rio_window/
cursor.rs

1use core::fmt;
2use std::error::Error;
3use std::hash::{Hash, Hasher};
4use std::sync::Arc;
5
6use cursor_icon::CursorIcon;
7
8use crate::platform_impl::{PlatformCustomCursor, PlatformCustomCursorSource};
9
10/// The maximum width and height for a cursor when using [`CustomCursor::from_rgba`].
11pub const MAX_CURSOR_SIZE: u16 = 2048;
12
13const PIXEL_SIZE: usize = 4;
14
15/// See [`Window::set_cursor()`][crate::window::Window::set_cursor] for more details.
16#[derive(Clone, Debug, Eq, Hash, PartialEq)]
17pub enum Cursor {
18    Icon(CursorIcon),
19    Custom(CustomCursor),
20}
21
22impl Default for Cursor {
23    fn default() -> Self {
24        Self::Icon(CursorIcon::default())
25    }
26}
27
28impl From<CursorIcon> for Cursor {
29    fn from(icon: CursorIcon) -> Self {
30        Self::Icon(icon)
31    }
32}
33
34impl From<CustomCursor> for Cursor {
35    fn from(custom: CustomCursor) -> Self {
36        Self::Custom(custom)
37    }
38}
39
40/// Use a custom image as a cursor (mouse pointer).
41///
42/// Is guaranteed to be cheap to clone.
43///
44/// ## Platform-specific
45///
46/// **Web**: Some browsers have limits on cursor sizes usually at 128x128.
47///
48/// # Example
49///
50/// ```no_run
51/// # use rio_window::event_loop::ActiveEventLoop;
52/// # use rio_window::window::Window;
53/// # fn scope(event_loop: &ActiveEventLoop, window: &Window) {
54/// use rio_window::window::CustomCursor;
55///
56/// let w = 10;
57/// let h = 10;
58/// let rgba = vec![255; (w * h * 4) as usize];
59///
60/// #[cfg(not(target_family = "wasm"))]
61/// let source = CustomCursor::from_rgba(rgba, w, h, w / 2, h / 2).unwrap();
62///
63/// #[cfg(target_family = "wasm")]
64/// let source = {
65///     use rio_window::platform::web::CustomCursorExtWebSys;
66///     CustomCursor::from_url(String::from("http://localhost:3000/cursor.png"), 0, 0)
67/// };
68///
69/// let custom_cursor = event_loop.create_custom_cursor(source);
70///
71/// window.set_cursor(custom_cursor.clone());
72/// # }
73/// ```
74#[derive(Clone, Debug, Eq, Hash, PartialEq)]
75pub struct CustomCursor {
76    /// Platforms should make sure this is cheap to clone.
77    pub(crate) inner: PlatformCustomCursor,
78}
79
80impl CustomCursor {
81    /// Creates a new cursor from an rgba buffer.
82    ///
83    /// The alpha channel is assumed to be **not** premultiplied.
84    pub fn from_rgba(
85        rgba: impl Into<Vec<u8>>,
86        width: u16,
87        height: u16,
88        hotspot_x: u16,
89        hotspot_y: u16,
90    ) -> Result<CustomCursorSource, BadImage> {
91        let _span = tracing::debug_span!(
92            "rio_window::Cursor::from_rgba",
93            width,
94            height,
95            hotspot_x,
96            hotspot_y
97        )
98        .entered();
99
100        Ok(CustomCursorSource {
101            inner: PlatformCustomCursorSource::from_rgba(
102                rgba.into(),
103                width,
104                height,
105                hotspot_x,
106                hotspot_y,
107            )?,
108        })
109    }
110}
111
112/// Source for [`CustomCursor`].
113///
114/// See [`CustomCursor`] for more details.
115#[derive(Debug)]
116pub struct CustomCursorSource {
117    pub(crate) inner: PlatformCustomCursorSource,
118}
119
120/// An error produced when using [`CustomCursor::from_rgba`] with invalid arguments.
121#[derive(Debug, Clone)]
122pub enum BadImage {
123    /// Produced when the image dimensions are larger than [`MAX_CURSOR_SIZE`]. This doesn't
124    /// guarantee that the cursor will work, but should avoid many platform and device specific
125    /// limits.
126    TooLarge { width: u16, height: u16 },
127    /// Produced when the length of the `rgba` argument isn't divisible by 4, thus `rgba` can't be
128    /// safely interpreted as 32bpp RGBA pixels.
129    ByteCountNotDivisibleBy4 { byte_count: usize },
130    /// Produced when the number of pixels (`rgba.len() / 4`) isn't equal to `width * height`.
131    /// At least one of your arguments is incorrect.
