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Fixed adding lines connected with arc (AddArcToPoint) to wxGraphicsPath

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Reworked calculations of the center of the arc and start/end angles of the arc to get correct results for any spatial orientation of starting and ending lines.

Closes #17552
This commit is contained in:
Artur Wieczorek
2016-05-29 17:41:16 +02:00
parent eb2fc93a9b
commit 60ae112694
1 changed files with 49 additions and 20 deletions
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69
src/common/graphcmn.cpp
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@@ -447,37 +447,66 @@ void wxGraphicsPathData::AddRoundedRectangle( wxDouble x, wxDouble y, wxDouble w
void wxGraphicsPathData::AddArcToPoint( wxDouble x1, wxDouble y1 , wxDouble x2, wxDouble y2, wxDouble r )
{
wxPoint2DDouble current;
GetCurrentPoint(&current.m_x,&current.m_y);
wxPoint2DDouble p1(x1,y1);
wxPoint2DDouble p2(x2,y2);
GetCurrentPoint(&current.m_x, &current.m_y);
wxPoint2DDouble p1(x1, y1);
wxPoint2DDouble p2(x2, y2);
wxPoint2DDouble v1 = current - p1;
v1.Normalize();
wxDouble v1Length = v1.GetVectorLength();
wxPoint2DDouble v2 = p2 - p1;
v2.Normalize();
wxDouble v2Length = v2.GetVectorLength();
wxDouble alpha = v1.GetVectorAngle() - v2.GetVectorAngle();
// Reduce angle value to the range [0..180] degrees.
if ( alpha < 0 )
alpha = 360 + alpha;
// TODO obtuse angles
if ( alpha > 180 )
alpha = 360 - alpha;
alpha = wxDegToRad(alpha);
// Degenerated cases: there is no need
// to draw an arc connecting points when:
// - There are no 3 different points provided,
// - Points (and lines) are colinear,
// - Radius equals zero.
if ( v1Length == 0 || v2Length == 0 ||
alpha == 0 || alpha == 180 || r == 0 )
{
AddLineToPoint(p1.m_x, p1.m_y);
AddLineToPoint(p2.m_x, p2.m_y);
return;
}
wxDouble dist = r / sin(alpha/2) * cos(alpha/2);
// calculate tangential points
wxPoint2DDouble t1 = dist*v1 + p1;
// Determine spatial relation between the vectors.
bool drawClockwiseArc = v1.GetCrossProduct(v2) < 0;
wxPoint2DDouble nv1 = v1;
nv1.SetVectorAngle(v1.GetVectorAngle()-90);
wxPoint2DDouble c = t1 + r*nv1;
alpha = wxDegToRad(alpha) / 2.0;
wxDouble distT = r / sin(alpha) * cos(alpha);
wxDouble distC = r / sin(alpha);
wxASSERT_MSG( distT <= v1Length && distT <= v2Length,
wxS("Radius is too big to fit the arc to given points") );
// Calculate tangential points
v1.Normalize();
v2.Normalize();
wxPoint2DDouble t1 = distT*v1 + p1;
wxPoint2DDouble t2 = distT*v2 + p1;
// Calculate the angle bisector vector
// (because central point is located on the bisector).
wxPoint2DDouble v = v1 + v2;
if ( v.GetVectorLength() > 0 )
v.Normalize();
// Calculate center of the arc
wxPoint2DDouble c = distC*v + p1;
// Calculate normal vectors at tangential points
// (with inverted directions to make angle calculations easier).
wxPoint2DDouble nv1 = t1 - c;
wxPoint2DDouble nv2 = t2 - c;
// Calculate start and end angle of the arc.
wxDouble a1 = nv1.GetVectorAngle();
wxDouble a2 = nv2.GetVectorAngle();
wxDouble a1 = v1.GetVectorAngle()+90;
wxDouble a2 = v2.GetVectorAngle()-90;
AddLineToPoint(t1.m_x,t1.m_y);
AddArc(c.m_x,c.m_y,r,wxDegToRad(a1),wxDegToRad(a2),true);
AddLineToPoint(p2.m_x,p2.m_y);
AddLineToPoint(t1.m_x, t1.m_y);
AddArc(c.m_x, c.m_y, r, wxDegToRad(a1), wxDegToRad(a2), drawClockwiseArc);
AddLineToPoint(p2.m_x, p2.m_y);
}
//-----------------------------------------------------------------------------