+
+/*
+Notes for wxWidgets DrawEllipticArcRot(...)
+
+wxDCBase::DrawEllipticArcRot(...) draws a rotated elliptic arc or an ellipse.
+It uses wxDCBase::CalculateEllipticPoints(...) and wxDCBase::Rotate(...),
+which are also new.
+
+All methods are generic, so they can be implemented in wxDCBase.
+DoDrawEllipticArcRot(...) is virtual, so it can be called from deeper
+methods like (WinCE) wxDC::DoDrawArc(...).
+
+CalculateEllipticPoints(...) fills a given list of wxPoints with some points
+of an elliptic arc. The algorithm is pixel-based: In every row (in flat
+parts) or every column (in steep parts) only one pixel is calculated.
+Trigonometric calculation (sin, cos, tan, atan) is only done if the
+starting angle is not equal to the ending angle. The calculation of the
+pixels is done using simple arithmetic only and should perform not too
+bad even on devices without floating point processor. I didn't test this yet.
+
+Rotate(...) rotates a list of point pixel-based, you will see rounding errors.
+For instance: an ellipse rotated 180 degrees is drawn
+slightly different from the original.
+
+The points are then moved to an array and used to draw a polyline and/or polygon
+(with center added, the pie).
+The result looks quite similar to the native ellipse, only e few pixels differ.
+
+The performance on a desktop system (Athlon 1800, WinXP) is about 7 times
+slower as DrawEllipse(...), which calls the native API.
+An rotated ellipse outside the clipping region takes nearly the same time,
+while an native ellipse outside takes nearly no time to draw.
+
+If you draw an arc with this new method, you will see the starting and ending angles
+are calculated properly.
+If you use DrawEllipticArc(...), you will see they are only correct for circles
+and not properly calculated for ellipses.
+
+Peter Lenhard
+p.lenhard@t-online.de
+*/
+
+#ifdef __WXWINCE__
+void wxDCBase::DoDrawEllipticArcRot( wxCoord x, wxCoord y,
+ wxCoord w, wxCoord h,
+ double sa, double ea, double angle )
+{
+ wxList list;
+
+ CalculateEllipticPoints( &list, x, y, w, h, sa, ea );
+ Rotate( &list, angle, wxPoint( x+w/2, y+h/2 ) );
+
+ // Add center (for polygon/pie)
+ list.Append( (wxObject*) new wxPoint( x+w/2, y+h/2 ) );
+
+ // copy list into array and delete list elements
+ int n = list.Number();
+ wxPoint *points = new wxPoint[n];
+ int i = 0;
+ wxNode* node = 0;
+ for ( node = list.First(); node; node = node->Next(), i++ )
+ {
+ wxPoint *point = (wxPoint *)node->Data();
+ points[i].x = point->x;
+ points[i].y = point->y;
+ delete point;
+ }
+
+ // first draw the pie without pen, if necessary
+ if( GetBrush() != *wxTRANSPARENT_BRUSH )
+ {
+ wxPen tempPen( GetPen() );
+ SetPen( *wxTRANSPARENT_PEN );
+ DoDrawPolygon( n, points, 0, 0 );
+ SetPen( tempPen );
+ }
+
+ // then draw the arc without brush, if necessary
+ if( GetPen() != *wxTRANSPARENT_PEN )
+ {
+ // without center
+ DoDrawLines( n-1, points, 0, 0 );
+ }
+
+ delete [] points;
+
+} // DrawEllipticArcRot
+
+void wxDCBase::Rotate( wxList* points, double angle, wxPoint center )
+{
+ if( angle != 0.0 )
+ {
+ double pi(M_PI);
+ double dSinA = -sin(angle*2.0*pi/360.0);
+ double dCosA = cos(angle*2.0*pi/360.0);
+ for ( wxNode* node = points->First(); node; node = node->Next() )
+ {
+ wxPoint* point = (wxPoint*)node->Data();
