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Xara Group Ltd, Gaddesden Place, Hemel Hempstead, HP2 6EX, UK. http://www.xara.com/ =================================XARAHEADEREND============================ */ // Pressure - functions for smoothing freehand pressure data #include "camtypes.h" #include "pressure.h" //#include "paths.h" - in camtypes.h [AUTOMATICALLY REMOVED] #include "pathtrap.h" #include "valfunc.h" DECLARE_SOURCE("$Revision: 1282 $"); CC_IMPLEMENT_MEMDUMP(PressureSmoother, CC_CLASS_MEMDUMP) #define new CAM_DEBUG_NEW /******************************************************************************************** > PressureSmoother::PressureSmoother() Author; Jason Created: 30/1/97 Purpose: Constructor ********************************************************************************************/ PressureSmoother::PressureSmoother() { } /******************************************************************************************** > PressureSmoother::~PressureSmoother() Author; Jason Created: 30/1/97 Purpose: Destructor ********************************************************************************************/ PressureSmoother::~PressureSmoother() { } /******************************************************************************************** > ValueFunction *PressureSmoother::Smooth(Path *pSourceData, INT32 LineWidth) Author: Jason_Williams (Xara Group Ltd) Created: 21/1/97 Inputs: pSourceData - The path containing the pressure data to smooth. The pressure information should be held in the Width channel in the ExtraInfo of the path LineWidth - The maximum "radius" of the line (half the line width) which will be used when stroking this path. Returns: NULL if it failed (no error is set), else a pointer to a new ValueFunction object which represents the pressure information form this path. The caller is responsible for deleting this new object when they're finished with it. Purpose: Reads raw recorded pressure information from a path and smooths it, creating a new ValueFunction object representing the pressure function. Notes: Smoothing works as follows: 1) Create a graph of the pressure samples, with pressure (y) versus position along the path (x). Store this graph in a Path. 2) Smooth the straight line segments in this graph into curve segments At present, this is done by replacing everything between 2 local minima/maxima by an S-shaped curve. This interpolation can be done by a ValueFunctionPressureS object in real-time, so we create one of them. ********************************************************************************************/ ValueFunction *PressureSmoother::Smooth(Path *pSourceData, INT32 LineWidth) { ERROR3IF(pSourceData == NULL, "Illegal NULL param"); // Find the recorded pressure values (if any) PathWidth *pWidthArray = pSourceData->GetWidthArray(); if (pWidthArray == NULL) return(NULL); const INT32 NumCoords = pSourceData->GetNumCoords(); DocCoord *pCoords = pSourceData->GetCoordArray(); if (NumCoords < 2) return(NULL); // Create a ValueFunction to return. We use an "S" curve interpolated pressure function ValueFunctionPressure *pValFunc = new ValueFunctionPressureS; if (pValFunc == NULL) return(NULL); // Calculate the maximum pressure value recorded. This should be EXTRAVALUEMAX // but sometimes we seem to get bigger values. INT32 MaxPressure = pWidthArray[0]; for (INT32 i = 1; i < NumCoords; i++) { if (pCoords[i].y > MaxPressure) MaxPressure = pWidthArray[i]; } // If this pressure was smaller than EXTRAVALUEMAX, then we use that as the maximum, // because we don't want to scale thin strokes up to max width! if (MaxPressure < (INT32)EXTRAVALUEMAX) MaxPressure = EXTRAVALUEMAX; float Position = 0.0f; float LastPosition = Position; INT32 Diff = 0; INT32 LastDiff = pWidthArray[1] - pWidthArray[0]; pValFunc->AddPressure(Position, (float)pWidthArray[0] / (float)MaxPressure); // --- Now loop through the pressure samples, scaling them into the correct range, calculating // proper "position" values for them, and smoothing the data (by replacing all points between // minima and maxima with s-shaped interpolated segments) for (INT32 Index = 1; Index < NumCoords - 1; Index++) { // Record the pressure sample. We chuck away all samples between minima/maxima // as we go, and also wheedle out any zero-length sections that might crop up. // Then the ValueFunction will interpolate between the values as it sees fit (with S-shaped curves) if (Position > LastPosition) { LastPosition = Position; Diff = pWidthArray[Index] - pWidthArray[Index - 1]; if ((Diff > 0 && LastDiff <= 0) || (Diff < 0 && LastDiff >= 0)) { // We have found a min/maximum. Record this point. pValFunc->AddPressure(Position, (float)pWidthArray[Index] / (float)MaxPressure); LastDiff = Diff; } } // Work out approximate "travel" along the path so each width sample has a known position // [This should be calculated in the same way as in TrapEdgeList::ProcessEdgePositions, pathtrap.cpp] #if TRUE // This now simply calculates distance down the centreline. // Much faster & simpler, and it turns out it gives better results after all! const double dx = (double) (pCoords[Index-1].x - pCoords[Index].x); const double dy = (double) (pCoords[Index-1].y - pCoords[Index].y); Position += (float) sqrt((dx * dx) + (dy * dy)); #else /* // Calculate the line normals to the left and right of the point NormCoord Normal1; NormCoord Normal2; Normal1.SetNormalToLine(pCoords[Index], pCoords[Index - 1]); Normal2.SetNormalToLine(pCoords[Index + 1], pCoords[Index]); // Calculate the "left" parallel edge DocCoord P1( pCoords[Index-1].x + (INT32)((double) LineWidth * Normal1.x), pCoords[Index-1].y + (INT32)((double) LineWidth * Normal1.y)); DocCoord P2( pCoords[Index ].x + (INT32)((double) LineWidth * Normal2.x), pCoords[Index ].y + (INT32)((double) LineWidth * Normal2.y)); double dx = P1.x - P2.x; double dy = P1.y - P2.y; double LeftTravel = sqrt((dx * dx) + (dy * dy)); // Calculate the "right" parallel edge P1 = DocCoord( pCoords[Index-1].x - (INT32)((double) LineWidth * Normal1.x), pCoords[Index-1].y - (INT32)((double) LineWidth * Normal1.y)); P2 = DocCoord( pCoords[Index ].x - (INT32)((double) LineWidth * Normal2.x), pCoords[Index ].y - (INT32)((double) LineWidth * Normal2.y)); dx = P1.x - P2.x; dy = P1.y - P2.y; double RightTravel = sqrt((dx * dx) + (dy * dy)); // And increment Position by the larger of the 2 travel distances Position += (float)( (LeftTravel > RightTravel) ? LeftTravel : RightTravel ); */ #endif } // And always add a knot at the very end of the curve pValFunc->AddPressure(Position, (float)pWidthArray[NumCoords - 1] / (float)MaxPressure); pValFunc->NormalisePositions(); // And normalise all positions to lie between 0.0 and 1.0 return(pValFunc); }