xref: /dports/www/kf5-khtml/khtml-5.89.0/src/rendering/font.h

/*
 * This file is part of the html renderer for KDE.
 *
 * Copyright (C) 2000-2003 Lars Knoll (knoll@kde.org)
 *           (C) 2000 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef KHTMLFONT_H
#define KHTMLFONT_H

#include <khtml_global.h>
#include <khtml_settings.h>

#include <QCache>
#include <QFont>
#include <QFontMetrics>
#include <QPainter>

#include "misc/shared.h"

namespace DOM
{
class DOMString;
}

namespace khtml
{
class RenderStyle;
class CSSStyleSelector;

class CachedFontFamily;

class CachedFontInstance: public Shared<CachedFontInstance>
{
public:
    CachedFontInstance(CachedFontFamily *parent, int size);

    QFont        f;
    QFontMetrics fm; // note:stuff below is faster when applicable.
    // Also, do not rearrange these two fields --- one neefs f to initialize fm

    // We store cached width metrics as a two-level tree ---
    // top-level is row for the codepoint, second is column.
    // Some rows may have no information on them.
    // For a cell, value 255 means no known width (or a width >= 255)
    unsigned cachedCharWidth(unsigned short codePoint)
    {
        unsigned width = 0xFF;
        if (RowInfo *row = rows[codePoint >> 8]) {
            width = row->widths[codePoint & 0xFF];
        }
        if (width != 0xFF) {
            return width;
        } else {
            return calcAndCacheWidth(codePoint);
        }
    }

    unsigned cachedCharWidth(const QChar &c)
    {
        return cachedCharWidth(c.unicode());
    }

    // query again all metrics
    void invalidate();

    // Simple cached metrics, set on creation
    int ascent;
    int descent;
    int height;
    int lineSpacing;
    int xHeight;
    int m_zeroCharWidth;
    mutable bool invalidated;

    ~CachedFontInstance();
private:
    unsigned calcAndCacheWidth(unsigned short codePoint);

    struct RowInfo {
        unsigned char widths[256];

        RowInfo()
        {
            for (int i = 0; i < 256; ++i) {
                widths[i] = 0xFF;
            }
        }
    };

    RowInfo *rows[256];
    CachedFontFamily *parent;
    int size; // the size we were created with
};

class FontDef
{
public:
    FontDef()
        : family(KHTMLGlobal::defaultHTMLSettings()->stdFontName()), size(0), italic(false), smallCaps(false), weight(QFont::Normal) {}
    bool operator == (const FontDef &other) const
    {
        return (family == other.family &&
                size == other.size &&
                italic == other.italic &&
                smallCaps == other.smallCaps &&
                weight == other.weight);
    }

    QString family;
    short int size;
    bool italic         : 1;
    bool smallCaps      : 1;
    unsigned int weight         : 8;
};

class Font
{
    friend class RenderStyle;
    friend class CSSStyleSelector;

    static CachedFontInstance *defaultCFI;
public:
    static void initDefault();

    Font() : fontDef(), cfi(defaultCFI), scFont(nullptr), letterSpacing(0), wordSpacing(0) {}
    Font(const FontDef &fd)
        :  fontDef(fd), cfi(defaultCFI), scFont(nullptr), letterSpacing(0), wordSpacing(0)
    {}
    Font(const Font &o)
        : fontDef(o.fontDef), cfi(o.cfi), scFont(o.scFont), letterSpacing(o.letterSpacing), wordSpacing(o.wordSpacing)
    {
        if (o.scFont) {
            scFont = new QFont(*o.scFont);
        }
    }
    ~Font()
    {
        delete scFont;
    }

    bool operator == (const Font &other) const
    {
        return (fontDef == other.fontDef &&
                letterSpacing == other.letterSpacing &&
                wordSpacing == other.wordSpacing);
    }

    const FontDef &getFontDef() const
    {
        return fontDef;
    }

    void update(int logicalDpiY) const;

    static void invalidateCachedFontFamily(const QString &familyName);
    static void markAllCachedFontsAsValid();