+
+ // transform coordinates, if necessary
+ if( center.x ) point->x -= center.x;
+ if( center.y ) point->y -= center.y;
+
+ // calculate rotation, rounding simply by implicit cast to integer
+ int xTemp = point->x * dCosA - point->y * dSinA;
+ point->y = point->x * dSinA + point->y * dCosA;
+ point->x = xTemp;
+
+ // back transform coordinates, if necessary
+ if( center.x ) point->x += center.x;
+ if( center.y ) point->y += center.y;
+ }
+ }
+}
+
+void wxDCBase::CalculateEllipticPoints( wxList* points,
+ wxCoord xStart, wxCoord yStart,
+ wxCoord w, wxCoord h,
+ double sa, double ea )
+{
+ double pi = M_PI;
+ double sar = 0;
+ double ear = 0;
+ int xsa = 0;
+ int ysa = 0;
+ int xea = 0;
+ int yea = 0;
+ int sq = 0;
+ int eq = 0;
+ bool bUseAngles = false;
+ if( w<0 ) w = -w;
+ if( h<0 ) h = -h;
+ // half-axes
+ wxCoord a = w/2;
+ wxCoord b = h/2;
+ // decrement 1 pixel if ellipse is smaller than 2*a, 2*b
+ int decrX = 0;
+ if( 2*a == w ) decrX = 1;
+ int decrY = 0;
+ if( 2*b == h ) decrY = 1;
+ // center
+ wxCoord xCenter = xStart + a;
+ wxCoord yCenter = yStart + b;
+ // calculate data for start and end, if necessary
+ if( sa != ea )
+ {
+ bUseAngles = true;
+ // normalisation of angles
+ while( sa<0 ) sa += 360;
+ while( ea<0 ) ea += 360;
+ while( sa>=360 ) sa -= 360;
+ while( ea>=360 ) ea -= 360;
+ // calculate quadrant numbers
+ if( sa > 270 ) sq = 3;
+ else if( sa > 180 ) sq = 2;
+ else if( sa > 90 ) sq = 1;
+ if( ea > 270 ) eq = 3;
+ else if( ea > 180 ) eq = 2;
+ else if( ea > 90 ) eq = 1;
+ sar = sa * pi / 180.0;
+ ear = ea * pi / 180.0;
+ // correct angle circle -> ellipse
+ sar = atan( -a/(double)b * tan( sar ) );
+ if ( sq == 1 || sq == 2 ) sar += pi;
+ ear = atan( -a/(double)b * tan( ear ) );
+ if ( eq == 1 || eq == 2 ) ear += pi;
+ // coordinates of points
+ xsa = xCenter + a * cos( sar );
+ if( sq == 0 || sq == 3 ) xsa -= decrX;
+ ysa = yCenter + b * sin( sar );
+ if( sq == 2 || sq == 3 ) ysa -= decrY;
+ xea = xCenter + a * cos( ear );
+ if( eq == 0 || eq == 3 ) xea -= decrX;
+ yea = yCenter + b * sin( ear );
+ if( eq == 2 || eq == 3 ) yea -= decrY;
+ } // if iUseAngles
+ // calculate c1 = b^2, c2 = b^2/a^2 with a = w/2, b = h/2
+ double c1 = b * b;
+ double c2 = 2.0 / w;
+ c2 *= c2;
+ c2 *= c1;
+ wxCoord x = 0;
+ wxCoord y = b;
+ long x2 = 1;
+ long y2 = y*y;
+ long y2_old = 0;
+ long y_old = 0;
+ // Lists for quadrant 1 to 4
+ wxList pointsarray[4];
+ // Calculate points for first quadrant and set in all quadrants
+ for( x = 0; x <= a; ++x )
+ {
+ x2 = x2+x+x-1;
+ y2_old = y2;
+ y_old = y;
+ bool bNewPoint = false;
+ while( y2 > c1 - c2 * x2 && y > 0 )
+ {
+ bNewPoint = true;
+ y2 = y2-y-y+1;
+ --y;
+ }
+ // old y now to big: set point with old y, old x
+ if( bNewPoint && x>1)
+ {
+ int x1 = x - 1;
+ // remove points on the same line
+ pointsarray[0].Insert( (wxObject*) new wxPoint( xCenter + x1 - decrX, yCenter - y_old ) );
+ pointsarray[1].Append( (wxObject*) new wxPoint( xCenter - x1, yCenter - y_old ) );
+ pointsarray[2].Insert( (wxObject*) new wxPoint( xCenter - x1, yCenter + y_old - decrY ) );
+ pointsarray[3].Append( (wxObject*) new wxPoint( xCenter + x1 - decrX, yCenter + y_old - decrY ) );
+ } // set point
+ } // calculate point
+
+ // Starting and/or ending points for the quadrants, first quadrant gets both.
