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kc3-lang/ftgl/src/FTContour.cpp
sammy
- src/FTContour.cpp
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/* * FTGL - OpenGL font library * * Copyright (c) 2001-2004 Henry Maddocks <ftgl@opengl.geek.nz> * 2008 Sam Hocevar <sam@zoy.org> * 2008 Éric Beets <ericbeets@free.fr> * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "config.h" #include "FTContour.h" #include <math.h> static const unsigned int BEZIER_STEPS = 5; void FTContour::AddPoint(FTPoint point) { if(pointList.empty() || (point != pointList[pointList.size() - 1] && point != pointList[0])) { pointList.push_back(point); } } void FTContour::AddOutsetPoint(FTPoint point) { outsetPointList.push_back(point); } void FTContour::AddFrontPoint(FTPoint point) { frontPointList.push_back(point); } void FTContour::AddBackPoint(FTPoint point) { backPointList.push_back(point); } void FTContour::evaluateQuadraticCurve(FTPoint A, FTPoint B, FTPoint C) { for(unsigned int i = 1; i < BEZIER_STEPS; i++) { float t = static_cast<float>(i) / BEZIER_STEPS; FTPoint U = (1.0f - t) * A + t * B; FTPoint V = (1.0f - t) * B + t * C; AddPoint((1.0f - t) * U + t * V); } } void FTContour::evaluateCubicCurve(FTPoint A, FTPoint B, FTPoint C, FTPoint D) { for(unsigned int i = 0; i < BEZIER_STEPS; i++) { float t = static_cast<float>(i) / BEZIER_STEPS; FTPoint U = (1.0f - t) * A + t * B; FTPoint V = (1.0f - t) * B + t * C; FTPoint W = (1.0f - t) * C + t * D; FTPoint M = (1.0f - t) * U + t * V; FTPoint N = (1.0f - t) * V + t * W; AddPoint((1.0f - t) * M + t * N); } } // This function is a bit tricky. Given a path ABC, it returns the // coordinates of the outset point facing B on the left at a distance // of 64.0. Ask Sam for details, even ASCII art cannot possibly explain // this properly. FTPoint FTContour::ComputeOutsetPoint(FTPoint A, FTPoint B, FTPoint C) { /* Build the rotation matrix from 'ba' vector */ FTPoint ba = (A - B).Normalise(); FTPoint bc = C - B; /* Rotate bc to the left */ FTPoint tmp(bc.X() * -ba.X() + bc.Y() * -ba.Y(), bc.X() * ba.Y() + bc.Y() * -ba.X()); /* Compute the vector bisecting 'abc' */ FTGL_DOUBLE sgn = -64.0; FTGL_DOUBLE norm = sqrt(tmp.X() * tmp.X() + tmp.Y() * tmp.Y()); if((tmp.Y() / norm) < 0) sgn = 64.0; tmp.X(sgn * sqrt((norm - tmp.X()) / (norm + tmp.X()))); tmp.Y(64.0); /* Rotate the new bc to the right */ return FTPoint(tmp.X() * -ba.X() + tmp.Y() * ba.Y(), tmp.X() * -ba.Y() + tmp.Y() * -ba.X()); } void FTContour::outsetContour() { size_t size = PointCount(); FTPoint vOutset; for(unsigned int pointIndex = 0; pointIndex < size; ++pointIndex) { int prev = (pointIndex%size + size - 1) % size; int cur = pointIndex%size; int next = (pointIndex%size + 1) % size; /* Build the outset shape with d = 1.0f */ vOutset = ComputeOutsetPoint(Point(prev), Point(cur), Point(next)); AddOutsetPoint(vOutset); } } FTContour::FTContour(FT_Vector* contour, char* tags, unsigned int n) { // See http://freetype.sourceforge.net/freetype2/docs/glyphs/glyphs-6.html // for a full description of FreeType tags. for(unsigned int i = 0; i < n; i++) { FTPoint cur(contour[i]); // Only process point tags we know. if(n < 2 || FT_CURVE_TAG(tags[i]) == FT_Curve_Tag_On) { AddPoint(cur); } else if(FT_CURVE_TAG(tags[i]) == FT_Curve_Tag_Conic) { // Previous point is either the real previous point (an "on" // point), or the midpoint between the current one and the // previous "conic off" point. FTPoint prev(contour[(i - 1 + n) % n]); if(FT_CURVE_TAG(tags[(i - 1 + n) % n]) == FT_Curve_Tag_Conic) { prev = (cur + prev) * 0.5; AddPoint(prev); } // Next point is either the real next point or the midpoint. FTPoint next(contour[(i + 1) % n]); if(FT_CURVE_TAG(tags[(i + 1) % n]) == FT_Curve_Tag_Conic) { next = (cur + next) * 0.5; } evaluateQuadraticCurve(prev, cur, next); } else if(FT_CURVE_TAG(tags[i]) == FT_Curve_Tag_Cubic && FT_CURVE_TAG(tags[(i + 1) % n]) == FT_Curve_Tag_Cubic) { evaluateCubicCurve(FTPoint(contour[(i - 1 + n) % n]), cur, FTPoint(contour[(i + 1) % n]), FTPoint(contour[(i + 2) % n])); } } /* Create (or not) front outset and/or back outset */ outsetContour(); } void FTContour::buildFrontOutset(float outset) { for(size_t i = 0; i < PointCount(); ++i) { FTPoint point = FTPoint(Point(i).X() + Outset(i).X() * outset, Point(i).Y() + Outset(i).Y() * outset, 0); AddFrontPoint(point); } } void FTContour::buildBackOutset(float outset) { for(size_t i = 0; i < PointCount(); ++i) { FTPoint point = FTPoint(Point(i).X() + Outset(i).X() * outset, Point(i).Y() + Outset(i).Y() * outset, 0); AddBackPoint(point); } }