feat: load cursor from data

I want to add a function to load cursor from data

wayland-cursor/src/lib.rs

@@ -45,6 +45,7 @@
 //! # }
 //! ```
 
+use std::borrow::Cow;
 use std::env;
 use std::fs::File;
 use std::io::{Error as IoError, Read, Result as IoResult, Seek, SeekFrom, Write};
@@ -83,6 +84,22 @@ pub struct CursorTheme {
  backend: WeakBackend,
 }
 
+/// An error that occurs when a binding a global fails.
+#[derive(Debug)]
+pub enum CursorLoadError {
+ /// When give a icon name, but XCursorTheme cannot find a path
+ IconPathNotFound(String),
+
+ /// When the path finded before, but it cannot be opened
+ IconFileCannotOpen(std::io::Error),
+
+ /// When the file is opened, but cannot get the data
+ IconFileNotReadable(std::io::Error),
+
+ /// When the data of icon is get, but xparser cannot parse it
+ IconFileNotParsable,
+}
+
 impl CursorTheme {
  /// Load a cursor theme from system defaults.
  ///
@@ -177,6 +194,63 @@ impl CursorTheme {
  }
  }
 
+ /// try to load data from theme, else, it will try to load from fallback data
+ ///
+ /// This method returns [`None`] if this cursor is not provided either by the theme, or by one of its parents,
+ /// and the data by fallback function cannot parse it
+ /// fallback function will receive a enum which discribe the error, you can print some messages
+ /// or do some other things before return the finally fallback data
+ pub fn get_cursor_with_default_data<F>(&mut self, name: &str, fallback: F) -> Option<&Cursor>
+ where
+ F: Fn(CursorLoadError) -> Cow<'static, [u8]>,
+ {
+ match self.cursors.iter().position(|cursor| cursor.name == name) {
+ Some(i) => Some(&self.cursors[i]),
+ None => {
+ let cursor = self.load_cursor_with_default_data(name, self.size, fallback)?;
+ self.cursors.push(cursor);
+ self.cursors.iter().last()
+ }
+ }
+ }
+
+ fn load_cursor_with_default_data<F>(
+ &mut self,
+ name: &str,
+ size: u32,
+ fallback: F,
+ ) -> Option<Cursor>
+ where
+ F: Fn(CursorLoadError) -> Cow<'static, [u8]>,
+ {
+ let conn = Connection::from_backend(self.backend.upgrade()?);
+ let err_reason = 'fallback: {
+ let Some(icon_path) = XCursorTheme::load(&self.name).load_icon(name) else {
+ break 'fallback CursorLoadError::IconPathNotFound(name.to_owned());
+ };
+ let mut icon_file = match File::open(icon_path) {
+ Ok(icon_file) => icon_file,
+ Err(e) => {
+ break 'fallback CursorLoadError::IconFileCannotOpen(e);
+ }
+ };
+ let mut buf = Vec::new();
+ let Some(images) = ({
+ if let Err(e) = icon_file.read_to_end(&mut buf) {
+ break 'fallback CursorLoadError::IconFileNotReadable(e);
+ }
+ xparser::parse_xcursor(&buf)
+ }) else {
+ break 'fallback CursorLoadError::IconFileNotParsable;
+ };
+
+ return Some(Cursor::new(&conn, name, self, &images, size));
+ };
+ let data = fallback(err_reason);
+ let images = xparser::parse_xcursor(data.as_ref())?;
+ Some(Cursor::new(&conn, name, self, &images, size))
+ }
+
  /// This function loads a cursor, parses it and pushes the images onto the shm pool.
  ///
  /// Keep in mind that if the cursor is already loaded, the function will make a duplicate.