include/minikin/MinikinFont.h

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef MINIKIN_FONT_H
#define MINIKIN_FONT_H

#include <string>
#include <memory>

#include <minikin/FontFamily.h>
#include <minikin/Hyphenator.h>

// An abstraction for platform fonts, allowing Minikin to be used with
// multiple actual implementations of fonts.

namespace minikin {

class MinikinFont;

// Possibly move into own .h file?
// Note: if you add a field here, either add it to LayoutCacheKey or to skipCache()
struct MinikinPaint {
    MinikinPaint() : font(nullptr), size(0), scaleX(0), skewX(0), letterSpacing(0), wordSpacing(0),
            paintFlags(0), fakery(), hyphenEdit(), fontFeatureSettings() { }

    bool skipCache() const {
        return !fontFeatureSettings.empty();
    }

    MinikinFont *font;
    float size;
    float scaleX;
    float skewX;
    float letterSpacing;
    float wordSpacing;
    uint32_t paintFlags;
    FontFakery fakery;
    HyphenEdit hyphenEdit;
    std::string fontFeatureSettings;
};

// Only a few flags affect layout, but those that do should have values
// consistent with Android's paint flags.
enum MinikinPaintFlags {
    LinearTextFlag = 0x40,
};

struct MinikinRect {
    float mLeft, mTop, mRight, mBottom;
    bool isEmpty() const {
        return mLeft == mRight || mTop == mBottom;
    }
    void set(const MinikinRect& r) {
        mLeft = r.mLeft;
        mTop = r.mTop;
        mRight = r.mRight;
        mBottom = r.mBottom;
    }
    void offset(float dx, float dy) {
        mLeft += dx;
        mTop += dy;
        mRight += dx;
        mBottom += dy;
    }
    void setEmpty() {
        mLeft = mTop = mRight = mBottom = 0;
    }
    void join(const MinikinRect& r);
};

// Callback for freeing data
typedef void (*MinikinDestroyFunc) (void* data);

class MinikinFont {
public:
    explicit MinikinFont(int32_t uniqueId) : mUniqueId(uniqueId) {}

    virtual ~MinikinFont();

    virtual float GetHorizontalAdvance(uint32_t glyph_id,
        const MinikinPaint &paint) const = 0;

    virtual void GetBounds(MinikinRect* bounds, uint32_t glyph_id,
        const MinikinPaint &paint) const = 0;

    // Override if font can provide access to raw data
    virtual const void* GetFontData() const {
        return nullptr;
    }

    // Override if font can provide access to raw data
    virtual size_t GetFontSize() const {
        return 0;
    }

    // Override if font can provide access to raw data.
    // Returns index within OpenType collection
    virtual int GetFontIndex() const {
        return 0;
    }

    virtual const std::vector<minikin::FontVariation>& GetAxes() const = 0;

    virtual std::shared_ptr<MinikinFont> createFontWithVariation(
            const std::vector<FontVariation>&) const {
        return nullptr;
    }

    static uint32_t MakeTag(char c1, char c2, char c3, char c4) {
        return ((uint32_t)c1 << 24) | ((uint32_t)c2 << 16) |
            ((uint32_t)c3 << 8) | (uint32_t)c4;
    }

    int32_t GetUniqueId() const { return mUniqueId; }
private:
    const int32_t mUniqueId;
};

}  // namespace minikin

#endif  // MINIKIN_FONT_H