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Diffstat (limited to 'src/opengl/gl2paintengineex/qtriangulatingstroker.cpp')
| -rw-r--r-- | src/opengl/gl2paintengineex/qtriangulatingstroker.cpp | 549 |
1 files changed, 549 insertions, 0 deletions
diff --git a/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp b/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp new file mode 100644 index 0000000..6082f49 --- /dev/null +++ b/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp @@ -0,0 +1,549 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtOpenGL module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qtriangulatingstroker_p.h" +#include <qmath.h> + +QT_BEGIN_NAMESPACE + +#define CURVE_FLATNESS Q_PI / 8 + + + + +void QTriangulatingStroker::endCapOrJoinClosed(const qreal *start, const qreal *cur, + bool implicitClose, bool endsAtStart) +{ + if (endsAtStart) { + join(start + 2); + } else if (implicitClose) { + join(start); + lineTo(start); + join(start+2); + } else { + endCap(cur); + } + int count = m_vertices.size(); + m_vertices.add(m_vertices.at(count-2)); + m_vertices.add(m_vertices.at(count-1)); +} + + +void QTriangulatingStroker::process(const QVectorPath &path, const QPen &pen) +{ + const qreal *pts = path.points(); + const QPainterPath::ElementType *types = path.elements(); + int count = path.elementCount(); + if (count < 2) + return; + + float realWidth = qpen_widthf(pen); + if (realWidth == 0) + realWidth = 1; + + m_width = realWidth / 2; + + bool cosmetic = pen.isCosmetic(); + if (cosmetic) { + m_width = m_width * m_inv_scale; + } + + m_join_style = qpen_joinStyle(pen); + m_cap_style = qpen_capStyle(pen); + m_vertices.reset(); + m_miter_limit = pen.miterLimit() * qpen_widthf(pen); + + // The curvyness is based on the notion that I originally wanted + // roughly one line segment pr 4 pixels. This may seem little, but + // because we sample at constantly incrementing B(t) E [0<t<1], we + // will get longer segments where the curvature is small and smaller + // segments when the curvature is high. + // + // To get a rough idea of the length of each curve, I pretend that + // the curve is a 90 degree arc, whose radius is + // qMax(curveBounds.width, curveBounds.height). Based on this + // logic we can estimate the length of the outline edges based on + // the radius + a pen width and adjusting for scale factors + // depending on if the pen is cosmetic or not. + // + // The curvyness value of PI/14 was based on, + // arcLength=2*PI*r/4=PI/2 and splitting length into somewhere + // between 3 and 8 where 5 seemed to be give pretty good results + // hence: Q_PI/14. Lower divisors will give more detail at the + // direct cost of performance. + + // simplfy pens that are thin in device size (2px wide or less) + if (realWidth < 2.5 && (cosmetic || m_inv_scale == 1)) { + if (m_cap_style == Qt::RoundCap) + m_cap_style = Qt::SquareCap; + if (m_join_style == Qt::RoundJoin) + m_join_style = Qt::MiterJoin; + m_curvyness_add = 0.5; + m_curvyness_mul = CURVE_FLATNESS / m_inv_scale; + m_roundness = 1; + } else if (cosmetic) { + m_curvyness_add = realWidth / 2; + m_curvyness_mul = CURVE_FLATNESS; + m_roundness = qMax<int>(4, realWidth * CURVE_FLATNESS); + } else { + m_curvyness_add = m_width; + m_curvyness_mul = CURVE_FLATNESS / m_inv_scale; + m_roundness = qMax<int>(4, realWidth * m_curvyness_mul); + } + + // Over this level of segmentation, there doesn't seem to be any + // benefit, even for huge penWidth + if (m_roundness > 24) + m_roundness = 24; + + m_sin_theta = qFastSin(Q_PI / m_roundness); + m_cos_theta = qFastCos(Q_PI / m_roundness); + + const qreal *endPts = pts + (count<<1); + const qreal *startPts; + + Qt::PenCapStyle cap = m_cap_style; + + if (!types) { + startPts = pts; + + bool endsAtStart = startPts[0] == *(endPts-2) && startPts[1] == *(endPts-1); + + if (endsAtStart || path.hasImplicitClose()) + m_cap_style = Qt::FlatCap; + moveTo(pts); + m_cap_style = cap; + pts += 2; + lineTo(pts); + pts += 2; + while (pts < endPts) { + join(pts); + lineTo(pts); + pts += 2; + } + + endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart); + + } else { + bool endsAtStart; + while (pts < endPts) { + switch (*types) { + case QPainterPath::MoveToElement: { + if (pts != path.points()) + endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart); + + startPts = pts; + int end = (endPts - pts) / 2; + int i = 2; // Start looking to ahead since we never have two moveto's in a row + while (i<end && types[i] != QPainterPath::MoveToElement) { + ++i; + } + endsAtStart = startPts[0] == pts[i*2 - 2] && startPts[1] == pts[i*2 - 1]; + if (endsAtStart || path.hasImplicitClose()) + m_cap_style = Qt::FlatCap; + + moveTo(pts); + m_cap_style = cap; + pts+=2; + ++types; + break; } + case QPainterPath::LineToElement: + if (*(types - 1) != QPainterPath::MoveToElement) + join(pts); + lineTo(pts); + pts+=2; + ++types; + break; + case QPainterPath::CurveToElement: + if (*(types - 1) != QPainterPath::MoveToElement) + join(pts); + cubicTo(pts); + pts+=6; + types+=3; + break; + default: + Q_ASSERT(false); + break; + } + } + + endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart); + } +} + +void QTriangulatingStroker::moveTo(const qreal *pts) +{ + m_cx = pts[0]; + m_cy = pts[1]; + + float x2 = pts[2]; + float y2 = pts[3]; + normalVector(m_cx, m_cy, x2, y2, &m_nvx, &m_nvy); + + + // To acheive jumps we insert zero-area tringles. This is done by + // adding two identical points in both the end of previous strip + // and beginning of next strip + bool invisibleJump = m_vertices.size(); + + switch (m_cap_style) { + case Qt::FlatCap: + if (invisibleJump) { + m_vertices.add(m_cx + m_nvx); + m_vertices.add(m_cy + m_nvy); + } + break; + case Qt::SquareCap: { + float sx = m_cx - m_nvy; + float sy = m_cy + m_nvx; + if (invisibleJump) { + m_vertices.add(sx + m_nvx); + m_vertices.add(sy + m_nvy); + } + emitLineSegment(sx, sy, m_nvx, m_nvy); + break; } + case Qt::RoundCap: { + QVarLengthArray<float> points; + arcPoints(m_cx, m_cy, m_cx + m_nvx, m_cy + m_nvy, m_cx - m_nvx, m_cy - m_nvy, points); + m_vertices.resize(m_vertices.size() + points.size() + 2 * int(invisibleJump)); + int count = m_vertices.size(); + int front = 0; + int end = points.size() / 2; + while (front != end) { + m_vertices.at(--count) = points[2 * end - 1]; + m_vertices.at(--count) = points[2 * end - 2]; + --end; + if (front == end) + break; + m_vertices.at(--count) = points[2 * front + 1]; + m_vertices.at(--count) = points[2 * front + 0]; + ++front; + } + + if (invisibleJump) { + m_vertices.at(count - 1) = m_vertices.at(count + 1); + m_vertices.at(count - 2) = m_vertices.at(count + 0); + } + break; } + default: break; // ssssh gcc... + } + emitLineSegment(m_cx, m_cy, m_nvx, m_nvy); +} + +void QTriangulatingStroker::cubicTo(const qreal *pts) +{ + const QPointF *p = (const QPointF *) pts; + QBezier bezier = QBezier::fromPoints(*(p - 1), p[0], p[1], p[2]); + + QRectF bounds = bezier.bounds(); + float rad = qMax(bounds.width(), bounds.height()); + int threshold = qMin<float>(64, (rad + m_curvyness_add) * m_curvyness_mul); + if (threshold < 4) + threshold = 4; + qreal threshold_minus_1 = threshold - 1; + float