50 lines
2.7 KiB
Markdown
50 lines
2.7 KiB
Markdown
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# Table Rendering Tweaks: Centering, Line Breaks, Padding
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## Task Description
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Three visual tweaks to the EPUB table rendering based on comparison with a Wikipedia article (Anders Celsius):
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1. Full-width spanning rows (like "Anders Celsius", "Scientific career", "Signature") should be center-aligned
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2. `<br>` tags and block elements within table cells should create actual line breaks (e.g., "(aged 42)" then "Uppsala, Sweden" on the next line)
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3. Cell padding was too tight — text too close to grid borders
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## Changes Made
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### 1. Forced Line Breaks in Table Cells
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**`lib/Epub/Epub/ParsedText.h`**:
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- Added `std::vector<bool> forceBreakAfter` member to track mandatory line break positions
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- Added `void addLineBreak()` public method
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**`lib/Epub/Epub/ParsedText.cpp`**:
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- `addWord()`: grows `forceBreakAfter` vector alongside other word vectors
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- `addLineBreak()`: sets `forceBreakAfter.back() = true` on the last word
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- `computeLineBreaks()` (DP algorithm): respects forced breaks — cannot extend a line past a forced break point, and forced breaks override continuation groups
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- `computeHyphenatedLineBreaks()` (greedy): same — stops line at forced break, won't backtrack past one
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- `hyphenateWordAtIndex()`: when splitting a word, transfers the forced break flag to the remainder (last part)
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**`lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp`** — `startNewTextBlock()`:
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- When `inTable`, instead of being a no-op, now: flushes the word buffer, calls `addLineBreak()` on the current ParsedText, and resets `nextWordContinues`
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- This means `<br>`, `<p>`, `<div>` etc. within table cells now produce real visual line breaks
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### 2. Center-Aligned Full-Width Spanning Cells
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**`lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp`** — `processTable()`:
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- Before laying out a cell's content, checks if `cell.colspan >= numCols` (spans full table width)
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- If so, sets the cell's BlockStyle alignment to `CssTextAlign::Center`
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- This correctly centers section headers and title rows in Wikipedia infobox-style tables
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### 3. Increased Cell Padding
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**`lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp`**:
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- `TABLE_CELL_PAD_X`: 2 → 4 pixels (horizontal padding)
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- Added `TABLE_CELL_PAD_Y = 2` pixels (vertical padding)
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- Row height now includes `2 * TABLE_CELL_PAD_Y` for top/bottom padding
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**`lib/Epub/Epub/Page.cpp`**:
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- `TABLE_CELL_PADDING_X`: 2 → 4 pixels (matches parser constant)
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- Added `TABLE_CELL_PADDING_Y = 2` pixels
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- Cell text Y position now accounts for vertical padding: `baseY + 1 + TABLE_CELL_PADDING_Y`
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## Follow-up Items
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- The padding constants are duplicated between `ChapterHtmlSlimParser.cpp` and `Page.cpp` — could be unified into a shared header
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- Vertical centering within cells (when a cell has fewer lines than the tallest cell) is not implemented
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