fix image example buffer size calculation (#359)

* fix image example buffer size calculation

* make deprecated since field semver-compliant

* replace manual slice size calculations with std::mem::size_of_val

* remove legacy numeric method `::max_value` in favor of the associated constant `::MAX`

* add type annotations to `std::mem::transmute` calls

* make cargo fmt happy

examples/image.rs

@@ -9,13 +9,13 @@ fn main() {
     decoder.set_transformations(Transformations::ALPHA);
     let mut reader = decoder.read_info().unwrap();
 
-    let mut buffer = vec![0u32; reader.output_buffer_size()];
+    let mut buffer = vec![0u32; reader.output_buffer_size() / 4];
 
     // View of pixels as individual subpixels (avoids allocating a second pixel buffer).
     let mut u8_buffer = unsafe {
         std::slice::from_raw_parts_mut(
             buffer.as_mut_ptr() as *mut u8,
-            buffer.len() * std::mem::size_of::<u32>(),
+            std::mem::size_of_val(&buffer),
         )
     };
 

src/key_handler.rs

@@ -6,7 +6,7 @@ use instant::{Duration, Instant};
 #[cfg(not(feature = "web"))]
 use std::time::{Duration, Instant};
 
-use crate::{InputCallback, Key, KeyRepeat};
+use crate::{key, InputCallback, Key, KeyRepeat};
 
 pub struct KeyHandler {
     pub key_callback: Option<Box<dyn InputCallback>>,
@@ -47,7 +47,7 @@ impl KeyHandler {
         for (idx, is_down) in self.keys.iter().enumerate() {
             if *is_down {
                 unsafe {
-                    keys.push(std::mem::transmute(idx as u8));
+                    keys.push(std::mem::transmute::<u8, key::Key>(idx as u8));
                 }
             }
         }
@@ -85,7 +85,7 @@ impl KeyHandler {
         for (idx, is_down) in self.keys.iter().enumerate() {
             if *is_down && self.is_key_index_pressed(idx, repeat) {
                 unsafe {
-                    keys.push(std::mem::transmute(idx as u8));
+                    keys.push(std::mem::transmute::<u8, key::Key>(idx as u8));
                 }
             }
         }
@@ -99,7 +99,7 @@ impl KeyHandler {
         for (idx, is_down) in self.keys.iter().enumerate() {
             if !(*is_down) && self.is_key_index_released(idx) {
                 unsafe {
-                    keys.push(std::mem::transmute(idx as u8));
+                    keys.push(std::mem::transmute::<u8, key::Key>(idx as u8));
                 }
             }
         }

src/lib.rs

@@ -527,7 +527,7 @@ impl Window {
     /// ```
     #[inline]
     #[deprecated(
-        since = "0.26",
+        since = "0.26.0",
         note = "use `set_target_fps` instead, this function will be removed in the future"
     )]
     pub fn limit_update_rate(&mut self, time: Option<Duration>) {

src/os/posix/wayland.rs

@@ -218,10 +218,7 @@ impl DisplayInfo {
         // Add a black canvas into the framebuffer
         let frame: Vec<u32> = vec![0xFF00_0000; (size.0 * size.1) as usize];
         let slice = unsafe {
-            std::slice::from_raw_parts(
-                frame.as_ptr() as *const u8,
-                frame.len() * std::mem::size_of::<u32>(),
-            )
+            std::slice::from_raw_parts(frame.as_ptr() as *const u8, std::mem::size_of_val(&frame))
         };
         tempfile
             .write_all(slice)
@@ -276,7 +273,7 @@ impl DisplayInfo {
 
         // Give the buffer to the surface and commit
         surface.attach(Some(buffer), 0, 0);
-        surface.damage(0, 0, i32::max_value(), i32::max_value());
+        surface.damage(0, 0, i32::MAX, i32::MAX);
         surface.commit();
 
         let xdg_config = Rc::new(RefCell::new(None));
@@ -348,10 +345,7 @@ impl DisplayInfo {
         fd.seek(SeekFrom::Start(0))?;
 
         let slice = unsafe {
-            std::slice::from_raw_parts(
-                buffer.as_ptr() as *const u8,
-                buffer.len() * std::mem::size_of::<u32>(),
-            )
+            std::slice::from_raw_parts(buffer.as_ptr() as *const u8, std::mem::size_of_val(buffer))
         };
 
         fd.write_all(slice)?;
@@ -363,8 +357,7 @@ impl DisplayInfo {
         }
 
         self.surface.attach(Some(buf), 0, 0);
-        self.surface
-            .damage(0, 0, i32::max_value(), i32::max_value());
+        self.surface.damage(0, 0, i32::MAX, i32::MAX);
         self.surface.commit();
 
         Ok(())

src/os/posix/x11.rs

@@ -1200,7 +1200,7 @@ impl Window {
     }
 
     fn update_key_state(&mut self, sym: xlib::KeySym, is_down: bool) {
-        if sym > u32::max_value() as xlib::KeySym {
+        if sym > u32::MAX as xlib::KeySym {
             return;
         }
 

src/os/wasm/mod.rs

@@ -25,12 +25,7 @@ use web_sys::{window, CanvasRenderingContext2d, HtmlCanvasElement, ImageData};
 #[inline(always)]
 #[allow(dead_code)] // Only used on 32-bit builds currently
 pub fn u32_as_u8<'a>(src: &'a [u32]) -> &'a [u8] {
-    unsafe {
-        std::slice::from_raw_parts(
-            src.as_ptr() as *mut u8,
-            src.len() * std::mem::size_of::<u32>(),
-        )
-    }
+    unsafe { std::slice::from_raw_parts(src.as_ptr() as *mut u8, std::mem::size_of_val(&src)) }
 }
 
 struct MouseState {