From e7639921efd644b4312ebca2bc83282b96cbc6b7 Mon Sep 17 00:00:00 2001
From: ShootingStarDragons <ShootingStarDragons@protonmail.com>
Date: Thu, 7 Dec 2023 22:13:36 +0800
Subject: [PATCH] feat: load cursor from data

I want to add a function to load cursor from data
---
 wayland-cursor/src/lib.rs | 45 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/wayland-cursor/src/lib.rs b/wayland-cursor/src/lib.rs
index ff6ae747273..17c9e3c959a 100644
--- a/wayland-cursor/src/lib.rs
+++ b/wayland-cursor/src/lib.rs
@@ -45,7 +45,9 @@
 //! # }
 //! ```
 
+use std::borrow::Cow;
 use std::env;
+use std::fmt::Debug;
 use std::fs::File;
 use std::io::{Error as IoError, Read, Result as IoResult, Seek, SeekFrom, Write};
 use std::ops::{Deref, Index};
@@ -81,6 +83,24 @@ pub struct CursorTheme {
     pool_size: i32,
     file: File,
     backend: WeakBackend,
+    fallback: Option<FallBack>,
+}
+
+struct FallBack(Box<dyn Fn(&str) -> Cow<'static, [u8]>>);
+
+impl FallBack {
+    fn new<F>(fallback: F) -> Self
+    where
+        F: Fn(&str) -> Cow<'static, [u8]> + 'static,
+    {
+        Self(Box::new(fallback))
+    }
+}
+
+impl Debug for FallBack {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("fallback function")
+    }
 }
 
 impl CursorTheme {
@@ -160,23 +180,46 @@ impl CursorTheme {
             pool_size: INITIAL_POOL_SIZE,
             cursors: Vec::new(),
             backend: conn.backend().downgrade(),
+            fallback: None,
         })
     }
 
     /// Retrieve a cursor from the theme.
     ///
     /// This method returns [`None`] if this cursor is not provided either by the theme, or by one of its parents.
+    ///
+    /// If a fallback is set, it will use the data from fallback
     pub fn get_cursor(&mut self, name: &str) -> Option<&Cursor> {
         match self.cursors.iter().position(|cursor| cursor.name == name) {
             Some(i) => Some(&self.cursors[i]),
             None => {
-                let cursor = self.load_cursor(name, self.size)?;
+                let cursor = match self.load_cursor(name, self.size) {
+                    None => {
+                        let Some(ref fallback) = self.fallback else {
+                            return None;
+                        };
+                        let data = fallback.0(name);
+                        let images = xparser::parse_xcursor(&data)?;
+                        let conn = Connection::from_backend(self.backend.upgrade()?);
+                        Cursor::new(&conn, name, self, &images, self.size)
+                    }
+                    Some(cursor) => cursor,
+                };
                 self.cursors.push(cursor);
                 self.cursors.iter().last()
             }
         }
     }
 
+    /// Set the set_callback, the return value of the fallback function should be the source of
+    /// xcursor
+    pub fn set_callback<F>(&mut self, fallback: F)
+    where
+        F: Fn(&str) -> Cow<'static, [u8]> + 'static,
+    {
+        self.fallback = Some(FallBack::new(fallback))
+    }
+
     /// 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.