Facing problem with Q3Canvas

[jnana]

Hi All,

I want to zoom in a region on canvas. For that first I am drawing a rectangle on canvas, size of the rectangle is decided by mouse move event. Then zooming in the mouse movement area to full region. The problem is view of the canvas rectangle which I am drawing to show the selected region.If the region is from initial view port area then the the rectangle is visible. The problem is, by moving scroll bar if mouse is in different viewport region, then it is not showing the whole rectangle area. It is only showing the rectangle area which is in initial view port(scroll bar at zero position). However zooming in is done properly.

I am attaching the code part also. Please rectify my mistake.

Thanks
Jnana



void
DiagramView :: contentsMouseMoveEvent(QMouseEvent* a_e)
{
if(cursor().shape() == Qt::CrossCursor) {
//QPoint myPoint = viewportToContents(a_e->pos());
m_zoomEndPoint = (inverseWorldMatrix()).map(a_e->pos());
int width = m_zoomEndPoint.x()-m_zoomStartPoint.x();
int height = m_zoomEndPoint.y()-m_zoomStartPoint.y();
if((width>0)&&(height>0)) {
if(!m_zoomRegionRect) {
qDebug(QString("%1 %2").arg(width).arg(height));
//! canvas item do not exist
m_zoomRegionRect = new Q3CanvasRectangle(m_zoomStartPoint.x(),
m_zoomStartPoint.y(),
width, height, canvas());
m_zoomRegionRect->setBrush(Qt::DiagCrossPattern);
m_zoomRegionRect->setPen(QPen(Qt::darkGreen,
2, Qt::DashDotDotLine));
m_zoomRegionRect->setZ(100);
m_zoomRegionRect->show();
} else {
m_zoomRegionRect->setSize(width, height);
canvas()->setChanged(m_zoomRegionRect->boundingRect());
}
canvas()->update();
}
return;
}
}
void
DiagramView :: contentsMousePressEvent(QMouseEvent* a_e)
{
m_zoomStartPoint = (inverseWorldMatrix()).map(a_e->pos());
}

void
DiagramView :: contentsMouseReleaseEvent(QMouseEvent* )
{
if(cursor().shape() == Qt::CrossCursor) {
if(m_zoomRegionRect) {
m_zoomRegionRect->hide();
canvas()->update();
delete m_zoomRegionRect;
m_zoomRegionRect = 0;
m_zoomStartFlag = true;
emit ZoomToRegion(m_zoomStartPoint, m_zoomEndPoint);
canvas()->update();
}
return;
}
}

[wysota]

You should map the scrollarea's coordinates to the viewport coordinates either by adding values of the scrollbars or by using mapFromParent.


m_zoomStartPoint = (inverseWorldMatrix()).map(mapFromParent(a_e->pos()));

[jnana]

Hi ,

Still it is not working.



void
DiagramView :: contentsMouseMoveEvent(QMouseEvent* a_e)
{
if(cursor().shape() == Qt::CrossCursor) {
//QPoint myPoint = viewportToContents(a_e->pos());
m_zoomEndPoint = (inverseWorldMatrix()).map(mapFromParent(a_e->pos()));
int width = m_zoomEndPoint.x()-m_zoomStartPoint.x();
int height = m_zoomEndPoint.y()-m_zoomStartPoint.y();
if((width>0)&&(height>0)) {
if(!m_zoomRegionRect) {
//! canvas item do not exist
m_zoomRegionRect = new Q3CanvasRectangle(m_zoomStartPoint.x(),
m_zoomStartPoint.y(),
width, height, canvas());
m_zoomRegionRect->setBrush(Qt::DiagCrossPattern);
m_zoomRegionRect->setPen(QPen(Qt::darkGreen,
2, Qt::DashDotDotLine));
m_zoomRegionRect->setZ(100);
m_zoomRegionRect->show();
} else {
m_zoomRegionRect->setSize(width, height);
canvas()->setChanged(m_zoomRegionRect->boundingRect());
}
canvas()->update();
}
return;
}
}
void
DiagramView :: contentsMousePressEvent(QMouseEvent* a_e)
{
m_zoomStartPoint = (inverseWorldMatrix()).map(mapFromParent(a_e->pos()));
}

void
DiagramView :: contentsMouseReleaseEvent(QMouseEvent* )
{
if(cursor().shape() == Qt::CrossCursor) {
if(m_zoomRegionRect) {
m_zoomRegionRect->hide();
canvas()->update();
delete m_zoomRegionRect;
m_zoomRegionRect = 0;
m_zoomStartFlag = true;
emit ZoomToRegion(m_zoomStartPoint, m_zoomEndPoint);
canvas()->update();
}
return;
}
}

[Kapil]

hi.

are u deriving the class DiagramView from Q3CanvasView...

For me something like this works pretty fine...



void CanvasMouse::contentsMousePressEvent(QMouseEvent* e)
{
if(e->button() == Qt::LeftButton)
{
QPoint pPress = inverseWorldMatrix().map(e->pos());
}
}


though it seems a crude method but try something like this that try to call the mouse events in the class where u have created the canvas... where u have set its size and its view... it might help...

Kapil