AttributedString::ReadingDirection is ignored

General JUCE discussion
1

juce::AttributedString::ReadingDirection is ignored - the reading direction seems to be determined purely by the first character in the string.

/* BEGIN_JUCE_PIP_METADATA

  dependencies:     juce_core, juce_data_structures, juce_events, juce_graphics,
                    juce_gui_basics
  exporters:        xcode_mac, vs2022, linux_make

  type:             Component
  mainClass:        MainComponent

 END_JUCE_PIP_METADATA */

#pragma once

class MainComponent final : public juce::Component {
public:
  MainComponent() { setSize(400, 200); }

  void paint(juce::Graphics &g) override {
    g.fillAll(juce::Colours::white);

    const juce::String arabic =
        juce::CharPointer_UTF8{"\xd9\x85\xd8\xb1\xd8\xad\xd8\xa8\xd8\xa7."};

    auto bounds = getLocalBounds().reduced(10).toFloat();

    using ReadingDirection = juce::AttributedString::ReadingDirection;
    drawRow(g, bounds.removeFromTop(50.0f), "natural", arabic,
            ReadingDirection::natural);
    drawRow(g, bounds.removeFromTop(50.0f), "left-to-right", arabic,
            ReadingDirection::leftToRight);
    drawRow(g, bounds.removeFromTop(50.0f), "right-to-left", arabic,
            ReadingDirection::rightToLeft);
  }

private:
  static void drawRow(juce::Graphics &g, juce::Rectangle<float> bounds,
                      const juce::String &label, const juce::String &text,
                      juce::AttributedString::ReadingDirection direction) {
    g.setColour(juce::Colours::black);
    g.setFont(16.0f);
    g.drawText(label, bounds.removeFromLeft(170.0f),
               juce::Justification::centredLeft);

    juce::AttributedString string;
    string.append(text, juce::FontOptions{32.0f}, juce::Colours::black);
    string.setJustification(juce::Justification::centred);
    string.setReadingDirection(direction);

    juce::TextLayout layout;
    layout.createLayout(string, bounds.getWidth());
    layout.draw(g, bounds);
  }
};

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image1024×724 38.2 KB

This commit appears to be the cause - the comments in the SheenBidi source explain that the SBLevelDefaultLTR and SBLevelDefaultRTL constants are only used if there’s no “strong” character.

2

Maybe the enum could have some extra options to allow for the fallback vs forced approaches?

enum ReadingDirection
{
    natural,

    leftToRight, // Falls back to LTR if there's no "strong" character at the start
    rightToLeft, // Falls back to RTL if there's no "strong" character at the start

    leftToRightForced, // Always LTR, reguardless of the string's content
    rightToLeftForced, // Always RTL, reguardless of the string's content
};