Does the point lie in the region?

I am doing this in my paintEvent

painter.drawPie(rect, angle*16, 45*16);

But before drawing the pie I want to know whether the current mouse position lies under the pie region or not.

Mouse tracking is开发者_Python百科 on. And I can get the mouseEvents. No problem from that side. But what is the math involved to know wheather the point lies inside the pie or not?

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It's unfortunate that QPainterPath doesn't have an addPie() function. You can, however, use Qt's implementation of QPainter::drawPie() as a reference:

http://qt.gitorious.org/qt/qt/blobs/4.7/src/gui/painting/qpainter.cpp#line4439

You can essentially create the QPainterPath the same way they do it and call contains() on it.

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I have not tried this, but you could try to intersect two QPainterPaths (one triangle and one circle) to get a QPainterPath for your pie-segment and then call QPainterPath::contains(QPointF&) with the mouse position as parameter.

Now that I write this, the check is probably easy to implement: if the point is inside the circle and inside the triangle, then it's inside the pie. Both subtests are easy to implement.