vx, vy; + + float cx = m_cx, cy = m_cy; + float x, y; + + for (int i=1; i<threshold; ++i) { + qreal t = qreal(i) / threshold_minus_1; + QPointF p = bezier.pointAt(t); + x = p.x(); + y = p.y(); + + normalVector(cx, cy, x, y, &vx, &vy); + + emitLineSegment(x, y, vx, vy); + + cx = x; + cy = y; + } + + m_cx = cx; + m_cy = cy; + + m_nvx = vx; + m_nvy = vy; +} + +void QTriangulatingStroker::join(const qreal *pts) +{ + // Creates a join to the next segment (m_cx, m_cy) -> (pts[0], pts[1]) + normalVector(m_cx, m_cy, pts[0], pts[1], &m_nvx, &m_nvy); + + switch (m_join_style) { + case Qt::BevelJoin: + break; + case Qt::SvgMiterJoin: + case Qt::MiterJoin: { + // Find out on which side the join should be. + int count = m_vertices.size(); + float prevNvx = m_vertices.at(count - 2) - m_cx; + float prevNvy = m_vertices.at(count - 1) - m_cy; + float xprod = prevNvx * m_nvy - prevNvy * m_nvx; + float px, py, qx, qy; + + // If the segments are parallel, use bevel join. + if (qFuzzyIsNull(xprod)) + break; + + // Find the corners of the previous and next segment to join. + if (xprod < 0) { + px = m_vertices.at(count - 2); + py = m_vertices.at(count - 1); + qx = m_cx - m_nvx; + qy = m_cy - m_nvy; + } else { + px = m_vertices.at(count - 4); + py = m_vertices.at(count - 3); + qx = m_cx + m_nvx; + qy = m_cy + m_nvy; + } + + // Find intersection point. + float pu = px * prevNvx + py * prevNvy; + float qv = qx * m_nvx + qy * m_nvy; + float ix = (m_nvy * pu - prevNvy * qv) / xprod; + float iy = (prevNvx * qv - m_nvx * pu) / xprod; + + // Check that the distance to the intersection point is less than the miter limit. + if ((ix - px) * (ix - px) + (iy - py) * (iy - py) <= m_miter_limit * m_miter_limit) { + m_vertices.add(ix); + m_vertices.add(iy); + m_vertices.add(ix); + m_vertices.add(iy); + } + // else + // Do a plain bevel join if the miter limit is exceeded or if + // the lines are parallel. This is not what the raster + // engine's stroker does, but it is both faster and similar to + // what some other graphics API's do. + + break; } + case Qt::RoundJoin: { + QVarLengthArray<float> points; + int count = m_vertices.size(); + float prevNvx = m_vertices.at(count - 2) - m_cx; + float prevNvy = m_vertices.at(count - 1) - m_cy; + if (m_nvx * prevNvy - m_nvy * prevNvx < 0) { + arcPoints(0, 0, m_nvx, m_nvy, -prevNvx, -prevNvy, points); + for (int i = points.size() / 2; i > 0; --i) + emitLineSegment(m_cx, m_cy, points[2 * i - 2], points[2 * i - 1]); + } else { + arcPoints(0, 0, -prevNvx, -prevNvy, m_nvx, m_nvy, points); + for (int i = 0; i < points.size() / 2; ++i) + emitLineSegment(m_cx, m_cy, points[2 * i + 0], points[2 * i + 1]); + } + break; } + default: break; // gcc warn-- + } + + emitLineSegment(m_cx, m_cy, m_nvx, m_nvy); +} + +void QTriangulatingStroker::endCap(const qreal *) +{ + switch (m_cap_style) { + case Qt::FlatCap: + break; + case Qt::SquareCap: + emitLineSegment(m_cx + m_nvy, m_cy - m_nvx, m_nvx, m_nvy); + break; + case Qt::RoundCap: { + QVarLengthArray<float> points; + int count = m_vertices.size(); + arcPoints(m_cx, m_cy, m_vertices.at(count - 2), m_vertices.at(count - 1), m_vertices.at(count - 4), m_vertices.at(count - 3), points); + int front = 0; + int end = points.size() / 2; + while (front != end) { + m_vertices.add(points[2 * end - 2]); + m_vertices.add(points[2 * end - 1]); + --end; + if (front == end) + break; + m_vertices.add(points[2 * front + 0]); + m_vertices.add(points[2 * front + 1]); + ++front; + } + break; } + default: break; // to shut gcc up... + } +} + +void QTriangulatingStroker::arcPoints(float cx, float cy, float fromX, float fromY, float