1 // Copyright 2019 Google LLC. 2 #ifndef Metrics_DEFINED 3 #define Metrics_DEFINED 4 5 #include <map> 6 #include "modules/skparagraph/include/TextStyle.h" 7 8 namespace skia { 9 namespace textlayout { 10 class StyleMetrics { 11 public: StyleMetrics(const TextStyle * style)12 StyleMetrics(const TextStyle* style) : text_style(style) {} 13 StyleMetrics(const TextStyle * style,SkFontMetrics & metrics)14 StyleMetrics(const TextStyle* style, SkFontMetrics& metrics) 15 : text_style(style), font_metrics(metrics) {} 16 17 const TextStyle* text_style; 18 19 // SkFontMetrics contains the following metrics: 20 // 21 // * Top distance to reserve above baseline 22 // * Ascent distance to reserve below baseline 23 // * Descent extent below baseline 24 // * Bottom extent below baseline 25 // * Leading distance to add between lines 26 // * AvgCharWidth average character width 27 // * MaxCharWidth maximum character width 28 // * XMin minimum x 29 // * XMax maximum x 30 // * XHeight height of lower-case 'x' 31 // * CapHeight height of an upper-case letter 32 // * UnderlineThickness underline thickness 33 // * UnderlinePosition underline position relative to baseline 34 // * StrikeoutThickness strikeout thickness 35 // * StrikeoutPosition strikeout position relative to baseline 36 SkFontMetrics font_metrics; 37 }; 38 39 class LineMetrics { 40 public: LineMetrics()41 LineMetrics() { } 42 LineMetrics(size_t start,size_t end,size_t end_excluding_whitespace,size_t end_including_newline,bool hard_break)43 LineMetrics(size_t start, 44 size_t end, 45 size_t end_excluding_whitespace, 46 size_t end_including_newline, 47 bool hard_break) 48 : fStartIndex(start) 49 , fEndIndex(end) 50 , fEndExcludingWhitespaces(end_excluding_whitespace) 51 , fEndIncludingNewline(end_including_newline) 52 , fHardBreak(hard_break) {} 53 // The following fields are used in the layout process itself. 54 55 // The indexes in the text buffer the line begins and ends. 56 size_t fStartIndex = 0; 57 size_t fEndIndex = 0; 58 size_t fEndExcludingWhitespaces = 0; 59 size_t fEndIncludingNewline = 0; 60 bool fHardBreak = false; 61 62 // The following fields are tracked after or during layout to provide to 63 // the user as well as for computing bounding boxes. 64 65 // The final computed ascent and descent for the line. This can be impacted by 66 // the strut, height, scaling, as well as outlying runs that are very tall. 67 // 68 // The top edge is `baseline - ascent` and the bottom edge is `baseline + 69 // descent`. Ascent and descent are provided as positive numbers. Raw numbers 70 // for specific runs of text can be obtained in run_metrics_map. These values 71 // are the cumulative metrics for the entire line. 72 double fAscent = 0.0; 73 double fDescent = 0.0; 74 double fUnscaledAscent = 0.0; 75 // Total height of the paragraph including the current line. 76 // 77 // The height of the current line is `round(ascent + descent)`. 78 double fHeight = 0.0; 79 // Width of the line. 80 double fWidth = 0.0; 81 // The left edge of the line. The right edge can be obtained with `left + 82 // width` 83 double fLeft = 0.0; 84 // The y position of the baseline for this line from the top of the paragraph. 85 double fBaseline = 0.0; 86 // Zero indexed line number 87 size_t fLineNumber = 0; 88 89 // Mapping between text index ranges and the FontMetrics associated with 90 // them. The first run will be keyed under start_index. The metrics here 91 // are before layout and are the base values we calculate from. 92 std::map<size_t, StyleMetrics> fLineMetrics; 93 }; 94 95 } // namespace textlayout 96 } // namespace skia 97 98 #endif // Metrics_DEFINED 99