[Uml-devel] kdesdk/umbrello/umbrello

[Klas Kalass]

CVS commit by kalass: 

avoid using sin and cos on the angle delivered by atan because those values
have significant errors.
Fixed rounding errors, this improves the rendering quality of associations
and compositions.


  M +14 -11    linepath.cpp   1.5


--- kdesdk/umbrello/umbrello/linepath.cpp  #1.4:1.5
@@ -358,4 +358,7 @@ void LinePath::calculateHead() {
         int xb = getPoint(size -1).x();
         int yb = getPoint(size -1).y();
+        double deltaX = xb - xa;
+        double deltaY = yb - ya;
+        double hypotenuse = sqrt(deltaX*deltaX + deltaY*deltaY); // the length
         int halfLength = 10;
         double arrowAngle = 0.5 * atan(sqrt(3.0) / 3.0);
@@ -365,16 +368,16 @@ void LinePath::calculateHead() {
                 halfLength += 3;        // longer
         }
-        double slope = atan2(double(yb - ya), double(xb - xa)); //slope of line
-        double cosx = halfLength * cos(slope);
+        double slope = atan2(deltaY, deltaX);   //slope of line
+        double cosx = halfLength * deltaX/hypotenuse;
 
-        double siny = halfLength * sin(slope);
+        double siny = halfLength * deltaY/hypotenuse;
         double arrowSlope = slope + arrowAngle;
 
         m_LastPoint = getPoint(size - 1);
-        m_ArrowPointA.setX( (int)(m_LastPoint.x() - halfLength * cos(arrowSlope) ) );
-        m_ArrowPointA.setY( (int)(m_LastPoint.y() - halfLength * sin(arrowSlope)) );
+        m_ArrowPointA.setX( (int)round(m_LastPoint.x() - halfLength * cos(arrowSlope) ) );
+        m_ArrowPointA.setY( (int)round(m_LastPoint.y() - halfLength * sin(arrowSlope)) );
         arrowSlope = slope - arrowAngle;
-        m_ArrowPointB.setX( (int)(m_LastPoint.x() - halfLength * cos(arrowSlope)) );
-        m_ArrowPointB.setY( (int)(m_LastPoint.y() - halfLength * sin(arrowSlope)) );
+        m_ArrowPointB.setX( (int)round(m_LastPoint.x() - halfLength * cos(arrowSlope)) );
+        m_ArrowPointB.setY( (int)round(m_LastPoint.y() - halfLength * sin(arrowSlope)) );
 
         if(xa > xb)
@@ -388,8 +391,8 @@ void LinePath::calculateHead() {
                 siny = siny > 0 ? siny * -1 : siny;
 
-        m_MidPoint.setX( (int)(m_LastPoint.x() + cosx) );
-        m_MidPoint.setY( (int)(m_LastPoint.y() + siny) );
-        m_FullPoint.setX( (int)(m_LastPoint.x() + cosx * 2) );
-        m_FullPoint.setY( (int)(m_LastPoint.y() + siny * 2) );
+        m_MidPoint.setX( (int)round(m_LastPoint.x() + cosx) );
+        m_MidPoint.setY( (int)round(m_LastPoint.y() + siny) );
+        m_FullPoint.setX( (int)round(m_LastPoint.x() + cosx * 2) );
+        m_FullPoint.setY( (int)round(m_LastPoint.y() + siny * 2) );
 
         m_PointArray.setPoint(0, m_LastPoint);