+ pointsarray[0].Insert( (wxObject*) new wxPoint( xCenter + a - decrX, yCenter ) );
+ pointsarray[0].Append( (wxObject*) new wxPoint( xCenter, yCenter - b ) );
+ pointsarray[1].Append( (wxObject*) new wxPoint( xCenter - a, yCenter ) );
+ pointsarray[2].Append( (wxObject*) new wxPoint( xCenter, yCenter + b - decrY ) );
+ pointsarray[3].Append( (wxObject*) new wxPoint( xCenter + a - decrX, yCenter ) );
+
+ // copy quadrants in original list
+ if( bUseAngles )
+ {
+ // Copy the right part of the points in the lists
+ // and delete the wxPoints, because they do not leave this method.
+ points->Append( (wxObject*) new wxPoint( xsa, ysa ) );
+ int q = sq;
+ bool bStarted = false;
+ bool bReady = false;
+ bool bForceTurn = ( sq == eq && sa > ea );
+ while( !bReady )
+ {
+ for( wxNode *node = pointsarray[q].First(); node; node = node->Next() )
+ {
+ // once: go to starting point in start quadrant
+ if( !bStarted &&
+ (
+ ( (wxPoint*) node->Data() )->x < xsa+1 && q <= 1
+ ||
+ ( (wxPoint*) node->Data() )->x > xsa-1 && q >= 2
+ )
+ )
+ {
+ bStarted = true;
+ }
+
+ // copy point, if not at ending point
+ if( bStarted )
+ {
+ if( q != eq || bForceTurn
+ ||
+ ( (wxPoint*) node->Data() )->x > xea+1 && q <= 1
+ ||
+ ( (wxPoint*) node->Data() )->x < xea-1 && q >= 2
+ )
+ {
+ // copy point
+ wxPoint* pPoint = new wxPoint( *((wxPoint*) node->Data() ) );
+ points->Append( (wxObject*) pPoint );
+ }
+ else if( q == eq && !bForceTurn || ( (wxPoint*) node->Data() )->x == xea)
+ {
+ bReady = true;
+ }
+ }
+ } // for node
+ ++q;
+ if( q > 3 ) q = 0;
+ bForceTurn = false;
+ bStarted = true;
+ } // while not bReady
+ points->Append( (wxObject*) new wxPoint( xea, yea ) );
+
+ // delete points
+ for( q = 0; q < 4; ++q )
+ {
+ for( wxNode *node = pointsarray[q].First(); node; node = node->Next() )
+ {
+ wxPoint *p = (wxPoint *)node->Data();
+ delete p;
+ }
+ }
+ }
+ else
+ {
+ // copy whole ellipse, wxPoints will be deleted outside
+ for( wxNode *node = pointsarray[0].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[1].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[2].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[3].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ } // not iUseAngles
+} // CalculateEllipticPoints
+
+#endif
+
projects / wxWidgets.git / blobdiff