skia_safe/modules/paragraph/metrics.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168
use crate::{paragraph::TextStyle, prelude::*, FontMetrics};
use skia_bindings::{self as sb, skia_textlayout_LineMetrics, skia_textlayout_StyleMetrics};
use std::{marker::PhantomData, ops::Range, ptr};
#[repr(C)]
#[derive(Clone, Debug)]
pub struct StyleMetrics<'a> {
pub text_style: &'a TextStyle,
/// [`FontMetrics`] contains the following metrics:
///
/// * Top distance to reserve above baseline
/// * Ascent distance to reserve below baseline
/// * Descent extent below baseline
/// * Bottom extent below baseline
/// * Leading distance to add between lines
/// * AvgCharWidth average character width
/// * MaxCharWidth maximum character width
/// * XMin minimum x
/// * XMax maximum x
/// * XHeight height of lower-case 'x'
/// * CapHeight height of an upper-case letter
/// * UnderlineThickness underline thickness
/// * UnderlinePosition underline position relative to baseline
/// * StrikeoutThickness strikeout thickness
/// * StrikeoutPosition strikeout position relative to baseline
pub font_metrics: FontMetrics,
}
native_transmutable!(
skia_textlayout_StyleMetrics,
StyleMetrics<'_>,
style_metrics_layout
);
impl<'a> StyleMetrics<'a> {
pub fn new(style: &'a TextStyle, metrics: impl Into<Option<FontMetrics>>) -> Self {
Self {
text_style: style,
font_metrics: metrics.into().unwrap_or_default(),
}
}
}
#[derive(Clone, Debug)]
pub struct LineMetrics<'a> {
// The following fields are used in the layout process itself.
/// The index in the text buffer the line begins.
pub start_index: usize,
/// The index in the text buffer the line ends.
pub end_index: usize,
pub end_excluding_whitespaces: usize,
pub end_including_newline: usize,
pub hard_break: bool,
// The following fields are tracked after or during layout to provide to
// the user as well as for computing bounding boxes.
/// The final computed ascent and descent for the line. This can be impacted by
/// the strut, height, scaling, as well as outlying runs that are very tall.
///
/// The top edge is `baseline - ascent` and the bottom edge is `baseline +
/// descent`. Ascent and descent are provided as positive numbers. Raw numbers
/// for specific runs of text can be obtained in run_metrics_map. These values
/// are the cumulative metrics for the entire line.
pub ascent: f64,
pub descent: f64,
pub unscaled_ascent: f64,
/// Total height of the paragraph including the current line.
///
/// The height of the current line is `round(ascent + descent)`.
pub height: f64,
/// Width of the line.
pub width: f64,
/// The left edge of the line. The right edge can be obtained with `left +
/// width`
pub left: f64,
/// The y position of the baseline for this line from the top of the paragraph.
pub baseline: f64,
/// Zero indexed line number
pub line_number: usize,
/// Mapping between text index ranges and the FontMetrics associated with
/// them. The first run will be keyed under start_index. The metrics here
/// are before layout and are the base values we calculate from.
style_metrics: Vec<sb::IndexedStyleMetrics>,
pd: PhantomData<&'a StyleMetrics<'a>>,
}
impl<'a> LineMetrics<'a> {
// TODO: may support constructors (but what about the lifetime bounds?).
/// Returns the number of style metrics in the given index range.
pub fn get_style_metrics_count(&self, range: Range<usize>) -> usize {
let lower = self
.style_metrics
.partition_point(|ism| ism.index < range.start);
let upper = self
.style_metrics
.partition_point(|ism| ism.index < range.end);
upper - lower
}
/// Returns indices and references to style metrics in the given range.
pub fn get_style_metrics(&'a self, range: Range<usize>) -> Vec<(usize, &'a StyleMetrics<'a>)> {
let lower = self
.style_metrics
.partition_point(|ism| ism.index < range.start);
let upper = self
.style_metrics
.partition_point(|ism| ism.index < range.end);
self.style_metrics[lower..upper]
.iter()
.map(|ism| (ism.index, StyleMetrics::from_native_ref(&ism.metrics)))
.collect()
}
// We can't use a `std::map` in rust, it does not seem to be safe to move. So we copy it into a
// sorted Vec.
pub(crate) fn from_native_ref<'b>(lm: &skia_textlayout_LineMetrics) -> LineMetrics<'b> {
let sm_count = unsafe { sb::C_LineMetrics_styleMetricsCount(lm) };
let mut style_metrics = vec![
sb::IndexedStyleMetrics {
index: 0,
metrics: sb::skia_textlayout_StyleMetrics {
text_style: ptr::null(),
font_metrics: sb::SkFontMetrics {
fFlags: 0,
fTop: 0.0,
fAscent: 0.0,
fDescent: 0.0,
fBottom: 0.0,
fLeading: 0.0,
fAvgCharWidth: 0.0,
fMaxCharWidth: 0.0,
fXMin: 0.0,
fXMax: 0.0,
fXHeight: 0.0,
fCapHeight: 0.0,
fUnderlineThickness: 0.0,
fUnderlinePosition: 0.0,
fStrikeoutThickness: 0.0,
fStrikeoutPosition: 0.0
}
}
};
sm_count
];
unsafe { sb::C_LineMetrics_getAllStyleMetrics(lm, style_metrics.as_mut_ptr()) }
LineMetrics {
start_index: lm.fStartIndex,
end_index: lm.fEndIndex,
end_excluding_whitespaces: lm.fEndExcludingWhitespaces,
end_including_newline: lm.fEndIncludingNewline,
hard_break: lm.fHardBreak,
ascent: lm.fAscent,
descent: lm.fDescent,
unscaled_ascent: lm.fUnscaledAscent,
height: lm.fHeight,
width: lm.fWidth,
left: lm.fLeft,
baseline: lm.fBaseline,
line_number: lm.fLineNumber,
style_metrics,
pd: PhantomData,
}
}
}