mirror/JUCE
1
0
Fork 0
mirror of https://github.com/juce-framework/JUCE.git synced 2026-01-09 23:34:20 +00:00
Code Activity

TextLayout: Implement better line balancing algorithm

Browse source 
The previous implementation was unstable when 'by character' line
breaking was used on long lines of text.

Co-authored-by: Tom Poole <tom@juce.com>
This commit is contained in:
Oli 2025-08-07 15:17:01 +01:00 • committed by Attila Szarvas
parent 7a30354ce9
commit 8dc4dcd56b
1 changed files with 49 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

65
modules/juce_graphics/fonts/juce_TextLayout.cpp
View file

@ -283,39 +283,72 @@ void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& te
createLayoutWithBalancedLineLengths (text, maxWidth, 1.0e7f);
}
void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text, float maxWidth, float maxHeight)
void TextLayout::createLayoutWithBalancedLineLengths (const AttributedString& text,
float maxWidth,
float maxHeight)
{
auto minimumWidth = maxWidth / 2.0f;
auto bestWidth = maxWidth;
float bestLineProportion = 0.0f;
auto bestScore = std::numeric_limits<float>::max();
auto widthProbeText = text;
if (widthProbeText.getWordWrap() == AttributedString::byChar)
widthProbeText.setWordWrap (AttributedString::byWord);
std::optional<float> advanceWidth;
while (maxWidth > minimumWidth)
{
createLayout (text, maxWidth, maxHeight);
createLayout (widthProbeText, maxWidth, maxHeight);
if (getNumLines() < 2)
const auto numLines = getNumLines();
if (numLines < 2)
return;
auto line1 = lines.getUnchecked (lines.size() - 1)->getLineBoundsX().getLength();
auto line2 = lines.getUnchecked (lines.size() - 2)->getLineBoundsX().getLength();
auto shortest = jmin (line1, line2);
auto longest = jmax (line1, line2);
auto prop = shortest > 0 ? longest / shortest : 1.0f;
std::vector<float> lineLengths;
lineLengths.reserve ((size_t) numLines);
std::transform (lines.begin(),
lines.end(),
std::back_inserter (lineLengths),
[] (const auto& line) { return line->getLineBoundsX().getLength(); });
if (prop > 0.9f && prop < 1.1f)
return;
const auto longestLineLength = *std::max_element (lineLengths.begin(), lineLengths.end());
if (prop > bestLineProportion)
auto accumulateScore = [longestLineLength] (auto scoreSum, auto lineLength)
{
bestLineProportion = prop;
const auto unusedSpace = 1.0f - (lineLength / longestLineLength);
return scoreSum + (unusedSpace * unusedSpace);
};
const auto score = std::accumulate (lineLengths.begin(),
lineLengths.end(),
0.0f, accumulateScore) / (float) numLines;
if (score < bestScore)
{
bestScore = score;
bestWidth = maxWidth;
if (score < 0.4f)
break;
}
maxWidth -= 10.0f;
if (! advanceWidth.has_value())
{
advanceWidth = std::numeric_limits<float>::max();
for (const auto& line : lines)
for (const auto& run : line->runs)
for (const auto& glyph : run->glyphs)
advanceWidth = jmin (*advanceWidth, glyph.width);
}
maxWidth -= *advanceWidth;
}
if (! approximatelyEqual (bestWidth, maxWidth))
createLayout (text, bestWidth, maxHeight);
createLayout (text, bestWidth, maxHeight);
}
//==============================================================================