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//! Draw and interact with text.
use crate::alignment;
use crate::{Color, Point, Rectangle, Size, Vector};
/// A paragraph.
#[derive(Debug, Clone, Copy)]
pub struct Text<'a, Font> {
/// The content of the paragraph.
pub content: &'a str,
/// The bounds of the paragraph.
pub bounds: Rectangle,
/// The size of the [`Text`].
pub size: f32,
/// The color of the [`Text`].
pub color: Color,
/// The font of the [`Text`].
pub font: Font,
/// The horizontal alignment of the [`Text`].
pub horizontal_alignment: alignment::Horizontal,
/// The vertical alignment of the [`Text`].
pub vertical_alignment: alignment::Vertical,
}
/// The result of hit testing on text.
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Hit {
/// The point was within the bounds of the returned character index.
CharOffset(usize),
/// The provided point was not within the bounds of a glyph. The index
/// of the character with the closest centeroid position is returned,
/// as well as its delta.
NearestCharOffset(usize, Vector),
}
impl Hit {
/// Computes the cursor position corresponding to this [`HitTestResult`] .
pub fn cursor(self) -> usize {
match self {
Self::CharOffset(i) => i,
Self::NearestCharOffset(i, delta) => {
if delta.x > f32::EPSILON {
i + 1
} else {
i
}
}
}
}
}
/// A renderer capable of measuring and drawing [`Text`].
pub trait Renderer: crate::Renderer {
/// The font type used.
type Font: Default + Clone;
/// The icon font of the backend.
const ICON_FONT: Self::Font;
/// The `char` representing a ✔ icon in the [`ICON_FONT`].
///
/// [`ICON_FONT`]: Self::ICON_FONT
const CHECKMARK_ICON: char;
/// The `char` representing a ▼ icon in the built-in [`ICON_FONT`].
///
/// [`ICON_FONT`]: Self::ICON_FONT
const ARROW_DOWN_ICON: char;
/// Returns the default size of [`Text`].
fn default_size(&self) -> u16;
/// Measures the text in the given bounds and returns the minimum boundaries
/// that can fit the contents.
fn measure(
&self,
content: &str,
size: u16,
font: Self::Font,
bounds: Size,
) -> (f32, f32);
/// Measures the width of the text as if it were laid out in a single line.
fn measure_width(&self, content: &str, size: u16, font: Self::Font) -> f32 {
let (width, _) = self.measure(content, size, font, Size::INFINITY);
width
}
/// Tests whether the provided point is within the boundaries of text
/// laid out with the given parameters, returning information about
/// the nearest character.
///
/// If `nearest_only` is true, the hit test does not consider whether the
/// the point is interior to any glyph bounds, returning only the character
/// with the nearest centeroid.
fn hit_test(
&self,
contents: &str,
size: f32,
font: Self::Font,
bounds: Size,
point: Point,
nearest_only: bool,
) -> Option<Hit>;
/// Draws the given [`Text`].
fn fill_text(&mut self, text: Text<'_, Self::Font>);
}
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