    /**
     * Draws a piece from the given piece of text.
     * @param p painter
     * @param x x-coordinate to begin drawing, always denotes leftmost position
     * @param y y-coordinate of baseline of text
     * @param str string to draw a piece from
     * @param slen total length of string
     * @param pos zero-based offset of beginning of piece
     * @param len length of piece
     * @param width additional pixels to be distributed equally among all
     *      spaces
     * @param d text direction
     * @param from begin with this position relative to @p pos, -1 to start
     *      at @p pos
     * @param to stop before this position relative to @p pos, -1 to use full
     *      length of piece
     * @param bg if valid, fill the background of the drawn piece with this
     *      color
     * @param uy y-coordinate of top position, used for background and text
     *      decoration painting
     * @param h total height of line, only used for background and text
     *      decoration painting
     * @param deco combined text decoration (see Decoration)
     */
    void drawText(QPainter *p, int x, int y, const QChar *str, const int slen, int pos, int len, int width,
                  Qt::LayoutDirection d, int from = -1, int to = -1, QColor bg = QColor(),
                  int uy = -1, int h = -1, int deco = 0) const;

    /** returns the width of the given string chunk in pixels.
     *
     * The method also considers various styles like text-align and font-variant
     * @param str pointer to string
     * @param slen total length of string
     * @param pos zero-based position in string where to start measuring
     * @param len count of characters up to which the width should be determined
     * @param fast Use simplest/fastest algorithm (for e.g strings without special/combining chars)
     * @param start starting position of inline text box within str, only
     * used when toAdd is specified.
     * @param end ending position of inline text box within str, only
     * used when toAdd is specified.
     * @param toAdd amount of pixels to distribute evenly among all spaces of
     * str. Note that toAdd applies to all spaces within str, but only those
     * within [pos, pos+len) are counted towards the width.
     */
    int width(const QChar *str, int slen, int pos, int len, bool fast, int start = 0, int end = 0, int toAdd = 0) const;
    /** return the width of the given char in pixels.
     *
     * The method also considers various styles like text-align and font-variant
     * @param str pointer to string
     * @param slen total length of string
     * @param pos zero-based position of char in string
     */
    int charWidth(const QChar *str, int slen, int pos, bool fast) const;

    /** Text decoration constants.
     *
     * The enumeration constant values match those of ETextDecoration, but only
     * a subset is supported.
     */
    enum Decoration { UNDERLINE = 0x1, OVERLINE = 0x2, LINE_THROUGH = 0x4 };
    // Keep in sync with ETextDecoration

    /** draws text decoration
     * @param p painter
     * @param x x-coordinate
     * @param y top y-coordinate of line box
     * @param baseline baseline
     * @param width length of decoration in pixels
     * @param height height of line box
     * @param deco decoration to be drawn (see Decoration). The enumeration
     *      constants may be combined.
     */
    void drawDecoration(QPainter *p, int x, int y, int baseline, int width, int height, int deco) const;

    /** returns letter spacing
     */
    int getLetterSpacing() const
    {
        return letterSpacing;
    }
    /** returns word spacing
     */
    int getWordSpacing() const
    {
        return wordSpacing;
    }

    // for SVG
    int ascent() const
    {
        return cfi->ascent;
    }
    int descent() const
    {
        return cfi->descent;
    }
    int height() const
    {
        return cfi->height;
    }
    int lineSpacing() const
    {
        return cfi->lineSpacing;
    }
    int xHeight() const
    {
        return cfi->xHeight;
    }

    // return -1 if '0' char glyph not in font
    int zeroCharWidth() const
    {
        return cfi->m_zeroCharWidth;
    }
    //FIXME: IMPLEMENT ME
    unsigned unitsPerEm() const
    {
        return 0;
    }
    int spaceWidth() const
    {
        return 0;
    }
    int tabWidth() const
    {
        return 8 * spaceWidth();
    }

    bool isInvalidated() const
    {
        return cfi->invalidated;
    }
    void validate() const
    {
        cfi->invalidated = false;
    }

    // SVG helper function
    float floatWidth(QChar *str, int pos, int len, int extraCharsAvailable, int &charsConsumed, DOM::DOMString &glyphName) const;

    float floatWidth(QChar *str, int pos, int len) const;

private:
    static CachedFontFamily *queryFamily(const QString &name, int weight, bool italic);

    mutable FontDef fontDef;
    mutable WTF::SharedPtr<CachedFontInstance> cfi;
    mutable QFont *scFont;
    short letterSpacing;
    short wordSpacing;
};

} // namespace

#endif