/*
* FTGL - OpenGL font library
*
* Copyright (c) 2001-2004 Henry Maddocks <ftgl@opengl.geek.nz>
* Copyright (c) 2008 Sam Hocevar <sam@zoy.org>
* 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)
{
/* 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 = 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)
{
for(size_t i = 0; i < PointCount(); ++i)
{
AddFrontPoint(Point(i) + Outset(i) * outset);
}
}
void FTContour::buildBackOutset(float outset)
{
for(size_t i = 0; i < PointCount(); ++i)
{
AddBackPoint(Point(i) + Outset(i) * outset);
}
}