Return Result from image::resize

crates/bevy_image/src/image.rs

@@ -851,14 +851,20 @@ impl Image {
 
     /// Resizes the image to the new size, by removing information or appending 0 to the `data`.
     /// Does not properly scale the contents of the image.
-    pub fn resize(&mut self, size: Extent3d) {
-        self.texture_descriptor.size = size;
+    /// This method returns an error when `self.data` is `None` indicating it
+    /// was not able to be resized.
+    pub fn resize(&mut self, size: Extent3d) -> Result<(), ResizeError> {
         if let Some(ref mut data) = self.data {
+            self.texture_descriptor.size = size;
             data.resize(
                 size.volume() * self.texture_descriptor.format.pixel_size(),
                 0,
             );
+
+            return Ok(());
         }
+
+        Err(ResizeError::ResizedWithoutData)
     }
 
     /// Changes the `size`, asserting that the total number of data elements (pixels) remains the
@@ -1505,6 +1511,14 @@ pub enum TextureAccessError {
     WrongDimension,
 }
 
+/// An error that occurs when an image cannot be resized.
+#[derive(Error, Debug)]
+pub enum ResizeError {
+    /// Failed to resize an Image because it has no data.
+    #[error("unable to resize an image without data")]
+    ResizedWithoutData,
+}
+
 /// An error that occurs when loading a texture.
 #[derive(Error, Debug)]
 pub enum TextureError {

crates/bevy_ui/src/widget/viewport.rs

@@ -173,7 +173,8 @@ pub fn update_viewport_render_target_size(
         };
         let image = images.get_mut(image_handle).unwrap();
         if image.data.is_some() {
-            image.resize(size);
+            // Safe to ignore the Result here, because we know image has data.
+            let _ = image.resize(size);
         } else {
             image.texture_descriptor.size = size;
         }

examples/2d/pixel_grid_snap.rs

@@ -108,7 +108,7 @@ fn setup_camera(mut commands: Commands, mut images: ResMut<Assets<Image>>) {
     };
 
     // Fill image.data with zeroes
-    canvas.resize(canvas_size);
+    canvas.resize(canvas_size).unwrap();
 
     let image_handle = images.add(canvas);
 

release-content/migration-guides/image-resize-returns-result.md

@@ -0,0 +1,9 @@
+---
+title: Image resizing now returns Result
+pull_requests: [19380]
+---
+`bevy_image::Image::resize` now returns a `Result<(), ResizeError>` to allow for an error to be returned when`image.data` is `None` indicating that the operation was a no-op due to the lack of data to resize.
+
+Before we were setting the `image.texture_descriptor.size` even if `image.data` was `None`. Now we only set this size if `image.data` exists.
+
+To migrate code from previous versions all calls of `Image::reize` will need to check the new `Result` return value of the method and handle it however makes sense for the surrounding context.