src/core/SkFontPriv.h

/*
 * Copyright 2018 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkFontPriv_DEFINED
#define SkFontPriv_DEFINED

#include "SkFont.h"
#include "SkMatrix.h"
#include "SkTypeface.h"

class SkFontPriv {
public:
    /**
     *  Return a matrix that applies the paint's text values: size, scale, skew
     */
    static SkMatrix MakeTextMatrix(SkScalar size, SkScalar scaleX, SkScalar skewX) {
        SkMatrix m = SkMatrix::MakeScale(size * scaleX, size);
        if (skewX) {
            m.postSkew(skewX, 0);
        }
        return m;
    }

    static SkMatrix MakeTextMatrix(const SkFont& font) {
        return MakeTextMatrix(font.getSize(), font.getScaleX(), font.getSkewX());
    }

    static void ScaleFontMetrics(SkFontMetrics*, SkScalar);

    // returns -1 if buffer is invalid for specified encoding
    static int ValidCountText(const void* text, size_t length, SkTextEncoding);

    static SkTypeface* GetTypefaceOrDefault(const SkFont& font) {
        return font.getTypeface() ? font.getTypeface() : SkTypeface::GetDefaultTypeface();
    }

    static sk_sp<SkTypeface> RefTypefaceOrDefault(const SkFont& font) {
        return font.getTypeface() ? font.refTypeface() : SkTypeface::MakeDefault();
    }

    typedef const SkGlyph& (*GlyphCacheProc)(SkGlyphCache*, const char**, const char*);

    static GlyphCacheProc GetGlyphCacheProc(SkTextEncoding encoding, bool needFullMetrics);

    /**
        Returns the union of bounds of all glyphs.
        Returned dimensions are computed by font manager from font data,
        ignoring SkPaint::Hinting. Includes font metrics, but not fake bold or SkPathEffect.

        If text size is large, text scale is one, and text skew is zero,
        returns the bounds as:
        { SkFontMetrics::fXMin, SkFontMetrics::fTop, SkFontMetrics::fXMax, SkFontMetrics::fBottom }.

        @return  union of bounds of all glyphs
     */
    static SkRect GetFontBounds(const SkFont&);

    // Returns the number of elements (characters or glyphs) in the array.
    static int CountTextElements(const void* text, size_t byteLength, SkTextEncoding);

    static void GlyphsToUnichars(const SkFont&, const uint16_t glyphs[], int count, SkUnichar[]);
};

class SkAutoToGlyphs {
public:
    SkAutoToGlyphs(const SkFont& font, const void* text, size_t length, SkTextEncoding encoding) {
        if (encoding == kGlyphID_SkTextEncoding || length == 0) {
            fGlyphs = reinterpret_cast<const uint16_t*>(text);
            fCount = length >> 1;
        } else {
            fCount = font.countText(text, length, encoding);
            fStorage.reset(fCount);
            font.textToGlyphs(text, length, encoding, fStorage.get(), fCount);
            fGlyphs = fStorage.get();
        }
    }

    int count() const { return fCount; }
    const uint16_t* glyphs() const { return fGlyphs; }

private:
    SkAutoSTArray<32, uint16_t> fStorage;
    const uint16_t* fGlyphs;
    int             fCount;
};

#endif