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authorscuri <scuri>2010-06-21 22:55:10 +0000
committerscuri <scuri>2010-06-21 22:55:10 +0000
commit37a92b86d13e89d0dcec92be6d23ceced29dbc36 (patch)
treefaff61ef668379212b4ed948934533c3f2fe308b /src/ftgl/FTContour.cpp
parenta124216ee05a5d63ea8fcdafcd050ad1fadf0b09 (diff)
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diff --git a/src/ftgl/FTContour.cpp b/src/ftgl/FTContour.cpp
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+/*
+ * 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);
+ }
+}
+