Edit
kc3-lang/ftgl/src/FTContour.cpp
Frank Heckenbach
- src/FTContour.cpp
-
/* * FTGL - OpenGL font library * * Copyright (c) 2001-2004 Henry Maddocks <ftgl@opengl.geek.nz> * Copyright (c) 2008 Sam Hocevar <sam@hocevar.net> * Copyright (c) 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. // M // - - - - - - X // ^ / ' // | 64.0 / ' // X---->-----X ==> X--v-------X ' // A B \ A B \ .>' // \ \<' 64.0 // \ \ . // \ \ . // C X C X // FTPoint FTContour::ComputeOutsetPoint(FTPoint A, FTPoint B, FTPoint C) { // If the angle between 'ab' and 'bc' approaches 180 degrees, // the outset point goes to infinity, giving an invalid result. // Even for angles near 180 degrees, the point will be quite // far away from A, B and C. To avoid ugly results, limit // its distance to 64.0 * OutsetMax. static const FTGL_DOUBLE OutsetMax = 5; /* 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 norm = sqrt(tmp.X() * tmp.X() + tmp.Y() * tmp.Y()); FTGL_DOUBLE dist; if (norm - tmp.X() > (norm + tmp.X()) * OutsetMax * OutsetMax) dist = 64.0 * OutsetMax; else dist = 64.0 * sqrt((norm - tmp.X()) / (norm + tmp.X())); tmp.X(tmp.Y() < 0.0 ? dist : -dist); 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::SetParity(int parity) { size_t size = PointCount(); FTPoint vOutset; if(((parity & 1) && clockwise) || (!(parity & 1) && !clockwise)) { // Contour orientation is wrong! We must reverse all points. // FIXME: could it be worth writing FTVector::reverse() for this? for(size_t i = 0; i < size / 2; i++) { FTPoint tmp = pointList[i]; pointList[i] = pointList[size - 1 - i]; pointList[size - 1 -i] = tmp; } clockwise = !clockwise; } for(size_t i = 0; i < size; i++) { size_t prev, cur, next; prev = (i + size - 1) % size; cur = i; next = (i + size + 1) % size; vOutset = ComputeOutsetPoint(Point(prev), Point(cur), Point(next)); AddOutsetPoint(vOutset); } } FTContour::FTContour(FT_Vector* contour, char* tags, unsigned int n) { FTPoint prev, cur(contour[(n - 1) % n]), next(contour[0]); FTPoint a, b = next - cur; double olddir, dir = atan2((next - cur).Y(), (next - cur).X()); double angle = 0.0; // 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++) { prev = cur; cur = next; next = FTPoint(contour[(i + 1) % n]); olddir = dir; dir = atan2((next - cur).Y(), (next - cur).X()); // Compute our path's new direction. double t = dir - olddir; if(t < -M_PI) t += 2 * M_PI; if(t > M_PI) t -= 2 * M_PI; angle += t; // 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) { FTPoint prev2 = prev, next2 = next; // Previous point is either the real previous point (an "on" // point), or the midpoint between the current one and the // previous "conic off" point. if(FT_CURVE_TAG(tags[(i - 1 + n) % n]) == FT_Curve_Tag_Conic) { prev2 = (cur + prev) * 0.5; AddPoint(prev2); } // Next point is either the real next point or the midpoint. if(FT_CURVE_TAG(tags[(i + 1) % n]) == FT_Curve_Tag_Conic) { next2 = (cur + next) * 0.5; } evaluateQuadraticCurve(prev2, cur, next2); } else if(FT_CURVE_TAG(tags[i]) == FT_Curve_Tag_Cubic && FT_CURVE_TAG(tags[(i + 1) % n]) == FT_Curve_Tag_Cubic) { evaluateCubicCurve(prev, cur, next, FTPoint(contour[(i + 2) % n])); } } // If final angle is positive (+2PI), it's an anti-clockwise contour, // otherwise (-2PI) it's clockwise. clockwise = (angle < 0.0); } void FTContour::buildFrontOutset(float outset) { frontPointList.clear(); for(size_t i = 0; i < PointCount(); ++i) { AddFrontPoint(Point(i) + Outset(i) * outset); } } void FTContour::buildBackOutset(float outset) { backPointList.clear(); for(size_t i = 0; i < PointCount(); ++i) { AddBackPoint(Point(i) + Outset(i) * outset); } }