toX, float toY, QVarLengthArray<float> &points) +{ + float dx1 = fromX - cx; + float dy1 = fromY - cy; + float dx2 = toX - cx; + float dy2 = toY - cy; + + // while more than 180 degrees left: + while (dx1 * dy2 - dx2 * dy1 < 0) { + float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta; + float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta; + dx1 = tmpx; + dy1 = tmpy; + points.append(cx + dx1); + points.append(cy + dy1); + } + + // while more than 90 degrees left: + while (dx1 * dx2 + dy1 * dy2 < 0) { + float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta; + float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta; + dx1 = tmpx; + dy1 = tmpy; + points.append(cx + dx1); + points.append(cy + dy1); + } + + // while more than 0 degrees left: + while (dx1 * dy2 - dx2 * dy1 > 0) { + float tmpx = dx1 * m_cos_theta - dy1 * m_sin_theta; + float tmpy = dx1 * m_sin_theta + dy1 * m_cos_theta; + dx1 = tmpx; + dy1 = tmpy; + points.append(cx + dx1); + points.append(cy + dy1); + } + + // remove last point which was rotated beyond [toX, toY]. + if (!points.isEmpty()) + points.resize(points.size() - 2); +} + +static void qdashprocessor_moveTo(qreal x, qreal y, void *data) +{ + ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::MoveToElement, x, y); +} + +static void qdashprocessor_lineTo(qreal x, qreal y, void *data) +{ + ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::LineToElement, x, y); +} + +static void qdashprocessor_cubicTo(qreal, qreal, qreal, qreal, qreal, qreal, void *) +{ + Q_ASSERT(0); // The dasher should not produce curves... +} + +QDashedStrokeProcessor::QDashedStrokeProcessor() + : m_dash_stroker(0), m_inv_scale(1) +{ + m_dash_stroker.setMoveToHook(qdashprocessor_moveTo); + m_dash_stroker.setLineToHook(qdashprocessor_lineTo); + m_dash_stroker.setCubicToHook(qdashprocessor_cubicTo); +} + +void QDashedStrokeProcessor::process(const QVectorPath &path, const QPen &pen) +{ + + const qreal *pts = path.points(); + const QPainterPath::ElementType *types = path.elements(); + int count = path.elementCount(); + + m_points.reset(); + m_types.reset(); + + qreal width = qpen_widthf(pen); + if (width == 0) + width = 1; + + m_dash_stroker.setDashPattern(pen.dashPattern()); + m_dash_stroker.setStrokeWidth(pen.isCosmetic() ? width * m_inv_scale : width); + m_dash_stroker.setMiterLimit(pen.miterLimit()); + qreal curvyness = sqrt(width) * m_inv_scale / 8; + + if (count < 2) + return; + + const qreal *endPts = pts + (count<<1); + + m_dash_stroker.begin(this); + + if (!types) { + m_dash_stroker.moveTo(pts[0], pts[1]); + pts += 2; + while (pts < endPts) { + m_dash_stroker.lineTo(pts[0], pts[1]); + pts += 2; + } + } else { + while (pts < endPts) { + switch (*types) { + case QPainterPath::MoveToElement: + m_dash_stroker.moveTo(pts[0], pts[1]); + pts += 2; + ++types; + break; + case QPainterPath::LineToElement: + m_dash_stroker.lineTo(pts[0], pts[1]); + pts += 2; + ++types; + break; + case QPainterPath::CurveToElement: { + QBezier b = QBezier::fromPoints(*(((const QPointF *) pts) - 1), + *(((const QPointF *) pts)), + *(((const QPointF *) pts) + 1), + *(((const QPointF *) pts) + 2)); + QRectF bounds = b.bounds(); + int threshold = qMin<float>(64, qMax(bounds.width(), bounds.height()) * curvyness); + if (threshold < 4) + threshold = 4; + qreal threshold_minus_1 = threshold - 1; + for (int i=0; i<threshold; ++i) { + QPointF pt = b.pointAt(i / threshold_minus_1); + m_dash_stroker.lineTo(pt.x(), pt.y()); + } + pts += 6; + types += 3; + break; } + default: break; + } + } + } + + m_dash_stroker.end(); +} + +QT_END_NAMESPACE + |