Qt-interest Archive, June 2007
Painting rectangles with border
Message 1 in thread
Hi,
Qt currently paints a rectangle by painting the area of the rectangle with
the brush and then painting the border with the pen on top of it as the
following program shows:
#include <QtGui>
#include <QtDebug>
int main(int argc, char ** argv) {
QApplication app(argc, argv);
QRect r(10, 10, 100, 100);
QPixmap pix(200, 200);
pix.fill(Qt::transparent);
{
QPainter p(&pix);
QPen pen(QColor(255, 0, 0, 128));
pen.setWidth(10);
pen.setMiterLimit(50);
pen.setJoinStyle(Qt::MiterJoin);
p.setPen(pen);
p.setBrush(QBrush(Qt::blue));
p.drawRect(r);
}
QLabel label;
label.setPixmap(pix);
label.show();
app.exec();
}
One sees that the border overlaps the inner rectangle in the resulting
picture.
But is this what one expects? I expect that the border is painted with the
pen and the unpainted inner rest is drawn with the brush.
Could anyone give me a hint to the documentation where it states that
rectangles are drawn in the current way and not as I expect it?
Christoph
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Message 2 in thread
Christoph Bartoschek wrote:
> Hi,
>
> Qt currently paints a rectangle by painting the area of the rectangle with
> the brush and then painting the border with the pen on top of it as the
> following program shows:
...
> One sees that the border overlaps the inner rectangle in the resulting
> picture.
>
> But is this what one expects? I expect that the border is painted with the
> pen and the unpainted inner rest is drawn with the brush.
>
> Could anyone give me a hint to the documentation where it states that
> rectangles are drawn in the current way and not as I expect it?
http://doc.trolltech.com/4.3/coordsys.html
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Message 3 in thread
Gunnar Sletta wrote:
> http://doc.trolltech.com/4.3/coordsys.html
Hi,
this page does not state that the border of a rectangle and the filled area
overlap.
There is only a discussion about how the coordinates of a border match to
the pixels of the canvas.
Or am I missing a paragraph?
Christoph
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Message 4 in thread
look at the example picture for QRect(1, 2, 6, 4):
it shows how the border (filled with a light green) and the actual
rectangle that is filled with the brush (hatched with darker horizontal
lines) overlap.
Cheers,
Peter
> -----Original Message-----
> From: Christoph Bartoschek [mailto:bartoschek@xxxxxx]
> Sent: Monday, June 11, 2007 5:34 PM
> To: qt-interest@xxxxxxxxxxxxx
> Subject: Re: Painting rectangles with border
>
> Gunnar Sletta wrote:
>
> > http://doc.trolltech.com/4.3/coordsys.html
>
> Hi,
>
> this page does not state that the border of a rectangle and the filled
> area
> overlap.
>
> There is only a discussion about how the coordinates of a border match
to
> the pixels of the canvas.
>
> Or am I missing a paragraph?
>
> Christoph
>
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Message 5 in thread
Peter Prade wrote:
> look at the example picture for QRect(1, 2, 6, 4):
>
> it shows how the border (filled with a light green) and the actual
> rectangle that is filled with the brush (hatched with darker horizontal
> lines) overlap.
Ok, thanks. I have to learn to draw rectangles in two steps from now on.
Christoph
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