Add custom cursor icon support on Windows

CHANGELOG.md

@@ -5,6 +5,7 @@
 - On X11, fix deadlock when calling `set_fullscreen_inner`.
 - On Web, prevent the webpage from scrolling when the user is focused on a winit canvas
 - On Windows, drag and drop is now optional and must be enabled with `WindowBuilderExtWindows::with_drag_and_drop(true)`.
+- Add custom cursor icon support on Windows.
 - On Wayland, fix deadlock when calling to `set_inner_size` from a callback.
 - On macOS, add `hide__other_applications` to `EventLoopWindowTarget` via existing `EventLoopWindowTargetExtMacOS` trait. `hide_other_applications` will hide other applications by calling `-[NSApplication hideOtherApplications: nil]`.
 - On android added support for `run_return`.

Cargo.toml

@@ -33,7 +33,7 @@ raw-window-handle = "0.3"
 bitflags = "1"
 
 [dev-dependencies]
-image = "0.23"
+png = "0.16"
 simple_logger = "1"
 
 [target.'cfg(target_os = "android")'.dependencies]

examples/cursor.rs

@@ -1,7 +1,9 @@
+use std::{fs::File, path::Path};
 use winit::{
+    dpi::{PhysicalPosition, PhysicalSize},
     event::{ElementState, Event, KeyboardInput, WindowEvent},
     event_loop::{ControlFlow, EventLoop},
-    window::{CursorIcon, WindowBuilder},
+    window::{CursorIcon, Icon, RgbaIcon, WindowBuilder},
 };
 
 fn main() {
@@ -13,6 +15,71 @@ fn main() {
 
     let mut cursor_idx = 0;
 
+    let custom_cursor_icon = {
+        let base_path = Path::new(concat!(
+            env!("CARGO_MANIFEST_DIR"),
+            "/examples/icons/icon_folder/"
+        ));
+
+        Icon::from_rgba_fn(move |size, _| {
+            let path = base_path.join(format!("{}.png", size.width));
+            let (icon_rgba, icon_size) = {
+                let decoder = png::Decoder::new(File::open(path)?);
+                let (info, mut reader) = decoder.read_info()?;
+
+                let mut rgba = vec![0; info.buffer_size()];
+                reader.next_frame(&mut rgba).unwrap();
+
+                (rgba, PhysicalSize::new(info.width, info.height))
+            };
+            Ok(RgbaIcon::from_rgba_with_hot_spot(
+                icon_rgba,
+                icon_size,
+                PhysicalPosition::new(0, 0),
+            ))
+        })
+        .unwrap()
+    };
+
+    let cursors = vec![
+        CursorIcon::Custom(custom_cursor_icon),
+        CursorIcon::Default,
+        CursorIcon::Crosshair,
+        CursorIcon::Hand,
+        CursorIcon::Arrow,
+        CursorIcon::Move,
+        CursorIcon::Text,
+        CursorIcon::Wait,
+        CursorIcon::Help,
+        CursorIcon::Progress,
+        CursorIcon::NotAllowed,
+        CursorIcon::ContextMenu,
+        CursorIcon::Cell,
+        CursorIcon::VerticalText,
+        CursorIcon::Alias,
+        CursorIcon::Copy,
+        CursorIcon::NoDrop,
+        CursorIcon::Grab,
+        CursorIcon::Grabbing,
+        CursorIcon::AllScroll,
+        CursorIcon::ZoomIn,
+        CursorIcon::ZoomOut,
+        CursorIcon::EResize,
+        CursorIcon::NResize,
+        CursorIcon::NeResize,
+        CursorIcon::NwResize,
+        CursorIcon::SResize,
+        CursorIcon::SeResize,
+        CursorIcon::SwResize,
+        CursorIcon::WResize,
+        CursorIcon::EwResize,
+        CursorIcon::NsResize,
+        CursorIcon::NeswResize,
+        CursorIcon::NwseResize,
+        CursorIcon::ColResize,
+        CursorIcon::RowResize,
+    ];
+
     event_loop.run(move |event, _, control_flow| {
         *control_flow = ControlFlow::Wait;
 
