99 lines
3.6 KiB
C
99 lines
3.6 KiB
C
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// Copyright 2019 Google LLC.
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#ifndef Metrics_DEFINED
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#define Metrics_DEFINED
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#include <map>
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#include "modules/skparagraph/include/TextStyle.h"
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namespace skia {
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namespace textlayout {
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class StyleMetrics {
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public:
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StyleMetrics(const TextStyle* style) : text_style(style) {}
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StyleMetrics(const TextStyle* style, SkFontMetrics& metrics)
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: text_style(style), font_metrics(metrics) {}
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const TextStyle* text_style;
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// SkFontMetrics contains the following metrics:
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//
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// * Top distance to reserve above baseline
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// * Ascent distance to reserve below baseline
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// * Descent extent below baseline
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// * Bottom extent below baseline
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// * Leading distance to add between lines
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// * AvgCharWidth average character width
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// * MaxCharWidth maximum character width
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// * XMin minimum x
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// * XMax maximum x
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// * XHeight height of lower-case 'x'
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// * CapHeight height of an upper-case letter
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// * UnderlineThickness underline thickness
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// * UnderlinePosition underline position relative to baseline
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// * StrikeoutThickness strikeout thickness
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// * StrikeoutPosition strikeout position relative to baseline
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SkFontMetrics font_metrics;
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};
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class LineMetrics {
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public:
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LineMetrics() { }
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LineMetrics(size_t start,
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size_t end,
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size_t end_excluding_whitespace,
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size_t end_including_newline,
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bool hard_break)
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: fStartIndex(start)
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, fEndIndex(end)
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, fEndExcludingWhitespaces(end_excluding_whitespace)
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, fEndIncludingNewline(end_including_newline)
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, fHardBreak(hard_break) {}
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// The following fields are used in the layout process itself.
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// The indexes in the text buffer the line begins and ends.
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size_t fStartIndex = 0;
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size_t fEndIndex = 0;
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size_t fEndExcludingWhitespaces = 0;
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size_t fEndIncludingNewline = 0;
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bool fHardBreak = false;
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// The following fields are tracked after or during layout to provide to
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// the user as well as for computing bounding boxes.
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// The final computed ascent and descent for the line. This can be impacted by
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// the strut, height, scaling, as well as outlying runs that are very tall.
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//
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// The top edge is `baseline - ascent` and the bottom edge is `baseline +
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// descent`. Ascent and descent are provided as positive numbers. Raw numbers
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// for specific runs of text can be obtained in run_metrics_map. These values
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// are the cumulative metrics for the entire line.
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double fAscent = 0.0;
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double fDescent = 0.0;
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double fUnscaledAscent = 0.0;
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// Total height of the paragraph including the current line.
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//
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// The height of the current line is `round(ascent + descent)`.
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double fHeight = 0.0;
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// Width of the line.
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double fWidth = 0.0;
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// The left edge of the line. The right edge can be obtained with `left +
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// width`
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double fLeft = 0.0;
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// The y position of the baseline for this line from the top of the paragraph.
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double fBaseline = 0.0;
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// Zero indexed line number
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size_t fLineNumber = 0;
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// Mapping between text index ranges and the FontMetrics associated with
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// them. The first run will be keyed under start_index. The metrics here
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// are before layout and are the base values we calculate from.
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std::map<size_t, StyleMetrics> fLineMetrics;
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};
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} // namespace skia
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} // namespace skia
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#endif // Metrics_DEFINED
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