plotting 2d in qt

[buzzz321]

Hi,

I have tried to plot some 2d stuff (like pixels for a start but sprites and stuff would be nice too) on to a Qimage but i tend to get weird results like this screenshot.png with this code

RenderArea::RenderArea(QWidget *parent) :
		QWidget(parent) {
	image = new QImage(500, 500, QImage::Format_ARGB32_Premultiplied);
	image->fill(0);
	for (int n = 0; n < 500; ++n) {
		for (int i = 0; i < 500; ++i) {
			image->setPixel(i, n, 0x00ff00ff);
		}
	}
 
	setBackgroundRole(QPalette::Base);
	setAutoFillBackground(true);
	this->update();
}
 
void RenderArea::paintEvent(QPaintEvent * /* event */) {
	QPainter painter(this);
	QRect rect(0, 0, image->width(), image->height());
	painter.drawImage(rect, *image);
 
	this->update();
}

RenderArea::RenderArea(QWidget *parent) :
		QWidget(parent) {
	image = new QImage(500, 500, QImage::Format_ARGB32_Premultiplied);
	image->fill(0);
	for (int n = 0; n < 500; ++n) {
		for (int i = 0; i < 500; ++i) {
			image->setPixel(i, n, 0x00ff00ff);
		}
	}

	setBackgroundRole(QPalette::Base);
	setAutoFillBackground(true);
	this->update();
}

void RenderArea::paintEvent(QPaintEvent * /* event */) {
	QPainter painter(this);
	QRect rect(0, 0, image->width(), image->height());
	painter.drawImage(rect, *image);

	this->update();
}

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any ideas on what i have been doing wrong? Is this a good method ( if I get it to work) or is the graphiview / scene route better for "high"speed 2d plotting?

Best regards Anders Olme