Impact of letter spacing on Arabic text

ParagraphSlide.cpp

class ParagraphSlide0 : public ParagraphSlide_Base {
public:
    ParagraphSlide0() { fName = "Paragraph0"; }

    void draw(SkCanvas* canvas) override {
        canvas->drawColor(SK_ColorWHITE);
        auto multiplier = 5.67;
        const char* text = "English English\n\nمرحبا بالعالم";

        auto fontCollection = sk_make_sp<FontCollection>();
        fontCollection->setDefaultFontManager(ToolUtils::TestFontMgr());
        fontCollection->enableFontFallback();

        ParagraphStyle paragraph_style;
        paragraph_style.turnHintingOff();
        ParagraphBuilderImpl builder(paragraph_style, fontCollection, get_unicode());

        TextStyle text_style;
        text_style.setFontFamilies({SkString("Roboto"),
                                    SkString("Noto Color Emoji"),
                                    SkString("Noto Serif CJK JP")});
        text_style.setFontSize(10 * multiplier);
        text_style.setLetterSpacing(10);
        text_style.setWordSpacing(0);
        text_style.setColor(SK_ColorBLACK);
        text_style.setHeight(1);
        builder.pushStyle(text_style);
        builder.addText(text, strlen(text));
        builder.pop();

        auto paragraph = builder.Build();
        paragraph->layout(this->size().width());

        paragraph->paint(canvas, 0, 0);
    }
};