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Hi
I have a custom class inherited from QCanvasPolygonalitem.I am using this class to draw a triangular shaped polygon inside a QCanvas having scroll bars.My polygon can rotate as well as move inside the canvas.The problem i am facing is that if my polygon moves inside the area currently visible on the canvas i can see polygon moving but if i scroll the canvas view even a little or my polygon moves to area not initially visible on the screen (as i have a very big bitmap) my polygon disappears and i dont see the polygon again.The code works perfect till the time polygon is inside the area initially visible on the canvas but not after i scroll.Please help me in this regard to give me idea what can be the cause of problem.Thanks.
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Boardwalk for $500? In 2007? Ha!
Play Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games.#include <qcanvas.h>
#include <qpainter.h>
#include <qmessagebox.h>
///********************This class displays UGV polygon during Simulation****************************
class MyCanvasItem : public QCanvasPolygonalItem
{
public:
MyCanvasItem( int width, int height, QCanvas *c ) : QCanvasPolygonalItem( c )
{
m_width = width;
m_height = height;
angle=0;
}
~MyCanvasItem()
{
hide(); // Required to avoid segfault - see docs
}
QPointArray areaPoints() const
{
QPointArray points( 3 );
points.setPoint( 0,-m_width,-m_width );
points.setPoint( 1,-m_width,m_width );
points.setPoint( 2,2*m_width, 0 );
return points;
}
void calldraw()
{
update();
}
public:
///This function is called eachtime we are changing the position or the angle of the car by canvas->update()
void drawShape( QPainter &p )
{
//painter=p;
p.save();
QWMatrix t,t1,r;
t.translate(x() ,y());
t.rotate(angle);
p.setWorldMatrix(t);
p.drawPolygon( areaPoints());
invalidate();
// draw car body
// painter_rect=p.window();
p.restore();
update();
}
QRect areaRec()
{
return painter_rect;
}
public:
int angle;
QPainter painter;
private:
int m_width;
int m_height;
QRect painter_rect;
};
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