;

			w = iniSeleccioX - x + 1;
		}
		else
		{
			if (auxX >= posMaxX)
				w = posMaxX - iniSeleccioX + 1;
			else
				w = auxX - iniSeleccioX + 1;

			x = iniSeleccioX;
		}

		if (auxY < iniSeleccioY)
		{
			if (auxY < 0)
				y = 0;
			else
				y = auxY;

			h = iniSeleccioY - y + 1;
		}
		else
		{
			if (auxY >= posMaxY)
				h = posMaxY - iniSeleccioY + 1;
			else
				h = auxY - iniSeleccioY + 1;

			y = iniSeleccioY;
		}

		update();
	}

	//emit UpdateMouseCoords(event->x(), event->y());*/
	event -> ignore();
}


void FotoEditorFotos::mouseReleaseEvent(QMouseEvent *event)
{
	if (event -> button() == Qt::LeftButton) 
                // Do something with the selection rectangle...
		seleccio = false;
}


void FotoEditorFotos::paintEvent(QPaintEvent *event)
{
	int pixX, pixY;

	if (pixmap.width() < width())
		pixX = (width() - pixmap.width()) / 2;
	else
		pixX = 0;
	if (pixmap.height() < height())
		pixY = (height() - pixmap.height()) / 2;
	else
		pixY = 0;

	QPainter painter;
	painter.begin(this);
	QPen pen(Qt::blue, 2, Qt::DashLine);
	painter.setPen(pen);
	//painter.rotate(5);
	//painter.setBrush(Qt::Dense1Pattern);
	painter.drawPixmap(pixX, pixY, pixmap);
	if (seleccio)
		painter.drawRect(x, y, w, h);
	painter.end();
}

To copy to clipboard, switch view to plain text mode 

That's the code for the widget that I insert in the scroll area and the code for the scroll area is the next:

FotoAreaEditorFotos::FotoAreaEditorFotos(EditorFotos *parent)
	: QScrollArea(parent)
{
	foto = new FotoEditorFotos;
 
	setBackgroundRole(QPalette::Dark);
	setWidget(foto);
}
 
 
void FotoAreaEditorFotos::mouseMoveEvent(QMouseEvent *event)
{
	QScrollBar *scrollBar;
 
	if (event ->buttons() != Qt::LeftButton) return;
 
	int auxX = event -> x();
	int auxY = event -> y();
	int posMaxX = viewport() -> width() - 1;
	int posMaxY = viewport() -> height() - 1;
 
	if (auxX <= 0)
	{
		scrollBar = horizontalScrollBar();
		scrollBar -> setValue(scrollBar -> value() - scrollBar -> singleStep());
	}
	else if (auxX >= posMaxX)
	{
		scrollBar = horizontalScrollBar();
		scrollBar -> setValue(scrollBar -> value() + scrollBar -> singleStep());
	}
 
	if (auxY <= 0)
	{
		scrollBar = verticalScrollBar();
		scrollBar -> setValue(scrollBar -> value() - scrollBar -> singleStep());
	}
	else if (auxY >= posMaxY)
	{
		scrollBar = verticalScrollBar();
		scrollBar -> setValue(scrollBar -> value() + scrollBar -> singleStep());
	}
}
 
 
void FotoAreaEditorFotos::paintEvent(QPaintEvent *event)
{
        //I put directly the size of the pixmap (256, 259) because it's a test version, in the final version I have to make a method to return the pixmap size ;)
	if (viewport() -> width() <= 259)
	{
		setWidgetResizable(false);
		foto -> resize(259, viewport() -> height());
	}
	else
		setWidgetResizable(true);
 
	if (viewport() -> height() <= 256)
	{
		setWidgetResizable(false);
		foto -> resize(qMax(259, viewport() -> width()), 256);
	}
	else
		setWidgetResizable(widgetResizable());
}

FotoAreaEditorFotos::FotoAreaEditorFotos(EditorFotos *parent)
	: QScrollArea(parent)
{
	foto = new FotoEditorFotos;

	setBackgroundRole(QPalette::Dark);
	setWidget(foto);
}


void FotoAreaEditorFotos::mouseMoveEvent(QMouseEvent *event)
{
	QScrollBar *scrollBar;

	if (event ->buttons() != Qt::LeftButton) return;

	int auxX = event -> x();
	int auxY = event -> y();
	int posMaxX = viewport() -> width() - 1;
	int posMaxY = viewport() -> height() - 1;

	if (auxX <= 0)
	{
		scrollBar = horizontalScrollBar();
		scrollBar -> setValue(scrollBar -> value() - scrollBar -> singleStep());
	}
	else if (auxX >= posMaxX)
	{
		scrollBar = horizontalScrollBar();
		scrollBar -> setValue(scrollBar -> value() + scrollBar -> singleStep());
	}

	if (auxY <= 0)
	{
		scrollBar = verticalScrollBar();
		scrollBar -> setValue(scrollBar -> value() - scrollBar -> singleStep());
	}
	else if (auxY >= posMaxY)
	{
		scrollBar = verticalScrollBar();
		scrollBar -> setValue(scrollBar -> value() + scrollBar -> singleStep());
	}
}


void FotoAreaEditorFotos::paintEvent(QPaintEvent *event)
{
        //I put directly the size of the pixmap (256, 259) because it's a test version, in the final version I have to make a method to return the pixmap size ;)
	if (viewport() -> width() <= 259)
	{
		setWidgetResizable(false);
		foto -> resize(259, viewport() -> height());
	}
	else
		setWidgetResizable(true);

	if (viewport() -> height() <= 256)
	{
		setWidgetResizable(false);
		foto -> resize(qMax(259, viewport() -> width()), 256);
	}
	else
		setWidgetResizable(widgetResizable());
}

To copy to clipboard, switch view to plain text mode 

All that code paint the image centered in the scroll area and if the image is larger thn the scroll area shows the scroll bars. Moreover if the user press the mouse under the viewport a selection rectangle is shown and if the rectangle is at the limits of the viewport of the scroll area, the scroll bars move automaticaly. Enjoy it.

[SkripT]

Hi all. These days I have made a new version for the code above. Now the image can be scaled and rotated and every time the image is painted automaticly at the center (applying the little bit of trigonometry that I remember ). Well, all goes perfect but there's a little problem: the updating of the rubberband is very slow . The cause is that every time that i call the update function of the widget, paintEvent has to scale and rotate the pixmap to paint it again and, after, paint the rectangle of the rubber band under the pixmap. This means that when I move the mouse, the rubber band takes a little time in being painted under the cursor (the rubber band is delayed respect the cursor when I move the mouse a little fast). Could anyone tell me if there's a solution for it? Something like paint only the viewport of the scroll area or paint only the portion of the image that has to be updated? Thanks