qoutlinemapper_p.h

Go to the documentation of this file.

// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QOUTLINEMAPPER_P_H
#define QOUTLINEMAPPER_P_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <QtGui/private/qtguiglobal_p.h>
#include <QtCore/qrect.h>
 
#include <QtGui/qtransform.h>
#include <QtGui/qpainterpath.h>
 
#define QT_FT_BEGIN_HEADER
#define QT_FT_END_HEADER
 
#include <private/qrasterdefs_p.h>
#include <private/qdatabuffer_p.h>
#include "qpaintengineex_p.h"
 
QT_BEGIN_NAMESPACE
 
// These limitations comes from qrasterizer.cpp, qcosmeticstroker.cpp, and qgrayraster.c.
// Any higher and rasterization of shapes will produce incorrect results.
#if Q_PROCESSOR_WORDSIZE == 8
constexpr int QT_RASTER_COORD_LIMIT = ((1<<23) - 1); // F24dot8 in qgrayraster.c
#else
constexpr int QT_RASTER_COORD_LIMIT = ((1<<15) - 1); // F16dot16 in qrasterizer.cpp and qcosmeticstroker.cpp
#endif
//#define QT_DEBUG_CONVERT
 
Q_GUI_EXPORT bool qt_scaleForTransform(const QTransform &transform, qreal *scale);
 
/********************************************************************************
 * class QOutlineMapper
 *
 * Used to map between QPainterPath and the QT_FT_Outline structure used by the
 * freetype scanconverter.
 *
 * The outline mapper uses a path iterator to get points from the path,
 * so that it is possible to transform the points as they are converted. The
 * callback can be a noop, translate or full-fledged xform. (Tests indicated
 * that using a C callback was low cost).
 */
class QOutlineMapper
{
public:
    QOutlineMapper() :
        m_element_types(0),
        m_elements(0),
        m_points(0),
        m_tags(0),
        m_contours(0),
        m_in_clip_elements(false)
    {
    }
 
    /*!
      Sets up the matrix to be used for conversion. This also
      sets up the qt_path_iterator function that is used as a callback
      to get points.
    */
    void setMatrix(const QTransform &m)
    {
        m_transform = m;
 
        qreal scale;
        qt_scaleForTransform(m, &scale);
        m_curve_threshold = scale == 0 ? qreal(0.25) : (qreal(0.25) / scale);
    }
 
    void setClipRect(QRect clipRect);
 
    void beginOutline(Qt::FillRule fillRule)
    {
#ifdef QT_DEBUG_CONVERT
        printf("QOutlineMapper::beginOutline rule=%d\n", fillRule);
#endif
        m_valid = true;
        m_elements.reset();
        m_element_types.reset();
        m_points.reset();
        m_tags.reset();
        m_contours.reset();
        m_outline.flags = fillRule == Qt::WindingFill
                          ? QT_FT_OUTLINE_NONE
                          : QT_FT_OUTLINE_EVEN_ODD_FILL;
        m_subpath_start = 0;
    }
 
    void endOutline();
 
    void clipElements(const QPointF *points, const QPainterPath::ElementType *types, int count);
 
    void convertElements(const QPointF *points, const QPainterPath::ElementType *types, int count);
 
    inline void moveTo(const QPointF &pt) {
#ifdef QT_DEBUG_CONVERT
        printf("QOutlineMapper::moveTo() (%f, %f)\n", pt.x(), pt.y());
#endif
        closeSubpath();
        m_subpath_start = m_elements.size();
        m_elements << pt;
        m_element_types << QPainterPath::MoveToElement;
    }
 
    inline void lineTo(const QPointF &pt) {
#ifdef QT_DEBUG_CONVERT
        printf("QOutlineMapper::lineTo() (%f, %f)\n", pt.x(), pt.y());
#endif
        m_elements.add(pt);
        m_element_types << QPainterPath::LineToElement;
    }
 
    void curveTo(const QPointF &cp1, const QPointF &cp2, const QPointF &ep);
 
    inline void closeSubpath() {
        int element_count = m_elements.size();
        if (element_count > 0) {
            if (m_elements.at(element_count-1) != m_elements.at(m_subpath_start)) {
#ifdef QT_DEBUG_CONVERT
                printf(" - implicitly closing\n");
#endif
                // Put the object on the stack to avoid the odd case where
                // lineTo reallocs the databuffer and the QPointF & will
                // be invalidated.
                QPointF pt = m_elements.at(m_subpath_start);
 
                // only do lineTo if we have element_type array...
                if (m_element_types.size())
                    lineTo(pt);
                else
                    m_elements << pt;
 
            }
        }
    }
 
    QT_FT_Outline *outline() {
        if (m_valid)
            return &m_outline;
        return nullptr;
    }
 
    QT_FT_Outline *convertPath(const QPainterPath &path);
    QT_FT_Outline *convertPath(const QVectorPath &path);
 
    inline QPainterPath::ElementType *elementTypes() const { return m_element_types.size() == 0 ? nullptr : m_element_types.data(); }
 
public:
    QDataBuffer<QPainterPath::ElementType> m_element_types;
    QDataBuffer<QPointF> m_elements;
    QDataBuffer<QT_FT_Vector> m_points;
    QDataBuffer<char> m_tags;
    QDataBuffer<int> m_contours;
 
    QRect m_clip_rect;
    QRectF m_clip_trigger_rect;
    QRectF controlPointRect; // only valid after endOutline()
 
    QT_FT_Outline m_outline;
 
    int m_subpath_start;
 
    QTransform m_transform;
 
    qreal m_curve_threshold;
 
    bool m_valid;
    bool m_in_clip_elements;
};
 
QT_END_NAMESPACE
 
#endif // QOUTLINEMAPPER_P_H