tdf#159547 of-pie connector lines aren't quite geometrically correct
Fixed code computing the left endpoints of of-pie connector lines, so
that they're tangent to the circle when the composite slice is large enough
(and they terminate at the tangent point).
Change-Id: I4ff4d8e31f47259f0f48721b532dc245ede83003
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/167712
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Jenkins
diff --git a/chart2/source/view/charttypes/PieChart.cxx b/chart2/source/view/charttypes/PieChart.cxx
index d99e3d9..fcb79ef 100644
--- a/chart2/source/view/charttypes/PieChart.cxx
+++ b/chart2/source/view/charttypes/PieChart.cxx
@@ -807,6 +807,47 @@ bool PieChart::isSeparateStackingForDifferentSigns( sal_Int32 /* nDimensionIndex
return false;
}
// Determine left endpoints of connecting lines. These will terminate either
// at the corners of the composite wedge (if the wedge is small enough), or
// tangent to the left pie circle (if the wedge is larger). The endpoints
// are at the returned values (xl0, +/-yl0).
// static
void PieChart::leftConnEndpoints(double* xl0_p, double* yl0_p,
const PieDataSrcBase *pDataSrc,
const VDataSeries *pSeries,
const ShapeParam &aParam)
{
const sal_Int32 nEnd = pDataSrc->getNPoints(pSeries, SubPieType::LEFT);
const double compFrac = pDataSrc->getData(pSeries, nEnd - 1,
SubPieType::LEFT) / aParam.mfLogicYSum;
// Assuming temporarily that the left circle is at the origin,
// the tangent point (xp0, yp0) on the left circle satisfies
// (1) xp0 = (1-r) / t
// (2) xp0^2 + yp0^2 = 1
// where the left-hand circle has radius 1, the right-hand circle
// has radius r, and the right-hand circle is centered at (t, 0).
const double r0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale;
const double rho = m_fRightScale / m_fLeftScale;
const double xp0 = (1 - rho) / (m_fRightShift - m_fLeftShift);
// Determine if the composite wedge is large enough that the
// connecting lines hit the tangent point, instead of the corners of
// the wedge
assert(abs(xp0) <= 1.0);
const double theta = acos(xp0);
double xl0, yl0;
if (compFrac < theta / M_PI) {
xl0 = r0 * cos(compFrac * M_PI);
yl0 = r0 * sin(compFrac * M_PI);
} else {
xl0 = r0 * xp0;
yl0 = sqrt(r0 * r0 - xl0 * xl0);
}
*xl0_p = xl0;
*yl0_p = yl0;
}
void PieChart::createShapes()
{
///a ZSlot is a vector< vector< VDataSeriesGroup > >. There is only one
@@ -941,19 +982,9 @@ void PieChart::createShapes()
//
double xl0, xl1, yl0, yl1, x0, y0, x1, y1, y2, y3;
// Get coordinates of "corners" of left composite wedge
sal_Int32 nEnd = pDataSrc->getNPoints(pSeries, SubPieType::LEFT);
double compFrac = pDataSrc->getData(pSeries, nEnd - 1,
SubPieType::LEFT) / aParam.mfLogicYSum;
if (compFrac < 0.5) {
xl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale *
cos(compFrac * M_PI) + m_fLeftShift;
yl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale *
sin(compFrac * M_PI);
} else {
xl0 = m_fLeftShift;
yl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale;
}
leftConnEndpoints(&xl0, &yl0, pDataSrc, pSeries, aParam);
xl0 += m_fLeftShift;
// Coordinates of bar top left corner
xl1 = m_fBarLeft;
@@ -1000,39 +1031,22 @@ void PieChart::createShapes()
//
double xl0, xl1, yl0, yl1, x0, y0, x1, y1, y2, y3;
// Get coordinates of "corners" of left composite wedge
sal_Int32 nEnd = pDataSrc->getNPoints(pSeries, SubPieType::LEFT);
double compFrac = pDataSrc->getData(pSeries, nEnd - 1,
SubPieType::LEFT) / aParam.mfLogicYSum;
// The following isn't quite right. The tangent points on the left
// pie are only at pi/2 and -pi/2 for composite wedges over 1/2 the
// total if left and right pies are the same diameter. And the
// threshold of 1/2 isn't quite right either. So there
// really should be a more sophisticated approach here. TODO
if (compFrac < 0.5) {
// Translated, per below
xl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale *
cos(compFrac * M_PI) + m_fLeftShift - m_fRightShift;
yl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale *
sin(compFrac * M_PI);
} else {
// Translated, per below
xl0 = m_fLeftShift - m_fRightShift;
yl0 = aParam.mfUnitCircleOuterRadius * m_fLeftScale;
}
leftConnEndpoints(&xl0, &yl0, pDataSrc, pSeries, aParam);
// Translated, per below
xl0 += m_fLeftShift - m_fRightShift;
// Compute tangent point on the right-hand circle of the line
// through (xl0, yl0). If we translate things so the right-hand
// circle is centered on the origin, then this point (x,y)
// satisfies these two equations, where r is the radius of the
// satisfies these two equations, where r1 is the radius of the
// right-hand circle:
// (1) x^2 + y^2 = r^2
// (1) x^2 + y^2 = r1^2
// (2) (y - yl0) / (x - xl0) = -x / y
const double r = aParam.mfUnitCircleOuterRadius * m_fRightScale;
xl1 = (r*r * xl0 + yl0 * r * sqrt(xl0*xl0 + yl0*yl0 - r*r)) /
const double r1 = aParam.mfUnitCircleOuterRadius * m_fRightScale;
xl1 = (r1*r1 * xl0 + yl0 * r1 * sqrt(xl0*xl0 + yl0*yl0 - r1*r1)) /
(xl0*xl0 + yl0*yl0);
yl1 = sqrt(r*r - xl1*xl1);
yl1 = sqrt(r1*r1 - xl1*xl1);
// Now translate back to the coordinates we use
xl0 += m_fRightShift;
diff --git a/chart2/source/view/charttypes/PieChart.hxx b/chart2/source/view/charttypes/PieChart.hxx
index ccbe9cb..a7b1584 100644
--- a/chart2/source/view/charttypes/PieChart.hxx
+++ b/chart2/source/view/charttypes/PieChart.hxx
@@ -225,6 +225,15 @@ struct PieLabelInfo;
const PieDataSrcBase *pDataSrc,
sal_Int32 n3DRelativeHeight);
// Determine left endpoints of connecting lines. These will terminate either
// at the corners of the composite wedge (if the wedge is small enough), or
// tangent to the left pie circle (if the wedge is larger). The endpoints
// are at the returned values (xl0, +/-yl0).
static void leftConnEndpoints(double* xl0_p, double* yl0_p,
const PieDataSrcBase *pDataSrc,
const VDataSeries *pSeries,
const ShapeParam &aParam);
private: //member
// Constants for of-pie charts. Some of these will want to become
// user-selectable values. TODO
