From 31955cc78bd3865fd7e69dd0a3794f18c1009c6a Mon Sep 17 00:00:00 2001
From: Alix Bott <bott.alix@gmail.com>
Date: Fri, 31 May 2024 01:57:22 +0200
Subject: [PATCH] Add ImageFormatSetting::Guess to image loader (#13575)
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# Objective

- Allow using image assets that don't have an extensions and whose
format is unknown. This is useful for loading images from arbitrary HTTP
URLs.

## Solution

- This PR adds a new variant to `ImageFormatSetting` called `Guess`. The
loader will use `image::guess_format` to deduce the format based on the
content of the file.

## Testing

- I locally removed the extension of bevy_bird_dark, and ran a modified
version of the `sprite` example:
```rust
//! Displays a single [`Sprite`], created from an image.

use bevy::{
    prelude::*,
    render::texture::{ImageFormatSetting, ImageLoaderSettings},
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Startup, setup)
        .run();
}

fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn(Camera2dBundle::default());
    commands.spawn(SpriteBundle {
        texture: asset_server
            .load_with_settings("branding/bevy_bird_dark", |s: &mut ImageLoaderSettings| {
                s.format = ImageFormatSetting::Guess
            }),
        ..default()
    });
}

```

## Changelog

### Added

`ImageFormatSetting::Guess` to automatically guess the format of an
image asset from its content.

Co-authored-by: François Mockers <mockersf@gmail.com>
---
 crates/bevy_render/src/texture/image.rs       | 20 +++++++++++++++++++
 .../bevy_render/src/texture/image_loader.rs   | 13 ++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/crates/bevy_render/src/texture/image.rs b/crates/bevy_render/src/texture/image.rs
index 4b0a46bd3a..e951ff83a8 100644
--- a/crates/bevy_render/src/texture/image.rs
+++ b/crates/bevy_render/src/texture/image.rs
@@ -109,6 +109,26 @@ impl ImageFormat {
             ImageFormat::Basis | ImageFormat::Ktx2 => return None,
         })
     }
+
+    pub fn from_image_crate_format(format: image::ImageFormat) -> Option<ImageFormat> {
+        Some(match format {
+            image::ImageFormat::Avif => ImageFormat::Avif,
+            image::ImageFormat::Bmp => ImageFormat::Bmp,
+            image::ImageFormat::Dds => ImageFormat::Dds,
+            image::ImageFormat::Farbfeld => ImageFormat::Farbfeld,
+            image::ImageFormat::Gif => ImageFormat::Gif,
+            image::ImageFormat::OpenExr => ImageFormat::OpenExr,
+            image::ImageFormat::Hdr => ImageFormat::Hdr,
+            image::ImageFormat::Ico => ImageFormat::Ico,
+            image::ImageFormat::Jpeg => ImageFormat::Jpeg,
+            image::ImageFormat::Png => ImageFormat::Png,
+            image::ImageFormat::Pnm => ImageFormat::Pnm,
+            image::ImageFormat::Tga => ImageFormat::Tga,
+            image::ImageFormat::Tiff => ImageFormat::Tiff,
+            image::ImageFormat::WebP => ImageFormat::WebP,
+            _ => return None,
+        })
+    }
 }
 
 #[derive(Asset, Reflect, Debug, Clone)]
diff --git a/crates/bevy_render/src/texture/image_loader.rs b/crates/bevy_render/src/texture/image_loader.rs
index 6bd906c1d0..3f5f4e3124 100644
--- a/crates/bevy_render/src/texture/image_loader.rs
+++ b/crates/bevy_render/src/texture/image_loader.rs
@@ -51,6 +51,7 @@ pub enum ImageFormatSetting {
     #[default]
     FromExtension,
     Format(ImageFormat),
+    Guess,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -100,6 +101,18 @@ impl AssetLoader for ImageLoader {
                 ImageType::Extension(ext)
             }
             ImageFormatSetting::Format(format) => ImageType::Format(format),
+            ImageFormatSetting::Guess => {
+                let format = image::guess_format(&bytes).map_err(|err| FileTextureError {
+                    error: err.into(),
+                    path: format!("{}", load_context.path().display()),
+                })?;
+                ImageType::Format(ImageFormat::from_image_crate_format(format).ok_or_else(
+                    || FileTextureError {
+                        error: TextureError::UnsupportedTextureFormat(format!("{format:?}")),
+                        path: format!("{}", load_context.path().display()),
+                    },
+                )?)
+            }
         };
         Ok(Image::from_buffer(
             #[cfg(all(debug_assertions, feature = "dds"))]