132    DimensionsVsPixelCount {
133        width: u16,
134        height: u16,
135        width_x_height: u64,
136        pixel_count: u64,
137    },
138    /// Produced when the hotspot is outside the image bounds
139    HotspotOutOfBounds {
140        width: u16,
141        height: u16,
142        hotspot_x: u16,
143        hotspot_y: u16,
144    },
145}
146
147impl fmt::Display for BadImage {
148    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
149        match self {
150            BadImage::TooLarge { width, height } => write!(
151                f,
152                "The specified dimensions ({width:?}x{height:?}) are too large. The maximum is \
153                 {MAX_CURSOR_SIZE:?}x{MAX_CURSOR_SIZE:?}.",
154            ),
155            BadImage::ByteCountNotDivisibleBy4 { byte_count } => write!(
156                f,
157                "The length of the `rgba` argument ({byte_count:?}) isn't divisible by 4, making \
158                 it impossible to interpret as 32bpp RGBA pixels.",
159            ),
160            BadImage::DimensionsVsPixelCount { width, height, width_x_height, pixel_count } => {
161                write!(
162                    f,
163                    "The specified dimensions ({width:?}x{height:?}) don't match the number of \
164                     pixels supplied by the `rgba` argument ({pixel_count:?}). For those \
165                     dimensions, the expected pixel count is {width_x_height:?}.",
166                )
167            },
168            BadImage::HotspotOutOfBounds { width, height, hotspot_x, hotspot_y } => write!(
169                f,
170                "The specified hotspot ({hotspot_x:?}, {hotspot_y:?}) is outside the image bounds \
171                 ({width:?}x{height:?}).",
172            ),
173        }
174    }
175}
176
177impl Error for BadImage {}
178
179/// Platforms export this directly as `PlatformCustomCursorSource` if they need to only work with
180/// images.
181#[allow(dead_code)]
182#[derive(Debug)]
183pub(crate) struct OnlyCursorImageSource(pub(crate) CursorImage);
184
185#[allow(dead_code)]
186impl OnlyCursorImageSource {
187    pub(crate) fn from_rgba(
188        rgba: Vec<u8>,
189        width: u16,
190        height: u16,
191        hotspot_x: u16,
192        hotspot_y: u16,
193    ) -> Result<Self, BadImage> {
194        CursorImage::from_rgba(rgba, width, height, hotspot_x, hotspot_y).map(Self)
195    }
196}
197
198/// Platforms export this directly as `PlatformCustomCursor` if they don't implement caching.
199#[allow(dead_code)]
200#[derive(Debug, Clone)]
201pub(crate) struct OnlyCursorImage(pub(crate) Arc<CursorImage>);
202
203impl Hash for OnlyCursorImage {
204    fn hash<H: Hasher>(&self, state: &mut H) {
205        Arc::as_ptr(&self.0).hash(state);
206    }
207}
208
209impl PartialEq for OnlyCursorImage {
210    fn eq(&self, other: &Self) -> bool {
211        Arc::ptr_eq(&self.0, &other.0)
212    }
213}
214
215impl Eq for OnlyCursorImage {}
216
217#[derive(Debug)]
218#[allow(dead_code)]
219pub(crate) struct CursorImage {
220    pub(crate) rgba: Vec<u8>,
221    pub(crate) width: u16,
222    pub(crate) height: u16,
223    pub(crate) hotspot_x: u16,
224    pub(crate) hotspot_y: u16,
225}
226
227impl CursorImage {
228    pub(crate) fn from_rgba(
229        rgba: Vec<u8>,
230        width: u16,
231        height: u16,
232        hotspot_x: u16,
233        hotspot_y: u16,
234    ) -> Result<Self, BadImage> {
235        if width > MAX_CURSOR_SIZE || height > MAX_CURSOR_SIZE {
236            return Err(BadImage::TooLarge { width, height });
237        }
238
239        if rgba.len() % PIXEL_SIZE != 0 {
240            return Err(BadImage::ByteCountNotDivisibleBy4 {
241                byte_count: rgba.len(),
242            });
243        }
244
245        let pixel_count = (rgba.len() / PIXEL_SIZE) as u64;
246        let width_x_height = width as u64 * height as u64;
247        if pixel_count != width_x_height {
248            return Err(BadImage::DimensionsVsPixelCount {
249                width,
250                height,
251                width_x_height,
252                pixel_count,
253            });
254        }
255
256        if hotspot_x >= width || hotspot_y >= height {
257            return Err(BadImage::HotspotOutOfBounds {
258                width,
259                height,
260                hotspot_x,
261                hotspot_y,
262            });
263        }
264
265        Ok(CursorImage {
266            rgba,
267            width,
268            height,
269            hotspot_x,
270            hotspot_y,
271        })
272    }
273}
274
275// Platforms that don't support cursors will export this as `PlatformCustomCursor`.
276#[derive(Debug, Clone, Hash, PartialEq, Eq)]
277pub(crate) struct NoCustomCursor;
278
279#[allow(dead_code)]
280impl NoCustomCursor {
281    pub(crate) fn from_rgba(
282        rgba: Vec<u8>,
283        width: u16,
284        height: u16,
285        hotspot_x: u16,
286        hotspot_y: u16,
287    ) -> Result<Self, BadImage> {
288        CursorImage::from_rgba(rgba, width, height, hotspot_x, hotspot_y)?;
289        Ok(Self)
290    }
291}
rio_window/cursor.rs

rio_window/
cursor.rs
