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Simplify MarkdownLineHeightSpan logic #522

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tomekzaw opened this issue Oct 18, 2024 · 1 comment · May be fixed by #535
Open

Simplify MarkdownLineHeightSpan logic #522

tomekzaw opened this issue Oct 18, 2024 · 1 comment · May be fixed by #535
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enhancement New feature or request

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@tomekzaw
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The current implementation of MarkdownLineHeightSpan is a bit tricky:

react-native-live-markdown/android/src/main/java/com/expensify/livemarkdown/spans/MarkdownLineHeightSpan.java

Lines 6 to 18 in b753c7a

public class MarkdownLineHeightSpan implements MarkdownSpan, LineHeightSpan {
private final float mLineHeight;
public MarkdownLineHeightSpan(float lineHeight) {
mLineHeight = lineHeight;
}
@Override
public void chooseHeight(CharSequence text, int start, int end, int spanstartv, int lineHeight, Paint.FontMetricsInt fm) {
fm.top -= mLineHeight / 4;
fm.ascent -= mLineHeight / 4;
}
}

Also, we need to obtain information about existing spans before applying MarkdownLineHeightSpan:

react-native-live-markdown/android/src/main/java/com/expensify/livemarkdown/MarkdownUtils.java

Lines 149 to 157 in b753c7a

case "h1":
setSpan(ssb, new MarkdownBoldSpan(), start, end);
CustomLineHeightSpan[] spans = ssb.getSpans(0, ssb.length(), CustomLineHeightSpan.class);
if (spans.length >= 1) {
int lineHeight = spans[0].getLineHeight();
setSpan(ssb, new MarkdownLineHeightSpan(lineHeight * 1.5f), start, end);
}
// NOTE: size span must be set after line height span to avoid height jumps
setSpan(ssb, new MarkdownFontSizeSpan(mMarkdownStyle.getH1FontSize()), start, end);

The objective of this task is to eliminate division by 4 as well as calling .getSpans() method if needed.
@tomekzaw tomekzaw added the enhancement New feature or request label Oct 18, 2024
@tomekzaw tomekzaw changed the title Eliminate weird logic related to MarkdownLineHeightSpan Simplfy MarkdownLineHeightSpan logic Oct 18, 2024
@tomekzaw tomekzaw changed the title Simplfy MarkdownLineHeightSpan logic Simplify MarkdownLineHeightSpan logic Oct 18, 2024
@tomekzaw
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tomekzaw commented Nov 4, 2024

Proposal: Add h1.lineHeight to markdownStyle.

If style.lineHeight is undefined and markdownStyle.h1.lineHeight is undefined, we don't set CustomLineHeightSpan for headings (the line height is calculated automatically by Android).

If style.lineHeight is defined and markdownStyle.h1.lineHeight is undefined, we don't set CustomLineHeightSpan for headings (React Native applies CustomLineHeightSpan for whole text).

If markdownStyle.h1.lineHeight is defined, we set CustomLineHeightSpan for headings.

@tomekzaw tomekzaw linked a pull request Nov 5, 2024 that will close this issue
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Customize line height for headings Expensify/react-native-live-markdown
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@tomekzaw