@@ -29,9 +96,9 @@ fn main() {
                     },
                 ..
             } => {
-                println!("Setting cursor to \"{:?}\"", CURSORS[cursor_idx]);
-                window.set_cursor_icon(CURSORS[cursor_idx]);
-                if cursor_idx < CURSORS.len() - 1 {
+                println!("Setting cursor to \"{:?}\"", cursors[cursor_idx]);
+                window.set_cursor_icon(cursors[cursor_idx].clone());
+                if cursor_idx < cursors.len() - 1 {
                     cursor_idx += 1;
                 } else {
                     cursor_idx = 0;
@@ -48,41 +115,3 @@ fn main() {
         }
     });
 }
-
-const CURSORS: &[CursorIcon] = &[
-    CursorIcon::Default,
-    CursorIcon::Crosshair,
-    CursorIcon::Hand,
-    CursorIcon::Arrow,
-    CursorIcon::Move,
-    CursorIcon::Text,
-    CursorIcon::Wait,
-    CursorIcon::Help,
-    CursorIcon::Progress,
-    CursorIcon::NotAllowed,
-    CursorIcon::ContextMenu,
-    CursorIcon::Cell,
-    CursorIcon::VerticalText,
-    CursorIcon::Alias,
-    CursorIcon::Copy,
-    CursorIcon::NoDrop,
-    CursorIcon::Grab,
-    CursorIcon::Grabbing,
-    CursorIcon::AllScroll,
-    CursorIcon::ZoomIn,
-    CursorIcon::ZoomOut,
-    CursorIcon::EResize,
-    CursorIcon::NResize,
-    CursorIcon::NeResize,
-    CursorIcon::NwResize,
-    CursorIcon::SResize,
-    CursorIcon::SeResize,
-    CursorIcon::SwResize,
-    CursorIcon::WResize,
-    CursorIcon::EwResize,
-    CursorIcon::NsResize,
-    CursorIcon::NeswResize,
-    CursorIcon::NwseResize,
-    CursorIcon::ColResize,
-    CursorIcon::RowResize,
-];

examples/window_icon.rs

@@ -1,21 +1,20 @@
-extern crate image;
-use std::path::Path;
+use std::{ffi::OsStr, fs::File, path::Path};
 use winit::{
+    dpi::PhysicalSize,
     event::Event,
     event_loop::{ControlFlow, EventLoop},
-    window::{Icon, WindowBuilder},
+    window::{Icon, RgbaIcon, WindowBuilder},
 };
 
 fn main() {
     simple_logger::init().unwrap();
 
-    // You'll have to choose an icon size at your own discretion. On X11, the desired size varies
-    // by WM, and on Windows, you still have to account for screen scaling. Here we use 32px,
-    // since it seems to work well enough in most cases. Be careful about going too high, or
-    // you'll be bitten by the low-quality downscaling built into the WM.
-    let path = concat!(env!("CARGO_MANIFEST_DIR"), "/examples/icon.png");
+    let path = Path::new(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/examples/icons/icon_folder/"
+    ));
 
-    let icon = load_icon(Path::new(path));
+    let icon = load_icon(&path);
 
     let event_loop = EventLoop::new();
 
@@ -44,13 +43,31 @@ fn main() {
 }
 
 fn load_icon(path: &Path) -> Icon {
-    let (icon_rgba, icon_width, icon_height) = {
-        let image = image::open(path)
-            .expect("Failed to open icon path")
-            .into_rgba();
-        let (width, height) = image.dimensions();
-        let rgba = image.into_raw();
-        (rgba, width, height)
+    let decode_png = |path: &Path| {
+        let decoder = png::Decoder::new(File::open(path).unwrap());
+        let (info, mut reader) = decoder.read_info().unwrap();
+
+        let mut rgba = vec![0; info.buffer_size()];
+        reader.next_frame(&mut rgba).unwrap();
+
+        (rgba, PhysicalSize::new(info.width, info.height))
     };
-    Icon::from_rgba(icon_rgba, icon_width, icon_height).expect("Failed to open icon")
+    if path.is_file() {
+        if path.extension() == Some(OsStr::new("png")) {
+            let (icon_rgba, icon_size) = decode_png(path);
+            Icon::from_rgba(&icon_rgba, icon_size).unwrap()
+        } else {
+            panic!("unsupported file extension: {:?}", path.extension());
+        }
+    } else if path.is_dir() {
+        let path = path.to_owned();
+        Icon::from_rgba_fn(move |size, _| {
+            let path = path.join(format!("{}.png", size.width));
+            let (icon_rgba, icon_size) = decode_png(&path);
+            Ok(RgbaIcon::from_rgba(icon_rgba, icon_size))
+        })
+        .unwrap()
+    } else {
+        panic!("path {} is neither file nor directory", path.display());
+    }
 }

src/dpi.rs

@@ -225,7 +225,7 @@ impl<P: Pixel, X: Pixel> Into<[X; 2]> for LogicalPosition<P> {
 }
 
 /// A position represented in physical pixels.
-#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PhysicalPosition<P> {
     pub x: P,