Address review comments, improve example

This fixes some glitchy rendering by redrawing everything every frame,
and using double buffering. Also fix double-borrowing issue with split
top screen.

ctru-rs/examples/gfx-3d-mode.rs

@@ -1,4 +1,4 @@
-use ctru::gfx::TopScreen3D;
+use ctru::gfx::{Screen, Side, TopScreen3D};
 use ctru::prelude::*;
 
 /// See `graphics-bitmap.rs` for details on how the image is generated.
@@ -16,24 +16,14 @@ fn main() {
     let apt = Apt::init().expect("Couldn't obtain APT controller");
     let _console = Console::init(gfx.bottom_screen.borrow_mut());
 
-    println!("Press Start to exit.\nPress A to switch which side is drawn to.");
+    println!("Press Start to exit.\nPress A to switch sides (be sure to have 3D mode enabled).");
 
-    let top_screen = TopScreen3D::from(&gfx.top_screen);
+    gfx.top_screen.borrow_mut().set_double_buffering(true);
-
-    // TODO set double buffering for top screen
-
-    let mut left = top_screen.left_mut();
-    let left_buf = left.get_raw_framebuffer();
-    let mut right = top_screen.right_mut();
-    let right_buf = right.get_raw_framebuffer();
 
-    // We assume the image is the correct size already, so we ignore width + height.
+    let top_screen = TopScreen3D::from(&gfx.top_screen);
-    let mut buf = left_buf.ptr;
+    let (mut left, mut right) = top_screen.split_mut();
 
-    // Copy the image into the left-side frame buffer
+    let mut current_side = Side::Left;
-    unsafe {
-        buf.copy_from(IMAGE.as_ptr(), IMAGE.len());
-    }
 
     // Main loop
     while apt.main_loop() {
@@ -44,23 +34,31 @@ fn main() {
             break;
         }
 
-        if hid.keys_down().contains(KeyPad::KEY_A) {
+        let left_buf = left.get_raw_framebuffer();
-            // Clear the side we just drew to by zeroing it out
+        let right_buf = right.get_raw_framebuffer();
+
+        // Clear both buffers every time, in case the user switches sides this loop
         unsafe {
-                buf.copy_from(ZERO.as_ptr(), ZERO.len());
+            left_buf.ptr.copy_from(ZERO.as_ptr(), ZERO.len());
+            right_buf.ptr.copy_from(ZERO.as_ptr(), ZERO.len());
         }
 
-            // flip which buffer we're writing to, and redraw the image
+        if hid.keys_down().contains(KeyPad::KEY_A) {
-            buf = if buf == left_buf.ptr {
+            // flip which buffer we're writing to
-                right_buf.ptr
+            current_side = match current_side {
-            } else {
+                Side::Left => Side::Right,
-                left_buf.ptr
+                Side::Right => Side::Left,
+            };
+        }
+
+        let buf = match current_side {
+            Side::Left => left_buf.ptr,
+            Side::Right => right_buf.ptr,
         };
 
         unsafe {
             buf.copy_from(IMAGE.as_ptr(), IMAGE.len());
         }
-        }
 
         // Flush and swap framebuffers
         gfx.flush_buffers();

ctru-rs/src/gfx.rs

@@ -35,8 +35,17 @@ pub trait Screen: private::Sealed {
     /// Note that the pointer of the framebuffer returned by this function can
     /// change after each call to this function if double buffering is enabled.
     fn get_raw_framebuffer(&mut self) -> RawFrameBuffer {
-        let side = self.side();
+        let mut width = 0;
-        RawFrameBuffer::for_screen_side(self, side)
+        let mut height = 0;
+        let ptr = unsafe {
+            ctru_sys::gfxGetFramebuffer(self.as_raw(), self.side().into(), &mut width, &mut height)
+        };
+        RawFrameBuffer {
+            ptr,
+            width,
+            height,
+            screen: PhantomData,
+        }
     }
 
     /// Sets whether to use double buffering. Enabled by default.
@@ -58,7 +67,6 @@ pub trait Screen: private::Sealed {
     }
 }
 
-#[non_exhaustive]
 /// The top screen. Mutable access to this struct is required to write to the top
 /// screen's frame buffer. To enable 3D mode, it can be converted into a [`TopScreen3D`].
 pub struct TopScreen {
@@ -182,41 +190,19 @@ impl Gfx {
     }
 }
 
-impl<'screen> RawFrameBuffer<'screen> {
-    fn for_screen_side(screen: &'screen mut (impl Screen + ?Sized), side: Side) -> Self {
-        let mut width = 0;
-        let mut height = 0;
-        let ptr = unsafe {
-            ctru_sys::gfxGetFramebuffer(screen.as_raw(), side.into(), &mut width, &mut height)
-        };
-        Self {
-            ptr,
-            width,
-            height,
-            screen: PhantomData,
-        }
-    }
-}
-
 impl TopScreen3D<'_> {
-    /// Immutably borrow the left side of the screen.
+    /// Immutably borrow the two sides of the screen as `(left, right)`.
-    pub fn left(&self) -> Ref<dyn Screen> {
+    pub fn split(&self) -> (Ref<dyn Screen>, Ref<dyn Screen>) {
-        Ref::map(self.screen.borrow(), |screen| &screen.left)
+        Ref::map_split(self.screen.borrow(), |screen| {
-    }
+            (&screen.left as _, &screen.right as _)
-
+        })
-    /// Mutably borrow the left side of the screen.
-    pub fn left_mut(&self) -> RefMut<dyn Screen> {
-        RefMut::map(self.screen.borrow_mut(), |screen| &mut screen.left)
-    }
-
-    /// Immutably borrow the right side of the screen.
-    pub fn right(&self) -> Ref<dyn Screen> {
-        Ref::map(self.screen.borrow(), |screen| &screen.right)
     }
 
-    /// Mutably borrow the right side of the screen.
+    /// Mutably borrow the two sides of the screen as `(left, right)`.
-    pub fn right_mut(&self) -> RefMut<dyn Screen> {
+    pub fn split_mut(&self) -> (RefMut<dyn Screen>, RefMut<dyn Screen>) {
-        RefMut::map(self.screen.borrow_mut(), |screen| &mut screen.right)
+        RefMut::map_split(self.screen.borrow_mut(), |screen| {
+            (&mut screen.left as _, &mut screen.right as _)
+        })
     }
 }