Details
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Bug
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Resolution: Out of scope
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P2: Important
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4.5.0
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None
Description
Rendering of simple lines using QGraphicsView is broken. The lines are almost vertical (just one pixel of horizontal shift): Line ( x1, y1, x1+1, y2) and with y2-y1 very large. The problem happens when using native engine and no AA. Running with "-graphicssystem raster" solves the issue.
Test case (use the scrollbar down and up and watch the artifacts):
#include <QtGui/QtGui>
class GraphLine : public QGraphicsView
{
public:
GraphLine() : QGraphicsView()
{
QGraphicsScene *scene = new QGraphicsScene(this);
setScene(scene);
QLineF fline1;
QLineF fline2;
QLineF fline3;
QLineF fline4;
QLineF fline5;
QLineF fline6;
QLineF fline7;
QLineF fline8;
float dy = -1000.0;
float dx = 100.0;
fline1.setLine (15.0, 10.0, 16.0, 20010.0);
fline2.setLine (25.0, 20.0, 26.0, 20020.0);
fline3.setLine (55.0, 50.0, 56.0, 20050.0);
fline4.setLine (65.0, 60.0, 66.0, 20060.0);
fline5.setLine (15.0+dx, 10.0+dy, 16.0+dx, 20010.0-dy);
fline6.setLine (25.0+dx, 20.0+dy, 26.0+dx, 20020.0-dy);
fline7.setLine (55.0+dx, 50.0+dy, 56.0+dx, 20050.0-dy);
fline8.setLine (65.0+dx, 60.0+dy, 66.0+dx, 20060.0-dy);
QGraphicsLineItem* line1 = new QGraphicsLineItem(fline1);
QGraphicsLineItem* line2 = new QGraphicsLineItem(fline2);
QGraphicsLineItem* line3 = new QGraphicsLineItem(fline3);
QGraphicsLineItem* line4 = new QGraphicsLineItem(fline4);
QGraphicsLineItem* line5 = new QGraphicsLineItem(fline5);
QGraphicsLineItem* line6 = new QGraphicsLineItem(fline6);
QGraphicsLineItem* line7 = new QGraphicsLineItem(fline7);
QGraphicsLineItem* line8 = new QGraphicsLineItem(fline8);
scene->addItem(line1);
scene->addItem(line2);
scene->addItem(line3);
scene->addItem(line4);
scene->addItem(line5);
scene->addItem(line6);
scene->addItem(line7);
scene->addItem(line8);
setMinimumSize(200, 400);
setWindowTitle(tr("Lines"));
}
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
GraphLine widget;
widget.show();
return app.exec();
}