Window icons (#497)

src/platform/linux/x11/util/icon.rs

@@ -0,0 +1,34 @@
+use {Icon, Pixel, PIXEL_SIZE};
+use super::*;
+
+impl Pixel {
+    pub fn to_packed_argb(&self) -> Cardinal {
+        let mut cardinal = 0;
+        assert!(CARDINAL_SIZE >= PIXEL_SIZE);
+        let as_bytes = &mut cardinal as *mut _ as *mut u8;
+        unsafe {
+            *as_bytes.offset(0) = self.b;
+            *as_bytes.offset(1) = self.g;
+            *as_bytes.offset(2) = self.r;
+            *as_bytes.offset(3) = self.a;
+        }
+        cardinal
+    }
+}
+
+impl Icon {
+    pub fn to_cardinals(&self) -> Vec<Cardinal> {
+        assert_eq!(self.rgba.len() % PIXEL_SIZE, 0);
+        let pixel_count = self.rgba.len() / PIXEL_SIZE;
+        assert_eq!(pixel_count, (self.width * self.height) as usize);
+        let mut data = Vec::with_capacity(pixel_count);
+        data.push(self.width as Cardinal);
+        data.push(self.height as Cardinal);
+        let pixels = self.rgba.as_ptr() as *const Pixel;
+        for pixel_index in 0..pixel_count {
+            let pixel = unsafe { &*pixels.offset(pixel_index as isize) };
+            data.push(pixel.to_packed_argb());
+        }
+        data
+    }
+}

src/platform/linux/x11/util/mod.rs

@@ -4,6 +4,7 @@
 mod atom;
 mod geometry;
 mod hint;
+mod icon;
 mod input;
 mod window_property;
 mod wm;
@@ -11,6 +12,7 @@ mod wm;
 pub use self::atom::*;
 pub use self::geometry::*;
 pub use self::hint::*;
+pub use self::icon::*;
 pub use self::input::*;
 pub use self::window_property::*;
 pub use self::wm::*;

src/platform/linux/x11/util/window_property.rs

@@ -3,6 +3,9 @@ use std::fmt::Debug;
 
 use super::*;
 
+pub type Cardinal = c_long;
+pub const CARDINAL_SIZE: usize = mem::size_of::<c_long>();
+
 #[derive(Debug, Clone)]
 pub enum GetPropertyError {
     XError(XError),