experimental/sktext/src/Paint.h

// Copyright 2021 Google LLC.
#ifndef Painter_DEFINED
#define Painter_DEFINED
#include "experimental/sktext/include/Text.h"
#include "experimental/sktext/include/Types.h"
#include "include/core/SkCanvas.h"
namespace skia {
namespace text {

struct DecoratedBlock {
    DecoratedBlock(uint32_t count, SkPaint fg, SkPaint bg)
        : charCount(count)
        , foregroundColor(fg)
        , backgroundColor(bg) { }
    uint32_t    charCount;
    SkPaint     foregroundColor;
    SkPaint     backgroundColor;
};

class TrivialFontChain : public FontChain {
public:
    TrivialFontChain(const char* ff, SkScalar size)
        : fTypeface(sk_sp<SkTypeface>(SkFontMgr::RefDefault()->matchFamilyStyle(ff, SkFontStyle::Normal()))),
          fSize(size) { }
    size_t count() const override { return (size_t)1; }
    sk_sp<SkTypeface> operator[](size_t index) const  override {
        SkASSERT(index == 0);
        return fTypeface;
    }
    float size() const override { return fSize; }

private:
    sk_sp<SkTypeface> fTypeface;
    SkScalar fSize;
};

class Paint : public FormattedText::Visitor {
public:
    static sk_sp<FormattedText> layout(std::u16string text,
                                TextDirection textDirection, TextAlign textAlign,
                                SkSize reqSize,
                                SkSpan<Block> fontBlocks);
    void paint(SkCanvas* canvas, SkPoint xy, sk_sp<FormattedText> formattedText, SkSpan<DecoratedBlock> decoratedBlocks);
    // Simplification (using default font manager, default font family and default everything possible)
    static bool drawText(std::u16string text, SkCanvas* canvas, SkScalar x, SkScalar y);
    static bool drawText(std::u16string text, SkCanvas* canvas, SkScalar width);
    static bool drawText(std::u16string text, SkCanvas* canvas,
                         TextDirection textDirection, TextAlign textAlign,
                         SkColor foreground, SkColor background,
                         const SkString& fontFamily, SkScalar fontSize, SkFontStyle fontStyle,
                         SkScalar x, SkScalar y);
    static bool drawText(std::u16string text, SkCanvas* canvas,
                         TextDirection textDirection, TextAlign textAlign,
                         SkColor foreground, SkColor background,
                         const SkString& fontFamily, SkScalar fontSize, SkFontStyle fontStyle,
                         SkSize reqSize, SkScalar x, SkScalar y);
private:
    friend class Processor;
    void onBeginLine(TextRange, float baselineY) override;
    void onEndLine(TextRange, float baselineY) override;
    void onGlyphRun(SkFont font,
                    TextRange textRange,
                    int glyphCount,
                    const uint16_t glyphs[],
                    const SkPoint  positions[],
                    const SkPoint offsets[]) override;
    void onPlaceholder(TextRange, const SkRect& bounds) override;

    // We guarantee that the text range will be inside one of the decorated blocks
    DecoratedBlock findDecoratedBlock(TextRange textRange);

    SkCanvas* fCanvas;
    SkPoint fXY;
    SkTArray<Block> fFontBlocks;
    SkTArray<DecoratedBlock> fDecoratedBlocks;
};
} // namespace text
} // namespace skia
#endif // Painter_DEFINED