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Ink annotation graphics

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Jakub Melka
2020-04-05 16:01:09 +02:00
parent 992e4b32f3
commit cc11073d70
7 changed files with 839 additions and 159 deletions
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75
PdfForQtLib/sources/pdfannotation.cpp
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@ -430,7 +430,6 @@ PDFAnnotationPtr PDFAnnotation::parse(const PDFObjectStorage* storage, PDFObject
annotation->m_inkPath.lineTo(point);
}
}
annotation->m_inkPath.closeSubpath();
}
}
}
@ -1938,4 +1937,78 @@ void PDFCaretAnnotation::draw(AnnotationDrawParameters& parameters) const
painter.fillPath(path, QBrush(getStrokeColor(), Qt::SolidPattern));
}
void PDFInkAnnotation::draw(AnnotationDrawParameters& parameters) const
{
QPainter& painter = *parameters.painter;
QPainterPath path = getInkPath();
painter.setPen(getPen());
painter.setBrush(getBrush());
QPainterPath boundingPath;
QPainterPath currentPath;
const int elementCount = path.elementCount();
for (int i = 0; i < elementCount; ++i)
{
QPainterPath::Element element = path.elementAt(i);
switch (element.type)
{
case QPainterPath::MoveToElement:
{
// Reset the path
if (!currentPath.isEmpty())
{
boundingPath.addPath(currentPath);
painter.drawPath(currentPath);
currentPath.clear();
}
currentPath.moveTo(element.x, element.y);
break;
}
case QPainterPath::LineToElement:
{
const QPointF p0 = currentPath.currentPosition();
const QPointF p1(element.x, element.y);
QLineF line(p0, p1);
QPointF normal = line.normalVector().p2() - p0;
// Jakub Melka: This computation should be clarified. We use second order Bezier curves.
// We must calculate single control point. Let B(t) is bezier curve of second order.
// Then second derivation is B''(t) = 2(p0 - 2*Pc + p1). Second derivation curve is its
// normal. So, we calculate normal vector of the line (which has norm equal to line length),
// then we get following formula:
//
// Pc = (p0 + p1) / 2 - B''(t) / 4
//
// So, for bezier curves of second order, second derivative is constant (which is not surprising,
// because second derivative of polynomial of order 2 is also a constant). Control point is then
// used to paint the path.
QPointF controlPoint = -normal * 0.25 + (p0 + p1) * 0.5;
currentPath.quadTo(controlPoint, p1);
break;
}
case QPainterPath::CurveToElement:
case QPainterPath::CurveToDataElement:
default:
Q_ASSERT(false);
break;
}
}
// Reset the path
if (!currentPath.isEmpty())
{
boundingPath.addPath(currentPath);
painter.drawPath(currentPath);
currentPath.clear();
}
const qreal penWidth = painter.pen().widthF();
parameters.boundingRectangle = boundingPath.boundingRect();
parameters.boundingRectangle.adjust(-penWidth, -penWidth, penWidth, penWidth);
}
} // namespace pdf