Make default cursor respect output scale

First part of https://github.com/YaLTeR/niri/issues/16

1 files changed, 103 insertions, 0 deletions

diff --git a/src/cursor.rs b/src/cursor.rs
new file mode 100644
index 00000000..454cd99b
--- /dev/null
+++ b/src/cursor.rs
@@ -0,0 +1,103 @@
+use std::collections::HashMap;
+use std::fs::File;
+use std::io::Read;
+
+use anyhow::{anyhow, Context};
+use smithay::backend::allocator::Fourcc;
+use smithay::backend::renderer::element::texture::TextureBuffer;
+use smithay::backend::renderer::gles::{GlesRenderer, GlesTexture};
+use smithay::utils::{Physical, Point, Transform};
+use xcursor::parser::{parse_xcursor, Image};
+use xcursor::CursorTheme;
+
+const CURSOR_SIZE: i32 = 24;
+static FALLBACK_CURSOR_DATA: &[u8] = include_bytes!("../resources/cursor.rgba");
+
+pub struct Cursor {
+    images: Vec<Image>,
+    cache: HashMap<i32, (TextureBuffer<GlesTexture>, Point<i32, Physical>)>,
+}
+
+impl Cursor {
+    pub fn load() -> Self {
+        let images = match load_xcursor() {
+            Ok(images) => images,
+            Err(err) => {
+                warn!("error loading xcursor default cursor: {err:?}");
+
+                vec![Image {
+                    size: 32,
+                    width: 64,
+                    height: 64,
+                    xhot: 1,
+                    yhot: 1,
+                    delay: 1,
+                    pixels_rgba: Vec::from(FALLBACK_CURSOR_DATA),
+                    pixels_argb: vec![],
+                }]
+            }
+        };
+
+        Self {
+            images,
+            cache: HashMap::new(),
+        }
+    }
+
+    pub fn get(
+        &mut self,
+        renderer: &mut GlesRenderer,
+        scale: i32,
+    ) -> (TextureBuffer<GlesTexture>, Point<i32, Physical>) {
+        self.cache
+            .entry(scale)
+            .or_insert_with_key(|scale| {
+                let _span = tracy_client::span!("create cursor texture");
+
+                let size = CURSOR_SIZE * scale;
+
+                let nearest_image = self
+                    .images
+                    .iter()
+                    .min_by_key(|image| (size - image.size as i32).abs())
+                    .unwrap();
+                let frame = self
+                    .images
+                    .iter()
+                    .find(move |image| {
+                        image.width == nearest_image.width && image.height == nearest_image.height
+                    })
+                    .unwrap();
+
+                let texture = TextureBuffer::from_memory(
+                    renderer,
+                    &frame.pixels_rgba,
+                    Fourcc::Abgr8888,
+                    (frame.width as i32, frame.height as i32),
+                    false,
+                    *scale,
+                    Transform::Normal,
+                    None,
+                )
+                .unwrap();
+                (texture, (frame.xhot as i32, frame.yhot as i32).into())
+            })
+            .clone()
+    }
+}
+
+fn load_xcursor() -> anyhow::Result<Vec<Image>> {
+    let _span = tracy_client::span!();
+
+    let theme = CursorTheme::load("default");
+    let path = theme
+        .load_icon("default")
+        .ok_or_else(|| anyhow!("no default icon"))?;
+    let mut file = File::open(path).context("error opening cursor icon file")?;
+    let mut buf = vec![];
+    file.read_to_end(&mut buf)
+        .context("error reading cursor icon file")?;
+    let images = parse_xcursor(&buf).context("error parsing cursor icon file")?;
+
+    Ok(images)
+}