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Resolve #861.
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@ASmirnov-HORIS
ASmirnov-HORIS committed Oct 3, 2024
1 parent a834e8e commit da4cc96
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Showing 2 changed files with 53 additions and 25 deletions.
8 changes: 4 additions & 4 deletions demo/plot-common/src/commonMain/kotlin/demo/plot/common/model/plotConfig/LatexElements.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -12,17 +12,17 @@ class LatexElements {
return listOf(
getPlotSpec("""Power degree: \\(a^b\\)""", listOf(
"""\(x^1\)""",
"""-2·\(3^5\) + 7""",
"""\(-2^3\)-5""",
"""-2·\(3^{-13}\) + 7""",
"""a·\(b^{cde}\)""",
"""a\(^{b}\)""",
"""A\(^{-B}\)""",
)),
getPlotSpec("""Index: \\(a_b\\)""", listOf(
"""\(x_1\)""",
"""-2·\(3_5\) + 7""",
"""\(-2_3\)-5""",
"""-2·\(3_{-13}\) + 7""",
"""a·\(b_{cde}\)""",
"""a\(_{b}\)""",
"""A\(_{-B}\)""",
)),
)
}
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70 changes: 49 additions & 21 deletions plot-base/src/commonMain/kotlin/org/jetbrains/letsPlot/core/plot/base/render/svg/RichText.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ object RichText {
private fun parseText(text: String, wrapLength: Int = -1, maxLinesCount: Int = -1): List<List<Term>> {
val lines = text.split("\n")
.map { line ->
val specialTerms = PowerTerm.toPowerTerms(line) + LinkTerm.parse(line)
val specialTerms = PowerTerm.toPowerTerms(line) + SubscriptTerm.toSubscriptTerms(line) + LinkTerm.parse(line)
if (specialTerms.isEmpty()) {
listOf(TextTerm(line))
} else {
Expand Down Expand Up @@ -142,58 +142,86 @@ object RichText {
}

private class PowerTerm(
base: String,
degree: String,
) : IndexTerm(base, degree, true) {
companion object {
fun toPowerTerms(text: String): List<Pair<Term, IntRange>> {
return toTerms(text, "\\^") { base, degree -> PowerTerm(base, degree) }
}
}
}

private class SubscriptTerm(
base: String,
index: String,
) : IndexTerm(base, index, false) {
companion object {
fun toSubscriptTerms(text: String): List<Pair<Term, IntRange>> {
return toTerms(text, "_") { base, index -> SubscriptTerm(base, index) }
}
}
}

private open class IndexTerm(
private val base: String,
private val degree: String,
private val index: String,
isSuperior: Boolean,
) : Term {
override val visualCharCount: Int = base.length + degree.length
override val visualCharCount: Int = base.length + index.length
override val svg: List<SvgTSpanElement>

init {
val shift = if (isSuperior) { "-" } else { "" }
val backShift = if (isSuperior) { "" } else { "-" }
val baseTSpan = SvgTSpanElement(base)
val indentTSpan = SvgTSpanElement(INDENT_SYMBOL).apply {
setAttribute(SvgTSpanElement.FONT_SIZE, "${INDENT_SIZE_FACTOR}em")
}
val degreeTSpan = SvgTSpanElement(degree).apply {
setAttribute(SvgTSpanElement.FONT_SIZE, "${SUPERSCRIPT_SIZE_FACTOR}em")
setAttribute(SvgTSpanElement.DY, "-${SUPERSCRIPT_RELATIVE_SHIFT}em")
val indexTSpan = SvgTSpanElement(index).apply {
setAttribute(SvgTSpanElement.FONT_SIZE, "${INDEX_SIZE_FACTOR}em")
setAttribute(SvgTSpanElement.DY, "$shift${INDEX_RELATIVE_SHIFT}em")
}
// The following tspan element is used to restore the baseline after the degree
// Restoring works only if there is some symbol after the degree, so we use ZERO_WIDTH_SPACE_SYMBOL
// The following tspan element is used to restore the baseline after the index
// Restoring works only if there is some symbol after the index, so we use ZERO_WIDTH_SPACE_SYMBOL
// It could be considered as standard trick, see https://stackoverflow.com/a/65681504
// Attribute 'baseline-shift' is better suited for such usecase -
// it doesn't require to add an empty tspan at the end to restore the baseline (as 'dy').
// Sadly we can't use 'baseline-shift' as it is not supported by CairoSVG.
val restoreBaselineTSpan = SvgTSpanElement(ZERO_WIDTH_SPACE_SYMBOL).apply {
// Size of shift depends on the font size, and it should be equal to the superscript shift size
setAttribute(SvgTSpanElement.FONT_SIZE, "${SUPERSCRIPT_SIZE_FACTOR}em")
setAttribute(SvgTSpanElement.DY, "${SUPERSCRIPT_RELATIVE_SHIFT}em")
setAttribute(SvgTSpanElement.FONT_SIZE, "${INDEX_SIZE_FACTOR}em")
setAttribute(SvgTSpanElement.DY, "$backShift${INDEX_RELATIVE_SHIFT}em")
}

svg = listOf(baseTSpan, indentTSpan, degreeTSpan, restoreBaselineTSpan)
svg = listOf(baseTSpan, indentTSpan, indexTSpan, restoreBaselineTSpan)
}

override fun estimateWidth(font: Font, widthCalculator: (String, Font) -> Double): Double {
val baseWidth = widthCalculator(base, font)
val degreeFontSize = (font.size * SUPERSCRIPT_SIZE_FACTOR).roundToInt()
val superscriptFont = Font(font.family, degreeFontSize, font.isBold, font.isItalic)
val degreeWidth = widthCalculator(degree, superscriptFont)
return baseWidth + degreeWidth
val indexFontSize = (font.size * INDEX_SIZE_FACTOR).roundToInt()
val indexFont = Font(font.family, indexFontSize, font.isBold, font.isItalic)
val indexWidth = widthCalculator(index, indexFont)
return baseWidth + indexWidth
}

companion object {
private const val ZERO_WIDTH_SPACE_SYMBOL = "\u200B"
private const val INDENT_SYMBOL = " "
private const val INDENT_SIZE_FACTOR = 0.1
private const val SUPERSCRIPT_SIZE_FACTOR = 0.7
private const val SUPERSCRIPT_RELATIVE_SHIFT = 0.4
val REGEX = """\\\(\s*(?<base>\d+)\^(\{\s*)?(?<degree>-?\d+)(\s*\})?\s*\\\)""".toRegex()
private const val INDEX_SIZE_FACTOR = 0.7
private const val INDEX_RELATIVE_SHIFT = 0.4

fun toPowerTerms(text: String): List<Pair<Term, IntRange>> {
return REGEX.findAll(text).map { match ->
fun toTerms(text: String, symbol: String, toTerm: (String, String) -> IndexTerm): List<Pair<Term, IntRange>> {
return getRegex(symbol).findAll(text).map { match ->
val groups = match.groups as MatchNamedGroupCollection
PowerTerm(groups["base"]!!.value, groups["degree"]!!.value) to match.range
toTerm(groups["base"]!!.value, groups["index"]!!.value) to match.range
}.toList()
}

private fun getRegex(symbol: String): Regex {
return """\\\(\s*(?<base>(?:-?[a-zA-Z0-9]+)*)$symbol(\{\s*)?(?<index>-?[a-zA-Z0-9]+)(\s*\})?\s*\\\)""".toRegex()
}
}
}

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