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//! Shared types for CSS shadow properties (used by both `box-shadow` and `text-shadow`).
use alloc::string::{String, ToString};
use core::fmt;
use crate::corety::AzString;
use crate::props::{
basic::{
color::{parse_css_color, ColorU, CssColorParseError, CssColorParseErrorOwned},
pixel::{
parse_pixel_value_no_percent, CssPixelValueParseError, CssPixelValueParseErrorOwned,
PixelValueNoPercent,
},
formatter::PrintAsCssValue,
};
/// What direction should a `box-shadow` be clipped in (inset or outset).
#[derive(Debug, Default, Copy, Clone, PartialEq, Ord, PartialOrd, Eq, Hash)]
#[repr(C)]
pub enum BoxShadowClipMode {
#[default]
Outset,
Inset,
}
impl fmt::Display for BoxShadowClipMode {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
BoxShadowClipMode::Outset => Ok(()), // Outset is the default, not written
BoxShadowClipMode::Inset => write!(f, "inset"),
/// Represents a single CSS shadow value, shared by both `box-shadow` and `text-shadow`.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct StyleBoxShadow {
pub offset_x: PixelValueNoPercent,
pub offset_y: PixelValueNoPercent,
pub blur_radius: PixelValueNoPercent,
pub spread_radius: PixelValueNoPercent,
pub clip_mode: BoxShadowClipMode,
pub color: ColorU,
impl Default for StyleBoxShadow {
fn default() -> Self {
Self {
offset_x: PixelValueNoPercent::default(),
offset_y: PixelValueNoPercent::default(),
blur_radius: PixelValueNoPercent::default(),
spread_radius: PixelValueNoPercent::default(),
clip_mode: BoxShadowClipMode::default(),
color: ColorU::BLACK,
impl StyleBoxShadow {
/// Scales the pixel values of the shadow for a given DPI factor.
pub fn scale_for_dpi(&mut self, scale_factor: f32) {
self.offset_x.scale_for_dpi(scale_factor);
self.offset_y.scale_for_dpi(scale_factor);
self.blur_radius.scale_for_dpi(scale_factor);
self.spread_radius.scale_for_dpi(scale_factor);
impl PrintAsCssValue for StyleBoxShadow {
fn print_as_css_value(&self) -> String {
let mut components = Vec::new();
if self.clip_mode == BoxShadowClipMode::Inset {
components.push("inset".to_string());
components.push(self.offset_x.to_string());
components.push(self.offset_y.to_string());
// Only print blur, spread, and color if they are not default, for brevity
if self.blur_radius.inner.number.get() != 0.0
|| self.spread_radius.inner.number.get() != 0.0
{
components.push(self.blur_radius.to_string());
if self.spread_radius.inner.number.get() != 0.0 {
components.push(self.spread_radius.to_string());
if self.color != ColorU::BLACK {
// Assuming black is the default
components.push(self.color.to_hash());
components.join(" ")
// Formatting to Rust code for StyleBoxShadow
impl crate::format_rust_code::FormatAsRustCode for StyleBoxShadow {
fn format_as_rust_code(&self, tabs: usize) -> String {
let t = String::from(" ").repeat(tabs);
format!(
"StyleBoxShadow {{\r\n{} offset_x: {},\r\n{} offset_y: {},\r\n{} color: \
{},\r\n{} blur_radius: {},\r\n{} spread_radius: {},\r\n{} clip_mode: \
BoxShadowClipMode::{:?},\r\n{}}}",
t,
crate::format_rust_code::format_pixel_value_no_percent(&self.offset_x),
crate::format_rust_code::format_pixel_value_no_percent(&self.offset_y),
crate::format_rust_code::format_color_value(&self.color),
crate::format_rust_code::format_pixel_value_no_percent(&self.blur_radius),
crate::format_rust_code::format_pixel_value_no_percent(&self.spread_radius),
self.clip_mode,
t
)
// --- PARSER ---
/// Error returned when parsing a CSS shadow value fails.
#[derive(Clone, PartialEq)]
pub enum CssShadowParseError<'a> {
TooManyOrTooFewComponents(&'a str),
ValueParseErr(CssPixelValueParseError<'a>),
ColorParseError(CssColorParseError<'a>),
impl_debug_as_display!(CssShadowParseError<'a>);
impl_display! { CssShadowParseError<'a>, {
TooManyOrTooFewComponents(e) => format!("Expected 2 to 4 length values for box-shadow, found an invalid number of components in: \"{}\"", e),
ValueParseErr(e) => format!("Invalid length value in box-shadow: {}", e),
ColorParseError(e) => format!("Invalid color value in box-shadow: {}", e),
}}
impl_from!(
CssPixelValueParseError<'a>,
CssShadowParseError::ValueParseErr
);
impl_from!(CssColorParseError<'a>, CssShadowParseError::ColorParseError);
/// Owned version of `CssShadowParseError`.
