Zach Nelson
32a5c1c358
## Summary
**What is the goal of this PR?**
### Problem
Inter-word gap widths were computed as two separately-snapped integers:
```cpp
gap = getSpaceWidth(fontId, style); // fp4::toPixel(spaceAdvance)
gap += getSpaceKernAdjust(fontId, leftCp, rightCp, style); // fp4::toPixel(kern1 + kern2)
```
Because `fp4::toPixel(a) + fp4::toPixel(b)` can differ from
`fp4::toPixel(a + b)` by +/-1 pixel when the fractional parts straddle a
rounding boundary, each inter-word space could be one pixel wider or
narrower than the correct value. This affected line-break width
decisions and word-position accumulation across the whole paragraph
layout pipeline.
### Fix
Replaces `getSpaceKernAdjust()` with `getSpaceAdvance(fontId, leftCp,
rightCp, style)`, which combines the space glyph advance and both
flanking kern values (`kern(leftCp, ' ')` + `kern(' ', rightCp)`) into a
single fixed-point sum before the snap:
```cpp
return fp4::toPixel(spaceAdvanceFP + kern(leftCp, ' ') + kern(' ', rightCp));
```
This is the same single-snap pattern already used by `getTextAdvanceX`
for word widths.
### Changes
- **`GfxRenderer`**: Replaces `getSpaceKernAdjust()` with
`getSpaceAdvance()`. `getSpaceWidth()` is retained for the
single-space-word case in `measureWordWidth` where no adjacent-word kern
context is available.
- **`ParsedText`**: All four call sites (`computeLineBreaks`,
`computeHyphenatedLineBreaks`, and both loops in `extractLine`) updated
to use `getSpaceAdvance()`. The now-redundant `spaceWidth`
pre-computation and parameter are removed from all three internal layout
functions.
---
### AI Usage
While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.
Did you use AI tools to help write this code? _**YES to analyze for
correctness**_
50 lines
2.4 KiB
C++
50 lines
2.4 KiB
C++
#pragma once
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#include <EpdFontFamily.h>
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#include <functional>
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#include <memory>
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#include <string>
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#include <vector>
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#include "blocks/BlockStyle.h"
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#include "blocks/TextBlock.h"
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class GfxRenderer;
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class ParsedText {
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std::vector<std::string> words;
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std::vector<EpdFontFamily::Style> wordStyles;
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std::vector<bool> wordContinues; // true = word attaches to previous (no space before it)
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BlockStyle blockStyle;
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bool extraParagraphSpacing;
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bool hyphenationEnabled;
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void applyParagraphIndent();
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std::vector<size_t> computeLineBreaks(const GfxRenderer& renderer, int fontId, int pageWidth,
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std::vector<uint16_t>& wordWidths, std::vector<bool>& continuesVec);
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std::vector<size_t> computeHyphenatedLineBreaks(const GfxRenderer& renderer, int fontId, int pageWidth,
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std::vector<uint16_t>& wordWidths, std::vector<bool>& continuesVec);
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bool hyphenateWordAtIndex(size_t wordIndex, int availableWidth, const GfxRenderer& renderer, int fontId,
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std::vector<uint16_t>& wordWidths, bool allowFallbackBreaks);
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void extractLine(size_t breakIndex, int pageWidth, const std::vector<uint16_t>& wordWidths,
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const std::vector<bool>& continuesVec, const std::vector<size_t>& lineBreakIndices,
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const std::function<void(std::shared_ptr<TextBlock>)>& processLine, const GfxRenderer& renderer,
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int fontId);
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std::vector<uint16_t> calculateWordWidths(const GfxRenderer& renderer, int fontId);
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public:
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explicit ParsedText(const bool extraParagraphSpacing, const bool hyphenationEnabled = false,
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const BlockStyle& blockStyle = BlockStyle())
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: blockStyle(blockStyle), extraParagraphSpacing(extraParagraphSpacing), hyphenationEnabled(hyphenationEnabled) {}
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~ParsedText() = default;
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void addWord(std::string word, EpdFontFamily::Style fontStyle, bool underline = false, bool attachToPrevious = false);
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void setBlockStyle(const BlockStyle& blockStyle) { this->blockStyle = blockStyle; }
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BlockStyle& getBlockStyle() { return blockStyle; }
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size_t size() const { return words.size(); }
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bool isEmpty() const { return words.empty(); }
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void layoutAndExtractLines(const GfxRenderer& renderer, int fontId, uint16_t viewportWidth,
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const std::function<void(std::shared_ptr<TextBlock>)>& processLine,
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bool includeLastLine = true);
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}; |