Method findCharacterPos

src/SFML/Graphics/Text.cpp:624–672

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Vector2f Text::findCharacterPos(std::size_t index) const
{
    ensureGeometryUpdate();

    // Adjust the index if it's out of range
    index = std::min(index, m_glyphs.size());

    // Precompute the variables needed by the algorithm
    const bool  isBold          = m_style & Bold;
    const float whitespaceWidth = m_font->getGlyph(U' ', m_characterSize, isBold).advance;
    const float letterSpacing   = (whitespaceWidth / 3.0f) * (m_letterSpacingFactor - 1.0f);
    const float lineSpacing     = m_font->getLineSpacing(m_characterSize) * m_lineSpacingFactor;

    // Special handling for newlines:
    // The old shaping implementation placed newline characters
    // at the start of the new line that they create
    // The new implementation places them at the end of the previous line
    // Placing them at the end of the previous line is normally what is expected
    // since the cursor is rendered before the glyph whose location marks the
    // location at which new characters will be inserted into the text
    // We provide a workaround for the old behavior until findCharacterPos can be removed

    if (m_glyphs.empty())
    {
        // Get the position of the Text itself in global coordinates
        return getTransform().transformPoint({});
    }

    if (index == m_glyphs.size())
    {
        // Return the position of the last glyph + its advance in global coordinates
        const auto& lastGlyph = m_glyphs.back();

        // Newline, past-the-end
        if (m_string[m_string.getSize() - 1] == '\n')
            return getTransform().transformPoint(
                Vector2f{0.0f, lastGlyph.position.y + lineSpacing - static_cast<float>(m_characterSize)});

        return getTransform().transformPoint(
            lastGlyph.position + Vector2f{lastGlyph.glyph.advance + letterSpacing, -static_cast<float>(m_characterSize)});
    }

    // Newline, not past-the-end
    if (m_string[index] == '\n')
        return getTransform().transformPoint(
            Vector2f{0.0f, m_glyphs[index].position.y + lineSpacing - static_cast<float>(m_characterSize)});

    return getTransform().transformPoint(m_glyphs[index].position - Vector2f{0.0f, static_cast<float>(m_characterSize)});
}


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