#[derive(Debug, Clone, PartialEq)]
#[repr(C, u8)]
pub enum CssShadowParseErrorOwned {
TooManyOrTooFewComponents(AzString),
ValueParseErr(CssPixelValueParseErrorOwned),
ColorParseError(CssColorParseErrorOwned),
impl<'a> CssShadowParseError<'a> {
/// Converts the borrowed error into an owned version for storage.
pub fn to_contained(&self) -> CssShadowParseErrorOwned {
CssShadowParseError::TooManyOrTooFewComponents(s) => {
CssShadowParseErrorOwned::TooManyOrTooFewComponents(s.to_string().into())
CssShadowParseError::ValueParseErr(e) => {
CssShadowParseErrorOwned::ValueParseErr(e.to_contained())
CssShadowParseError::ColorParseError(e) => {
CssShadowParseErrorOwned::ColorParseError(e.to_contained())
impl CssShadowParseErrorOwned {
/// Converts the owned error back into a borrowed version.
pub fn to_shared<'a>(&'a self) -> CssShadowParseError<'a> {
CssShadowParseErrorOwned::TooManyOrTooFewComponents(s) => {
CssShadowParseError::TooManyOrTooFewComponents(s.as_str())
CssShadowParseErrorOwned::ValueParseErr(e) => {
CssShadowParseError::ValueParseErr(e.to_shared())
CssShadowParseErrorOwned::ColorParseError(e) => {
CssShadowParseError::ColorParseError(e.to_shared())
/// Parses a CSS box-shadow, such as `"5px 10px #888 inset"`.
///
/// Note: This parser does not handle the `none` keyword, as that is handled by the
/// `CssPropertyValue` enum wrapper. It also does not handle comma-separated lists
/// of multiple shadows; it only parses a single shadow value.
#[cfg(feature = "parser")]
pub fn parse_style_box_shadow<'a>(
input: &'a str,
) -> Result<StyleBoxShadow, CssShadowParseError<'a>> {
let mut parts: Vec<&str> = input.split_whitespace().collect();
let mut shadow = StyleBoxShadow::default();
// The `inset` keyword can appear anywhere. Find it, set the flag, and remove it.
if let Some(pos) = parts.iter().position(|&p| p == "inset") {
shadow.clip_mode = BoxShadowClipMode::Inset;
parts.remove(pos);
// The color can also be anywhere. Find it, set the color, and remove it.
// It's the only part that isn't a length. We iterate from the back because
// it's slightly more common for the color to be last.
if let Some((pos, color)) = parts
.iter()
.enumerate()
.rev()
.find_map(|(i, p)| parse_css_color(p).ok().map(|c| (i, c)))
shadow.color = color;
// The remaining parts must be 2, 3, or 4 length values.
match parts.len() {
2..=4 => {
shadow.offset_x = parse_pixel_value_no_percent(parts[0])?;
shadow.offset_y = parse_pixel_value_no_percent(parts[1])?;
if parts.len() > 2 {
shadow.blur_radius = parse_pixel_value_no_percent(parts[2])?;
if parts.len() > 3 {
shadow.spread_radius = parse_pixel_value_no_percent(parts[3])?;
_ => return Err(CssShadowParseError::TooManyOrTooFewComponents(input)),
Ok(shadow)
#[cfg(all(test, feature = "parser"))]
mod tests {
use super::*;
use crate::props::basic::pixel::PixelValue;
fn px_no_percent(val: f32) -> PixelValueNoPercent {
PixelValueNoPercent {
inner: PixelValue::px(val),
#[test]
fn test_parse_box_shadow_simple() {
let result = parse_style_box_shadow("10px 5px").unwrap();
assert_eq!(result.offset_x, px_no_percent(10.0));
assert_eq!(result.offset_y, px_no_percent(5.0));
assert_eq!(result.blur_radius, px_no_percent(0.0));
assert_eq!(result.spread_radius, px_no_percent(0.0));
assert_eq!(result.color, ColorU::BLACK);
assert_eq!(result.clip_mode, BoxShadowClipMode::Outset);
fn test_parse_box_shadow_with_color() {
let result = parse_style_box_shadow("10px 5px #888").unwrap();
assert_eq!(result.color, ColorU::new_rgb(0x88, 0x88, 0x88));
fn test_parse_box_shadow_with_blur() {
let result = parse_style_box_shadow("5px 10px 20px").unwrap();
assert_eq!(result.offset_x, px_no_percent(5.0));
assert_eq!(result.offset_y, px_no_percent(10.0));
assert_eq!(result.blur_radius, px_no_percent(20.0));
fn test_parse_box_shadow_with_spread() {
let result = parse_style_box_shadow("2px 2px 2px 1px rgba(0,0,0,0.2)").unwrap();
assert_eq!(result.offset_x, px_no_percent(2.0));
assert_eq!(result.offset_y, px_no_percent(2.0));
assert_eq!(result.blur_radius, px_no_percent(2.0));
assert_eq!(result.spread_radius, px_no_percent(1.0));
assert_eq!(result.color, ColorU::new(0, 0, 0, 51));
fn test_parse_box_shadow_inset() {
let result = parse_style_box_shadow("inset 0 0 10px #000").unwrap();
assert_eq!(result.clip_mode, BoxShadowClipMode::Inset);
assert_eq!(result.offset_x, px_no_percent(0.0));
assert_eq!(result.offset_y, px_no_percent(0.0));
assert_eq!(result.blur_radius, px_no_percent(10.0));
fn test_parse_box_shadow_mixed_order() {
let result = parse_style_box_shadow("5px 1em red inset").unwrap();
assert_eq!(
result.offset_y,
inner: PixelValue::em(1.0)
assert_eq!(result.color, ColorU::RED);
fn test_parse_box_shadow_invalid() {
assert!(parse_style_box_shadow("10px").is_err());
assert!(parse_style_box_shadow("10px 5px 4px 3px 2px").is_err());
// Two colors: rposition picks "blue" as the color, leaving "red" which
// fails to parse as a pixel value.
assert!(parse_style_box_shadow("10px 5px red blue").is_err());
assert!(parse_style_box_shadow("10% 5px").is_err()); // No percent allowed